Tag: plant pathology

• Okra (Abelmoschus esculentus) is affected by several fungal and viral diseases.
• Major diseases: Powdery mildew, Fusarium wilt, Alternaria leaf spot, Yellow vein mosaic.
• Effective management requires knowledge of pathogens, symptoms, and control measures.

• White or grayish powdery growth on upper leaf surfaces, later covering entire leaf.
• Lower leaf surfaces may also be infected.
• Affected leaves dry and fall prematurely, reducing yield.

Disease Cycle:

• Overwinters as dormant mycelium or cleistothecia on infected leaves.
• Secondary spread by wind-borne conidia.
• Favored by 60–80% relative humidity and dry conditions.

Management:

• Spray fungicides: wettable sulphur (0.25%), dinocap (0.1%), carbendazim (0.1%), hexaconazole (0.05%), or difenoconazole (0.05%).
• Repeat sprays at 10–14 day intervals.
• Biocontrol: Ampelomyces quisqualis, Trichoderma spp., Bacillus subtilis.
• Use azadirachtin (0.03% EC) as needed.

• Yellowing, stunting, wilting, and rolling of leaves.
• Dark brown vascular discoloration in stems.
• Severe cases: stem blackening and plant death.

Etiology:

• Produces hyaline mycelium, microconidia (single/two-celled), macroconidia (3–4 septa), and chlamydospores.

Disease Cycle:

• Survives as chlamydospores in soil and infected seeds.
• Optimum temperature for growth: 25°C; disease develops at 22–28°C.

Management:

• Use healthy, treated seed (carbendazim 0.2%).
• Practice crop rotation and soil solarization.
• Remove and destroy affected plants.
• Grow resistant varieties: CS-3232, CS-8899, IS-6653, IS-7194, Pusa Makhameli, Pusa Sawani.

• Brown leaf spots with pale margins and yellow halos.
• Lesions enlarge, show concentric rings, and coalesce.
• Severe infection causes leaf drying and defoliation.

Etiology:

• Produces cylindrical conidiophores and brown, muriform conidia with transverse and longitudinal septa.

Disease Cycle:

• Survives in infected plant debris, weed hosts, and seeds.
• Secondary spread by wind-borne conidia.

Management:

• Remove and destroy infected debris and weeds.
• Seed treatment with Thiram (6 g/kg).
• Spray Mancozeb (0.2%) after disease appearance.

• Vein yellowing and thickening, forming a network pattern.
• Leaves become chlorotic and yellow under severe infection.
• Plants are stunted with small, pale fruits.

Disease Cycle:

• Transmitted by whitefly (Bemisia tabaci) in a persistent manner.
• Wild and cultivated plants act as inoculum sources.
• Favored by dry, hot weather with low rainfall.

Management:

• Destroy wild hosts and avoid mixed cropping with pumpkin.
• Adjust sowing dates to avoid peak whitefly populations.
• Remove infected plants up to 55 days after sowing.
• Grow resistant cultivars: Punjab Padmini, Punjab-8, Prabhani Kranti, Hissar Unnat.
• Spray systemic insecticides (cypermethrin, deltamethrin, triazophos) to control vectors.

• Use disease-free, treated seeds and resistant varieties.
• Practice crop rotation, field sanitation, and timely removal of infected plants.
• Apply recommended fungicides and insecticides judiciously.
• Adopt biological control agents where feasible.
• Monitor fields regularly for early detection and management.

• Botanical name: Camellia sinensis
• Chromosome number: 2n = 30
• Origin: China
• Tea is susceptible to various fungal, algal, and oomycete diseases affecting yield and quality.
• Effective disease management is crucial for sustainable tea cultivation.

• Circular, raised, purple to reddish-brown lesions on leaves.
• Older spots become greenish-gray, resembling lichen.
• Most lesions develop on upper leaf surface; rarely harmful to plant vigor.

Disease Cycle:

• Alga produces rust-colored spore-like bodies on leaf spots.
• Dispersed by wind or rain; favored by high humidity and poor drainage.

Management:

• Avoid plant stress and poorly drained sites.
• Promote air circulation; prune and destroy infected parts.
• Apply Bordeaux mixture; improve soil nutrition (NPK).

• Small, oval, pale yellow-green spots on young leaves.
• Spots enlarge, turn brown/gray with concentric rings and black dots.
• Leads to defoliation; affects leaves of all ages.

