Crop Protection: Chomping At The Bit
Tackling insects and diseases early is a key step to preserving yields.
April 6, 2009
How are retailers dealing with the key insects and diseases in their area? CropLife® magazine talked to a few CropLife 100 retailers to get their take.
Integrated pest management practices and timely scouting are the keys to protecting your grower-customers' yields from insects and diseases, says Ernie Holycross, plant manager for Allerton Supply Co., Homer, IL. "I still like to scout and see if it's worth spraying, because every year's a little different," he says.
For example, soybean cyst nematode (SCN) is a common problem in his area, so SCN-resistant soybeans varieties are plentiful. "However, 90% are only resistant to certain SCN races," he says, so he reminds growers to scout for threshold levels.
He also talks to them about the importance of soil sampling. "We need to take soil samples every two years to see if the SCN is growing in numbers," he explains. Yet despite knowing the damage SCN can cause, some growers balk at paying $25 to $35 per soil sample as soybean prices drop.
Other soybean pest concerns include Japanese and bean leaf beetles and soybean aphids. "We're going to try some insecticides on some high-yielding soybean plots to see if we can bump yields no matter what the bean leaf beetle or Japanese beetle infestation," he says.
On the corn side, corn rootworm beetles, and larvae are bad every year in his territory, but Holycross says his growers — who primarily plant genetically modified corn — tend to forget about the secondary pests like wireworms and grubs. "We haven't had a major infestation yet, but need to keep scouting," he says.
Soybean grower-customers of Hills, IA-based Eldon C. Stutsman primarily deal with soybean aphids every season, says Steve Meyerholz, agronomy manager. "Aphids are the worst," he says. "We generally spray pretty early and pretty regularly. The threshold is 250 aphids per plant, but we'll spray earlier than that because we think there's more damage being done if we wait for the threshold amount."
Bean leaf beetles hurt the soybeans earlier, he says, so "we'll add an insecticide at the first Roundup spray to get rid of them."
Weather affects insects. "In dry years we get spider mites," says Meyerholz. "Last year we ended up spraying the majority of our soybean acres for spider mites."
The insects and diseases may be a little different in the South compared to the Midwest, but the concerns are the same.
"The key to managing these and all insects is to scout and properly identify the insect in order to choose the best insecticide," Kenty says. "This is especially true of stinkbugs since there are several different types and not all are controlled equally by the different insecticides available."
However, the most problematic insect the past few years has been the plant bug. "Typically associated with damage in cotton, their populations build up in soybeans and corn," says Kenty. "If left unchecked in areas where cotton is grown, the population being hosted in corn and soybeans will seek out cotton as the corn and soybeans acres mature and dry down. This may seem like simple migration from one host to another — but the concentration is magnified as the plant bugs move to the lower number of acres of cotton. Timely scouting and a good pest management program are the best offense."
Kenty and Holycross note that gray leaf spot is the most prevalent corn disease. Kenty adds that "aflatoxin always looms as a potential problem to plague the selling of the crop."
Soil-borne diseases attack soybeans, including Phytophthora and Pythium, and in the South, the late-season foliar disease, frogeye leaf spot.
A comprehensive, aggressive crop management program that includes seed treatments, sound season-long fertility, and foliar disease monitoring/timely fungicide application are recommended. "It is more effective to take a proactive approach to pest management than to wait for a pest to reach economic thresholds," says Kenty.
Meyerholz says that while his growers' crops don't have a lot of disease problems, around 40% of his growers continue to use Headline fungicide as a preventive measure in soybeans. Holycross, on the other hand, says his aerial spraying in corn will be cut nearly in half due to financing.