Peppers

Root-knot nematodes (Meloidogyne spp.)

Symptoms of infestation by root-knot nematodes are similar in all crops: wilting of plants and if infested plants are pulled from the soil the roots can be seen to be distorted, swollen and bearing knots (galls). The galls on pepper are much smaller than those on cucurbits or tomatoes. The infested roots eventually rot and affected plants die.

Spider mites (Tetranychus spp.)

Spider mites suck the sap of the plants, causing mottling of the upper leaf surface. Infested leaves first show a white to yellowing speckling, and then eventually turn bronze and fall off as the infestation becomes heavy. Spider mites prefer the lower surface of the leaves, but in severe infestations occur on both leaf surfaces as well as on stems and fruits. High infestations cause defoliation.

Aphids (Aphis gossypii, Myzus persicae)

Aphids (cotton aphid and green peach aphid) occur in colonies initially around tender plant parts (growing points, young stems and leaves, flower buds) and on the lower leaf surface. When numerous they can be found on all above ground parts of the plant. Aphids damage plants in three ways: by sucking their sap, excreting a sticky substance (honeydew) that coats the plants, or/and by transmitting viral diseases.

Feeding by aphids causes distortion (curling, wrinkling or cupping) of young leaves, chlorotic spotting and mottling of older leaves, and may lead to stunting and wilting of plants. Growth of sooty mould on honeydew excreted by aphids reduces photosynthesis and affects fruit quality.

Aphids cause indirect damage as vectors of important viruses such as alfalfa mosaic, chilli veinal mottle, cucumber mosaic, pepper mottle, pepper severe mosaic, pepper veinal mottle, potato Y and tobacco etch virus.

Cutworms (Agrotis spp., Spodoptera spp.)

Cutworms are the caterpillars of various moths, belonging mostly to the genus Agrotis. Young caterpillars feed on leaves making small holes. After few days they drop to the soil where they live until pupation. Caterpillars remain in the soil during the daytime coming out at night to feed. They cut stems of young seedlings at the level of the soil, killing them and affecting establishment of the crop. Some Spodoptera species, in particular S. littoralis act sometimes as cutworms.

Caterpillars, in particular under hot conditions, hide during the day in the soil around the base of the plants, and may cut them, especially seedlings, at the base of the stem. At night they climb into plants to feed.

Fruit flies (Ceratitis spp., Bactrocera spp., Dacus spp.)

Fruit fly females lay eggs under the epidermis of the fruit. After emerging from eggs maggots generally move to the core to feed, but they may also feed on the walls of the fruit. This causes secondary rot and premature fruit fall. An infested fruit usually has a small dimple where the female fly deposited an egg. As the maggot matures inside the fruit, the fruits turn red prematurely, becoming soft and rotten.

Soft spots can often be seen where the maggot has fed on the fruit. When infested fruit is picked, the cap usually separates from the fruit because the maggot has eaten the core. Fruit may drop from the plant. Maggots remain in peppers until fully grown (from 2 to 3 weeks). At this time the maggot leaves the pepper, drops to the soil to pupate. Yield losses can be considerable. One maggot can destroy an entire fruit.

Fruit borers (Helicoverpa spp.; Spodoptera spp.)

Moths of fruitborers are active at dusk and at night, feeding on nectar and laying eggs on leaves. Caterpillars feed on leaves, flowers and fruits. Although severe leaf damage by feeding of African bollworm (Helicoverpa spp.) caterpillars may slow plant growth due to reduced leaf area, caterpillar feeding on leaves is usually of not economic importance. The bollworms are about 2-3.5 cm long.

The main damage occurs on flowers and fruits. Attack on flower buds results in flower abortion. Caterpillars usually bore holes in fruits, causing extensive damage and promoting decay from secondary infection by diseases.

African armyworm (Spodoptera spp.) species are basically leaf-eaters and may cause defoliation when present in large numbers. They also feed on fruits, rendering them unmarketable.

Leafmining flies (Leafminers) Liriomyza spp.

Female flies make numerous small, whitish punctures on the foliage when feeding and depositing eggs. These punctures can serve as entry points for disease-causing organisms such as bacteria and fungi. The eggs hatch into tiny yellow maggots that feed on leaf tissues leaving a wandering track known as mines. Full-grown maggots come out of the mines to pupate in the soil beneath the plants or on the foliage. Maggots are the most destructive stage.

The mines may reduce photosynthetic activity, affecting development of flowers and fruits. In severe infestation, the leaves might be completely mined, dry and fall off prematurely, causing loss of vigour and turgidity of the plant. This may eventually result in wilting, in particular in warm weather, leading to yield loss, fruit sunscald, or in serious cases death of the plant, especially of young pants.

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 predispose fruits to 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 transmits the leaf curl disease of chillies.

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.

Broad mite or yellow tea mite (Polyphagotarsonemus latus)

Broad mites are tiny (0.1-0.2 mm long) and cannot be seen with the naked eye, and are even difficult to detect with a hand lens. An attack by the broad mites can be detected by the symptoms of damage. They live on the underside of leaves, tender stems, fruits, flower peduncles and flowers. Their feeding produces discolouration, necrosis of tissues and deformation. Initial attack occurs on the stems of terminal shoots and the lower surface of young leaves.

Young leaves turn narrow, twisted or crumpled, fail to elongate and finally may wilt and dry, giving the plant a scorched appearance. Older leaves are generally cupped with corky brown areas between the main veins on the lower side of the leaves. The succulent part of the stem of young plants may become slightly swollen, roughened or russeted. The foliage becomes rigid. Attacked fruits become deformed with a cork-like surface or fail to develop. Severely infested fruits fall, and yield is significantly reduced. Symptoms remain for a long period of time after control.