Tomato pests to look out for

This crop is targeted by a wide range of pests. Infestation will vary from place to place, and from season to season, but some form of pest control will invariably be necessary.

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The following are some of the main tomato pests encountered in South Africa:

•  African bollworm 
(Helicoverpa armigera)

The bollworm is a major pest of many crops. On tomatoes, the larvae feed mainly on the flowers and fruit, and can cause huge losses if not controlled.

The moth lays creamy-white eggs of about 0,5mm in diameter singly on the flowers and leaves. They hatch within three to five days under good conditions. The young caterpillars are hairy, and vary from black to dark beige in colour.

When fully grown (after two to three weeks), the larvae are up to 40mm long, with a characteristic broad white to pale yellow stripe on either side of the body and small black spots on the upper side. Mature larval colours range from shades of green and reddish yellow, to reddish brown and black. The underside is greyish white.

Pupation takes place in the soil. The adult moth has a wingspan of 40mm, and a body length of 18mm. The forewings have two characteristic brown markings, while the hindwings have two distinct pale spots.

In the warmer parts of KwaZulu-Natal, bollworm is present throughout the year, although populations are smaller during the cooler months (with temperatures below 18°C).

•  Cutworm 
(Agrotis spp)

Cutworms feed at night and do substantial damage by cutting off the stems of young plants at or near ground level. During the day, cutworms can be found just below the surface of the soil next to the damaged plants.

The caterpillars, which may reach a length of up to 35 mm, are usually greasy-looking, and grey to dark brown or almost black in colour, with several black tubercles (bumps) on each segment.

The moth has brown or greyish forewings, and light brown hindwings.