Chinch Bugs Added To Pasture Watch Lists

 

 

Producers have scoured fields for weeks, watching for fall armyworms in pastures, and cotton bollworms and soybean loopers in crop fields. Extension crop specialists and entomologists have another pest to add to the watch list — chinch bugs.

 

Alabama Cooperative Extension System Entomologist, Dr. Kathy Flanders, said chinch bugs have been reported in pearl millet and a mixed stand of grasses, including barnyard grass.

 

“Chinch bugs puncture plants with their syringe-like mouth parts and suck out the plant juice,” she said. “They tend to feed at the base of the plants, and feeding causes different symptoms on different crops.”

 

Small grains, summer annual forage grasses, corn, sorghum and turf grasses are all hosts of chinch bugs. Damaged grasses may be tinged with purple or yellow, or they may turn completely brown. Damage from chinch bugs causes plants to become visibly stunted. The base of the stem may become brittle, causing the plant to snap off near ground level.

 

 

 

There are usually two to three generations of chinch bugs in Alabama. Chinch bugs overwinter as adults, and become active when warmer temperatures return each spring. Adults lay eggs in protected crevices of grass plants, most often near thebase of the plant. After about two weeks, chinch bug nymphs hatch from the eggs and begin to feed.

 

Young chinch bugs are yellow or reddish brown with a white band running across the back. Older nymphs are black, with visible wing buds. Adults are black with white wings.

 

Because chinch bug populations build as the summer progresses, summer annual forage grasses are particularly vulnerable to damage. They spend much of their time feeding in protected places on the plant, hiding in cracks in the soil, or under crop debris.

 

Heavy rains can kill chinch bugs, so they tend to be more prevalent in dry weather. The rain also closes up many of the cracks and crevices in the soil, leaving fewer places for the chinch bugs to hide.

 

 

Flanders said once chinch bugs are in an area, they can be hard to get rid of.

 

“Chinch bugs can move from one grass crop to another as the season progresses,” Flanders said. “Forage producers who grow winter forage grasses and summer annual forage grasses in close proximity can inadvertently create a haven for chinch bugs by providing a year-round habitat.”

 

Chinch bugs feed at the base of the plant in protected locations, and therefore are very difficult to control with insecticides.

 

Directing a spray application down to the base of the plant is essential and using a high volume of water per acre (25-35 gallons per acre) will increase the chances of success.

 

An insecticide application for chinch bugs is most likely to pay off in young corn or sorghum that has been planted in rows. It is difficult to get insecticides down to the base of a broadcast-seeded crop or a crop with narrow-row spacing. If the foliar canopy is too thick, the insecticide cannot penetrate to the base. In that case it may be necessary to cut and remove the existing forage before spraying.

 

Flanders said producers should keep in mind most insecticides have some form of a pre-harvest interval. This means livestock need to be removed before the insecticide application, and not allowed back in the field until after the specified grazing interval. Likewise, a hay crop cannot be mechanically harvested until after the specified interval for hay. Insecticide seed treatments may provide a few weeks of protection from chinch bugs, but cannot provide season-long control.

 

 

Chinch bugs can also be an unwelcome side effect for farmers who grow susceptible crops in a continuous conservation tillage system.

 

Flanders said one solution to chronic chinch bug problems in conservation tillage systems is to temporarily break out of conservation tillage.

 

Accumulated crop residue can be turned under by deep plowing, in turn giving chinch bugs fewer places to hide. When the new crop is planted, an insecticide seed treatment or an at-plant insecticide can be used to deter any remaining chinch bugs.

 

If needed, one to two foliar applications of insecticide can be applied post-emergence. Growers following a mandated conservation tillage program may be able to petition to be allowed to perform this one-time, deep tillage in order to get rid of chinch bugs.

 

“Chinch bug feeding is less deleterious in a vigorously growing crop,” Flanders said. “Therefore, proper fertilization, timely seeding, good weed control, and irrigation can lessen chinch bug problems. Use of a crop rotation that includes unaffected crops has also been suggested for chinch bug control. Legumes are not hosts, and may be a good choice for an alternative forage.”