ELE HORT 355 Protected Cultivation of Horticultural Crops PDF

ELE HORT 355 PROTECTED CULTIVATION OF HORTICULTURAL CROPS LECTURE OUTLINE S. No. Title of the Lecture Page No. 1 Protected cultivation – Importance and scope, status 3 of protected cultivation in India 2 Greenhouse/ polyhouse designs, different types of 6 protected structures based on soil 3 Different types of Cladding material involved in Green 9 house/ polyhouse 4 Greenhouse design 11 5 Environmental control in polyhouses 12 6 Artificial lights, Automation in polyhouses 15 7 Types of Growing media, Soil preparation and 17 substrate management in polyhouses for growing crops 8 Types of benches and containers used in polyhouses 19 9 Irrigation and Fertigation management 21 10 Use of polyhouses for Propagation and production of 24 quality planting material 11 Greenhouse cultivation of Rose, Soil, Climate, 27 Varieties, Propagation and intercultural operations 12 Rose, harvesting, Post harvest management, Pest and 30 Diseases 13 Greenhouse cultivation of Carnation, Soil, Climate, 32 Varieties, Propagation and intercultural operations 14 Carnation, harvesting, Post harvest management, 34 Pests and Diseases 15 Greenhouse cultivation of Chrysanthemum, Soil, 36 Climate, Varieties, Propagation and intercultural operations 16 Chrysanthemum, harvesting, Post harvest 38 management, Pests and Diseases 17 Greenhouse cultivation of pot plants Gerberas 40 18 Greenhouse cultivation of Orchids, Soil, Climate, 43 Varieties, Propagation and intercultural operations 19 Orchids, harvesting, Post harvest management, Pests 45 and Diseases 20 Greenhouse cultivation of Anthurium 46 21 Greenhouse cultivation of Lillium 49 22 Greenhouse cultivation of Tulip 51 23 Greenhouse cultivation of Tomato, Soil, Climate, 53 Varieties, Propagation and intercultural operations 24 Tomato, harvesting, Post harvest management, Pests 56 and Diseases 25 Greenhouse cultivation of Bell pepper 57 26 Greenhouse cultivation of Cucumber 60 27 Greenhouse Cultivation of Strawberry 63 28 Greenhouse cultivation of Pot plants and containers 65 29 Off-season production of flowers 66 1 30 Off-season production of vegetables 68 31 Polyhouse cultivation of economically important 70 medicinal plants like stevia, etc 32 Polyhouse cultivation of economically important 72 aromatic plants like Davanam, etc 2 Lecture 1 : Protected cultivation – Importance and scope, status of protected cultivation In India and World After the advent of green revolution, more emphasis is laid on the quality of the agricultural product along with the quality of production to meet the ever-growing food and nutritional requirements. Both these demands can be met when the environment for the plant growth is suitably controlled. The need to protect the crops against unfavourable conditions led to the development of protected agriculture. Greenhouse is the most practical method of achieving the objectives of protected agriculture, where natural environment is modified by using sound engineering principles to achieve optimum plant growth and yield. Poly house cultivation has become an important policy of Indian Agriculture. Protected cultivation practices can be defined as a cropping technique wherein the micro climate surrounding the plant body is controlled partially or fully as per the requirement of the vegetable / flower species grown during their period of growth. With the advancement in agriculture various types of protected cultivation practices suitable for a specific type of agro- climatic zone have emerged. Among these protective cultivation practices, Green house, Plastic house, Cloth house, Net house and shade house etc is useful for the Telangana State. A greenhouse is a framed or inflated structure covered with a transparent or translucent material in which crops could be grown under the condition of at least partially controlled environment and which is large enough to permit a person to work within it to carry out cultural operations. Greenhouses are the most common types of structures used for production of ornamental and vegetable crops under controlled conditions. These structures provide the potential to control all environmental parameters, although to varying degrees depending upon the design of the structure and its components. Importance of Greenhouses (or) Specific Benefits of Greenhouses : 1. Crop is protected from cold, wind, storm, rain and frost. 2. Due to controlled conditions there is better germination, plant growth and crops mature faster. 3. Improved quality and quantity of produce with long shelf life. 4. Use of water is optimized and there is reduction in its consumption by 40 – 50 %. 5. Effective utilization of inputs. 6. Incidence of disease and pests is reduced or eliminated. 7. Crops can be grown throughout the year. 8. Best technology for commercial production of high value crops like flowers, medicinal plants, etc. 9. Can be used for solar drying of farm produce. 10. Involvement of labour force can be reduced. 11. Crop cultivation under inclement climatic conditions. 12. Certain crops cultivated year round to meet the market demands. 13. High value and high quality, even organic, crops grown for export markets. 14. Income from small land holdings increased several fold. 15. Successful nurseries from seeds or by vegetative propagation prepared as and when necessary. 3 16. More Self-employment opportunities for educated youth on farm. 17. Manipulation of microclimate and insect proof feature of the greenhouse for plant breeding and, thus, the evolution of new varieties and production of seeds. Scope of Greenhouse in India : The scope in Indian horticulture is tremendous. If popularly organized, the promising fields having wide scope for protected cultivation in India are 1. Cultivation in problematic agro climate : In India majority of uncultivated area is under problematic conditions such as barren, uncultivable fallow lands and deserts. Even a fraction of this area bought under greenhouse cultivation could produce substantial returns for the local inhabitants. 2. Greenhouses around big cities : The substantial demand persists for fresh vegetables and ornamentals around the year in big cities. Demand for off season and high value crops also exists in big cities. Therefore greenhouse cultivation can be promoted to meet the urban requirements. 3. Export of horticultural produce : There is a good international demand for horticultural produce, mainly the cut flowers. Promotion of greenhouse cultivation of export oriented crops will be of definite help towards export promotion. Ex. Cultivation of Gherkins in greenhouses around Hyderabad are exported to different countries. 4. Greenhouses for plant propagation : GH technology is being now a days considered as suitable approach for raising of seedlings and cuttings which require control environment for their growth. GH facility could increase the capacity of producing the plant material. 5. Greenhouse technology for biotechnology : Material generated through tissue culture are need to be propagated in control environment. The hydroponics or Nutrient Film Technique (NFT) are also required controlled environmental conditions for growing plants. 6. Greenhouse for cultivation of rare and medicinal plants : India has wide variety of medicinal herbs and rare plants like orchids which have been identified for large scale cultivation. The greenhouse could provide the right type of environmental conditions for the intensive cultivation of these plants. Status of protected cultivation In World : Greenhouse crop production is now a growing reality throughout the world with an estimated 405,000 ha of greenhouses spread over all the continents. There are more than 55 countries now in the world where cultivation of crops is undertaken on a commercial scale under cover, and it is continuously growing at a fast rate internationally. In India, protected cultivation technology for commercial production is hardly three decades old (DRDO). In developed countries viz. Japan, Holland, Russia, UK, China and others, it is about two century old. China started protected cultivation in 1990’s and today the area under protected cultivation in China is more than 2.5 m ha and 90 percent area is under vegetables. Israel is one country which has taken big advantage of this technology by producing quality fruits, vegetables, flowers, etc in water deficit area. Several thousand acres are now under glass in the United States and equally large area in England and Holland, where horticulture under glass was practiced over a century ago. 4 Status of protected cultivation In India : India’s first exposure to truly hi-tech protected farming of vegetables and other high-value horticultural produce came through the Indo-Israel project on greenhouse cultivation, initiated at the New Delhi-based Indian Agricultural Research Institute (IARI) in 1998, shortly after the establishment of diplomatic ties with that country. However, the Israleli experts left India in 2003 at the end of this five-year project, IARI continued to maintain the facility, calling it the Centre for Protected Cultivation Technology (CPCT). It has, in the past 10 years, managed to refine and upscale the system to reduce costs, besides designing greenhouse structures to suit local conditions. The area under greenhouse cultivation, reported by the end of 20th century was about 110 ha in India and world over 275,000 hectare. During last decade this area must have increased by 10 percent if not more. The states that have consistently expanded the area under protected cultivation for the period of 2007-2012 are Andhra Pradesh, Gujrat, Maharashtra, Haryana, Punjab, Tamil Nadu and West Bengal. Maharashtra and Gujrat had a cumulative area of 5,730.23 hectares and 4,720.72 hectares respectively under the protected cultivation till 2012. Status of protected cultivation in Telangana : At present (March 2018) There are about 1150 acres (917 farmers) of vegetables and flowers produced in Telangana under polyhouses. The major crops of tomato, cucumber, capsicum, gerbera, chrysanthemum, roses, accounted for 31 % of the total statewide vegetable and flower crop value. Currently, almost one-sixth of Telangana vegetables are produced on polythene mulch. Nearly 90 % of the polyethylene mulched crops are grown with drip irrigation. 5 Lecture 2 : Greenhouse / polyhouse designs, different types of protected structures on soil and climate Greenhouse type based on Shape : 1. Lean-to Type Greenhouse : A lean-to design is used when the greenhouse is placed against the side of an existing building. This design makes the best use of sunlight and minimizes the requirement of roof supports. The roof of the building is extended with appropriate greenhouse covering material and the area is properly enclosed. 2. Even Span Type Greenhouse : In this type, the two roof slopes are of equal pitch and width. This design is used for the greenhouse of small size, and it is constructed on levelled ground. Several single and multiple span types are available for use in various regions of India. For single span type, the sp- in general varies from 5 to 9 m, whereas the length is around 24 m. The height varies from 2.5 to 4.3 m. 3. Saw Tooth Type Greenhouse : These are also similar to the ridge and furrow type greenhouses except that, there is provision for natural ventilation. In this type, specific natural ventilation flow path develops in a saw tooth type greenhouse. 