CP 102 Principles of Plant Disease Diagnosis and Management PDF

08/09/2024 CP 102 PRINCIPLES OF PLANT DISEASE DIAGNOSIS Chapter II AND MANAGEMENT The Diagnostic Process JOANNE A. LANGRES, M.Sc. Faculty, DPSS, CSU-CAA...

08/09/2024 CP 102 PRINCIPLES OF PLANT DISEASE DIAGNOSIS Chapter II 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 At the end of this lesson, the student must be able to: 1. Understand the concept of plant disease diagnosis; 2. Identify the different techniques for plant disease SYMPTOMS OF PLANT DISEASES diagnosis; and 3. Know the general diagnostic process of plant disease diagnosis. 3 4 SYMPTOMS OF PLANT DISEASES SYMPTOMS OF PLANT DISEASES Primary symptom Localized symptoms ▪ are results of the causal agent’s activities on ▪ are characterized by distinct and very limited the invaded tissues. structural changes usually in the form of the lesions. Secondary symptoms Systemic symptoms ▪ are the effects on the distant and uninvaded ▪ are more generalized pathological condition such plant parts. as mottle, mosaic and wilting. 5 6 1  08/09/2024 Localized or Systemic Symptoms Localized or Systemic Symptoms 7 8 GENERAL CLASSIFICATION OF SYMPTOMS GENERAL CLASSIFICATION OF SYMPTOMS i. CHANGE IN THE NATURAL COLORING OF THE PLANT ii. NECROTIC SYMPTOMS a. Chlorosis – failure of development of the green color involved the death or protoplast, cells or tissues. of the leaf in the achlorophyllous organ. Examples are spot, blight, scorch, canker b. Anthocynescene – changes in the anthocyanin content, and die-back. Necrosis may be localize a watersoluble pigment, gives the plant a purplish or or generalize necrosis is confine to limited reddish coloration. areas while in generalize necrosis, the c.Formation of melanin in diseased plants results in a dark death of host cells, the entire plant part brown or black discoloration of the affected tissues. become necrotic. 9 10 GENERAL CLASSIFICATION OF SYMPTOMS iii. HYPOPLASTIC SYMPTOMS appear when there is an inhibition or failure in the differentiation or development of some aspect of plant growth. Examples are stunting, mottle, mosaic, resetting and curling. 11 12 2  08/09/2024 GENERAL CLASSIFICATION OF SYMPTOMS iv. HYPERPLASTIC SYMPTOMS are expressed with the occurrence of excessive multiplication, enlargement or overdevelopment may result from an increase in the size of the cells (hypertrophy) or an abnormal increase in the number of cells of hyperplasia. 13 14 SPECIFIC SYMPTOMS AND THEIR DESCRIPTION SPECIFIC SYMPTOMS AND THEIR DESCRIPTION BLAST BLIGHT sudden death of young buds, extensive, usually sudden death of host inflorescence or young fruits tissue, such as leaf blight ABSCISSION BLEEDING premature falling of leaves, fruits and flowers due to early laying down of abscission layer. flow of plant sap from wounds 15 16 SPECIFIC SYMPTOMS AND THEIR DESCRIPTION SPECIFIC SYMPTOMS AND THEIR DESCRIPTION CALLUS CHLOROSIS overgrowth of tissue formed in response yellowing caused by factors other than to injury in an effort to heal the wound light such as viruses or mycoplasma CANKER BLOTCH sunken or necrotic area with cracked large, irregular spots on leaves and fruits border that may appear in leaves, fruits, with necrotic injury of epidermal cells. stems and branches 17 18 3  08/09/2024 SPECIFIC SYMPTOMS AND THEIR DESCRIPTION SPECIFIC SYMPTOMS AND THEIR DESCRIPTION DIE-BACK FASCIATION drying backward from the tip of twigs or branches clustering of roots, flowers, fruits or twigs around a common focus DAMPING-OFF ETIOLATION rotting of seedling prior to emergence or rotting of seedlings at an area just above yellowing of normally green tissues, elongation of the soil line stems caused by inadequate light 19 20 SPECIFIC SYMPTOMS AND THEIR DESCRIPTION SPECIFIC SYMPTOMS AND THEIR DESCRIPTION GUMMOSIS MOSAIC oozing out of viscid gums from wounds presence, usually on leaves or variegated in barks patterns of green and yellow shades with sharply defined boarders FLECKS LEAK extremely tiny spots on leaves, fruits or the host's juices exude or leak out from stems, etc. soft-rotted portion 21 22 SPECIFIC SYMPTOMS AND THEIR DESCRIPTION SPECIFIC SYMPTOMS AND THEIR DESCRIPTION MUMMIFICATION PITTING an infected fruit is converted to a dry, definite depressions or pits are found on hard, shriveled mummy surface of fruits, tubers and other fleshly organs MOTTLING PHYLLODY variegation is less defined than mosaic and the boundaries of light and dark metamorphosis of sepals, petals, stamens or carpels into a leaf-like structures variegated areas are more defused 23 24 4  08/09/2024 SPECIFIC SYMPTOMS AND THEIR DESCRIPTION SPECIFIC SYMPTOMS AND THEIR DESCRIPTION ROTTING SARCODY disintegration and decomposition of abnormal swelling of bark around the host tissue wounds due to the accumulation of elaborated food materials ROSETTING RUSETTING shortening of the internodes of shoots and stems forming a crowding of foliage in a superficial brownish roughening of the skin following injury to epidermis rosette 25 26 SPECIFIC SYMPTOMS AND THEIR DESCRIPTION SPECIFIC SYMPTOMS AND THEIR DESCRIPTION SCAB SPOT slightly raised, rough, ulcer-like lessions localized necrotic area also referred to as due to the overgrowth of epidermal lesion, may be circular, angular and cortical