Disease Cycle:

• Fungal spores in black dots on lesions.
• Spread by rain splash; infect new leaves under wet conditions.

Management:

• Avoid plant stress; ensure adequate spacing for air flow.
• Spray Copper Oxychloride or Bordeaux mixture (0.1%) in winter and summer.

• Pinhole-sized spots on young leaves (<1 month old).
• Spots enlarge, become transparent, then light brown.
• Blister-like symptoms with water-soaked zones; blisters turn white and velvety, then brown.
• Young stems may bend, break, or die.

Disease Cycle:

• Continuous cycle in wet conditions; spores dispersed by wind.
• Direct penetration of leaf tissue; symptoms in 10 days.

Management:

• Prune and destroy affected leaves and shoots.
• Spray Bordeaux mixture, Copper Oxychloride (0.1%), or triazole fungicides (e.g., hexaconazole).
• Apply fungicides at 5-day intervals during rainy season.

• Black, hair-like fungal threads on upper branches and twigs.
• Rapid leaf drop due to volatile substances produced by fungus.

Disease Cycle:

• Spread via extension of hair-like threads from infected to healthy twigs.

Management:

• Remove and destroy crop debris.
• Prune out infected or dead branches.

• Small, brown, irregular spots on flower petals.
• Whole flower turns brown and drops prematurely.

Disease Cycle:

• Emerges in early spring during high moisture periods.

Management:

• Remove infected flowers and crop debris.
• Apply soil drenches with suitable fungicides.

• Browning and drooping of leaves; shoots dry and die.
• Cankers form on branches; tip dieback.

Disease Cycle:

• Spores produced on dead branches; spread by rain splash.
• Entry through wounds; survives on pruned branches.

Management:

• Plant in well-drained, acidic soils.
• Remove diseased twigs below cankered areas; disinfect tools.
• Apply protective fungicides during wet weather.

• Originates from dead leaves above soil; spreads to roots.
• Star-like mycelium under bark; mycelium surrounds stem base.
• Swollen ring of tissue above dead patch.

Management:

• Remove and destroy infected plants.
• Practice clean cultivation; remove fallen leaves.
• Dig trenches around infected bushes to expose soil to sunlight.

• Sudden yellowing and wilting of leaves; branch tip dieback.
• Gray blotches and sunken cankers on bark and stem.
• Cankers girdle stem; upper parts lose vigor and die.

Comments:

• Fungus enters through wounds; symptoms worsen in hot, dry weather.

Management:

• Plant in well-drained, acidic soils.
• Remove diseased twigs below cankers; disinfect tools.
• Apply protective fungicides during wet periods.

• Yellowing leaves; poor growth; wilting; discolored roots; rapid plant death.

Comments:

• Favored by poorly drained, warm soils.

Management:

• Plant in well-drained soils; avoid waterlogging.
• Apply appropriate fungicides to protect plants.

• Yellowing foliage; wilting or sudden death of plant parts.
• Withered leaves remain attached; red discoloration of roots; whitish mycelium visible.

Comments:

• Spread by mycelial strands in soil.

Management:

• Remove infected bushes and adjacent symptomatic plants.
• Remove all living/dead roots and stumps; destroy by burning.
• Treat surrounding bushes to prevent spread.

• Apply Benomyl or Copper Oxychloride (0.01%).
• Use botanical extracts (e.g., Azadirachta, A. nilagirica) at 10% concentration.
• Apply biocontrol agents (Bacillus sp., Pseudomonas sp., Trichoderma viride).

• Use Bacillus megaterium as a plant growth promoter and biocontrol agent.
• Induces systemic resistance and reduces disease incidence.

• Apply antagonistic fungi (e.g., Aspergillus niger, Trichoderma atroviride, T. citrinoviride) as foliar sprays.
• Reduces symptom severity and disease index.

• Combine cultural, chemical, and biological control methods for sustainable management.
• Use resistant varieties where available.
• Maintain field hygiene: remove debris, prune infected parts, ensure proper spacing.
• Apply fungicides judiciously to avoid resistance.
• Promote beneficial microorganisms for biocontrol.

• Papaya is susceptible to various fungal, viral, and post-harvest diseases.
• Diseases affect yield, fruit quality, and marketability.
• Effective management requires accurate diagnosis and integrated approaches.