4. Quonset Greenhouse : In Quonset greenhouse, the pipe arches or trusses are supported by pipe purlins running along the length of the greenhouse. In general, the covering material used fQr this type of greenhouses is polyethylene. Such greenhouses are typically less expensive than the gutter connected greenhouses and are useful when a small isolated cultural area is required. These houses are connected either in free standing style or arranged in an interlocking ridge and furrow. Greenhouse Type Based on Utility : Classification of greenhouses can also be made depending on the functions or utilities. Of the different utilities, artificial cooling and heating of the greenhouse are more expensive and elaborate. Hence based on the artificial cooling and heating, greenhouses are classified as that uses active heating system and active cooling system. 1. Greenhouses for Active Heating : During the night time, the air temperature inside greenhouse decreases and to avoid the cold bite to plants due to freezing, some amount of heat has to be supplied. The requirements for heating greenhouse depend on the rate at which the heat is lost to the outside environment. Various methods are adopted to reduce the heat losses, namely, using double layer polyethylene, thermopane glasses (two layers of factory sealed glass with dead air space) or to use heating systems, such as unit heaters, central heat, radiant heat and solar heating system. 2. Greenhouses for Active Cooling : During summer season, it is desirable to reduce the temperatures of greenhouse than the ambient temperature, for effective crop growth. Hence suitable modifications are made so that large volumes of cooled air are drawn into fog cooling. This greenhouse is designed in such a way that it permits a roof opening of 40 % and in some cases nearly 100 %. 6 Greenhouse Type Based on Construction : Based on construction, greenhouses can be Broadly classified as wooden framed, pipe framed and truss framed structures. 1. Wooden Framed Structures : In general, for greenhouses with span less than 6 m, only wooden framed structures are used. Side posts and columns are constructed of wood without the use of a truss. Pine wood is commonly used as it is inexpensive and possesses the required strength. Timber locally available, with good strength, durability and machinability also can be used for the construction. 2. Pipe Framed Structures : When the clear span is around 12 m, pipes are used for the construction of greenhouses. In general, the side posts, columns, cross-ties and purlins are constructed using pipes. Trusses are not used also in this type of greenhouse. The pipe components are not interconnected but depend on the attachment to the sash bars for support. 3. Truss Framed Structures : If the greenhouse span is greater than or equal to 15 m, truss frames are used. Flat steel, tubular steel or angle iron is welded together to form a truss encompassing rafters, chords and sturts. Sturts are support members under compression and chords are support members under tension. Angle iron purlins running throughout the length of greenhouse are bolted to each truss. Columns are used only in very wide truss frame houses of 21.3 m or more. Most frames are best suited for pre-fabrication. Different types of protected structures based on soil and climate : Poly house The crops grown in open field are exposed to vivid environmental conditions, attack of insects and pests, whereas the polyhouse provides a more stable environment. Polyhouse can be divided into two types. a) Naturally ventilated polyhouse These polyhouse do not have any environmental control system except for the provision of adequate ventilation and fogger system to prevent basically the damage from weather aberrations and other natural agents. b) Environmental controlled polyhouse This type of polyhouse helps to extend the growing season or permits off-season production by way of controlling light, temperature, humidity, carbon-dioxide level and nature of root medium. Shade House : Shade houses are used for the production of plants is warm climates or during summer months. Nurserymen use these structures for the growth of hydrangeas and azaleas during the summer months. Apart from nursey, flowers and foliage which require shade can also be grown in shade houses. E.g. Orchids, These shade structures make excellent holding areas for field- grown stock while it is being prepared for shipping to retail outlets. Shade houses are most often constructed as a pole-supported structure and covered with either lath (lathhouses) or polypropylene shade fabric. 7 Net House : Net houses are widely used as propagation structures in tropical areas, where artificial heating is not required and artificial cooling is expensive. In these areas, net houses may be constructed with roofs covered with glass or plastic film and its sides are covered with wire net. It provides necessary ventilation and maintains an ideal temperature for germination of seeds and subsequent growth of the seedlings. The roof of net house may be covered with gunny cloth or even with live plant creeper to cut off the solar radiant energy and to keep the house cool. Polypropylene shade nets with various percentages of ventilations are used. Black, green, and white coloured nets are used, while black colours are the most preferred as it retains heat outside. Growing rooms : A growing room is an insulated building from which natural light is usually excluded. In it, illumination is provided by artificial means. Growing rooms are now widely used commercially for the production of seedlings of bedding plants, tomatoes and cucumbers in most advanced countries. The seedlings are usually grown in trays or pots kept on benches. The automatic greenhouse : Today, the modern greenhouses can be almost completely automated thus assisting propagation. For instance, by the use of thermostat, air and bed temperature can be maintained as per the requirement. Similarly, automatic ventilation allows the ventilators to open and close in relation to temperature. Even, automatic systems of irrigation are installed in the modern greenhouses and water is supplied to the plants through drip or trickle system to each pot or plant by individual nozzle of time switch. 8 Lecture 3 : Different types of Cladding material involved in Green house/polyhouse Cladding material : transparent material mounted on the walls and roof of a green house. Rigid cladding material : cladding material with such a degree of rigidity that any deformation of the structure may result in damage to it. Ex. Glass. Flexible cladding material : cladding material with such a degree of flexibility that any deformation of the structure will not result in damage to it. Ex. Plastic film. Properties of ideal greenhouse covering material : 1. It should transmit the visible light portion of the solar radiation, which is utilized by plants for photosynthesis. 2. It should absorb the small of UV in the radiation and convert a portion of it into visible light useful for plants. 3. It should reflect or absorb IR radiation which are not useful to plants and causes greenhouse interiors to overheat. 4. It should be low cost. 5. It should have usable life of 10 to 20 years. Covering material : they are of glass, fiberglass, or plastic. Each type has its advantages and disadvantages. a. Glass – 90 % light transmission b. Fiberglass – 90-95 % light transmission c. Polyethylene – 65-75 % light transmission d. Vinyl – 90 % light transmission A) Glass : Glass type greenhouses are the most traditional covering used. They may be constructed with slanted sides, straight and caves. Aluminium, glass buildings provide low maintenance and have aesthetic lines, as well as ensuring that you get a weather- tight structure. Pre-fabricated glass kits are available for easy installation by amateur gardeners. The disadvantages of glass are its fragile condition (glass break easily) and high costs. B) Fiberglass : Fiberglass greenhouses – they are light, strong and hail-proof. Be careful, though low quality fiberglass will discolour, thus reducing penetration of light. Using a good quality fiberglass will however make it as expensive as building a glass one. C) Plastic : Plastic greenhouses are becoming very popular for the following reasons : i. Low cost (about 1/6 the cost of glass) ii. Absorbs sufficient heat iii. Low cost (about 1/6 the cost of glass) iv. Fruits and vegetables and other plants under plastic are comparable in quality to that of glass-grown varieties. v. Choice of polyethylene (PE), polyvinyl chloride (PVC), copolymers of these materials, and other readily available clear films. 9 1. Polyethylene : Commonly used plastic for greenhouse covering is thermoplastic. The basic characteristic is they soften on heating and hardens with cooling and the process is reversible. They are stiff, robust, resilience to resist loads and deformations. Polyethylene used for covering year round production have UV inhibitor in it otherwise last only one heating season. Standard length 30.5, 33.5, 45.7, 61.0 and 67.0 m. A polyethylene covering is colder than air inside greenhouse in winter due to which when warm air inside come in contact no time the water falls as beads over the plant. The wet foliage causes diseases and also the constantly wetted soil becomes waterlogged and oxygen deficient. With the water dripping problem, condensation also reduces light intensity within greenhouse usage of antifog surfactant is recommended. 2. Polyvinyl chloride film : UV resistant vinyl films of 0.2 and 0.3 mm thickness are guaranteed for 4-5 years respectively. This extended life of polyvinyl film is advantageous as compared to polyethylene which has only 1 or 2 years. But the advent of 4 year polyethylene the advantage of vinyl film has gone. The cost of 0.3 mm vinyl is 3 times that of 0.15 mm polyethylene. The vinyl films tend to hold a static electric charge due to which it attracts and holds the dust that reduces the light transmittance unless the dust is washed away. In Japan 95 % greenhouses are under plastic and within the group 90 % are covered of vinyl film. 3. Polyester film : Polyesters offers long life and are strong. Films of 0.13 mm thickness are used for roofs will last for 4 years, while 0.08 mm films are used on vertical wall have life expectancy of seven years. Although polyester having the higher cost as compared to polyethylene it offers the extra life expectancy. The advantage include light transmittance equal to that for glass. Polyester is still frequently used in heat retention screens because its high capacity to block radiant energy. 