CP 102 Principles of Plant Disease Diagnosis and Management Part 1 PDF 2024

29/08/2024 CP 102 PRINCIPLES OF PLANT Chapter I DISEASE DIAGNOSIS AND MANAGEMENT The Diagnostic Process JOANNE A. LANGRES, M.Sc. Faculty, DPSS, CSU-C...

29/08/2024 CP 102 PRINCIPLES OF PLANT Chapter I DISEASE DIAGNOSIS AND MANAGEMENT The Diagnostic Process JOANNE A. LANGRES, M.Sc. Faculty, DPSS, CSU-CAA College of Agriculture and Agri-Industries Caraga State University Ampayon, Butuan City, Agusan del Norte, Ph 1 2 Learning Objectives Plant Disease Diagnosis The science and art of the methods At the end of this lesson, the student must be able to: of examining plants to diagnose their diseases. 1. Understand the concept of plant disease diagnosis; The identification of specific plant diseases through their 2. Identify the different techniques for plant disease characteristic symptoms and signs. diagnosis; and Includes the identification of biotic 3. Know the general diagnostic process of plant disease or abiotic factors causing the diagnosis. disease. 3 4 CHARACTERISTICS OF PLANT DISEASE WHAT IS A 1. A malfunctioning process that results in suffering DISEASE? 2. Generally harmful/detrimental 3. Produce symptoms 4. Caused by an agent 5 6 1  29/08/2024 A plant is healthy or normal when it can carry out its physiological functions to the A plant is diseased when there is any best of its genetic potential. abnormal change in: -structure (shorter, taller, has more These functions include: branches or fewer leaves than normal) or in (1) normal cell division, differentiation and -function (reduced vigor; stunted growth; development; discoloration; fruit development; shorter (2) absorption of water and minerals from life; change in ordinary behavior of the the soil and translocation of these plant), or both. throughout the plant; (3) photosynthesis and translocation of A plant usually produces evidences of diseased condition in the form of photosynthetic products to areas of symptoms. utilization or storage, metabolism and reproduction. 7 8 VITAL PROCESSES OF PLANTS DISEASE TRIANGLE AFFECTED BY DISEASE Plant diseases can be analyzed convenientlyHOST 1. Root absorption using the concept called PLANT the “Disease Triangle”. The 2. Uptake of water & minerals three factors must interact to cause plant disease at 3. Photosynthesis the three corners of a 4. Respiration triangle. Those three factors are: 5. Reproduction a. Susceptible Host ENVIRONMENT b. Virulent Pathogen c. Favorable Environment 9 10 VITAL PROCESSES OF PLANTS VITAL PROCESSES OF PLANTS AFFECTED BY DISEASE AFFECTED BY DISEASE 1. Root absorption 3. Photosynthesis ▪ Infection of roots may cause roots to rot and make them ▪ Infection of the foliage, as happens in leaf spots, blights, rusts, unable to absorb water and nutrients from the soil. mildews, mosaics, and so on, interferes with photosynthesis 4. Transport of photosynthates / Respiration 2. Uptake of water and minerals ▪ Infection of phloem cells in the veins of leaves and in the bark ▪ Infection of xylem vessels, as happens in vascular wilts of stems and shoots, as happens in cankers and in diseases and in some cankers, interferes with the translocation of caused by viruses, mollicutes, and protozoa, interferes with the water and minerals to the crown of the plant downward translocation of photosynthetic products. 11 12 2  29/08/2024 VITAL PROCESSES OF PLANTS CLASSIFICATION OF PLANT DISEASES AFFECTED BY DISEASE According to affected plant organ 5. Reproduction ▪ Infection of flowers and fruits interferes with a. root diseases - affect water and mineral uptake reproduction. b. leaf diseases - affect photosynthesis c. fruit diseases - affect reproduction d. stem diseases - affect water conduction 13 14 CLASSIFICATION OF PLANT DISEASES CLASSIFICATION OF PLANT DISEASES According to symptom According to type of host plant leaf spots, rusts, smuts, anthracnose, wilts, fruit rots, vegetable diseases, forest tree diseases, field crop wilt, canker, downy mildews, powdery mildew, diseases, ornamental crop diseases