Disease management in chilli

Dear Farmers, chilli is major crop all over the world. It occurs in variety of different types of climatic conditions across the world.

There are some threats (diseases) on chilli production causing damage to the crop or sometimes death.

Fungal diseases of chilli and it's management

1) Die Back or anthracnose caused by Colletotrichum capsici 

Symptoms

1) Flowers dropped and dried up.

2) Drying up starts from flower stock to the steam and subsequently causes dieback of branches and stem.

3) There is profuse shedding of flowers.

4) Fungus necrosis of tender twigs from the tip backwards.

5) Partially affected plant bear fruits which are
few and of low quality. It also causes fruit rot disease in chillies.

Disease Management

1) Use of disease free seeds is important in preventing the disease.

2) Seed treatment with Thiram or Captan 4g/kg is found to be effective in eliminating the seed borne inoculum.

3) Chilli cultivar BG-1 and perennial are found to be resistant against the disease

4) Goodt control of disease by three springs with Ziram 0.2% or Copper oxychloride 0.25% or Zineb 0.15%.

1) Cercospora leaf spot- caused by Cercospora capsici

Symptoms

Leaf lesions typically are brown and circular with small to large light grey centres and dark brown margins The lesions may elarge to 1 cm or more in diameter and sometimes coalesce. Stem, petiole, and pod lesions also have light grey centres with dark borders but they are typically elliptical. Severely infected leaves drop off prematurely resulting in reduced yield.

Management

1) Crop debris should be removed and burnt.

2) Seed should be collected from healthy plants.

3) Spray twice at 10-15 days interval with Manozeb @ 0.25% or Chlorothalonil @ 0.1% , Captafol @ 0.3 or Triadimefon @0.1%.

3) Phytophthora leaf blight and fruit rot- caused by Phytophthora capsici

Symptoms

All plant parts are affected and severity of disease varies depending upon the climatic conditions and locality. Fruit rot phase of the disease is highly destructive with water soaked, dull green spots appear on the fruit. Fruit gradually expanded and become humified Leaf lesions are dark green, water soaked round or irregularly shaped area which expands rapidly.

Management

1) Cultural practices such as crop rotation, timely roughing of diseased plants, parts, avoid contact of roots and leaves to the ground soil, use of disease free seeds, mulching with straw, earthing up of plants after transplanting are recommended.

2) Biocontrol such as Pseudomonas cepacia, Bacillus polymixa and Streptomyces violacioniger

3) Application of fungicides such as mixture of Metalaxyl-Copper-oxychloride, Metalazyl-Dithianor, Oxadixyl-Chlorothalonil have been found effective in the control of both fruit rot and anthracnose.

4) Fusarium wilt-caused by Fusarium oxysporumf. Sp. Capsici

Symptoms

Wilting of plant, upward and inward rolling of leaves. Leaves turn yellow and die. Generally appear as localised areas of the field where a high percentage of plants wilt and die, although scattered wilted plants may also occur. By the time  above-ground symptoms are evident, the vascular system of the plant is discolored particularly in the lower stem and roots.

Management

1) Use wilt resistant varieties.

2) Drenching with 1% bordeaux mixture or blue copper 0.25 %

3) Seed treatment with 4g Trichoderma viridae formulation or 2g Carbendazim per kg seed is effective.

4) Mix 2kg Trichoderma viridae formulation with 50kg FYM, sprinkle water and cover with a thin polythene sheet, when mycelial groth is visible on the sheet after 15 days, apply mixture in rows of chilli in an area of one acre.

5) Powdery mildew-caused by Leveillula tourica

Symptoms

Symptoms first noticed on older leaves which progress to younger leaves. The infected leaf is covered with white to grey powdery masses of fungus where lower leaf surface also turn necrotic. Heavy infection leads to leaf shedding resulting in heavy losses in yield.

Management

1) Spray with wettable Sulphur @ 0.25% or Dinocap @ 0.05% 2 to 3 times at 10 to 15 days.

2) Varieties such as B15, R7, Padasali, Tinwari, Golden superior have been reported as moderately resistant.

Bacterial diseases and their management

1) Bacterial wilt-caused by Ralstonia solanacearum

Symptoms

Disease appear in field as well as nurseries in scattered pattern in patches. Initially slight wilting of lower leaves in older plants is noticed. In young sidlings the upper lives show the wilting symptoms first. With the progress of the disease the initial wilt is succeeded by sudden and permanent wilt of the entire plant with a slight or no leaf yellowing. Infected young plants. die rapidly whereas older plants may first show live dropping and discoloration or one side wilting or stunting and permanent death of plant.

Management

Cultural practices such as crop rotation with non host crops, good drainage, liberal use of nitrogenous fertilizers, selection of healthy seedlings, avoiding of root injuries can minimise the disease.

2) Bacterial leaf spot-caused by Xanthomas campestris pv. Vesicatoria

Symptoms

Leaves exhibit small circular or irregular, dark brown on black greasy spots. As the spots enlarge in size, the centre becomes lighter surrounded by a dark band of tissue. Many spots  coalesce to form irregular lesions. Severely affected leaves become chlorotic and fall off. Petioles and stems are also affected. On the fruits, raised water soaked spots with a pale yellow border are produced.

Management

1) Cultural practices such as crop rotation 3-4 years with non host crop.

2) Use of disease free seed can minimise the disease

3) Spraying with Agrimycin 100 @ 100 ppm alone or in combination with copper oxychloride @ 0.25% is recommended.

Viral Diseases of chilli and their management

1) Mosaics-caused by Tobacco mosaic Virus, Cucumovirus, Potyvirus

Symptoms

The induction of symptoms in chilli varies with respect to virus associated with the disease. Potato virus Y and its strains generally induce vein banding followed by necrosis of veins, petioles and stems of chilli. Pepper veinal mottle virus causes mossaic molting, distortion and filliformy of leaves with bushy appearance of infected plant. Pepper severe mossaic produce mosaic mottle, vein clearing and deformation of the infected leaves. Tobacco etch virus syndrome includes dark green vein banding, cupping, laminal necrosis of cucumber mossaic virus causes mosaic mottling, reduction of leaf lamina and distortion of leaves.

Transmission

All mossaic causing viruses are easily sap transmissible. The members and strains of Cucumoviruses and potyvisuses are mostly transmitted through aphid vectors, Myzuspersicae, Aphis craccivora, Aphis godsypii, Rhopalosiphummaydis in a non persistent manner.

2) Chilli leaf curl- Caused by Tobacco leaf curl bigeminivirus

Symptoms

The disease manifests itself in the form of curling of leaves followed by reduction in their size. The leaves of infected plants become pale yellow in colour. There is shortening of internodes, diseased plant gives witches broom appearance and severely infected plants remain stunted. Fruit formation in susceptible cultivars is rudimentary and distorted.

Management of viral diseases

1) The infected plants should be uprooted and burnt or buried to avoid further infection.

2) Avoid monoculture of chilli crop.

3) Planting sunflower, Snap bean, sorghum, sesame and pearl millet as barrier crops.

4) Selection of healthy and disease free seed.

5) Nursery beds should be covered with nylon net or straw to protect the sidlings from viral infection.

6) Raise 2-3 rows of maize as a border crop to restrict spread of aphid vectors.

7) Apply Carbofuron 3 G @4-5 kg/acre in main field to control sucking complex and insect vectors.

8) Use viral strains resistant breeds e.g. for India Punjab Lal, Gauhati black, Jawala, Perennial, Agronomico 9 and Agronomico 10 have been resistant to different strains of PVY, CMV and TMV.