4. Tefzel T2 film (Ethylene tetra fluoro ethylene) : It is the recent addition of plastic covering. This film was earlier used for transparent covering on solar collector. The life expectancy is 20 years or more. The light transmission is 95 % and is greater than that of any other covering material. Double layer will have about 90 % transmittance. It is more transparent to IR radiation so that less heat is trapped inside due to which the cost of cooling will be reduced. Disadvantage of Tefzel film is availability only in 1.27 m wide rolls which requires clamping rails on every 1.2 m. 5. Fiberglass reinforced plastic rigid panel : Most popular material in past. Life period varies with grade. Some grades give 5-10 years while better grades can last up to 20 years. Corrugated panels are used because of greater strength. Flat panels are used for side wall where load is not greater. Available width 1.3 m and length up to 7.3 m. Panels are flexible enough to conform to shape of Quonset greenhouse. Resistant to breakage by hails or Vandels. 6. Acrylic and polycarbonate rigid panel : Acrylic and polycarbonate films have been available for use since 15 years. The panels used for glazing the side walls and end walls of film plastic greenhouses and for retrofitting old greenhouses. Acrylic greenhouses are highly inflammable. Acrylic panels are popular due to high light transmission and longer life. Polycarbonate panels are for commercial greenhouses due to low price, flame resistance and resistance to hail damage. Available with coating to prevent condensation and also an acrylic coating for protection from UV light. 10 Lecture 4 : Greenhouse design Structural Design Many types of greenhouse structures are successfully employed in protected agriculture, and each type has its own advantages and is well suited for a particular case. The different structural designs of greenhouse based on the types of farmers are available. A straight side wall and an arched roof (Fig. a) is possibly the most common shape for a greenhouse, but the gable roof (Fig. b) is also widely used. Both structures can be free standing or gutter connected with the arch roof greenhouse. The arch roof and hoop style (Fig. c) greenhouses are most often constructed of galvanized iron pipe bent into form by a roller pipe bender. If tall growing crops are to be grown in a greenhouse or when benches are used, it is best to use a straight side wall structure (Fig. d) rather than a hoop style house, this ensures the best operational use of the greenhouse. A hoop type greenhouse is suitable for low growing crops, such as lettuce, or for nursery stock that are bound throughout the winter in greenhouses located in extremely cold regions. A Gothic arch frame structure to the structure. This form of structure, along with others, can be used as a single free standing greenhouse or as a large range of multi-span, gutter connected units. The greenhouses are to be designed for necessary safety, serviceability, general structural integrity and suitability. The structure should be able to take all the necessary dead, live, wind and snow loads. The foundation, columns and trusses are to be designed accordingly. The greenhouse structures are to be designed to take up the loads as per design loads prescribed by the National Greenhouse Manufactures Association (NGMA of USA) standards – 1994. The structure has to carry the following loads and is to be designed accordingly. a) Dead load : Weight of all permanent construction, cladding, heating and cooling equipment, water pipes and all fixed service equipments to the frame. b) Live load : Weights superimposed by use (include hanging baskets, shelves and persons working on roof). The greenhouse has to be designed for a maximum of 15 kg per square meter live load. Each member of roof should be capable of supporting 45 kg of concentrated load when applied at its centre. c) Wind load : The structure should be able to withstand winds of 130 kilometer per hour and at least 50 kg per square meter of wind pressure. d) Snow load : These are to be taken as per the average snowfall of the location. The greenhouse should be able to take dead load plus live load or dead load plus wind load plus half the live load. The ultimate design of a greenhouse consists of a balance of the following aspects : 1. Overall structural design and the properties of the individual structural components. 2. Specific mechanical and physical properties, which determine the structural behaviour of the covering materials. 3. Specific sensitivity of the crop to light and temperature to be grown in the greenhouse. 4. Specific requirements relevant to the physical properties of the covering material. 5. Agronomic requirements of the crop. 11 Lecture 5 : Environmental control in polyhouses Control of greenhouse environment means control of temperature, light, air composition and nature of root media. Precise control of different parameters of greenhouse environment results in better timing of crops, higher quality crops, disease control to maximize economic returns and conservation of energy that optimizes energy inputs. A. Temperature control : The thermostat can be coupled to water circulating pump or exhaust fan for controlling the temperature inside the greenhouse. Bimetallic strip (differential expansion) or thin metal tube filled with liquid or gas (movement of tube due to change in volume of a gas or liquid) acts as sensors and cultivation a mechanical switch. 1. Ventilation a) Natural Convection : A temperature difference is set between greenhouse temperature and ambient temperature and causes natural movement of air through roof vent provided in the roof. b) Forced Convection : If the rate of heating of room temperature becomes higher than the rate of heat removal through roof vents then heat removal is possible only through forced convection in which fan is provided in greenhouse. The rate of heat removal depends on capacity of fan and its rpm. 2. Evaporative Cooling System Developed to reduce the problem of excess heat inside the greenhouse. a) Fan and Pad Cooling System : Most common summer cooling system in greenhouses. A pad composed of excelsior (wood shreds) or cellulose material is placed vertically along one side of the greenhouse and exhaust fan an opposite side. Warm outside air is drawn in through the pad. Supplied water in the pad by the process of evaporation absorbs heat from the greenhouse and produces cooling effect. Khus-Khus grass mats can also be used as cooling pads. b) Fog Cooling : Fog or sprinklers can be used to cool green houses and maintain humidity but it is costlier than pad fan cooling. A high-pressure pumping apparatus generates fog containing water droplets with a mean size of less than 10 microns using suitable nozzles. These droplets are sufficiently small to stay suspended in air while they are evaporating and utilize the heat of greenhouse air. Fog is dispersed throughout the greenhouse, cooling the air everywhere. As the system does not wet foliage there is less scope of disease and pest attack. Both types of summer cooling systems can reduce the greenhouse air temperature well below outside temperature. The fan and pad cooling system completer evaporation not taking place but fog system will have complete evaporation because of minute size water droplets. A maximum night temperature of 13 to 15.5˚ C and a day temperature of 24˚ C are generally set to start the heaters and fans; respectively. B. Relative Humidity control : Humidistat coupled to water circulating pump or exhaust fan control the RH inside the fan and pad greenhouse. With the evaporative pad cooling system lowering the dry bulb temperature will generally rise the RH by 70-80 %. This is usually sufficient for crops such as carnation and chrysanthemum. The RH in Non-ventilated (NV) Greenhouse can be increased by providing foggers. 12 C. Light Intensity control : In certain areas where natural illumination is absent or very low, illumination for plants may be provided by artificial sources. Incandescent bulbs generate excessive heat and are unsatisfactory in most instances. Fluorescent tubes are useful as the sole source of light for African violets, gloxinias and many foliage plants which grow satisfactorily at low light intensities. Excessive light intensity destroys chlorophyll even though the synthesis of this green pigment in many plants is dependent upon light. D. CO2 control : The present, more sophisticated CO2 generator control systems are based on CO2 sensors. These sensors continually monitor the CO2 level in the greenhouse and a single sensor can be connected to the several greenhouses by sampling tubes and air samples drawn by a pump. The signal from the sensor is used to control the CO 2 generator so that a constant CO2 level can be maintained. Information from the single sensor with multiple sampling tubes is received by a computer, which in turn controls CO 2 generators in each greenhouse. E. Controlling Light in Greenhouses : 1. Light Quality : In commercial greenhouse production, light quality is important when selecting a light source for supplemental photosynthetic lighting or photoperiod control. A broad emission spectrum within the 400 to 700 nm range is desirable especially when adding light to increase photosynthetic rate. Light sources being used to extend day length and create artificially long days must provide sufficient light in the red range in order to affect the phytochrome photoreceptor. Reducing the far-red light and increasing the blue light experienced by the plant results in shorter, darker-colored and stronger plant. Light quality can also affect the development of certain foliar diseases such as Botrytis, Greenhouse glazings have been developed with additives or pigments that filter certain wavelengths of light and allow for a shift in the relative ratios of wavelengths of light entering the greenhouse. 2. Light Quantity : The Light Level might need to be increased or decreased to maintain optimal levels. Different plant species have different optimal light levels. However, for a given species, plant spacing, nutritional level and plant age can affect light level. For example, the optimal light level for a tomato seedling is lower than that for a well established and actively growing tomato. A range of 32.2 to 86.1 klux is required by crops like cucurbits, capsicum, brinjal and sweet potato, while cabbage and potato require 21.5 to 86.1 klux. Recommended Light Levels for Selected Plants in moles/m2/sec African violet 150 – 250 Foliage plants 150 – 250 Carnation, Chrysanthemum, Geranium, 250 – 450 Cucumber, Lettuce and Strawberry Roses and Tomato 450 – 750 Greenhouse shading methods : Two methods are commonly used to reduce light levels in greenhouses. The first is the application of a shading compound to the glazing. Retractable shade systems are being installed in many new greenhouses. These systems are placed in the gables of the greenhouse and are controlled by a computer that is in turn connected to a photometer (Light Meter). A desired light level can be programmed into a computer and the shade automatically pulled when light levels exceed the desired level. The shade will automatically be retracted when light levels fall below the desired level. 13 Stages of evolution of environmental control systems : Stages of evolution of environmental systems are manual controls, thermostats, step controllers microprocessor and computers. 1. Analog Control : In this system proportioning thermostats or electric sensors are used to gather temperature information. Analog controls are costlier than thermostats, but offer better performance. 