(Some species of Haplothrips are reported as pest in South Africa, we do not know if they are pests in Kenya or east Africa. Haplothrips are present in East Africa, but some of them are beneficial (predacious) and we do not know the status on the region. This will have to be reviewed when we finish with the datasheets). [br] When the status of Haplothrips in East Africa has been clarified we could decided if we leave this information on egg-laying habits. [br] Biological pesticides: check with list of Seif [br] FW: Include information on synthetic pesticides?
Black tea thrips (Heliothrips haemorrhoidales)
The adult thrips are about 1.5 mm long and dark brown or black in colour with whitish legs, antenna and wings. The nymphs are whitish or greenish in colour. They feed on leaves of all ages.
Attacked buds are small, crisp and are brittle (easy to break). When the damaged bud unfolds, the leaves have a brown line of dry scars (like cork) along either side of the main rib. Yellow mites cause similar corky lesions, but thrips feeding usually does not cause the leaves to curl up like yellow mite. Even a few thrips feeding on a bud can lower the quality of the bud, making the dried buds brittle and the processed tea bitter.
Attacked leaves show silvering and a fine speckling of black spots, which are the excreta of the thrips. Damaged, leaves become thicker and harder than the normal ones, duller (not shining) and having darker green colour, and may be puckered or deformed. Thrips may also feed on the surface of stems, but only near the tip of a young shoot. This stem feeding causes rough, brown dots or patches on the surface of the stem. A tea bush with many thrips is often stunted and dry. Thrips can cause economic damage mainly in periods of drought.
- Provide favourable growing conditions for the crop. Thrips are often a bigger problem in old, stunted and dry tea fields. A strong tea crop can tolerate thrips Tea plants often grow out of the damage quite quickly if well tended. In particular adequate irrigation is a critical factor in minimising damage.
- Use shade to increase humidity in regions with extensive dry seasons. Thrips are favoured by dry and hot weather conditions. Planting shade trees is one of the best ways to reduce thrips populations in dry conditions.
- Pluck frequently to remove thrips and their eggs. Because thrips feed mostly on buds and the youngest leaves, plucking can greatly reduce the number of thrips. Frequent plucking reduces thrips more than plucking only once a month.
- Conserve natural enemies. Predatory mites and pirate bugs are important for the natural control of thrips. For more information on Natural enemies click here