• Powdery Mildew: Oidium indicum, Oidium caricae, Leveillula taurica
• Leaf Blight: Corynespora cassiicola
• Damping-Off: Pythium aphanidermatum, Rhizoctonia solani
• Foot Rot: Pythium aphanidermatum
• Anthracnose: Colletotrichum gloeosporioides

• Speckled, water-soaked spots on leaf underside.
• Powdery patches enlarge, covering leaves.
• Leaves become chlorotic, distorted, and fall prematurely.

Management:

• Clean cultivation and balanced fertilization (increase K, reduce N).
• Dusting sulfur (30 g/10 L water) at symptom onset.
• Spray Triadimefon (0.1%) or systemic fungicides (Bayleton, carbendazim) at intervals.

• Water-soaked patches at stem base, girdling stem.
• Tissues turn brown/black and rot; terminal leaves yellow and wilt.
• Fruits shrivel and drop; plant may topple and die.
• Roots deteriorate; bark appears dry, honeycomb-like.

Management:

• Use well-drained nursery beds; remove and destroy diseased seedlings.
• Apply Trichoderma viride (15 g/plant) with FYM at planting.
• Seed treatment with captan (4 g/kg) or chlorothalonil (2 g/kg).
• Drench stem base with COC (0.25%), metalaxyl (0.1%), or Bordeaux mixture (1.2%).

• Gray to brown spots with dark margins and yellow halo on leaves.
• Necrotic areas form as spots coalesce.
• Fruits develop light spots that enlarge, become dark brown, and may show concentric rings.
• Premature fruit drop common.

Management:

• Remove and destroy affected fruits.
• Harvest fruits at maturity.
• Spray copper oxychloride (0.3%), carbendazim (0.1%), or thiophanate-methyl (0.1%) every 15 days.
• Hot water or fungicidal wax treatment for export fruits.

• Papaya Mosaic Virus (transmitted by Aphis gossypii)
• Papaya Leaf Curl Virus (transmitted by Bemisia tabaci)
• Papaya Ring Spot Virus (PRSV; transmitted by aphids)

• Mild mosaic pattern and deformation in young leaves.
• Dark green blister-like patches on yellowish-green leaves.
• Leaf vein clearing, downward curling, and shortened petioles.

• Severe curling, crinkling, and deformation of young leaves.
• Vein clearing and thickening; twisted petioles.
• Stunted growth, reduced yield, and possible defoliation.

• Prominent mosaic and chlorosis on leaves.
• Oily streaks on petioles and trunk.
• Distorted young leaves; concentric rings and C-shaped markings on fruits.

• Use disease-free seedlings for planting.
• Rogue and destroy infected plants promptly.
• Control vectors with insecticides (monocrotophos 0.05%, dimethoate 0.2%, metasystox 0.1%).

• Macrophomina Rot: Macrophomina phaseolina
• Rhizopus Rot (Soft Rot): Rhizopus stolonifer
• Phomopsis Rot: Phomopsis caricae
• Anthracnose: Colletotrichum gloeosporioides

• Small water-soaked spots on fruit surface.
• Spots deepen, causing internal rot and sclerotia formation.
• Inner tissues turn brownish-black with dark mycelial growth.

• Irregular water-soaked lesions on injured fruits.
• Lesions covered with whitish fungal growth, turning dark brown.
• Fruit becomes watery, emits foul odor, and infection spreads rapidly.

• Initial water-soaked spots become sunken and dark brown to black.
• Spots may be surrounded by white, raised tissue.
• Infected area becomes soft and pulpy.

• Harvest fruits at proper maturity and during cool hours.
• Dipping fruits in TBZ (1000 ppm) or benomyl (20 ppm) reduces storage decay.
• Dusting fruits with benzoic acid (0.1%) in kaolin reduces rotting.

• Adopt clean cultivation and use disease-free planting material.
• Monitor and manage vectors for viral diseases.
• Apply recommended fungicides and biological agents for fungal diseases.
• Practice proper post-harvest handling to minimize losses.

• Cabbage is susceptible to several economically important fungal diseases.
• Fungal pathogens affect yield and quality.
• Early identification and management are crucial for disease control.
• Integrated approaches are recommended for sustainable management.

• Pathogen: Rhizoctonia solani.
• Symptoms: Stem constriction at base, stunted growth, seedlings may break at ground level.
• Favored by mechanical injury and wet conditions.
• Management: Use certified disease-free transplants, avoid injury, ensure good drainage.

