What is in this article?:
• One of the keys to managing thrips is to know which species is causing the problem.
• Sounds simple, but even with a compound microscope and a trained eye it’s not easy. And, from the cab of a tractor or pickup truck it’s impossible.
TIMELY PLANTING and seed treatments are critical to thrips management.
Northeast North Carolina and southeast Virginia have been aptly dubbed ‘thrips central’ and getting ahead of these pesky, yield-robbing little insects is a must for high yielding crops from cotton to vegetables.
There are three primary species of thrips that attack crops in the Upper Southeast: tobacco thrips, western flower thrips and flower thrips.
One of the keys to managing thrips, says long-time thrips fighter and North Carolina State Entomologist George Kennedy is to know which species is causing the problem. Sounds simple, but even with a compound microscope and a trained eye it’s not easy. And, from the cab of a tractor or pickup truck it’s impossible.
Sometimes ‘when’ a species of thrips is found in a field can be a good way to identify the species. Typically, tobacco thrips are earlier season problems and are often responsible for early season transmission of tomato spotted wilt virus. Often this occurs when thrips feed on earlier planted vegetable crops and then move into peanuts and other crops in the region, Kennedy says.
Tobacco thrips are black, or at least darker than the other two primary thrips species and can sometimes be distinguished from western flower and flower thrips, if a grower is really skilled at scouting and identifying these pests.
Western flower thrips usually occur later in the season. It causes fruit and foliage damage, though usually fruit damage from direct feeding. It can be a significant cause of in-season spread of tomato wilt virus.
Flower thrips are usually the most abundant species of thrips found. Rarely does this species cause significant problems in crops.
Occasionally, when they occur in very high numbers, flower thrips can be a problem, but typically they are not a big enough threat to warrant an insecticide application.
Tobacco thrips are primarily a foliage feeder and western flower and flower thrips are primarily a flower feeder, but can feed on foliage.
Damage from flower and western flower thrips occurs when fruit is small and may be on the developing fruit within the flower shortly after pollination. As the fruit expands, dimpling can be seen throughout the cotton plant.
Damage from spider mites is very similar to damage done by western flower thrips.
Clearly, it is important to know whether the damage comes from mites or thrips, Kennedy stresses.