CORN EARWORMS are among the pests confronting southern corn growers.

Corn insect control: Now’s time to develop game plan for 2014 crop season

If growers farm in situations that increase the risk of insects attacking seedling corn, they should consider going to a higher rate of insecticide seed treatment.

As southern corn growers begin giving thought to their game plan for 2014 corn insect control, entomologists offer several strategies for accomplishing that. 

Challenges vary. In Georgia, it will be controlling stink bugs without methyl parathion, which can no longer be used.

“It first became available in 1949 and was one of the original organophosphates to be registered,” says University of Georgia Entomologist David Buntin. “We mainly used it for stink bugs in corn. Now, we’ll rely heavily on bifenthrin pyrethroid. 

“Stink bugs continue to be a major pest, and many growers treated two or three times in 2013. The brown stink bug is difficult to control, while southern green stink bugs are easier to control, and other pyrethroids also control it well.”

Growers will benefit from more available pyramided Bt hybrids. “Several provide excellent corn earworm protection,” Buntin says. 

The improved refuge compliance for corn in the South has resulted in much higher populations of southwestern corn borers.

“In 2013, we trapped higher numbers than we’d seen for the last seven or eight years,” says Angus Catchot, Mississippi State University Extension entomologist.

“We need to stay on top of this pest. Some non-Bt corn has cut more than 200 bushels, but it needs to be protected from the southwestern corn borer.

“Another pest that we need to continue to monitor in non-Delta areas is the sugarcane beetle. Control of this pest has to be planned up front since there are no rescue treatments.

“Control methods include higher rates of clothianidan seed treatments or pyrethroid in-furrow sprays. We have also seen good results with some of the granular insecticides.”

Catchot and several other southern entomologists are working on this issue to help growers reduce risk of yield loss.

If growers farm in situations that increase the risk of insects attacking seedling corn, they should consider going to a higher rate of insecticide seed treatment.

“The standard 250 rate sometimes is not sufficient for controlling some of our tough early season pests,” says Auburn University Entomologist Kathy Flanders. 

“We urge growers to order the 1250 rate if they plan to farm new ground, such as bringing pasture into corn, or if they are planting continuous corn or planting into a heavy cover crop.

“With general no-till, they could probably use the 250 rate, but if they do, we recommend they burn down the cover crop and leave nothing on the field for a month before planting because in no-till, there is quite a lot of wheat cover that harbors cutworms. Alternatively, growers can apply a low rate of a pyrethroid insecticide at planting to control the pest.” 

Additionally, selecting the appropriate Bt corn hybrid is critical.

“If the agronomics are there — high yield potential, area adaptation and a good disease package — our studies for the last three years show Bt corn for above-ground caterpillar pests pays off,” Flanders says. 

Insecticide seed treatments and rates are two of Tennessee corn growers’ main considerations as they enter the 2014 cropping season. 

“We especially need to consider the sugarcane beetle which, although a sporadic pest, can be devastating to the crop,” says Scott Stewart, Extension entomologist at Jackson, Tenn. “The low seed treatment rates cannot control it adequately. 

“For fields at high risk for sugarcane beetle, we recommend one of two options:  Use the highest labeled seed treatment rate, particularly Poncho 1250, or use an in-furrow application of granular or liquid insecticide. 

“A good option, particularly when applying starter fertilizer, is to spray a pyrethroid insecticide such as Capture LFR or Brigade.”

Next, growers can choose hybrids with the best agronomics, with the Bt technologies that best fit their needs.

“In Tennessee, we take full advantage of the Bt technologies in corn,” Stewart says. “We know they have good value on corn borers, our primary target pest.” 

Some South Carolina growers double-crop corn after wheat, which occasionally results in high infestations of earworms and fall armyworms late in the season.

“Growers who double-crop may especially benefit from planting a Bt hybrid,” says Entomologist Francis Reay-Jones, Clemson University Pee Dee Research and Extension Center, Florence.

“Foliar insecticides generally do not work well with worm infestations, either in the whorl or in the ear itself.” 

In 2013, the state had much higher infestations of southern green stink bugs across all crops than it had seen in prior years.

“Early in the season, especially in corn fields adjacent to wheat, southern green stink bugs migrated corn once the wheat matured and dried,” Reay-Jones says.

“We saw a lot of ear damage from stink bugs later in the season, with the typical banana-shaped corn ears. Stink bugs are difficult to control — some growers add a pyrethroid occasionally when they apply fungicides. These applications likely have only limited impact on either corn earworm infestations in the ear or stink bugs.”

Early season pests in South Carolina corn include sugarcane beetles, which caused issues in 2013 in the western part of the state. 

“High rates of insecticide seed treatments can help control them,” Reay-Jones says. “Some growers use soil insecticides at planting, but these are generally not as effective as high rates of seed treatments.”

Most early season insect control is prophylactic. “For example, most Arkansas corn growers use seed treatments,” says University of Arkansas Entomologist Glenn Studebaker.

“We saw increases in seedling pests in 2013, particularly stink bugs. Scouting and using a higher seed treatment rate can help. We also sometimes have areas with chinch bug outbreaks, and seed treatments really do help with that pest.

“In fields with a history of cutworm problems, particularly no-till fields, where there’s a lot of vegetation, growers can apply a pyrethroid behind the planter in addition to using a seed treatment.

“We also have some areas in southeastern Arkansas that have experienced sugarcane beetle problems. Using bifenthrin in the seed furrow at planting helps control this pest.”

See more articles from the Southern Corn and Soybean Production Guide!

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