Western Flower Thrips Alert


Symptoms include fruit scarring as a result of feeding or laying eggs in the plant’s tissue.

Who Am I?

Western flower thrips are small insects that are usually found on upper parts of plants, especially inside the flowers where they feed on pollen. Their life cycles includes distinct stages, such as the egg, larva, pupa, and adults that fly only weekly. Western flower thrips is a major vector of viruses, such as tomato spotted wilt virus, tomato chlorotic spot virus, impatiens necrotic spot virus, and groundnut ringspot virus.

Control Measures

Mass Trapping Devices: Thrips are attracted to bright floral colors; take advantage of this and use commercially available sticky traps that lure and capture them.

Sanitation: Try keeping the crops’ close surroundings and environmental conditions as neat as possible by removing weeds that thrips are especially attracted to such as sinapis arvensis (“wild mustard”).

Monitor the field regularly, and occasionally shake foliage or flowers gently onto a bright colored sheet of cardboard. Count the number of thrips that fall onto the sheet and estimate the level of infestation. When the average number of thrips that falls onto the sheet is above two, and the crop is known to have a low economic threshold, then a spraying application should be considered.

Keep in mind that it is hard to manage thrips effectively with insecticides. They have advanced maneuverability skills and their egg and pupa stages are protected, which makes it difficult. The following are a few generic names of products still used against the Western flower thrips in some parts of the world: Methiocarb, Acrinathrin, Dichlorvos, and Formetanate.

Spinosad-based products

Natural and successful commercially available enemies of thrips are of the genus Orius (“minute pirate bug”), omnivorous bugs in the Anthocoridae family.

*Names marked in red are considered to be highly poisonous to beneficial insects.

*Names marked in green are considered to be organic and IPM (integrated pest management) compatible.

Caution and careful notice should be taken when using any plant protection products (insecticides, fungicides, and herbicides). It is the grower’s sole responsibility to keep track of the legal uses and permissions with respect to the laws in their country and destination markets. Always read the instructions written on labels, and in a case of contradiction, work in accordance to the product label. Keep in mind that information written on the label usually applies to local markets. Pest control products intended for organic farming are generally considered to be less effective in comparison to conventional products. When dealing with organic, biologic, and to some extent a small number of conventional chemical products, a complete eradication of a pest or disease will often require several iterations of a specific treatment or combination of treatments.

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