• Pathogen: Fusarium oxysporum f. sp. conglutinans.
• Symptoms: Leaf yellowing, wilting, stunted growth, twisted stems, unilateral midrib curvature.
• Soil-borne and persists for years.
• Management: Grow resistant varieties, crop rotation, use disease-free seed.

• Pathogen: Leptosphaeria maculans (Phoma lingam).
• Symptoms: Light brown stem lesions with purplish margins, black dots (pycnidia), cankering at base.
• Seed and residue-borne.
• Management: Use disease-free seed, hot water seed treatment, crop rotation, sanitation.

• Pathogen: Alternaria brassicae, A. brassicicola.
• Symptoms: Circular brown to black spots with concentric rings and yellow halos.
• Seedborne and airborne spread.
• Management: Remove crop debris, seed treatment, crop rotation, fungicide application.

• Pathogen: Plasmodiophora brassicae (plasmodiophoromycete, not true fungus).
• Symptoms: Root galls, wilting, stunted and yellow leaves, premature bolting.
• Favored by acidic, moist soils.
• Management: Use clean seedbeds, long crop rotations, lime soil to raise pH, resistant varieties.

• Pathogens: Fusarium spp., Pythium spp., Rhizoctonia solani.
• Symptoms: Seedling collapse, wet rot at stem base, missing or wilted seedlings.
• Favored by high moisture and poor drainage.
• Management: Use sterilized soil, raised beds, good drainage, biocontrol agents.

• Pathogen: Hyaloperonospora brassicae (formerly Peronospora parasitica).
• Symptoms: Yellow patches on upper leaf surface, white fluffy growth below, leaf drop, black spots on curds.
• Favored by cool, moist conditions.
• Management: Resistant varieties, crop rotation, debris removal, avoid leaf wetting, fungicides.

• Pathogen: Erysiphe cruciferarum.
• Symptoms: White powdery growth on upper leaf surfaces, reduced vigor.
• Favored by dry, warm conditions.
• Management: Resistant varieties, fungicides, avoid excess nitrogen, reduce drought stress.

• Pathogen: Albugo candida (oomycete, not true fungus).
• Symptoms: White blisters on leaf undersides, yellow patches above, stem distortion, leaf galls.
• Favored by cool, moist weather.
• Management: Resistant varieties, crop rotation, fungicides.

• Pathogen: Mycosphaerella brassicicola.
• Symptoms: Grey leaf lesions with black dots in concentric rings, reduced growth, delayed harvest.
• Spread by seed and debris.
• Management: Hot water seed treatment, fungicides, remove infected plants and debris.

• Pathogens: Sclerotinia sclerotiorum, S. minor.
• Symptoms: Water-soaked lesions, fluffy white mycelium, black sclerotia inside stems.
• Favored by high humidity and dense canopy.
• Management: Improve air circulation, avoid injury, crop rotation, remove infected debris.

• Pathogen: Rhizoctonia solani.
• Symptoms: Tan or brown lesions on outer leaves, rapid head rot.
• Favored by wet, poorly drained soils.
• Management: Raised beds, proper fertilization, maintain plant health.

• Pathogen: Phytophthora megasperma.
• Symptoms: Leaf margin discoloration (red/purple), root and stem rot, plant wilting and death.
• Favored by poorly drained soils.
• Management: Improve drainage, crop rotation, soil treatments, fungicides.

• Use disease-free seed and resistant varieties.
• Practice crop rotation and field sanitation.
• Maintain proper drainage and avoid plant injury.
• Apply fungicides judiciously as needed.
• Monitor regularly for early detection and control.

• 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.

• Caused by Venturia inaequalis (fungus).
• First reported in Sweden (1819); in India, Kashmir valley (1935).
• Most economically important apple disease worldwide.

• 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.

• 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.

• 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.

• 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.

• Overwinters as mycelium in buds; spreads by wind-borne conidia.
• Sanitation: remove infected shoots and plant debris.
• Pre-bloom spray: lime sulphur (1:60); fungicides: dinocap (0.05%).
• Resistant varieties: Maharaja Chunth, Golden Chinese, Yantarka Altaskya, Dolgoe.

• Caused by Erwinia amylovora (bacterium).
• Affects blossoms, shoots, branches, fruits, and rootstock.
• Blossoms become water-soaked, turn brown/black, shrivel.
• Shoots wilt, forming “shepherd’s crook”; leaves blacken along veins.
• Milky, sticky ooze may appear on infected tissues.

