Friday, August 11, 2017

Wheat Stem Sawfly Causing Problems in Polk County Wheat Fields

Prepared by Phillip Glogoza, Jochum Wiersma and Ian McRae

As wheat harvest moves northward, we are detecting infestations of Wheat Stem Sawfly in fields in Polk County. Recent storms and strong winds have helped bring these problems to front and center.

UPDATE: NW MN Soybean Aphid Scouting Summary for July 31 to August 8, 2017

Soybean aphid populations continue to increase in west and south central Minnesota, though we are approaching a time when growth stage, day length and natural controls in those fields are likely to lead to declining populations soon. More fields have been treated, BUT not every field is at threshold and scouting to determine treatment needs is highly recommended. 

Also, be sure to follow up treatment by scouting to determine control success. Some of the fields we have scouted in NW MN show lots of dead aphids. HOWEVER, it is not uncommon to see plants where aphids survived, numbering into the 100's on some of those plants. These are fields most likely treated with a Pyrethroid - Organophosphate premix.

Where we have treated research plots with chlorpyrifos, kill has been very good. The only aphids in those sites have been winged, migrating aphids in the tops of plants. Their numbers and their babies have remained low in number and time should be on our side in those locations.

Reports for southern MN can be found at Southwest Minnesota IPM Stuff Newsletter

Comments from his August 10 report:

"Aphid treatment continues and has expanded to some new areas. Fields in the southern part of the state that have higher aphid populations are related to planting date and moisture. The earlier planted, wetter parts of the state as well as some of the extremely dry areas have lower aphid populations. Remember, there are always exceptions."

Bruce Potter 
UMN Extension IPM Specialist

Tuesday, August 8, 2017

Here are three recent updates, all relating to weed management issues:

Assessing and documenting yield loss due to dicamba injury in soybean
by Jeff Gunsolus, Extension weed scientist

Photo 1. Leaf cupping symptoms of dicamba injury in soybean. Photo: Bruce Potter
As we enter August, the big unknown in fields presenting dicamba injury symptoms will be dicamba’s impact on soybean yield. Unfortunately, due to the sensitivity of non-Xtend soybeans to dicamba, injury symptoms are not reliable indicators of yield loss. The level of yield loss depends on exposure at vegetative or reproductive stage of growth, persistence of injury symptoms, and growing conditions post-exposure.