With wheat harvest almost over for the year, insects will possibly be on the move into your garden. One of the main culprits to watch out for right now is thrips. K-State Research and Extension Entomologist J.P. Michaud says that there is a healthy population of thrips in the wheat fields in the area. With harvest removing one of their food sources, your garden is one place they may go.
Thrips are very small (1.25-mm or less), fringe winged, and yellowish brown to amber with an orange thorax. The male is slightly smaller and lighter in color than the female. Adult females insert eggs into the plant tissues. There are 2 larval stages, a pre-pupal and a pupal stage before adulthood. One adult female can live up to 45 days and produce 300 eggs in her lifetime. The key to controlling thrips is to contain them early to control the numbers. Once the eggs become adults in 8-20 days depending on temperature, they become very tough to control.
One main virus that thrips are capable of spreading is the tomato spotted wilt virus. The most characteristic symptom of TSWV appears on the fruit. On young fruit, white or yellow rings about 1/2 “in diameter develop on the fruit skin. The area within the ring is usually raised. Unfortunately, a virus cannot be controlled once a plant has been infected. There are a few things that you can do to help bring down your risk of getting the virus in the first place. First of all, controlling the weeds around the garden will remove an alternative host to lessen the insect’s ability to move into the garden. Next, if you see a plant that you suspect of having the virus, remove it from the area to lessen the chance of others contracting the disease. Insecticides such as a broad spectrum pyrethroid can be used to treat the flowers if used regularly, but thrips have a good resistance to chemicals, so entire control may not be achieved. Once again, your best protection is observation and early control.
Alicia Boor is the Agriculture and Natural Resources agent for Barton County K-State Research and Extension. You can contact her by e-mail at aboor@ksu.edu or calling 620-793-1910