By Megha Parajulee
EDITOR’S NOTE: Meg Parajulee is an entomologist at the Texas AgriLife Research and Extension Center in Lubbock. In the following report, he offers an update on cotton insect pests in Texas this year.
The Texas High Plains (THP), largest contiguous cotton patch in the world, had faced an unprecedented drought in 2011 and was unable to recover from the severe drought conditions until last fall. The insect pressure in cotton was relatively low during those dry years.
The region has now received significant moisture. In fact, THP cotton planting to date has been limited to less than 10 percent due to the frequent rain events, which would have approached 50 percent in more normal years. We expect the planting to speed up as soon as the weather clears up. With good area-wide moisture and roadside weed hosts in high abundance, a higher-than-usual insect pressure can be expected this year in the THP and throughout Texas.
Roadside weed hosts, Conservation Reserve Program grasses and wheat serve as excellent sources of thrips that could likely move to seedling cotton upon wheat harvest or weed senescence. Thrips are considered the most significant insect pest of THP cotton, primarily because their damage is generally compounded with early season environmental injury of seedling cotton brought on by high winds, sandstorms and cool/wet weather.
Tools For Thrips Control
At-planting insecticide seed treatment is recommended for thrips control in irrigated cotton, but foliar insecticides such as Bidrin and Orthene could provide effective thrips control.
Cotton producers should also be mindful of cotton fleahoppers this year due to good fall moisture helping support fleahopper overwintering populations, plus excellent spring moisture to support nymphal emergence. Because THP consists of about 30 percent non-Bt cotton, we also recommend watching for some caterpillar populations. Texas High Plains is generally a low lygus region, but non-cotton host habitat management may be the key to manage lygus if our atypically wet year continues.
In the far western part of Texas, cotton fields range from emergence to two-true leaves, and no obvious insect problems are seen in that area. In Central Texas, cotton is at the one- to two-true leaf stage that is experiencing some high thrips populations, most of which have been sprayed for thrips.
The St. Lawrence area is also behind on planting, and no insect issues are reported from that area. Lower Rio Grande Valley (LRGV) and Coastal Bend areas received persistent rain in March and April that delayed planting across much of that region.
Variable Conditions On Coast
According to Dr. Robert Bowling, Extension entomologist at Corpus Christi, cotton growth in South Texas is highly variable, ranging from emerged to nine-leaf stage. Thrips infestations have been light to moderate, and some area farmers treated seedling cotton in the Victoria area as preventive tankmix applications with herbicides.
Red spider mites were building on seedling cotton in the LRGV, but heavy rain suppressed this pest prior to reaching economic levels. Light populations of beneficial arthropods and fleahoppers are being reported in LRGV but have not been observed in the Coastal Bend region. Aphid populations are very light and scattered across the area.
One of the undesirable effects of this heavy rainfall could be degradation and leaching of the seed treatment insecticide applications.
Therefore, it is expected that the desired efficacy and duration of protection from seed treatments may be lower than the ideal two to three weeks. Farmers may need to scout more frequently and prepare for curative insecticide applications.
Areawide good moisture is certain to intensify the growth of several weed species, which support many sucking pests of cotton, which, combined with the wide range of planting dates, could provide challenges to managing arthropod pests in Texas cotton in 2015.
Contact Megha Parajulee in Lubbock, Texas, at firstname.lastname@example.org or (806) 746-6101.