• Bacteria overwinter in cankers and woody tissue.
• Spread by insects (bees, flies, ants) and rain splash.
• Prune and destroy infected parts 30 cm below visible symptoms.
• Disinfect tools with 10% sodium hypochlorite after each cut.
• Dormant sprays: copper sulphate or Bordeaux mixture; streptomycin for blossom protection.

• Caused by Agrobacterium tumefaciens (bacterium).
• Galls form on roots and stems near soil line; initially white/flesh-colored, later hard and corky.
• Plants become stunted with chlorotic leaves.

• Use disease-free planting material; avoid wounding roots and stems.
• Crop rotation with cereals or maize.
• Biological control: Agrobacterium radiobacter strain K1026 applied to wounds.
• Penicillin or vancomycin offers partial control.

• Combine cultural, chemical, and genetic resistance strategies.
• Regular monitoring and early detection are essential.
• Sanitation and removal of infected material reduce inoculum.
• Use of resistant varieties minimizes chemical dependence.

• 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.

• 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

• 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.

• 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.

• 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.

• 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.

• 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.

• 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.

• 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.

• 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.

• 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.

• 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.

• 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.

• 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.

• 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.

• 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.

• 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.

• 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.

• 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.

• 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.

• 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.

• 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.

• 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.

• 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.

• 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.

• 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.

• Pathogen: Pseudoperonospora cubensis (oomycete fungus).
• Hosts: All major cucurbits.
• Symptoms: Small yellow, water-soaked lesions on upper leaf surface; lesions turn brown and necrotic.
• Severe infection causes leaf curling, death, and reduced fruit quality.

• Survives on collateral hosts and plant debris.
• Spread by wind-borne sporangia and rain splash.
• Management: Remove weeds, avoid overhead irrigation, use resistant varieties.
• Fungicide sprays: Metalaxyl, chlorothalonil, or zineb at recommended intervals.

• Pathogens: Erysiphe cichoracearum and Sphaerotheca fuliginea.
• Symptoms: White, powdery mycelium on both leaf surfaces, stems, and petioles.
• Leads to leaf yellowing, drying, premature defoliation, and fruit deformation.

• Overwinters as cleistothecia or on collateral hosts.
• Spread by wind-borne conidia.
• Management: Use resistant varieties, ensure good air circulation, apply fungicides (e.g., Calixin, Karathane).

• Pathogen: Fusarium oxysporum f.sp. niveum.
• Symptoms: Seedling damping-off, yellowing and wilting of leaves, vascular discoloration, stem lesions.
• Older plants may collapse suddenly, especially under stress.

• Survives in soil as chlamydospores for years.
• Primary infection from soil; secondary spread by water and wind.
• Management: Seed treatment (Carboxin/Carbendazim), crop rotation, use resistant varieties, balanced fertilization, maintain soil pH 6.5–7.0.

• Pathogen: Pseudomonas syringae pv. lachrymans (bacterium).
• Symptoms: Small, angular, water-soaked leaf spots; milky exudate under moist conditions.
• Lesions dry to form shot-holes; fruit spots cause internal decay and deformation.

• Seed-borne and survives in crop debris.
• Spread by irrigation water and handling wet plants.
• Management: Use pathogen-free seed, crop rotation, avoid overhead irrigation, apply bactericides (e.g., Streptomycin), destroy crop debris.

• Pathogen: Cucumber mosaic virus (CMV).
• Symptoms: Mosaic, leaf distortion, stunting, flower abnormalities, fruit deformation.
• Transmitted by aphids (non-persistent) and cucumber beetles; survives on weeds and alternate hosts.

• Rogue infected plants and eliminate weed hosts.
• Control aphid vectors with insecticides (e.g., monocrotophos, phosphamidon).
• Use resistant varieties where available.

• Pathogen: Tomato spotted wilt virus (TSWV), a tospovirus.
• Symptoms: Leaf bronzing, chlorotic spots, mosaic, die-back, stunting, fruit ring spots and necrosis.
• Transmitted by thrips (e.g., Frankliniella occidentalis, Thrips palmi).

• Use mesh screening and phytosanitary measures in nurseries.
• Avoid planting near thrips reservoirs (ornamentals, older crops).
• Control weeds and volunteer cucurbits.
• Implement early insecticide programs to manage thrips populations.

• Combine cultural, chemical, and biological methods for effective disease control.
• Use resistant varieties and certified seeds.
• Practice crop rotation and field sanitation.
• Monitor regularly for early detection and timely intervention.

• 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.