2. Computerized environment control : The amplifiers and logic circuit analogs have now been replaced by computerized environmental system, which involves mircroprocessors, which gathers information on a variety of sensor like temperature, humidity, light intensity, wind directions controls offer significant energy and labour saving and increases production efficiency in propagation. The deviations from the present levels of temperature and humidity can trigger alarms by the computer. 14 Lecture 6 : Artificial lights, Automation in polyhouses Various methods of Supplemental Lighting in Greenhouses : Before selecting a light source for greenhouse lighting, numerous factors should be considered. Among these are the 1. Total energy emitted by the lamp. 2. Efficiency (% of electrical energy converted to light energy). 3. Wavelength emitted (especially in the 400 to 700 nm wavelengths). 4. Cost, life expectancy (of bulbs and fixtures), and the fixtures required (including ballasts). Supplemental lighting during daylight hours to enhance photosynthesis is proved to be highly effective. Such lighting is more profitable in High Density Plantings, such as rooting and seedling beds and the production of young plants. Many types of lamps have been used in the greenhouse. Basically they fall into 3 groups 1. Incandescent lamps (tungsten-filament) :- These lamps are generally not used for supplemental lighting in greenhouses for photosynthetic purposes. A large portion of the radiation given off these lamps is in the form of infrared (heat). Because of this, their efficiency rating is only 7 %. Lamps range from 40 to 500 watts. Life span ranges from 750 to 1000 hours. In order to produce enough light for effective photosynthetic lighting, a large numbers of these lights would be required. This would require a large number of fixtures and would result in large amounts of heat being produced. Further, most of the visible radiation that these lamps produce is in the red and far-red wavelengths that cause plants to become tall and to have weak stems. However, because relatively low light levels are required for photoperiodic lighting, incandescent plants are suitable and commonly used for this purpose. 2. Fluorescent lamps :- These lamps are most commonly used in growth chambers and seed germination rooms. They are rarely used to produce crops in greenhouses. As with benefits the crop. These fixtures cost money, require additional wiring and block natural sunlight. Fluorescent lamps are more efficient than incandescent lamps (20 % efficiency) and provide their light over a broader spectrum (more in the blue region) than incandescent lamps. 3. High Intensity Discharge (HID) Lamps :- Now a days, the HID lamps are preferred types for the final stages of the crop growth in the greenhouse. These are the most commonly used lamps for supplemental lighting in greenhouses. As with fluorescent lamps, these lamps require ballasts that can be very heavy and generate significant amounts of heat. Reflectors are used to direct the light generated downward and to improve uniformity of light distribution. Numerous types off bulbs are available for use in HID lamps such as high pressure mercury, metal halide, low pressure sodium and high pressure mercury. The most commonly used HID system at present utilizes high pressure sodium lamps. a) High-pressure mercury bulbs : have emission spectrum similar to fluorescent lamps but with a greater concentration of their radiation being emitted in the red region. Light energy is produced by these lamps using a two-step process. First the filament gives off UV light. This UV radiation excites a phosphor powder in the tube. This powder fluoresces and gives off visible light. Because of this two-step process, 15 these lamps have an efficiency of only 13 % and have a lifespan of about 10,000 hours. b) High-pressure metal halide bulbs : are the most common type of bulb used for supplemental lighting in greenhouses. They have a broader emission spectrum than low-pressure sodium bulbs and are cheaper than mercury bulbs. These bulbs have efficiency of 25 % and a lifespan of 24,000 hours. Supplemental lighting is used for most crops but is particularly popular with Chrysanthemum and geranium stock plants, rose and plug seedlings. Light intensities of 3.2 to 6.5 klux at plant height are generally used for seedlings and ornamental plants, with 4.3 klux being the most common level. Intensities of 6.5 to 10.8 klux are used for vegetable crops. 16 Lecture 7 : Types of Growing media, Soil preparation and substrate management in polyhouses for growing crops Soil mixes used for greenhouse production of potted plants and cut flowers are highly modified mixtures of soil, organic and inorganic materials. When top soil is included as a portion of the mixture, it is generally combined with other materials to improve the water holding capacity and aeration of the potting soil. Many greenhouses do not use topsoil as an additive to the soil mixes, but rather use a combination of these organic and inorganic components as an artificial soil mix. When managed properly as to watering and fertilization practices, these artificial mixes grow crops that are equal to those grown in top soil. Media preparation for greenhouse production The media used in greenhouse generally have physical and chemical properties which are distinct from field soils. A desirable medium should be a good balance between physical properties like water holding capacity and porosity. The medium should be well drained. Medium which is too compact creates problems of drainage and aeration which will lead to poor root growth and may harbour disease causing organisms. Highly porous medium will have low water and nutrient holding capacity, affects the plant growth and development. The media reaction (pH of 5.0 to 7.0 and the soluble salt EC level of 0.4 to 1.4 dS/m is optimum for most of the greenhouse crops). A low media pH (7.5) causes deficiency of micronutrients including boron. A low pH of the growth media can be raised to a desired level by using amendments like lime (calcium carbonate) and dolomite (Ca-Mg carbonate) and basic, fertilizers like calcium nitrate, calcium cynamide, sodium nitrate and potassium nitrate. A high pH of the media can be reduced by amendments like sulphur, gypsum and Epsom salts, acidic fertilizers like urea, ammonium sulphate, ammonium nitrate, mono ammonium phosphate and aqua ammonia and acids like phosphoric and sulphuric acids. It is essential to maintain a temperature of the plug mix between 70 to 75˚ F. Irrigation through mist is a must in plug growing. Misting for 12 seconds every 12 minutes on cloudy days and 12 seconds every 6 minutes on sunny days is desirable. The pH of water and mix should be monitored regularly. Gravel culture : Gravel culture is a general term which applies to the growing of plants with out soil in an inert medium into which nutrient solutions are usually pumped automatically at regular intervals. Haydite (shale and clay fused as high temperatures), soft – or hard-coal cinders, limestone chips, calcareous gravel, silica gravel, crushed granite and other inert and slowly decomposing materials are included in the term “gravel”. The more important greenhouse flowering crops include roses, carnations, chrysanthemums, gardenias, snapdragons, lilies, asters, pansies, annual chrysanthemum, dahlias, bachelor buttons and others. 17 Desirable nutrient level in greenhouse growth media : Sr. Category Concentration (mg/l) No. NO3 N P K 1 Transplants 75 125 10-15 250-300 2 Young pot and foliage plants 50 90 6-10 150-200 3 Plants in beds 125 225 10-15 200-300 Media ingredients and Mix Commercially available materials like peat, sphagnum moss, vermiculite, perlite and locally available materials like sand, red soil, common manure/ compost and rice husk can be used in different proportions to grow greenhouse crops. These ingredients should be high quality to prepare a good mix. They should be free from undesirable toxic elements like nickel, chromium, cadmium, lead, etc. Pasteurization of greenhouse plant growing media Greenhouse growing medium may contain harmful disease causing organisms, nematodes, insects and weed seeds, so it should be decontaminated by heat treatment or by treating with volatile chemicals like methyl bromide, chloropicrin, etc. Agent Method Recommendation Heat Steam 30 min at 180˚ F Methyl bromide 10 ml/cu. ft. of medium Cover with gas proof cover for 24-48 hr. Aerate for 24-28 hr before use. Chloropicrin (Tear gas) 3-5 ml/cu. ft. of Cover for 1-3 days with gas proof cover after medium sprinkling with water. Aerate for 14 days or until no odour is detected before using. Basamid 8.0 g/cu. ft. of medium Cover for 7days with gas proof cover and aerate for atleast a week before use. Formalin 20 ml/l of water (37 %) Apply 2 l/cu. ft. cover for 14 to 36 hr and aerate for at least 14 days. Fumigation in greenhouse : Physical propagation facilities such as the propagation room, containers, flats, knives, working surface, benches, etc. can be disinfected using one part of formalin in fifty parts of water or one part sodium hypochlorite in nine parts of water. An insecticide such as dichlorvos sprayed regularly will take care of the insects present if any. Care should be taken to disinfect the seed or the planting materials before they are moved into the greenhouse with a recommended seed treatment chemical for seeds and a fungicide – insecticide combination for cuttings and plugs respectively. Disinfectant solution such as trisodium phosphate or potassium permanganate placed at the entry of the greenhouse would help to get rid off the pathogens from the personnel entering the greenhouses. 18 Lecture 8 : Types of benches and containers used in polyhouses Benching : If you intend to grow pot plants in a greenhouse, you probably need some benches. Benches enable you to raise plants off of the greenhouse floor, keeping them away from disease and often better light. A tiered system of benches usually provides more useable space than if you were to only use the floor. Benches can be made out of metal, wood or plastic, and are usually either slatted or solid in construction. The surface of a bench should drain freely. Wooden benches if not treated with preservative can rot, and may become infested with pests such as ants or mealy bug. Capillary matting (i.e. a continually moist, absorbent material, sold by some greenhouse companies) will help to reduce the need for watering if used on a bench, to sit pots on. The duration of crop in greenhouse is the key to make the greenhouse technology profitable or the duration of production in greenhouses should be short. In this context, use of containers in greenhouse production assumes greater significance. The containers are used for the following activities in greenhouse production. Raising of seedlings in the nursery. Growing plants in greenhouses for hybrid seed production of flowers. Growing plants for cutflower production. Growing potted ornamental plants. Advantages of containers in greenhouse production Increase in production capacity by reducing crop time. High quality of the greenhouse product. Uniformity in plant growth with good vigour. Provide quick take off with little or no transplanting shock. Easy maintenance of sanitation in greenhouse. Easy to handle, grade and shift or for transportation. Better water drainage and aeration in pot media. Easy to monitor chemical