DECORAH -- Soybean aphids are about as schizophrenic as rain in Northeast Iowa.

Monday's weekly U.S. Department of Agriculture Crops and Weather Report indicates challenges continue to pop up for area farmers. Insect and moisture issues are on the forefront.

In May and early June it seemed the rain just wouldn't quit, leading to planting delays and record flooding. Now farmers say fields could use a shot of moisture.

Soybean fields are being infested with soybean aphids. While some plants are covered with more than 1,200 of the tiny yield-robbing insects, others in the same field don't have a single one. Deciding whether it pays to spray fields is difficult, given the erratic nature of the insects.

Brian Lang, a Iowa State University Extension crop specialist based in Decorah, said the economic threshold is about 650 insects per plant. Anything less than that, and paying $15 to more than $20 per acre to treat fields isn't worth it.

Usually, it's a pretty easy decision of whether to spray. Aphid populations have been fairly consistent in the past and usually dissipate naturally within the next couple of weeks.

But the uneven aphid populations and soybean development that's about two weeks behind normal make the decision to spray more difficult. Aphids suck nutrients from plants, curtailing crop development.

"If it was my field, I would spray if aphids exceeded 1,000 per plant, I wouldn't spray at 200 to 300 and scratching my head like everyone else at 400 to 500," Lang said.

With cash soybeans more than $12 per bushel and December beans on the Chicago Board of Trade topping $13, Jim Falck of rural Decorah didn't think twice about spraying for the pests. He finished 300 acres on Saturday.

"Some plants were infested and some unusually clean. But beans are worth too much money not to spray," Falck said. "I didn't want to take any chances.

In 2003, soybean aphids along with a lack of moisture were widely blamed for cutting bean yields in half or more.

Other soybean diseases showing up now in Northeast Iowa include downy mildew, sudden death syndrome and just a few reports of white mold.

Eighty percent of Iowa's soybeans are setting pods, the report said. The crop is rated 2 percent very poor, 7 percent poor, 26 percent fair, 49 percent good and 16 percent excellent.

Development of the state's corn crop is nine to 11 days behind the five-year average, the report said. Seventy percent is in the milk stage and 30 percent in the dough stage.

The crop is rated 2 percent very poor, 7 percent poor, 22 percent fair, 50 percent good and 19 percent excellent.

Falck said the tips of leaves are rolling up a bit in an effort to conserve moisture. That also slows development.

"The tips are pulling back a bit. The pastures and corn could use some rain," he said.

Contact Matthew Wilde

at (319) 291-1579 or

matt.wilde@wcfcourier.com.