Drought-like conditions blanketed a majority of the state this year, which has impacted the expected crop size. As the harvest slowly gets underway, the drier conditions have many farmers worried about combine fires and soybean pod filling.

Clarke McGrath, Iowa State University Extension crop specialist, said farmers have been “behind the eight ball from the outset.”

“Planting season was a wet mess and a lot of beans went in behind schedule, which cost us yield from the start. Then the drought hit and you could see the beans seem to stall out on their growth, it took forever for them to look like they would canopy. In later July and most of August, drought symptoms were common across fields, with some spots looking worse than others,” McGrath said.

In his area, producers saw a lot of leaf flipping.

“That’s when leaves flip over and you see their silvery-green undersides, a kind of plant defensive response. It reflects more light than when they are right side up so reduces the amount of sunlight the plant takes in. They’ll also fold their leaves together to a degree for the same reason, to reduce light on the upper surfaces of the leaves. It also conserves water for the plants, so while it helps the plant cope with drought conditions, it also typically reduces growth and ultimately yields since these responses reduce photosynthesis,” McGrath said.

McGrath said farmers in his area fought pockets of Japanese beetles and a few spider mites, but the drought was the biggest challenge for growers.

“The dry and pretty warm conditions did make some weeds tougher to contain than they usually are, especially waterhemp of course. I have to say I am impressed though, between the ag chem dealers and the farmers working long hours fighting windy days and fast growing weeds, fields look very clean for the most part. They used solid rates of chemicals and got good coverage, which was critical this year,” McGrath said. “Silage has been getting cut for probably two weeks and I’d expect to start to see some early corn and beans getting combined in the next week or two at the most.”

ISU Extension crop specialist Gentry Sorenson said the soybeans in his region needed a bit more time to dry down before they could be harvested. Northwest Iowa experienced drought conditions in Buena Vista, Clay, Pocahontas, Palo Alto and southern Kossuth counties.

“In regard to insects, some areas, mainly in the northern tier of counties, farmers did find pockets of soybean aphids that they sprayed. Waterhemp is the weed that causes trouble for many farmers in northwest Iowa,” he said.

Clarabell Probasco, ISU Extension specialist, said soybean crops in her area have been stressed for several weeks due to a lack of moisture.

“The dry conditions began during pod filling stages and have continued to persevere, which will ultimately affect the seed size of the bean inside the pods. With the drier conditions, some fields have begun to see pressure from spider mites sporadically throughout the fields,” Probasco said.

“We are still a handful of weeks away from any type of grain harvest but many growers who harvest corn silage for their livestock are in full swing with silage harvest.”

ISU Extension crop specialist Michael Witt said in west central Iowa, soybeans are a mixed bag with moisture being the largest factor of diversity.

“Some areas received ample rain and soybean crops are still fully green and looking like good yields. Others are yellowing/dropping leaves and will be in the realm of harvest in the next few weeks that missed most of the rains. The further west and northwest in my region (Harrison and Monona County river bottoms), the droughtier the areas are,” Witt said.

“These areas will see some drought damage to yields,” he said. “Insect infestations have been minimal except for a later season grasshopper infestation in corn, which is causing major damage/defoliation to outside rows and field edges.”

Waterhemp and marestail proved problematic in Witt’s area, which he said are the usual culprits.

“In some heavily damaged fields with herbicide growth regulator (dicamba) damage is present, there will be significant yield losses. Drought conditions and dicamba are not a combination for quality yields,” he said.

Meaghan Anderson, ISU Extension crop specialist, said farmers in her area struggled with cool and wet conditions early on and then dealt with a dry June and July. In the end, though, the soybean plants remained tough.

“I don’t think it will be the huge crop that was harvested last year, but it will still be pretty good. Japanese beetle are probably the most common insect issue I visit with farmers about, though they were never bad enough on a field level to reach thresholds for treating,” Anderson said.

“Soybean gall midge has reached central Iowa and was found in Warren and Polk counties for the first time this summer. Waterhemp is the worst issue in my area and was prevalent again this year. Many fields have some waterhemp above the soybean canopy,” she said.

Angie Rieck Hinz, ISU Extension Crops field specialist, said across her eight states, soybean fields are “highly variable.”

“Many beans in Hamilton, Humboldt and Webster counties are turning already because it has been dry. The top pods did not fill out. In Worth, Cerro Gordo and most of Franklin, the beans have looked good all year,” she said.

“There’s been no insect pressure in the soybeans, but the waterhemp is horrible this year. It was too hot and dry, even most post applications went on and impacted weed control.”