characteristics and plant nutrition with advanced irrigation systems like drips. Advantages and disadvantages of different plant growing containers Containers Advantages Disadvantages Clay pot Low cost Slow to work with pots an dry out fast Easy water management They are heavy to handle Fiber block Easy to handle Slow root penetration Short life Fiber tray Minimum use of space Hard to handle when wet Single peat pallet No media preparation Require individual handling Limited sizes Low storage requirement can be handled Prespaced peat No media preparation pallet Limited to small sizes Single peat Good root penetration Difficult to separate Pot Easy to handle in field Available (square/ round) in large sizes Strip peat pot Good root penetration Slow to separate 19 Portrays Easy to handle Reusable May be limited in sizes Plastic pack Easy to handle Roots may grow out of container Plastic pot Reusable Requires handling as single plant Good root penetration Polyurethane Easy to handle Requires less Requires regular fertilization foam medium Reusable Soil band Good root penetration Requires extensive labour Soil block Excellent root penetration Expensive machinery Perforated Easy to handle Requires regular fertigation Plastic tray Requires less medium Roots may grow out of the container Available in many sizes reusable Perforated Less expensive Less durable Polyethylene Reusable bags Requires less storage space Selectin of suitable containers depends upon the crop to be produced in greenhouse, plant characteristics like crop stage, duration, growth habit, root system, etc. Generally long duration, deep rooted and vigorous crop plants require bigger containers, compared to short duration, shallow and less vigorous ones. The containers provide optimum condition for germination of seed and growth and development of transplants. 20 Lecture 9 : Irrigation and Fertigation management Micro irrigation system is the best for watering plants in a greenhouse. Micro sprinklers or drip irrigation equipments can be used. Basically the watering system should ensure that water does not fall on the leaves or flowers as it leads to disease and scorching problems. In micro sprinkler system, water under high pressure is forced through nozzles arranged on a supporting stand at about 1 feet height. This facilitates watering at the base level of the plants. Equipments required for drip irrigation system include : i. A pump unit to generate 2.8 kg/cm2 pressure ii. Water filration system – sand/ silica/ screen filters Water out put in drippers a. 16 mm dripper at 2.8 kg/cm2 pressure gives 2.65 litres/hour (LPH)/ b. 15 mm dripper at 1 kg/cm2 pressure gives 1 to 4 litres per hour. Screen filters : Stainless steel screen of 120 mesh (0.13 mm) size. This is used for second stage filtration of irrigation water. Fertigation system : In fertigation system an automatic mixing and dispensing unit is installed which consists of three system pump and a supplying device. The fertilizers are dissolved separately in tanks and are mixed in a given ratio and supplied to the plants through drippers. Fertilizers Fertilizer dosage has to be dependent on growing media. Soilless mixes have lower nutrient holding capacity and therefore require more frequent fertilizer application. Essential elements are at their maximum availability in the pH range of 5.5 to 6.5. In general Micro elements are more readily available at lower pH ranges, while macro elements are more readily available at pH 6 and higher. Forms of inorganic fertilizers Dry fertilizers, slow release fertilizer and liquid fertilizer are commonly used in green houses. Slow release fertilizer They release the nutrient into the medium over a period of several months. These fertilizer granules are coated with porous plastic. When the granules become moistened the fertilizer inside is released slowly into the root medium. An important thing to be kept in mind regarding these fertilizers is that, they should never be added to the soil media before steaming or heating of media. Heating melts the plastic coating and releases all the fertilizer into the root medium at once. The high acidity would burn the root zone. 21 Liquid fertilizer These are 100 percent water soluble. These comes in powdered form. This can be either single nutrient to plant growth and results in steady growth of the plant. Fertilization with each watering is referred as fertigation. Fertilizer Application Methods 1. Constant feed Low concentration at every irrigation are much better. This provides continuous supply of nutrient to plant growth and results is steady growth of the plant. Fertilization with each watering is referred as fertigation. 2. Intermittent application Liquid fertilizer is applied in regular intervals of weekly, biweekly or even monthly. The problem with this wide variability in the availability of fertilizer in the root zone. At the time of application, high concentration of fertilizer will be available in the root zone and the plant immediately starts absorbing it. By the time next application is made there will be low or non-existent. This fluctuation results in uneven plant growth rates, even stress and poor quality crop. Fertilizer Injectors This device inject small amount of concentrated liquid fertilizer directly into the water lines so that greenhouse crops are fertilized with every watering. Multiple Injectors Multiple injectors are necessary when incompatible fertilizers are to be used for fertigation. Incompatible fertilizers when mixed together as concentrates from solid precipitates. This would change nutrient content of the stock solution and also would clog the siphon tube and injector. Multiple injectors would avoid this problem. These injectors can be of computer controlled H.E. ANDERSON is one of the popular multiple injector. Fertilizer Injectors Fertilizer injectors are of two basic types: Those that inject concentrated fertilizer into water lines on the basis of the venture principle and those that inject using positive displacement. A. Venturi Principle Injectors Basically these injectors work by means of a pressure difference between the irrigation line and the fertilizer stock tank. a) The most common example of this is the HOZON proportioner. b) Low pressure, or a suction, is created at the faucet connection of the Hozon at the suction tube opening. This draw up the fertilizer from the stock tank and is blended in to the irrigation water flowing through the Hozon faucet connection. c) The average ratio of Hozon proportioners is 1:16. However, Hozon proportioners are not very precise as the ratio can vary widely depending on the water pressure. d) These injectors are inexpensive and are suitable for small areas. Large amounts of fertilizer application would require huge stock tanks due to its narrow ratio. 22 B. Positive Displacement Injectors 1. These injectors are more expensive than Hozon types, but are very accurate in proportioning fertilizer into irrigation lines regardless of water pressure. 2. These injectors also have a much broader ratio with 1:100 and 1:200 ratio being the most common. Thus, stock tanks for large applications areas are of manageable size and these injectors have much larger flow rates. 3. Injection by these proportioners is controlled either by a water pump or an electrical pump. 4. Anderson injectors are very popular in the greenhouse industry with single and multiple head models. a. Ratios vary from 1:100 to 1:1000 by means of a dial on the pump head for feeding flexibility. b. Multihead installations permit feeding several fertilizers simultaneously without mixing. This is especially significant for fertilizers that are incompatible (forming precipitates, etc.) when mixed together in concentrated form. 5. Dosatron feature variable ratios (1:50 to 1:500) and a plain water bypass. 6. Plus injectors also feature variable ratios (1:50 to 1:1000) and operates on water pressure as low as 7 GPM. 7. Gewa injectors actually inject fertilizer into the irrigation lines by pressure. a. The fertilizer is contained in a rubber bag inside the metal tank. Water pressure forces the fertilizer out of the bag into the water supply. b. Care must be taken when filling the bags as they can tear. c. Ratios are variable form 1:15 to 1:300. 8. If your injector is installed directly in a water line, be sure to install a bypass around the injector so irrigation of plain water can be accomplished. General Problems of Fertigation : Nitrogen Nitrogen tends to accumulate at eh peripherous of wetted soil volume. Hence, only roots at the periphery of the wetted zone alone will have enough access to Nitrogen. Nitrogen is lost by leaching and denitrification. Since downward movement results in permanent loss of NO3 – N, increased discharge rate results in lateral movement of N and reduces loss by leaching. Phosphorous It accumulates near emitter and P fixing capacity decides its efficiency. Low pH near the emitter results in high fixation. Potassium It moves both literally and downward and does not accumulate near emitter. It distribution is more uniform than N & P. Micronutrients Excepting boron, all micronutrients accumulates near the emitter if supplied by fertigation. Boron is lost by leaching in a sandy soil low in organic matter. But chelated micronutrients of Fe, Zn can move away from the emitter but not far away from the rooting zone. 23 Lecture 10 : Use of polyhouses for Propagation and production of quality planting material Greenhouse has been used long back by horticulturists as a mean of forcing rapid growth of plants and extending the growing season particularly in colder areas. There are being use for whole sale production and propagation of floricultural plants, nursery stock of fruit corps and vegetable crops. A greenhouse greatly extends the variety and scope of propagation. Many kinds of green houses are used for propagation but the most suitable type is the one that admits the maximum amount of light. This is important, particularly where most of the propagation is done in late winter and early spring. Good light conditions are essential for the steady growth of the seedlings. Experiments have shown that a greenhouse that runs from east-to-west is best for better light penetration in winter and early spring, and consequently preferable for raising seedlings at this time of the year. Moreover, it is important that the green houses should be well away from any kind of shade such as a tree or building, including other greenhouse. Some shelter, however, from north to northeast winds is desirable. In India, construction of temporarily low-cost poly-houses is in fashion for raising nursery of fruit plant in off-season. Such low cost greenhouses are constructed either on wood or metal framework and are covered with polyethylene sheet of 0.10 to 0.15 mm thickness, which is resistant to ultra-violet rays. These houses are equipped with thermostat, cooler or an air conditioner or humidifier, etc for rigid control on temperature and humidity. Commercial greenhouses are usually independent structures of even span, gable-roof constructions, well proportioned so that the space is well utilized for convenient walk ways and propagating benches. Hot Frames (Hot Beds) : A hotbed is a bed of soil enclosed in a glass or plastic frame. It is heated by manure, electricity, steam, or hot-water pipe. Hotbeds are used for forcing plants or for raising early seedlings. Instead of relying on outside sources of supply for seedlings, you can grow vegetables and flowers best suited to your own garden. Seeds may be started in a heated bed weeks or months before they can be sown out of doors. At the proper time the hotbeds can be converted into a cold frame for hardening. Hot beds are small low structures, used for propagation of nursery plants under controlled conditions. Hot beds can be used throughout the years, except in area with severe winters, where their use can be restricted to spring, summer and fall. Seedlings can be started and leafy cutting rooted in hot beds early in the season. For small propagation operations, hot beds structures are suitable for producing many thousands of nursery plants, without the higher construction expenditure for larger, propagation houses. Cold Frames : The primary use of cold frames is in conditioning or hardening of rooted cuttings or young seedlings prior to field, nursery row or container planting. Cold frames can be used for starting new plants in late spring. When young, tender plants are first placed in a cold frame, the coverings are generally kept tightly closed to maintain a high humidity but as the plants become adjusted, the sash frames are gradually raised or ends of the hoop house to permit more ventilation and drier conditions. The installation of mist line or irrigation provision in cold frame is essential to maintain humid conditions. 