Pests and Diseases

Pests and diseases management(Chili)

1. Anthracnose (Colletotrichum capsici)

Anthracnose caused by Colletotrichum spp. is a major problem of ripened fruits. The fungus produces dark, sunken spots up to 2.5 cm across on sweet pepper. The spots occur on green and ripe fruits and their surface may be covered in moist weather with salmon-pink mass of spores. The fungus is seed-borne


  • Use certified disease-free seeds
  • Hot water treat own produced seeds.
  • Practice field sanitation (removal of crop debris after harvest)

2. Bacterial wilt (Ralstonia solanacearum)

The disease occurs in scattered plants or groups of plants in the field. Characteristic symptom is wilting of the entire plant with no leaf yellowing.                        

 The bacteria have a wide host range and can survive in the soil for long periods.

The disease is favoured by wet, warm conditions. Peppers are not as susceptible as eggplants, potatoes, tobacco or tomatoes. Rotation is not effective as the pathogen can survive for a long period - several years - in the soil and also attack a wide range of crops and solanaceous weeds.


Photo:  Bacterial wilt symptoms on pepper


  • Plant varieties that are tolerant / resistant, if available
  • Do not grow crops in soil where bacterial wilt has occurred
  • Remove wilted plants from the field to reduce spread of the disease from plant to plant
  • Control root-knot nematodes since they could facilitate infection and spread of bacterial wilt
  • Soil amendments (organic manures) can suppress bacterial wilt pathogen in the soil
  • Rotation is of limited value since the disease has a wide host range, but still it is recommended to avoid continuous planting of Solanaceous crops.

1.3. Fusarium wilt (Fusarium oxysporum f.sp. capsici)

Disease symptoms include drooping and yellowing of lower leaves followed by wilting of the entire plant. Leaves on infected plants remain attached and the vascular system of the plant is discolored, particularly in the lower stem and roots.


Photo. Chilli field infected with Fusarium wilt.

The fungus lives indefinitely in the soil and is spread in irrigation water. It is very susceptible to changes in temperature and soil moisture. The optimum temperature for disease development is 24 to 27° C.  Soil moisture has the greatest influence. The wilt does not occur in dry soil, but it is serious in poorly drained fields.



  • Plant resistant cultivars, if available
  • Lime the soil and ensure the soil has a good drainage

4. Powdery mildew (Leveillula taurica)

Yellowish blotches or spots appear on the upper leaf surface. The leaf surface is covered with a white to grey powdery fungal growth. The disease progresses from the older to younger leaves and shedding of the foliage is pronounced. Leaf defoliation leads to reduction in size and number of fruits. It also results in fruits being sun-burned. The disease is favoured by warm, humid and dry weather. The fungus causing powdery mildew also attacks eggplants and tomatoes. Overhead irrigation reduces disease severity.


  • Plant resistant cultivars, if available
  • Apply sulphur based fungicides (eg. Copperoxychloride) at the onset of disease symptoms
  • Remove and destroy crop debris after harvest.

5. Viral diseases

About 17 viruses have been reported to attack peppers. Those considered economically important in Africa include alfalfa mosaic, chilli veinal mottle, cucumber mosaic, pepper veinal mottle, potato Y, tobacco etch, tobacco mosaic, tomato spotted wilt and chilli leaf curl.  Most of these viruses are transmitted by insects, infected seed and a few by mechanical means and infected seed: the first six above listed viruses are spread by aphids; tobacco mosaic is mechanically transmitted and infected seed; tomato spotted wilt by thrips; and chilli leaf curl by whiteflies.

General symptoms include mosaic patterns on leaves, yellowing , ring spots, leaf deformation or distortion, curling of leaves, and/or stunting of plants. They may also cause reduction of fruit size, distortion, and/or ring patterns.

Photo. Symptoms of viral diseases on pepper

Management practices often used to reduce viral disease incidence include:

Plant resistant cultivars, if available

Select planting dates to avoid high population of vectors

Close plant spacing to compensate for diseased plants

Use barrier crops to minimize virus spread

Use oil sprays to reduce virus transmission by aphids

Use reflective mulches to repel aphids and thrips.

 Use certified disease-free seed in case of tobacco mosaic virus

6. Chilli Thrips (Frankliniella spp., Scirtothrips dorsalis, Thrips tabaci)

Thrips usually feed on all above ground parts of plants, preferring the underside of young leaves, flowers and fruits. Often they are concealed under the calyx. Plant damage results from thrips puncturing leaves and sucking the exuding sap. At the initial stage of infestation leaves have a silvery sheen and show small, dark spots of faecal material on the underside. When the attack increase leaves curl upward, wrinkle and finally dry up. This may cause fruit sunscald.

Heavy feeding damage turns leaves, buds and fruits bronze in colour. It may cause wilting, retardation of leaf development and distortion of young shoots resulting in stunted plants. Attack on fruits causes deformation and scarring (manifested as brown lines) of the fruits making them unmarketable, especially fruits for the export market. Thrips attack at the seedling and early stages of the crop delays crop development. Thrips transmit the tomato spotted wilt virus in peppers. S. dorsalis transmit the leaf curl disease of chillies.

Photo: Thrips damage on a chilli pod


  • Natural enemies of thrips are important for natural control. Main natural enemies include anthocorid bugs (Orius spp.) predatory mites and spiders
  • Cultural practices like periodical irrigation and hoeing would reduce infestation to some extent. In severe cases, spray insecticides like cypermethrin (1ml/1L of water) at 15 days interval

1.7. Aphids

Aphids suck the sap from the plants; they generally attack the crop in dry period and at the later stages of the crop. The quality of the produce is spoiled by imparting blackish colour to the Calyx and pods. They also act as a vector to virus.


The aphids can effectively be controlled by spraying the crop with insecticides like cypermethrin (1ml/1L of water) at 15 days interval

8. Whiteflies (Bemisia tabaci, Trialeurodes vaporariorum)

Whiteflies damage plants in three ways. Whitefly immature stages (nymphs) and adults suck sap from leaves. Their feeding, in addition to removing plant nutrients, produces chlorotic spots on infested leaves. Nymphs excrete a clear sugary liquid known as honeydew, which often completely covers the leaves during heavy infestation. Honeydew supports the growth of a black sooty mould, and as a result the leaves may turn black, affecting photosynthesis. Whiteflies are vector of important viral diseases such as chilli leaf curl, tiger disease, Serrano golden mosaic, and Texas pepper geminivirus.


  • In areas where whitefly-transmitted viral diseases are a problem keep, the seedlings protected under a fine meshed insect netting until they are ready for transplanting. Make sure the netting is always properly closed
  • Conserve natural enemies. Parasitic wasps, predatory mites, ladybird beetles, and lacewings are important natural enemies of whiteflies
  • Whenever necessary, spray with neem products. Neem products inhibit growth and development of immature stages, repel whitefly adults and reduce egg laying.

9. Blossom End Rot (Physiological disorder)

The end of the fruit becomes off-whitish to brown in colour and takes on a “sunken in” appearance. As the fruit matures, these symptoms become more pronounced and the colour of the rot becomes dark brown to almost black.

Photo: Blossom end rot on Capsicum fruits


Boost the soil with calcium by adding lime, dolomite, gypsum or composted animal manures before planting the seedlings.

Water regularly: Capsicum continue to flower and bear fruit for prolonged periods of time, so ensure the soil around their roots is kept moist

Avoid fertilizers with a high nitrogen content: Nitrogen fertilizers will promote leaf growth at the expense of fruit, allocating calcium to the leaves instead of to the fruit.