Anthracnose of chili
Fungal pathogen Colletotrichum spp.
Symptoms
1.Lesions on Fruit:
- Initial symptoms appear as small, circular, sunken spots on the fruit.
- These spots enlarge and can coalesce, forming large, dark, sunken lesions.
- The lesions often have concentric rings with dark acervuli (fungal fruiting bodies) visible in the center.
2.Stem and Leaf Lesions:
- On stems and leaves, symptoms include dark, elongated, and sunken lesions.
- Leaves may exhibit irregularly shaped brown spots which can lead to premature defoliation.
3.Seedlings:
- Infected seedlings show dark, water-soaked lesions on cotyledons and stems, which can result in damping-off.
4.Post-Harvest:
- Fruits may continue to develop symptoms after harvest, which can lead to significant post-harvest losses.
Etiology
1.Pathogen:
- *Colletotrichum spp.*, particularly *Colletotrichum capsici* and *Colletotrichum gloeosporioides*.
- These fungi are capable of infecting various plant parts including fruits, stems, leaves, and seeds.
2.Environmental Factors:
- Warm and humid conditions favor the development and spread of the disease.
- Rain splashes, high relative humidity, and temperatures around 25-30°C are conducive to disease proliferation.
Disease Cycle
1.Primary Infection:
- The pathogen survives in infected plant debris, seeds, and alternate hosts.
- Primary infection occurs through conidia (asexual spores) that are spread by rain splash, wind, insects, and contaminated tools.
2.Colonization:
- Once conidia land on susceptible plant tissues, they germinate and penetrate the plant surface, forming appressoria (specialized infection structures).
- The fungus then invades the plant tissue, causing necrotic lesions.
3.Secondary Spread:
- Secondary spread occurs through conidia produced on the initial lesions, which can infect other parts of the plant or nearby plants.
- Continuous cycles of spore production and infection can occur throughout the growing season under favorable conditions.
Management
1.Cultural Practices:
-Crop Rotation: Avoid planting chili in the same field for consecutive seasons to reduce pathogen build-up.
-Sanitation: Remove and destroy infected plant debris and volunteer plants that can harbor the pathogen.
-Proper Spacing: Ensure adequate plant spacing to reduce humidity around plants and improve air circulation.
-Mulching: Use organic or plastic mulch to prevent soil splash and reduce soil moisture around plants.
2.Resistant Varieties:
- Plant resistant or tolerant varieties if available to reduce disease incidence.
3.Chemical Control:
- Use fungicides such as azoxystrobin, mancozeb, and chlorothalonil as per local agricultural recommendations.
- Apply fungicides preventatively or at the first sign of disease and follow up as necessary, rotating modes of action to avoid resistance development.
4.Biological Control:
- Employ biocontrol agents like *Trichoderma spp.* and *Bacillus subtilis* which can inhibit *Colletotrichum* spp.
- These can be applied as soil amendments, seed treatments, or foliar sprays.
5.Post-Harvest Management:
- Handle harvested fruits carefully to avoid wounds which can serve as entry points for the pathogen.
- Store fruits in cool, dry conditions to slow disease progression.
Leaf Curl of Chilli
Symptoms:
-Leaf Deformation: Infected leaves exhibit upward or downward curling, crinkling, and may have a leathery texture.
-Stunted Growth: Affected plants often show reduced growth and may appear dwarfed.
-Chlorosis: Leaves may display yellowing (chlorosis) between veins, leading to a mosaic pattern.
-Fruit Deformation: Infected plants may produce fewer fruits, and the fruits that do develop can be small, misshapen, and may have surface distortions.
-Vein Swelling: Prominent veins on the underside of leaves may become thickened and swollen.
Etiology:
- The primary causal agent of leaf curl in chilli is the Chilli leaf curl virus (ChiLCV), which is a member of the genus *Begomovirus* in the family *Geminiviridae*.
- The virus is transmitted by thewhitefly (Bemisia tabaci). The whiteflies acquire the virus by feeding on infected plants and subsequently transmit it to healthy plants.
Disease Cycle:
1.Virus Acquisition: Whiteflies acquire the virus by feeding on the sap of infected chilli plants.
2.Incubation Period: The virus multiplies within the whitefly and becomes transmissible within a few hours to days.
3.Virus Transmission: Infected whiteflies move to healthy chilli plants and transmit the virus while feeding.
4.Plant Infection: The virus enters the plant through the feeding wounds created by the whitefly, spreading systemically through the plant’s vascular system.
5.Symptom Development: Infected plants start showing symptoms of leaf curl within 10-15 days of infection. The severity of symptoms can vary depending on environmental conditions and the plant’s growth stage.
Management:
1.Cultural Practices:
-Resistant Varieties: Use resistant or tolerant chilli varieties to minimize the impact of the virus.
-Sanitation: Remove and destroy infected plants to reduce the source of the virus.
-Crop Rotation: Rotate chilli with non-host crops to break the disease cycle.
-Timing of Planting: Adjust planting times to avoid peak whitefly populations.
2.Biological Control:
-Natural Enemies: Encourage natural enemies of whiteflies, such as lady beetles, lacewings, and parasitic wasps, to reduce whitefly populations.
3.Chemical Control:
-Insecticides: Use insecticides to control whitefly populations. However, repeated use can lead to resistance, so rotate insecticides with different modes of action.
-Oils and Soaps: Insecticidal soaps and horticultural oils can help in managing whitefly populations.
4.Physical Control:
-Yellow Sticky Traps: Use yellow sticky traps to monitor and reduce whitefly populations.
-Netting: Use insect-proof netting to protect young plants from whitefly infestation.
5.Integrated Pest Management (IPM):
- Combine cultural, biological, physical, and chemical control methods for a holistic approach to managing leaf curl of chilli. Regular monitoring and early detection are key components of IPM.
Thank you