anthracnose 15 16 CLASSIFICATION OF PLANT DISEASES NON-NFECTIOUS INFECTIOUS DISEASES DISEASES According to type of pathogen that caused the disease a. infectious diseases b. non-infectious diseases 17 18 3  29/08/2024 COMMON NON-PARASITIC CAUSES OF PLANT DISEASES B. Diseases caused by too high temperatures ✓ by inhibiting or inactivating certain enzyme systems and A. Diseases caused by adverse physical factors possibly accelerating other systems 1. Diseases caused by excessively low temperatures ✓ cause protein denaturation and coagulation, disruption of a. Freezing injury cell membranes and eventual death of cells ✓ ice crystals that form within the cells (intracellularly) ✓ Damage is increased several folds by lack of moisture and and or between cells (intercellularly) too intense light ✓ damage the cell membrane and eventually kill the cells a. sunscald b. Chilling injury ✓ prolonged exposure to high temperature and bright sunlight ✓ occurs at low temperatures that are slightly above ✓ exhibit light-colored, blistered and water-soaked freezing (pitting and water-soaking) 19 20 b. Heat necrosis of potato D. Diseases caused by too much or too little light ✓ grown in light soils where it is hot and dry. a. Etiolated plants ✓ yellow or brown discoloration in vascular system of affecter tuber ✓ exposed to reduced light intensity ✓ increases their susceptibility to infection by non C. Diseases caused by lack of oxygen obligate parasites, but decreases susceptibility to a. Black heart disease of potato obligate fungi ✓ Oxygen is insufficient so that oxygen that is ✓ increased susceptibility to virus infection available in the internal tissues of potato is used up b. Scorching and sun scalding faster than it can be supplied. ✓ too much bright light along with high ✓ The tissue suffocates and becomes black temperature 21 22 E. Diseases caused by adverse meteorological F. Air Pollutants conditions ✓ any factor mediated by the atmosphere that causes a. strong wind and heavy rains an unwanted effect. ✓ ripped, torn or water-soaked and predisposed to ✓ mainly gases and particulates (soot, dusts and ashes) infections ✓ produced from factories, smelting and refining plants, automobile exhaust and other man related b. lightning injury activities ✓ black and burned poles 23 24 4  29/08/2024 SUMMARY OF POLLUTANTS, SOURCES, SYMPTOMS, INJURY THRESHOLDS AND CHEMICAL ANALYSIS (After National Air Pollution Control Administration, US Dept. of Health Education and Welfare Publication No. AP-71, 1970) 25 26 G. Diseases caused by mineral Deficiencies H. Diseases caused by excesses of nutrient elements - affects the solubility and availability of other elements 1. high Ca level reduces mg and Fe 2. Too much N causes luxuriant vegetative growth 3. excess Cu results to stunting and death of plants 4. Na toxicity causes dwarfing 5. Excess Chloride causes burning of leaf margins and tips, bronzing and premature defoliation 27 28 2. Improper use of pesticides E. Diseases caused by improper agricultural practices ✓ excessively high concentration of the chemical 1. Unfavorable soil pH ✓ incorrect method of applying the pesticide ✓ Alkaline soils with extremely high pH affect the solubility of certain minerals for growth 3. Lack of or excess of soil moisture ✓ Acid soils, with very low pH, causes the ✓ inadequate moisture causes temporary or permanent wilting accumulation in toxic levels of iron and other of plants elements ✓ Prolonged drought ✓ Club root of crucifers (Plasmodiophora brassicae) ✓ Irregular water supply causes blossom-end rot and growth severe at ph 6 -7 but can be controlled at pH 7.8 cracks in tomato ✓ Scab of potato – severe from pH 5.2 to 8.0 but is ✓ Flooding reduces plant’s oxygen supply and weakening the controlled below pH 5.2 root system 29 30 5  29/08/2024 F. Diseases caused by naturally occurring toxic chemicals -Toxic levels of hydrogen sulfide may be formed in the presence of ferrous ion in flooded rice fields under anaerobic conditions causing a disease in rice. 31 32 End of Part 1 THANK YOü! 33 34 6