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Soybean aphids

More insects to watch for in 2013

While most people probably take little notice of such things, soybean growers and agricultural writers around Ohio are likely well aware that 2013 is an “on” year for the soybean aphid.


The every-other-year rise and fall of the soybean aphid population is a result of the predator/prey cycle for the aphids and the otherwise irksome Asian lady beetle that eats them. When aphid numbers are high, lady beetle numbers rise and decrease the aphid population. In 2013, entomologists are watching closely for soybean aphids and advising soybean growers to do the same.


“Although we have not yet found aphids on soybeans in Ohio, other states are reporting finding them in fields. During a regularly scheduled aphid scouting trip in mid-May made by our colleagues from other states, aphids were reported as ‘abundant near Toledo (Secor Park)’ on buckthorn, the aphid’s overwintering host. What this probably means is that soybean aphids will be present this year in Ohio soybean fields, which would continue the two-year cycle,” wrote Ohio State University Extension entomologists Ron Hammond and Andy Michel in a recent CORN Newsletter. “If you remember from this past winter, we were not sure what might happen in this year, and thus, had not made a prediction. However, based on what is being seen in other Midwest states, aphids will probably be present. At this time, there is no way to predict how common aphids will be, and whether they will reach economic levels. We urge growers to plan to scout for aphids later this summer and prepare to take action if economic thresholds are reached.”


It is also important to be on the lookout for the potato leafhopper, a pest that can cause significant economic losses for alfalfa growers by reducing yields and quality, Hammond said.


The bright green, wedge-shaped insects can cause hopper burn on leaves and stunt alfalfa plants. The damage can result in yellowing of alfalfa leaves and could cause significant yield loss and impact the plants’ nutritional value. Potato leafhoppers are an annual pest problem in Ohio in the spring as the pest migrates north from Gulf Coast states, often carried on winds in storm systems.


“In alfalfa, potato leafhopper is definitely our No. 1 pest,” Hammond said. “It’s an insect that, if allowed to go past threshold and develop young population, can lead to damage such as stunting.


“Most growers have already had their first cutting, so now is the time for scouting for this pest because we know it has arrived in Ohio. Growers can begin scouting for the leafhopper once alfalfa regrowth reaches sufficient height for sweep-net sampling,” he said.


With leafhopper-resistant alfalfa, the economic threshold is three times the normal threshold of three leafhoppers per inch of growth. With resistant varieties, the threshold would be 18 leafhoppers for 6-inch tall alfalfa.


“If the resistant alfalfa is a new planting this spring, growers might want to use thresholds meant for regular alfalfa during the very first growth from seeding,” he said. “After the first cutting, growers can then use three times the normal level threshold.


“Growers who take the time to sample and spray are better able to control the pests, while those growers who don’t, tend to get hit by them.”


There is a new tool available at to monitor other insect pest levels at www.insectforecast.com. The Insect Forecast Tool is a website that forecasts the daily migration of crop damaging insects up to five days in advance May through September. The tool can help crop producers monitor when corn rootworm larvae are hatching, and track the migration and moth flights of corn earworm and western bean cutworm throughout the growing season. The Insect Forecast tool analyzes this trapping data and weather patterns to issue one, two and three-to-five day forecasts for corn earworm and western bean cutworm.


Farmers in the Corn Belt can also sign up to receive email alerts from May through September to learn when these insects pose a rick in their area. The Insect Forecast tool is being sponsored for the fourth year by Monsanto and offered to farmers by its Genuity brand.


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