corn field waits for rain in Johnson County, Iowa

A corn field waits for rain in Johnson County, Iowa. The silver lining to the dryness has been slower disease spread.

Drought has been the main issue affecting Iowa farmers, but Mark Storr may have found a silver lining in it.

Storr, a technical service representative with BASF in Nevada, Iowa, said with less moisture, disease pressure has been less of an issue this year. This is especially true in west central Iowa, which was in the “Extreme Drought” classification of the U.S. Drought Monitor as August neared its end.

While the drought has been harmful to crops, the lack of moisture hasn’t allowed mold and toxins to develop this year either.

“Disease pressure was low,” Storr said. “There were areas of southern rust that showed up in corn in areas of southwest Iowa and frogeye leaf spot in western Iowa. Overall, disease pressure was low and yes, it’s directly as a result of the dry weather.”

Storr added that tar spot has been reported to be creeping into Iowa in certain areas.

While disease pressure seems to be lower overall in Iowa, a common foe in the field continues to be a major issue — waterhemp.

“Waterhemp continues to be an issue, and it’ll be an issue going forward,” Syngenta agronomy service representative Dean Grossnickle said. “The combination of being hot and dry played a role with the efficiency in the control of herbicides.”

Grossnickle said not enough water to activate the herbicides made things difficult in Iowa fields.

Storr also saw waterhemp as the major weed this year, saying it seems to thrive in a corn-and-beans rotation. Cover crops can sometimes break that up enough to disrupt waterhemp, but there is a lot of diversity in the weed at the moment.

“That genetic diversity has given rise to a lot of resistance,” Storr said. “There are multiple types of action it’s able to defeat. It’s our main problem weed.”

Storr also referenced velvet leaf and giant ragweed as the two other major issues in Iowa fields this season. Overall this year, Storr said weed management seems to still be a major issue in soybeans as there are more post-emergence options available in corn.

“Soybeans require a genetically modified platform to deal with (weeds) either with LibertyLink type seed and the Xtend system or dicamba,” Storr said. “All three of those are successful, but they can also demonstrate poor weed control. It’s all about understanding the chemistries that fit into those systems.”

Storr said timing in the applications and having “multiple modes of application” can be the most effective options for soybean management.

When it comes to pests in Iowa fields, Grossnickle said corn rootworm has been coming back into a prevalent spot. With downed corn and waterhemp taking a lot of the focus for farmers at the moment, Grossnickle warned that people need to keep this in mind.

“I think anybody who has trapped for them this year has seen the numbers kind of spike,” Grossnickle said. “Given the lack of soil moisture this year to kill them like we have in the past, I think pressure is going to be really high going into next year.”