• Pathogen: Phytoplasma, localized in phloem sieve tubes.
• Symptoms: Small, yellow, soft leaves; shortened petioles and internodes; bushy appearance.
• Flowers, if formed, remain green; fruiting is rare and fruits are hard, necrotic, and mummified.
• Spread by leafhoppers (mainly Hishimonas phycitis); survives in weed hosts.

• Grow tolerant varieties: Pusa Purple Round, Pusa Purple Cluster, Arka Sheel.
• Destroy affected plants and eradicate solanaceous weeds.
• Spray methyl demeton (2 ml/L) or apply phorate granules to soil.
• Seed dip in tetracycline (10–50 ppm) to reduce infection.

• Pathogen: Ralstonia solanacearum, a Gram-negative, motile rod.
• Symptoms: Sudden wilting, leaf epinasty, yellowing, stunting, vascular browning, bacterial ooze from cut stems.
• Soil and seed borne; survives in plant debris, wild hosts, and weeds.
• Spread via irrigation water, infested soil, and contaminated tools.

• Favoured by high soil moisture and temperature.
• Resistant varieties: Pant Samrat, Arka Nidhi, Arka Neelakantha, Surya, BB 1, 44, 49.
• Crop rotation with non-solanaceous crops; green manuring with Brassica spp.
• Soil solarization (125 μm polyethylene, 8–10 weeks); biological control with Pseudomonas fluorescens, Bacillus spp.
• Seed and soil treatment with antagonistic P. fluorescens; seedling dip before transplanting.

• Pathogen: Phomopsis vexans (asexual stage), Diaporthe vexans (sexual stage).
• Attacks all growth stages; most destructive on fruits.
• Symptoms: Damping-off in nursery, collar rot, leaf spots with pycnidia, stem cankers, sunken fruit spots, soft rot, mummified fruits.
• Pathogen is seed-borne and survives in plant debris as mycelium and pycnidia.

• Disseminated by rain splash, irrigation water, tools, and insects.
• Favoured by high humidity, temperatures around 26°C, and wet weather.
• Management: Remove crop debris, crop rotation, use disease-free seed.
• Hot water seed treatment (50°C, 30 min); seed treatment with thiophanate methyl (1 g/kg).
• Spray thiophanate methyl or carbendazim (0.1%) at 20-day intervals.

• Pathogen: Cercospora melongenae and related species.
• Symptoms: Large, brown to grayish-brown circular or irregular leaf spots; coalescence leads to premature leaf drop and fruit rot.
• Fungus survives in soil debris and infected seeds.
• Favoured by high humidity, warm days, cool nights, and persistent dew.

• Destroy crop debris; practice crop rotation and use disease-free seeds.
• Maintain wider plant spacing to reduce humidity.
• Spray zineb (0.25%), carbendazim (0.1%), or thiophanate methyl (0.1%) at 10–14 day intervals after disease onset.

• Use resistant/tolerant varieties and certified disease-free seeds.
• Practice crop rotation, field sanitation, and weed management.
• Apply chemical and biological controls judiciously.
• Monitor environmental conditions and implement timely interventions.

• Overview of diseases affecting tomatoes.
• Importance of disease management in agriculture.
• Focus on early blight, late blight, and bacterial diseases.

• Early Blight: Alternaria solani
• Late Blight: Phytophthora infestans
• Bacterial Wilt: Ralstonia solanacearum
• Leaf Curl Virus: Tomato leaf curl virus

• Dark spots on older leaves, stems, and fruits.
• Yield losses can reach 79% in severe cases.
• Weakens plants, reducing fruit set.

• Temperatures between 15 to 27°C.
• High humidity (>90%) and rainy weather.
• Weak plants from June-July sowing are more susceptible.

• Use pathogen-free seeds and remove infected debris.
• Water in the morning to minimize leaf wetness.
• Implement crop rotation with non-Solanaceous crops.

• Caused by Phytophthora infestans.
• Can infect leaves, stems, and fruits rapidly.
• Historically linked to the Irish potato famine.

• Dark brown blotches on leaves with green-gray edges.
• Fruits develop dark, mushy spots.
• High humidity leads to white fungal growth.

• High humidity (>90%) and low temperatures (10-25°C).
• Cloudy weather with rainfall enhances spread.
• Soil-borne spread through oospores.

• Destroy infected potato piles before planting.
• Crop rotation with cereals to prevent recurrence.
• Use prophylactic sprays of copper fungicides.