Thrips is an annoying garden pest. Though small in size, their small numbers cause significant damage to many different plants and crops, such as vegetables, ornamentals, and fruit trees. Although chemical insecticides often prove ineffective against them due to resistance building up quickly over time, preventive gardening methods may help decrease population and lessen damage done to your plants.
There are approximately 7,700 species of Thrips species across the world, comprised of miniature slender insects with fringed wings and distinct, asymmetrical mouthparts. Thrips flies are small bugs that live among flowers; western flower thrips (Freshmanella occidentalis) tends to be dark in color while chili thrips (Tyrina pyrifolia) has lighter green tones. Although visible with magnifying glasses or microscopes, their tiny size makes them nearly impossible to notice without help from special lenses or magnifiers. If you suspect thrips issues, inspect affected leaves and buds on their undersides closely for signs of infestation. Be alert for distorted growth patterns, stippling, silvery-white discoloration and small brownish excrement spots; infected flowers often fail to open completely or may become deformed as well as small brown specks of excrement on them. Another way of checking for thrips infestation is shaking damaged plants over white paper until their sticky sap stains the paper - an effective test!
Once thrips have been identified, it's crucial that they be separated from healthy plants in your greenhouse or garden as soon as possible. If possible, isolate these thrips until their damage begins to subside; otherwise if moving them is necessary, shower them off using water in either your sink or outdoors if possible in order to rid yourself of as many pests as possible.
Once thrips have been separated from healthy plants, immediately treat them with one of the fungicides listed below to protect against further damage. It may also be prudent to remove and discard any heavily infested leaves and flowers before bringing any new plants indoors for your home or landscape. Be especially wary when inspecting new plants when brought indoors as these should be carefully checked for signs of thrips infestation as thrips tend to collect at stem attachment points where leaves attach to stems - an area often ignored when inspecting new arrivals before they make an impression upon you.
Shearing plants used for hedging or shaping into specific forms should be avoided as this promotes new growth that may be susceptible to thrips damage. Furthermore, repeat-flowering or reblooming varieties should also be avoided for decorative purposes in landscape design as these are more prone to being affected by thrips damage than single bloomers.
Natural enemies of thrips include minute pirate bugs, lacewings, robber flies, parasitic wasps and nematodes; in addition, Orius intussusguttatus predatory mite may also prove effective against it. Orius may be more effective against vegetables and ornamentals than tomatoes; therefore, growers should use other products to manage thrips in these crops. Short-persistence organic contact insecticides tend to be preferred over longer-acting products in managing thrips populations. Furthermore, it should be remembered that thrips overwinters in various environments and conditions - from crop debris and mulches to soil. Thrips populations that take refuge here may become resistant to treatment more easily.
