CONTROLLING THRIPS

There are many species of thrips that cause severe loss of flowers, vegetables fruit and other crops. First, others are acknowledged to be virus vectors spreading viral diseases. Secondly, they also exact superficial damage on fruits making them appear uneatable; or, and spoiling the appearance of foliage and flowers.

MORPHOLOGY OF THRIPS

Thrips differ in size from 1-2mm in length depending on whether they are adult or they or immature. The immature, are wingless and yellow, becoming darker as they mature. Adults differ from orange, to dark brown or black.

LIFE CYCLE OF THRIPS

A female lays eggs that are 0.2 mm long, within leaves, fruits or flowers. Growth cycle consists of the egg hatching in a larva, then another lava stage commences.

After the second larva stage, a pupa emerges that gives rise to an adult. The growth cycle is completed in two weeks during favorable weather. Thrips cause spotted scars to flower petals as a result of their feeding habits.

ORGANIC METHODS OF CONTROLING THRIPS

To control thrips, formulate a spray that contains garlic, canola oil and natural pyrethrum a concoction that, despite controlling thrips, it is lethal to virus vectors like; aphids, whiteflies and jassids/leaf hoppers. It’s perfect for application on edible crops like; tomatoes, green beans, cucumbers as well as in roses, ornamentals flowers and various salad crops.

Secondly, removing infected leaves and flowers can assist in reduction of population significantly. Thirdly using yellow or blue sticky traps placed around plants can also trap a small proportion of trips moving from one plant to another. The traps are very useful to enable you to be aware of thrip activity at a very early stage and take remedial measures.

THRIPS ON AUBERGINE/EGG PLANT

Thrips attack the leaves and the fruit of egg plants causing considerable reduction of growth and surface deformities on fruit respectively. Both nymphs and adults leave scars and deformities on the plants. The extent of damage on plants and fruit depends on the stage the plant was attacked. Heavy invasion results to the death of the plant especially during its early growth. They also transmit tomato spotted wilt virus that leads to 100% loss of plant produce.

The plant is susceptible throughout it growth cycle making it the most dangerous pest for aubergine. The optimal condition for thrips is sizzling temperatures followed by a short period of rain. The most optimal temperature for the reproduction, growth and development of thrips is 20⁰C. Thrips are serious pests on eggplant in Zambia especially during the months of September to November. No data is obtainable showing the impact of the pest in Kenya.

THRIPS ON AVOCADO

Thrips start feeding near the calyx, producing a scar; that gradually covers the fruit wholly. Economic injury occurs on the fruit when it measures to 2 cm in length, 2-3 weeks after fruit set.

The pesticides approved in Kenya for the application on thrips on avocado are; Azadirachtin, Deltamethoate and Dimethoate

THRIPS ON MANGO

As thrips seek shelter on mango trees, they attack the young tender shoots. This makes the young leaves to develop to a creased form. It has been observed that the pest population increase exponentially during hot dry weather; making the hot seasons the most favorable for the pest. Thrips on mangoes are difficult to control using chemicals though Spinosad has proven to be effective. Other chemicals that can be effectively used are Chlorpyriphos-Ethyl, Deltamethrin, Malathaion

THRIPS ON CUCURBITS

There is significant reduction of growth when, thrips attack young leaves of cucurbits. This is because terminal buds are destroyed, thus stunting the crop. The most serious damage is due to the egg laying lesions on the fruit. Feeding cause’s damage not by the fact of punctures, but by deformations due to saliva injected. The tissues on which the trips feeds become sullen in appearance and spotted, they are particularly tarnished especially the petals. Thrips are a serious pest in Senegal on cucurbits especially during the months of July to October.

Thrips move by means of wind thus the establishment of windbreaks minimizes the thrip population. It is important to ensure host plants like tomato, cotton and tobacco are not near cucurbits. Plowing and harrowing before planting buries their eggs deep in the soil thus reducing their population. Solarization can kill eggs in the soil from previously infested crop. Plant crops that are natural repellants to thrips like, citronella and pyrethrum.