This presentation covers major diseases of apple, focusing on their causal agents, symptoms, disease cycles, and management strategies. Emphasis is placed on accurate identification and integrated management for sustainable apple production. Key topics include apple scab, powdery mildew, fire blight, and crown gall. Important academic keywords: pathogen, symptoms, disease cycle, management, resistant varieties.
Introduction to Apple Diseases
Apple is susceptible to various fungal, bacterial, and physiological diseases.
Major diseases impact yield, fruit quality, and tree longevity.
Effective management requires understanding pathogen biology and disease cycles.
Integrated approaches combine cultural, chemical, and genetic methods.
Apple Scab – Pathogen and Distribution
Caused by Venturia inaequalis (fungus).
First reported in Sweden (1819); in India, Kashmir valley (1935).
Most economically important apple disease worldwide.
Apple Scab – Symptoms
Black, circular, velvety spots on upper leaf surface; may coalesce.
Leaves become twisted, yellow, and may drop prematurely.
Fruits develop sooty, gray-black lesions, later sunken and tan.
Infected fruits may crack and become deformed; young fruits may drop.
Apple Scab – Disease Cycle and Spread
Primary inoculum: ascospores from fallen leaves in spring.
Ascospores dispersed by wind and rain during wet periods.
Secondary spread: conidia dispersed by wind and rain.
Apple Scab – Management
Sanitation: remove and destroy fallen leaves.
Use resistant varieties: Emira, Redfree, Ambstraking, Ambroyal, Ambrich, Ambred.
Fungicide sprays: captan (0.2%), dodine (0.25%) after petal fall.
Apply difolatan (0.3%) at green bud stage, followed by captan at petal fall.
Powdery Mildew – Pathogen and Symptoms
Caused by Podosphaera leucotricha (fungus).
White or grey powdery patches on young leaves, shoots, and fruits.
Leaves become narrow, curled; twigs covered with powdery mass.
Fruits remain small, deformed, with roughened surface.
Powdery Mildew – Disease Cycle and Management
Overwinters as mycelium in buds; spreads by wind-borne conidia.
Sanitation: remove infected shoots and plant debris.
This presentation covers major diseases of apple, focusing on their causal agents, symptoms, disease cycles, and management strategies. Emphasis is placed on accurate identification and integrated management for sustainable apple production. Key topics include apple scab, powdery mildew, and fire blight. Important academic keywords: pathogen, symptoms, disease cycle, management, resistant varieties.
Introduction to Apple Diseases
Apple is affected by several fungal and bacterial diseases.
Major diseases include apple scab, powdery mildew, fire blight, and crown gall.
Effective management requires understanding pathogen biology and integrated control methods.
Major Apple Diseases and Causal Agents
Apple scab: Venturia inaequalis
Powdery mildew: Podosphaera leucotricha
Fire blight: Erwinia amylovora
Crown gall: Agrobacterium tumefaciens
Other diseases: Black rot, sooty blotch, flyspeck, Phytophthora crown rot
Apple Scab – Pathogen and Distribution
Caused by Venturia inaequalis (fungus).
First reported in Sweden (1819); in India, on Ambri variety in Kashmir (1935).
Favored by cool, moist conditions during spring.
Apple Scab – Symptoms
Black, circular, velvety spots on upper leaf surface; may coalesce.
Leaves become twisted, yellow, and may drop prematurely.
Fruits show sooty, gray-black lesions that become sunken and tan.
Severely affected fruit may crack and drop early.
Apple Scab – Disease Cycle and Spread
Primary inoculum: ascospores from fallen leaves in spring.
Secondary spread: conidia dispersed by wind and rain.
Infection favored by wet weather during bud break and early fruit development.
Apple Scab – Management
Sanitation: remove and destroy fallen leaves.
Use resistant varieties: Emira, Redfree, Ambstraking, Ambroyal, Ambrich, Ambred.
Fungicide sprays: captan (0.2%), dodine (0.25%) after petal fall.
