Soybean pest may be heading east

By David Hotle, The JOURNAL


While Washington County is not one of the counties in which the soybean gall midge has been discovered, Iowa State University Extension agronomist Mehgan Anderson is not sure the new soybean pest isn?t heading east.

So far, since being discovered in Iowa, the fly that has caused injury to soybean crops has only been confirmed in 12 Iowa counties: Lyon, O?Brien, Clay, Plymouth, Cherokee, Buena Vista, Woodbury, Harrison, Shelby, Pottawattamie, Cass and Page counties. Anderson said though the pest has traveled east from reports of the insect?s presence in Nebraska in 2011 and in South Dakota in 2015. Not much is known about the soybean gall midge, and entomologists have not been able to even confirm the species yet, Plant injury as a result of the pests has been mostly at field edges.

?Soybean gall midge is the name we are giving this mystery fly,? Anderson said. ?Its causing a lot of issues in soybean fields in Iowa. I don?t see why they won?t continue moving east, but I don?t know at what pace that would be because we don?t know much about it.?

She said this is the first strain of fly to impact soybeans and when it was first found researchers believed the midges were showing up in fields that already had disease problems. The initial presumption was the midges weren?t doing any damage by themselves. More recently the Midge has been discovered to be a pest of the

Observations have shown cultural control practices, times of planting, row spacing, tillage and others don?t seem to have an impact on the infestation.

Injury is usually restricted to the base of the plant, Initially infested stems look swollen then turn brown and break off, resulting in the plant?s death. Anderson said it is the larvae of the midge that eats the stems.

Other than midges in northwestern Iowa the soybean crop this year has had few issues. Anderson said she has received reports of herbicide drift this year. She says insects and disease haven?t been as bad as they have in previous years. She credits some of the weather patterns for the good year. Anderson said ISU is just starting to hear about Sudden Death Syndrome this year.

Anderson also commented this year is a good year for soybeans. She said most things have been good, especially now that the area is getting some rain.

?People say soybeans can make up a lot of lost ground if we have good July and August weather,? she said.