24 Lath Houses : Lath houses have many uses in propagation, particularly in conjunction with the hardening off and acclimatization of liner plants prior to transplanting and for maintenance of shade requiring plants. In mid climates, they are used for propagation, along with a mist facility and can be used as overwintering structures for linear plants. Propagation frames : Sometimes in a greenhouse, the humidity is not enough to allow satisfactory rooting in the leaf cuttings. In such cases, enclosed frames covered with glass or plastic material may be used for rooting of cutting. These frames are useful only on grafted plants as these retain high humidity during the process of healing. Large inverted glass can also be kept over a container having cuttings. Though, high humidity is required is such frames but ventilation and shading is necessary after the rooting process has started in the cutting. Net House : Net houses are widely used as propagation structures in tropical areas, where artificial heating is not required and artificial cooling is expensive. In these areas, net houses may be constructed with roofs covered with glass or plastic film and its sides are covered with wire net. It provides necessary ventilation and maintains an ideal temperature for germination of seeds and subsequent growth of the seedlings. Bottom heat box : It is a simple box for promoting rooting of cutting is difficult-to-root fruit plants like mango and guava. The most ideal temperature to be maintained in the box is 30 ± 2˚ C because at this temperature, cuttings of mango, walnut, olive and guava root easily and profusely. The initiation of rooting in cutting varies from species-to-species but in general, it takes 1-2 months for proper development of the roots. Mist propagation unit : The rooting of softwood leafy cutting under spray or mist is a technique now widely used by nurserymen and other plant propagators throughout the world. The aim of misting is to maintain humidity by a continuous film of water on the leaves, thus reducing transpiration and keeping the cutting turgid until rooting take place. In this way, leafy cuttings can be fully exposed to light and air because humidity remains high and prevents damage even from bright sunshine. Mist also prevents disease infection in the cuttings by way of washing off fungus spores before they attack the tissues. While the leaves in this process must be kept continuously moist, it is important that only minimum water should be used. After rooting in the mist, hardening of the rooted cutting is important for better success in the field. When cuttings are rooted, misting should not cease abruptly as this may help in drying out of the young plants followed by scorching, instead, a weaving off process should be adopted in which misting is continued but the number of sprays/days gradually reduce. The way is to shift the rooted cutting to a greenhouse, fog chamber, and frames, maintained at higher temperature and low relative humidity. After phase-wise hardening only, the rooted cuttings are planted at permanent location or in the nursery. 25 Growing rooms : A growing room is an insulated building from which natural light is usually excluded. In it, illumination is provided by artificial means. Growing rooms are now widely used commercially for the production of seedlings of bedding plants, tomatoes and cucumbers in most advanced countries. The seedlings are usually grown in trays or pots kept on benches. 26 Lecture 11 : Greenhouse cultivation of Rose, Soil, Climate, Varieties, Propagation and Intercultural Operations Normally one-year-old budded plants having at least 3 canes on rootstocks like Rosa indica var. odorata or R. canina or R. manetti are most ideal for greenhouse cultivation. Cultivars : ‘Golden Gates’, ‘Grand Galla’, ‘First Red’, ‘Kiss’, ‘Konfetti’, ‘Mercedez’, ‘Ravel’, ‘Noblesse’, ‘Vivaldi’ and ‘Starlite’. Temperature requirement : The greenhouse temperature is generally maintained from 20˚ C or 21˚ C on cloudy days and 24˚ C – 28˚ C on sunny days. However, plenty of light, humid and moderate temperature ranging from 15˚ C to 28˚ C may be considered as optimum conditions for roses. Ideal humidity – 60-65 % and high RH results Powdery mildew and low RH causes desiccation and reduce flower quality, CO2 level 1000 – 1200 ppm is favourable. Growth media : Well drained soil rich in organic matter and oxygen is good for roses. Organic matter as high as 30 percent in the top 30 cm of the growing beds is preferred by many growers. The pH of the soil be around 6 to 6.5 with less EC. Layout and Planting : Raised beds are prepared, 5 beds each of 1.20 m width per 8 m bay. The width of path could be 0.40 m. There could be two rows of plants per bed. The lower number of rows per bed and higher number of paths allow better air circulation. Row to row distance could be 30 cm and plant to plant distance 17 cm. Each row of 24 m length could contain 140 plants so that planting density of 70,000 plants per hectare (7-13 plants/m2). Planting may be done in the months of February to April and/or July to September in a phased manner. Manuring : Organic manures can required to be added so that top 30 cms. Of the soil has 30 % organic matter content. A dose of 15 kg. FYM per square metre has been incorporate in to beds. Fertilizer Application : Application of nutrients should be based on analysis of soil and plant. Nitrogen and Potassium = 200 PPM No. of applications = Twice a week for 7 months along with irrigation. Phosphorus = Soil application @ 1.8 kg/m2 Irrigation and drainage : Rose plants require a lot of water, at least 6 mm/day i.e. about 60 cum/ha/day. A drainage line may be laid below the beds for disposal of excess water. Cultural practices : For proper growth of rose plant and high production special cultural practices are to be carried out as follows : 1. Initial plant development / mother shoot bending : If the young plant is allowed to flower immediately after planting there is serious risk that the important structural 27 frame work of the plant will be impaired. The various types of plants require different treatment. First flower is pinched after on month from the date of plantation so that 2 to 3 eyes bud will sprout on main branch to grow as branches and these branches in turn will form buds. When the plant attains this stage of growth, the mother shoot is to be bent towards the direction of path. This cultural operation in rose plants is done to be initiate bottom break ground shoot. The maximum leaf area is required to build up a strong root system. The mother shoot is bent nearer to the bud point. 2. Plant structure development : To develop more growing point and plant structure development plays an important role. After planting ground shoot will start growing from crown of plant. The weak ground shoot should be bent at ground level, for forming a basic and strong frame work of plant structure for production throughout their life cycle, the strong ground shoots should be cut at 5th five pair of leaves after four and half months from the date of plantation. The medium ground shoots should be cut 2 nd or 3rd five of leaves. 3. Bending in roses : Bending helps in maintaining enough leaf area on the plants. The maximum leaf area is required to build up a strong root system. Leaves are important for producing carbohydrates. The mass of leaves is also known as the lungs of the plant. The buds growing suckers should be removed in check new growth on the bended stem. The buds should be removed from the bended stem in order to check the incidence of thrips and bud root (botrytis). Only weak and blind shoots are selected for bending. Bending breaks apical dominance of the plant. It is continuous process and hence carried out throughout the life cycle. Bending should be such that the most of the stems lay below horizontal. In summer season it is generally advised not to go for bending as it provides favourable condition for mite’s incidence. Bending is done on 1st or 2nd five pair of leaves. One can also grow roses in green house without bending by keeping some blind shoots on plants in standing position for extra photosynthesis and uptake of water nutrients. While bending the stems, the care should be taken that the stem will not break and the leaves will not touch the soil on the bed. 4. Disbudding : Standard varieties are those with one flower on each stem. But as nearly all varieties produce some side buds below the center bud. These side buds have to be removed. The removal of these buds is known as disbudding. It should not be done too early or too late. If done too early it may harm leaves and if done too late then large wounds in the upper leaf axil can take place. When bud attain pea-size and show slight colour then it is right time to do disbudding. For most spray varieties, the center crown bud is to be removed. Disbudding is generally done on weak stem so that it can convert itself to thick stem and in future cuts can be taken. Thick stem produce strong sprouts whereas then stem gives out weak sprouts. 5. Pinching : Removal of unwanted vegetative growth from the axil of leaf below the terminal bud is called pinching. This helps to get good quality flowers and buds and avoids wastage of energy in the development of auxiliary bud if done at right stage and right time. It leads to apical dominance. 6. Wild shoot (root stock) removal : Wild shoots are the unwanted growth that take place at the union on the root stock. They should be removed at the earliest as these will deplete nutrients and checks growth and development of plant. They should not be cut but removed from its union by pressing it with thumb in order to check its further sprouting. 