Apply difolatan (0.3%) at green bud stage, followed by captan at petal fall.
Powdery Mildew – Pathogen and Symptoms
Caused by Podosphaera leucotricha (fungus).
White or gray powdery patches on young leaves, shoots, and fruits.
Leaves become narrow, curled, and distorted; twigs covered with powdery mass.
Affected fruits are small, deformed, and roughened.
Powdery Mildew – Disease Cycle and Management
Overwinters as mycelium in buds and fruits.
Spread by wind-borne conidia in spring and summer.
Sanitation: remove infected shoots and plant debris.
Spray lime sulphur (1:60) pre-bloom; dinocap (0.05%) or wettable sulphur.
Resistant varieties: Maharaja Chunth, Golden Chinese, Yantarka Altaskya, Dolgoe.
Fire Blight – Pathogen and Symptoms
Caused by Erwinia amylovora (bacterium).
Affects blossoms, shoots, branches, and sometimes rootstock.
Blossoms become water-soaked, then brown to black and shriveled.
Shoots wilt, forming “shepherd’s crook”; leaves blacken along veins.
Infected fruit shrivel, turn black, and may remain attached.
Fire Blight – Disease Cycle and Spread
Bacteria overwinter in cankers and healthy woody tissue.
Spread by insects (bees, flies, ants) and rain splash.
Infection occurs during warm, humid weather, especially at bloom.
Fire Blight – Management
Prune and burn infected twigs and branches 30 cm below visible symptoms.
Disinfect tools with 10% sodium hypochlorite after each cut.
Control insect vectors.
Use resistant varieties where available.
Dormant sprays: copper sulphate or Bordeaux mixture; streptomycin for blossom protection.
Other Important Apple Diseases (Brief Overview)
Cedar apple rust: Gymnosporangium juniperi-virginianae – orange leaf spots, fruit lesions.
Crown gall: Agrobacterium tumefaciens – tumor-like galls on roots and stems.
Black rot: Botryosphaeria obtusa – fruit rot, leaf spots, cankers.
Sooty blotch and flyspeck: superficial fruit blemishes, reduce market value.
Phytophthora crown, collar, and root rot: Phytophthora spp. – root decay, tree decline.
Summary: Integrated Disease Management in Apple
Combine cultural, chemical, and genetic approaches for effective control.
Regular orchard sanitation and pruning are essential.
Use disease-resistant varieties when possible.
Apply fungicides and bactericides judiciously, following recommended schedules.
Monitor orchards regularly for early detection and management.
This presentation covers the major diseases affecting pea (Pisum sativum), focusing on their causal agents, symptoms, disease cycles, and management strategies. Emphasis is placed on accurate identification, epidemiology, and integrated management practices. Key concepts include pathogen identification, symptomatology, disease cycle, epidemiology, and integrated disease management.
Introduction to Pea Diseases
Pea (Pisum sativum) is susceptible to several fungal diseases.
Major diseases include Fusarium wilt, powdery mildew, downy mildew, rust, and Ascochyta blight.
Effective management requires understanding pathogen biology and disease epidemiology.
Fusarium Wilt – Pathogen and Symptoms
Caused by Fusarium oxysporum f. sp. pisi.
Initial symptoms: drooping, yellowing, and premature leaf drop.
Pod formation is severely affected; collar region shows necrosis and discoloration.
Dark brown vascular discoloration visible in stem cross-section.
Fusarium Wilt – Disease Cycle and Management
Pathogen survives in soil for long periods; infects via root hairs.
Primary infection: soil, seed, water; secondary: conidia via rain splash.
Favored by soil temperatures of 23–27°C and warm weather.
Seed treatment with carbendazim (2 g/kg) and soil drenching with copper oxychloride (0.25%) recommended.
Powdery Mildew – Pathogen and Symptoms
Caused by Erysiphe pisi.
Appears as white powdery spots on leaves, stems, and pods.
Severely infected leaves become chlorotic, distorted, and may fall.
