Plenty of opportunity for pests in ’07

COLUMBUS – Ron Hammond, an OSU Extension entomologist with the Ohio Agricultural Research and Development Center, recently discussed information on how to best manage crop pests, particularly slugs and soybean aphids, that can cause plant damage and yield loss in both corn and soybeans.
Aphids. The soybean aphid, a sapsucker which first made its appearance in Ohio in 2001 is expected to show up in large numbers this season, following the pattern of low populations one year and high populations the next.
Last year, soybean aphids were practically a no-show.
“Our prediction this year is that we will have problems,” said Hammond.
“Based on observations last year, aphid populations built up at the end of the season, and trap collections done on overwintering buckthorn across the Midwest revealed significant populations and eggs. We know the soybean aphid is coming. Growers need to be ready for it.”
Asian ladybeetle. Hammond said that researchers speculate the level of soybean aphid populations may be tied to the population of the multicolored Asian ladybeetle, a known predator.
Put simply, when soybean aphid numbers are high, ladybeetle numbers are also high.
Although controlling the aphids during the summer months is light, the ladybeetles may prevent the aphids from overwintering by actively feeding on them in the fall.
Ladybeetle populations were low last year because the aphid numbers were also low, which would account for researchers’ assumptions that soybean aphid populations will be high this growing season.
For growers, the best way to manage the soybean aphid is to educate themselves on the insect, know when to scout, and to carefully time foliar insecticide applications if treatments are warranted.
Scouting. “Growers should start scouting their fields the first part of July and be ready to spray if insect populations reach the 250 insects-per plant threshold.
“Growers who have fields near buckthorn in northwest Ohio should start scouting their fields in early to mid-June as these areas may see aphids coming directly from buckthorn first,” said Hammond.
Aside from scouting and monitoring soybean fields, growers may have other alternative management options.
One option is to practice skip-row – a form of controlled traffic that leaves unplanted rows in the field at planting that act as tram lines.
In the event a grower would need to enter a field at any time during the growing season to spray for insects, the plants would remain undamaged, eliminating worries of lost yield.
Treatments. Another option is to apply seed treatments at planting. Insecticides such as Cruiser and Gaucho have been labeled for controlling soybean aphid.
However, Hammond said that recent Ohio Agricultural Research and Development Center research has shown that such at-planting seed treatments are ineffective for the aphid.
“The problem is that one would apply the treatment in early or mid-May at planting, and the aphid doesn’t show up to be a potential problem until mid-to-late July. That’s too far of a time spread for the treatment to have any impact,” said Hammond.
“Another problem is the potential for not enough aphids to show up to warrant sufficient control. Our research showed that there was no difference in performance between treated plots and untreated plots under this situation.
“The treatments might prevent aphids from reaching threshold for about a week or two, but a grower will need to treat those fields sooner or later if the aphids are building.”
Combo. A third preventive measure being recommended by some is to apply a fungicide/insecticide combo.
But research with Ohio State’s Department of Plant Pathology has shown that such a treatment, specifically a Quadris/Warrior combination, has been shown to boost soybean yields only in fields with high soybean aphid populations.
“There is no doubt that if you have high soybean aphid populations, a grower can save anywhere from 5 bushels to 18 bushels per acre with such treatments,” said Hammond.
“However, we don’t recommend general sprays just for plant health purposes.”
Slugs. Growers should also be on the lookout for slugs this growing season. Slugs recur every year in both soybean and corn fields, mainly in no-till fields where residue provides them with food and shelter.
“Based on fall sampling, we had a lot of adult slugs, so the potential is there for slug problems,” said Hammond.
“Whether or not we have a problem will, of course, depend on how early we get the crops planted and how the weather will hold up.”
Hammond said the key to outwitting slugs is to follow a careful Integrated Pest Management plan of fall sampling, scouting and the tactic of planting as early as possible to allow the crop to outgrow any slug damage.
“We are starting to get a good feel as to what’s going on with slugs and how to control them,” said Hammond.
“It takes management, understanding and treatments when warranted, which are not cheap. But losing your crop is not cheap, either.”