7. Support of the plants : The support system consists of bamboo/ GI pipes/ L’ angles inserted on both sides of bed at the start and end of the bed. Post are placed at intervals of 3 m on both sides of 28 the bed, along the sides of bed, fastened at the posts at 30 – 40 cm intervals are 14 guage GI wires or plastic string to support the plant. Between the wires across the bed, thin strings can be tied to keep the width of the bed constant. Support system makes intercultural operation easy and protects the buds from being damaged by not allowing the stems bend into the path. 8. Pruning : Stems are cut back leaving 4-5 nodes on the basic stock frame, removing all weak shoots and redirecting the wayward ones. This may be practised in a phased manner so that flowering takes place from September to March. Generally, flowering takes place 45 days after pruning. 29 Lecture 12 : Rose, harvesting, Post harvest management, Pest and Diseases Harvest : The post-harvest management of roses starts with their harvest. Roses should attain the right stage for harvesting. If cut too early, flower miss reserve food and therefore, may not develop into full flowers. If cut too late, longevity diminishes. As such, roses should be cut just as the buds are opening, after the sepals have almost fully curled up and the colour is fully visible. In small flowered varieties and Floribundas, the flowers are cut just when they begin to open the cluster. The cutting may be done in the evening or early morning with long stem. The lower end of cut stems are immediately placed in clean plastic buckets containing a clean solution of 500 ppm citric acid or in chrysal – RVB. Thereafter, the buckets containing cut roses are brought to the grading and packing Shed/Hall. Flower yield of 250-350 stem/m2 is considered to be ideal. Flower yield can be increased by spraying BAP 50-100 ppm before flowering flush. Hydration : Ideally, roses immediately after harvest should be graded, packed, precooled and despatched by refrigerated vehicle. In case of delay in grading and packaging flowers are shifted to the cold store. Before shifting to the cold store. Before shifting to the cold store, it is advisable to re-cut the stems, about 2 cm, above the previous level without removing lower leaves/thorns and again place them in clean containers in clean warm (40-48˚ C) water, adjusted with citric acid to pH 3.0 – 3.5. This treatment will prevent vascular blockage and hence neck drop. Preservatives : The followers are removed from the citric acid after 30-60 minutes (or when the leaves and petals are fully turgid) and put in the preservative solution. Thereafter, the flowers are shifted to the cold storage at 0 to 20 C. Roses may be kept for 4-5 days in a preservative solution in cold store, after that longevity may suffer. The composition of floral preservative is as under : Citric acid – 100-700 mg/litre HQC/captan – 16 mg/liter Sucrose – 20 mg/litre STS – 0.2 – 4 mM Cytokinin – 1.0 to 100.00 m. Packing : Packing comprises three steps : bunching, wrapping and packing. The head of roses are evened up and their stem tied with a rubber band into bunches in 10s, 20s, 25s, or 50s depending on the ultimate market. They are cut so that all the stems are of the same length. The bunches are placed in preservative solution and may be shifted to the cold store. They are brought back to the packing hall and the buds are wrapped and the bunches are sleeved in transport polyethylene. The wrap is a 15-20 cm. wide plastic strip which acts as a cushion for the buds. Many different cardboard boxes are used for packing. For long term transport it is best to use telescopic style boxes made of corrugated fibreboard. The size could be 100 cm x 45 cm x 22 cm. There may be 400 to 1000 stems per box and weight may vary from 14 to 18 kg/box. 30 Depending on the market, the box is either filled with one variety, one grade, or mixed colour one grade. Pest and Diseases : The principal pests of roses are : Red spider mite Leaf rollers White fly Thrips Aphids Nematode The principal diseases are : Powdery mildew Downy mildew Botrytis Pruning die back Black leaf spot Control The preventive spray programme with a volume of 1500 litres/spray at an average interval of once in a week is suggested. The chemicals could be as under. Dithane M-45 0.6 gm/litre Metasystox 1.25 ml/litre Karathane 1.00 ml/litre 31 Lecture 13 : Greenhouse cultivation of Carnation Soil, Climate, Varieties, Propagation and Intercultural Operation Perpetual carnations – Dianthus caryophyllus Family : Caryophyllaceae Carnation is an important flower crop having great commercial value as a cut flower due to its excellent keeping quality, wide array of colour and forms. It popularity ranks among the toop three cut flowers in the West. There are two basic groups of Carnations traded within the international markets. S. No. Types of Size and No. of Climate Varieties Carnation flowers Suitable 1 Standard Single big flower on Cool climate Master, Tanga, Sonsara, carnation stem Laurella, Solar, Dakar, Raggio di Sole, Cabaret and Isac 2 Spray A bunch of flowers Warm climate Bagatel, Cherrybag, carnation with smaller size Fantasia, Picaro, Ondelia, Sintomia and Macarena Climatic requirement : Most of the varieties of carnation are photo-period insensitive. Ideal temperature requirement is about 10˚ C in the night and 23˚ C in the day with RH 50-60 %. High day and night temperature induce abnormal flower opening and calyx splitting. High light intensity with a 12 hour day length may produce top quality flowers. For better quality providing long days for short period (4-6 weeks) when 4-7 pairs of leaves, CO2 level 750-1000 ppm found optimum on sunny days while 300-500 ppm on cloudy days. Bed Preparation : Carnation may be grown in raised bed of soil. This would allow 72 % utilization of land. Top width – 90 cm, Bottom width – 100 cm, Height – 45 cm, Pathway – 50 cm. Planting Distance : Plant to Plant distance : 15 cm and Row to Row distance : 15 cm. Planting : Rooted cuttings are planted at shallow depth. Deep planting will results in foot rot. Plant density of 20-30 plants/m2 is optimal (1.5 – 2.0 lakh/ha). Can be planted round the year under greenhouse environment. Fertilizer dose : A nutritional dose of 40 g N, 20 g P2O5, and 10 g K2O is ideal. Liquid feeding of carnation plants with nutrient levels of 190 ppm N and 156 ppm K, 1 ppm B with each irrigation water results in high grade carnation. Tank Day Fertilisers Dose/Plant A Monday andAmmonium nitrate 3g Thursday KNO3 5g MAP 2g MgSO4 2.5g B 1g B Tuesday KNO3 5g Friday CaNO3 8g Wednesday and Sunday – only water - Ca deficiency – weak stem with small flowers - B deficiency – calyx splitting and bud abortion 32 Irrigation : Overhead sprinkling is quite effective and economical than soil surface irrigation. At bod appearance stage, over-head sprinklers should be replaced with soil surface system. 20 litre/m2 (twice a week) Cultural Practices : For proper growth of carnation plant and high production special cultural practices are to be carried out as follows : 1) Support System : Both spray and standard carnation produce weak and lanky stems hence must be supported with 4 to 5 layers of support netting. Lack of support system may cause lodging of stems. Nets of mild steel wire or nylon wires can be used. Nets of mild steel is expensive but last long. 4 to 5 layers of wire nets are required during the growth period of the plant. Spread the first support net i.e. 7.5 cm x 7.5 cm on top of the beds before planting. When the plants starts to grow, the net should be lifted by 5 to 7 cm above ground. The wire should be support with iron poles. The poles should be placed at a distance of 3M along bed length. 2) Pinching : Removal of unwanted vegetative growth form the axil of leaf below the terminal bud is called pinching, this helps to get good quality flowers and buds and avoids wastage of energy in the development of auxiliary bud if done at right stage and right time. It leads to apical dominance. There are generally two methods of pinching as follows: a. Single pinch method b. Pinch and half method Single pinch method : First pinching is done after 3 to 4 weeks from date of plantation, when the plants are well established. Apex shoot is pinched on the 5th to 6th pair of leaf (nodes). This method is adopted in order to produce maximum number of flowers during September to March when the demand for flowers in the market is high. Pinch and half method : This method helps to get continuous production. After one month of 1 st pinching, second pinching is done only on half of the lateral shoot by leaving three pairs of leaves on the shoots. First the unpinched shoot will grow and produce flowers. Later on pinched shoots will grow and produce flowers. 3) Disbudding : Standard varieties are those with one flower on each stem. But as nearly all varieties produce some side buds below the center bud, those need to be removed. The removal of these buds is known as disbudding. It should not be done too early or too late. For most spray carnation varieties, the centre crown bud in many cases is also to be removed. 4) Weeding and loosening of the soil : This operation is done with the help of long handed weeding hook (khurpi). It is helpful for removal of weeds, breaking the top layer of algae and to facilitate better air circulation in soil, this is to be done very carefully to avoid damage of active roots. 5) Calyx banding : Reduces calyx splitting. Placing a rubber band or 6 mm wide clear plastic tape is used around the calyx of the flowers which have just start opening. This operation is referred as ‘Calyx banding’. 33 Lecture 14 : Carnation, Harvesting, Post Harvest Management, Pests and Diseases Harvest : Carnation flowers mature in 4-5 months period. Standard cultivars are harvested at “Paint Brush” stage with half-open flowers, or almost fully open flowers. Spray cultivars are harvested when there are 2 fully open flowers on the stem. Standard carnations can also be harvested at the stage of mature, large but tight buds with calyxes filled with petals or buds with petals just beginning to appear on the upper portion (i.e. at “cross” stage). Such buds may be stored under dry condition for 5-6 months (except yellow colour varieties). Flowers partly open when harvested at the star stages with petals emerging about 0.5 cm above calyx, may be stored upto 8 weeks. Flowers destined for storage should be free from diseases and pests. Harvesting should be done in the early morning and/or in the late afternoon, and they should not be wet at harvest. Immediately after harvesting flowers should be placed in a bucket of clean water inside the green house and transported to the grading hall. Yearly production of 300-400 flowers/m2 is ideal and economical. Flower Preservatives : All cut flowers auction centres in Western Europe require flowers to be pretreated with Silver Thiosulphate Solution (STS) or some other floral preservatives. The preservatives promote longevity and quality of cut flowers. They are mainly composed of sugar, germicide, STS, weak acid and growth substances. Concentration of preservative are indicated below :- i. 8-Hydroxquionoline sulphate or Hydroquionoline citrate 200-600 ppm ii. STS – 0.2 – 4 mM. iii. Cytokinin – 10-100 ppm. iv. Sugar – 0.5-2 % v. Citric acid – 50-100 ppm. Packing : Packing comprises three stages : bunching, wrapping and packing. The exact number of stems stipulated per bunch i.e. 5, 10, or multiples of 10 pieces should be tied with a rubber band at the base of the stem. The branches may be wrapped in paper. Plastic promote fungal attack. However, wrapping is not essential. Many different cardboard boxes are used for packing. For long-term transport, it is best to use telescopic style boxes made of corrugated fibreboard. Boxes must be strong enough to support the weight of at least 8 full boxes placed on top of one another under conditions of high humidity. Special boxes equipped with a container for water in which flowers are held in a vertical position have been developed in the West. The end of flowers can also be placed in absorbent cotton saturated with water and enclosed in waxed paper or polyethylene foil (0.004- 0.006 mm. thick) which permits air exchange. All gaps inside the boxes should be filled with shredded paper. Boxes are during forced air cooling must have vents on either side. Total vent size should equal 4-5 % of the area of the end wall of the box. Pre-cooling : After packing, the flower should be pre-cooled as soon as possible. Since temperature reduction from flowers is a rather slow process and metabolism may continue even at a low temperature, the heat from the freshly harvested flowers needs to be removed rapidly before shipping or storage. Pre-cooling is that rapid removal of field heat to bring the produce temperature down to or near to its subsequent storage or shipping temperature. 