Pods may be small and malformed.
Powdery Mildew – Disease Cycle and Management
Spread by airborne spores; thrives in warm (15–25°C), humid (>70%) conditions.
Cultural control: use resistant varieties, destroy infected stubble, avoid adjacent sowing to previous pea fields.
Chemical control: sprays of benomyl, carbendazim, sulphur, or triadimefon as per recommended doses and intervals.
Downy Mildew – Pathogen and Symptoms
Caused by Peronospora viciae.
Grayish-white mold on lower leaf surface; yellowish area on upper side.
Infected leaves turn yellow, die; stems may be stunted and distorted.
Brown blotches and mold may develop on pods.
Downy Mildew – Disease Cycle and Management
Primary infection: soil, seed, water; secondary: sporangia via rain splash or wind.
Favored by high humidity and low temperatures (5–15°C).
Remove and burn diseased plants promptly to reduce inoculum.
Rust – Pathogen and Symptoms
Caused by Uromyces pisi.
Initial symptoms: leaf flecking, progressing to reddish-brown pustules.
Pustules merge, burst, and release brown spores; severe cases cause plant drying and yield loss.
Rust – Disease Cycle and Management
Survives on infected plant debris and alternate hosts (e.g., Euphorbia).
Favored by frequent precipitation, dew, and temperatures of 20–25°C.
Cultural control: destroy debris, crop rotation with non-legumes, mixed cropping.
Chemical control: sulphur or triadimefon sprays as per recommendations.
Ascochyta Blight – Pathogens and Symptoms
Caused by Ascochyta pisi, A. pinodes, and A. pinodella.
Symptoms: purplish-brown flecks on lower leaves, stems, tendrils; lesions enlarge and coalesce.
Severe infection causes foot rot (purplish-black lesions at soil line), lodging, and pod lesions.
Pod infection leads to small, discolored, or shrunken seeds.
Ascochyta Blight – Disease Cycle and Management
Ascospores spread by wind; conidia by rain splash.
Primary infection from diseased seed or soil debris.
Favored by warm, humid conditions (15–25°C).
Use resistant varieties (e.g., B-90, CDC Frontier, CDC Luna), seed treatment with thiabendazole, and crop rotation.
Summary: Integrated Disease Management in Pea
Combine cultural, chemical, and genetic resistance strategies for effective control.
Use certified disease-free seed and resistant varieties.
Practice crop rotation and field sanitation.
Apply fungicides judiciously based on disease monitoring and recommendations.
This presentation covers major diseases of cucurbits, including their symptoms, etiology, disease cycles, and management strategies. Emphasis is placed on accurate identification and integrated management of fungal, bacterial, and viral pathogens affecting cucurbit crops. Key concepts include disease diagnosis, pathogen biology, epidemiology, and control measures. Important academic keywords: pathogen, symptoms, disease cycle, management, cucurbits.
Introduction to Diseases of Cucurbits
Cucurbits include cucumber, melon, watermelon, pumpkin, squash, and gourds.
Major diseases: Downy mildew, Powdery mildew, Fusarium wilt, Angular leaf spot, Cucumber mosaic, and Tospovirus.
Diseases caused by fungi, bacteria, and viruses.
Effective management requires accurate diagnosis and integrated control strategies.
This presentation covers major diseases of brinjal (eggplant), focusing on their causal agents, symptoms, disease cycles, and management strategies. Emphasis is placed on identification, epidemiology, and integrated disease management. Key topics include little leaf, bacterial wilt, Phomopsis fruit rot, and Cercospora leaf spot. Important academic keywords: Phytoplasma, Ralstonia solanacearum, Phomopsis, epidemiology, management.
Introduction to Brinjal Diseases
Brinjal (Solanum melongena) is affected by several major diseases.
Diseases reduce yield and fruit quality significantly.
Understanding pathogens and symptoms is crucial for effective management.
Little Leaf Disease of Brinjal
Pathogen: Phytoplasma, localized in phloem sieve tubes.