tissue or irregularly shaped SAVOYING SHOT-HOLE pocketing parts of the leaf; also curling or puckering due to underdevelopment of perforated appearance of a leaf as the dead areas of local lesions drop out veins of leaf margins 27 28 SPECIFIC SYMPTOMS AND THEIR DESCRIPTION SPECIFIC SYMPTOMS AND THEIR DESCRIPTION VEIN CLEARING WILTING leaf veins are transluscent or pale while drooping of leaves and branches, leaves the rest of the leaf is its normal color fade to yellow, then to brown and die STREAK OR STRIPE VIRESCENCE OR GREENING long, narrow necrotic lesions on leaves development of chlorophyll in tissues or or stems organs where it is normally absent 29 30 5  08/09/2024 - These are any observable part or remnant of the causal agent (pathogen) in diseased plants. - the pathogen or its parts or products seen on a host plant -the structures of the pathogens that are found associated with the infected plant SIGNS OF PLANT DISEASES -examples: fungal mycelia, conidia, oospores, teliospores, ascospores, zoospores, fruiting bodies, sclerotial bodies, chlamydospores; bacterial ooze, bacterial cells; nematode eggs, larvae and adult; virus particles; seed of phanerograms 31 32 SIGNS OF PLANT DISEASES SIGNS OF PLANT DISEASES Signs of plant disease refer to the structures of the fungal mycelia pathogen that are found associated with the infected spores and fruiting bodies plant. Some of these structures may not always be bacterial ooze present in disease plant because their formation depends sclerotial bodies on environmental conditions. Most of these signs are nematodes at various growth best seen and distinguished under a microscope. stages 33 34 35 36 6  08/09/2024 SIGNS OF PLANT DISEASES 37 38 SIGNS OF PLANT DISEASES PLANT DISEASE DIAGNOSIS DIAGNOSIS- the identification of specific plant diseases through their characteristic signs and symptoms including other factors that may be related to the disease process. Bacterial Ooze 39 40 PLANT DISEASE DIAGNOSIS CORRECT PLANT DISEASE DIAGNOSIS IS NECESSARY FOR RECOMMENDING THE APPROPRIATE CONTROL MEASURES. Pseudomonas cepacia Botrytis aclada 41 42 7  08/09/2024 PLANT DISEASE DIAGNOSIS ROBERT HEINRICH HERMANN KOCH German physician and one of the founders of bacteriology. With his collaborators, he devised KOCH'S POSTULATES new research methods to isolate pathogenic bacteria. Koch determined guidelines to prove that a disease is caused by a specific organism. 43 44 CONSTANT ASSOCIATION KOCH'S POSTULATES when we suspect a 1 2 3 4 pathogen that causes the disease of the plant, it must be found in all cases of the disease examined in the affected plant and CONSTANT ASSOCIATION ISOLATION INOCULATION RE-ISOLATION must be absent in healthy plants. 45 46 ISOLATION where the suspected pathogen is grown in the laboratory to obtain a pure culture which is capable of producing the original disease symptom 47 48 8  08/09/2024 INOCULATION RE-ISOLATION the suspected casula when the pure culture of organism must be re- the suspected pathogen is isolated and must inoculated in the healthy produce a pure culture test plant and must from the inoculated plant produce the symptom and must be identical to same as the infected plant. the original suspected pathogen. 49 50 Methods for Plant Disease Diagnosis A. Conventional Method Methods for Plant Disease Visual examination of disease Diagnosis specimen Direct isolation of pathogens (bacteria and fungi) in artificial media Laboratory identification by morphology and biochemical test. 51 52 Methods for Plant Disease Diagnosis Methods for Plant Disease Diagnosis B. Modern Methods B. Modern Techniques Polymerase chain reaction (PCR) DNA-based and serological methods now provide Enzyme-linked immunosorbent essential, quickness, cost assay (ELISA) efficiency, high-throughput tools for accurate plant Immunofluorescence (IF) disease diagnosis. Fluorescence in-situ hybridization (FISH) 53 54 9  08/09/2024 Collection of Samples IN THE FIELD Field Survey by farmer or District Staff Disease thought to be Detailed examination of caused by nematodes or samples in laboratory viruses ISOLATION General steps in diagnosing the diseases Possible fungal or bacterial diseases Isolation and detection of nematodes IDENTIFICATION Morphological identification of Isolation and Purification Identification by Expert fungal pathogen 55 56 Precautions in Diagnosis Confirmation of new disease by national/ Identification Well-known Pathogen international center a. Never overlook the possibility of several diseases occurring on the same plant or part of the plant. IDENTIFICATION Pathogenicity Testing b. There are several cases of insect damage that can be mistaken for disease caused by fungi, bacteria or viruses. Complete Diagnosis c. The cultural conditions under which a crop is grown must be carefully considered. Advise farmer of best control/ IDM Strategy 57 58 Collecting Plant Disease Samples a. Collect good quality specimens. b. Collect all parts of the plant which show evidence of disease. THANK c. Wrap specimen in moist paper and enclose in a plastic bag. d. Where it is necessary to preserve specimen for long-term storage, YOü! using Formalin-acetic acid-alcohol (FAA). e. Photographs of the diseased specimen may also be helpful in diagnosis. 59 60 10