34 Precooling units are available that can cool from 4 to more than 100 boxes of flowers in less than 1 hour as against the requirement of 12-24 hours if the boxes are stalked. The pre-cooling equipments can be installed in cold store or a separate pre-cooling chamber can be constructed alongside cold store. In the present model separate built-in pre-cooling and cold store units, which would be kept in grading shed have been suggested. Of the various methods of pre-cooling, forced air cooling is considered as the best for cut flowers. This operates by forcing cold aid through boxes which have vents at each end. One of the vents at each end of the box is connected to a hold in the wall of the chamber with suction. The speed of the air flow may bring down the temperature of the flowers to the air temperature in the cold room is less than an hour. The suction is switched off as soon as the temperature of carnation flowers is near 0˚ C. The humidity must be maintained at high level (90-95 %). Plant Protection Disorder : Calyx splitting : which is a well known problem in carnation production is caused by the formation of a large number of petals or by lateral buds inside the calyx at low temperatures. Cultivars with too many petals are susceptible to calyx splitting. Due to fluctuation in temperature and environmental conditions also influences calyx splitting. B deficiency will also leads to calyx splitting. Measures : 1. Selection of cultivars that are less prone to splitting. 2. Regulation of temperature and maintenance of optimal fertilizer level can minimize this disorder. 3. This can also be reduced by placing a rubber band or 6 mm wide clear plastic tape is used around the calyx of the flowers which have just start opening. This operation is referred as ‘Calyx banding’. Diseases : Pythium, Phytopthora rot, Fusarium wilt, Fusarium stme rot, Alternaria blight, Grey mold. Pests : Aphid, Mealybug, Spidermite, Thrips, Whitefly Control : 1. Soil Sterilisation – Chloropicrin 2. Dithane – 0.6 gm/litre 3. Metasystox – 1.25 ml/litre 4. Karathane – 1.00 ml/litre Volume of preventive spray – 1500 litre/spray and frequency is 50 sprays/year i.e. once in a week. 35 Lecture 15 : Greenhouse cultivation of Chrysanthemum, Soil, Climate, Varieties, Propagation and Intercultural Operations Chrysanthemum are among the top two best selling cut flowers in international trade. It is number one flower in China and Japan. In India it has been recognized as one among the five important commercially potential flower crops. Cultivation Structures : Polyhouse Greenhouse with 25 % shade net Types : Sprays and Standards Chrysanthemum are broadly classified into 3 groups on the basis of their response to temperature. Thermozero varieties flower at any temperature ranging 10-27˚ C but most consistently at a constant 16˚ C night temperature. Thermopositive varieties require higher temperature (27˚ C) for bud initiation and lower temperature inhibit completely. Thermonegative varieties flower at any temperature between 10 and 27˚ C, but flowering is delayed at higher temperature. Most promising cultivars in the international trade are Snow Ball, Snow Don White, Mountaineer, Sonar Bangla, Bright Golden Anne, and Chandrama among large flowering tyeps while Ajay, Birbal Sahani, Lehmans, Nanako, and Sonali Tara in case of small flowering types as sprays are most common. Temperature : 16-25˚ C for vegetative growth 16-18˚ C for flower induction Optimum night temperature – 15˚ C Optimum day temperature – 25˚ C Light requirement : 70,000 Lux or 3000-10,000 foot candles and minimum of 10 foot candles light required to prevent premature flower bud formation. CO2 requirement : 750-1500 ppm Relative Humidity : 75 % optimum Day length : Short and day neutral varieties are there however only photosensitive varieties (Short day plants) are grown in greenhouse for continuous production throughout the year. During vegetative phase day length more than 12 hours is required whereas for reproductive phase day length is less than 12 hours and night length should be more than 13 hours. Growing Media : pH of the soil around 6.5 with EC 1-1.5, well drained and aerated. Soil less media used is Rock wool and it can be sterilized by water steam or fumigation. Propagation Method : Rooted terminal stem cuttings or micro propagation Supporting : Various methods can be used to support chrysanthemum so that they will grow erect. The most satisfactory system of supporting is welded wire mesh of either 12.5 x 12.5 or 15 x 15 cm are used. Plant Density : 15 to 20 x 15 -20 cm for plants that will be pinched (64 plants/m2) 10 to 15 x 10 – 15 cm for plants that will be grown as single (32 plants/m2) 36 July-August is ideal time of planting chrysanthemum in North India. However, if controlled photoperiod facilities are available planting can be done round the year. Irrigation : Sprinkler irrigation from planting for every 7-10 days interval and gradually reduce the number of applications. Drip irrigation resorted at the end of sprinkler irrigation with fertilizer 2-3 drip lines for each row of bed with drippers placed at 30 cm. Nutrition : 25-50 ppm of N, 5-10 ppm P, 20-40 ppm K and 100-150 ppm Ca a) Planting to thinning : Fertigation : 20 : 20 : 20 – 150 ppm b) Thinning to darkening : N-90 ppm, P-50 ppm, K-150 ppm c) Darkening to buds : N-150-200 ppm, P-50 ppm and K-200-300 ppm d) Buds to harvesting : N-150 ppm, P-50 ppm and K-250 ppm Intercultural Operations : 1. Pinching : It encourages side branching. a) For standards : Pinching is not done if only one central bloom is desired on the main shoot. Single pinch is done if two flowers are desired and double pinch is done for 4 flowers. b) For sprays : Two pinchings are followed to encourage lateral growth. 1st pinching is done at 4 weeks after planting and 2nd pinching is done 7 weeks after planting. 2. Thinning : Following pinching several side shoots develop and these must be limited depending on the amount of space that is allows per plant. Standards : 2-3 stems Sprays : 3-4 stems Thinning operation is done 10-15 days after pinching. 3. Deshooting : It is done to remove side shoots which arise from axil of shoots for obtaining few flowers of better quality and size. In standards regular deshooting is done to produce single flower on single stem. 4. Dis-budding : For Sprays : As soon as the buds separated from one another, the central bud is pinched out to improve the spray shape. It is done between 2nd and 3rd week before harvesting. It is done to improve the size and quality of flower. For standards : Incase of standards side buds are removed to improve the size and quality of central bud. 5. Induction of flowering (Block cloth treatment) : Under natural long days (from late spring to early fall), short days can be created by blocking out all light with black plastic or cloth. Many growers use black cloth to provide short days to induce flowering of chrysanthemum. 37 Lecture 16 : Chrysanthemum, Harvesting, Post Harvest Management, Pest and Diseases Harvesting : For singles 11-15 weeks after planting are ready for harvesting For singles 13-19 weeks after planting are ready for harvesting Spray types are to be harvested when the central flower is opened or three out side flowers have opened with surrounding flower buds are well developed. Standards are harvested before the central florets are fully opened or the standards can be harvested in unopened stage i.e. when the inflorescences are 5-10 cm in diameter. Decorative types – petals in centre of top most flower fully developed Standard – outer rays florets ceased to elongate and few unfurl Pot mums – Flowers half to fully open Yield : considering 70 % growing area Standards may yield – 2.5 – 4.0 lakh/ha and sprays – 1.5 to 1.75 lakh/ha. Grading : depend on Stem length, colour and diameter of flower In USA generally SAF (Society of America Florists) Standards are followed Packaging : Standard chrysanthemum placed in sleeves packed in display boxes (91 x 43 x 15 cm). Placed in boxes as per grades and bulk packing sprays 10, 15, 20 stems placed in sleeves. Six sleeves 3 at each end packed in each box measuring 80 x 50 x 30 cm. Post Harvesting Handling : After harvesting placed in cool and clean water. Stems should be cut at equal distance (90 cm for the standards). The lower one third of the foliage on the stem is stripped off. Then the flowers can be graded, bunched. The 250 g bunch has been used widely for the spray types but bunches weighing 450 g are common. Less than 5 stems per bunch is not acceptable to most of retailers. The bunches are to be packed in plastic sleeves. The stem length need not be over 75 cm for most purposes. Precooling at 4˚ C for 12-20 hours, before grading has to be done to remove field heat. Storage : Can be stored at 1˚ C for 3 weeks in preservative solution like HQC or STS 0.1 %. Aphids : Damage by aphid’s results in loss of vigour, yellowing and premature leaf fall and stunted growth of attacked plants. Control : Spraying of Monocrotophos @0.05 % or Phosphamidon @0.02 % at 15-20 days interval. Thirps : Damaged flowers look discoloured, withered and dried due to scorching. Severe infestation adversely affects quality and quantity of flower production. Control : Spraying with Monocrotophos (0.04 %) twice or thrice at 15 days interval controls thrips population. Although the list of diseases that may attack chrysanthemum is long, mums are relatively trouble-free. 38 Leaf Spot Rust Wilt Powdery Mildew Ray Blight Ray Speck Gray Mold Spray the following chemicals weekly once chlorothalonil, mancozeb, nyclobutanil, propiconazola r thiophanate methyl 39 Lecture 17 : Greenhouse cultivation of pot plants Gerberas B.N. :

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