Update: Wheat Stem Sawfly infestation levels found in Polk County

prepared by Phillip Glogoza, Jochum Wiersma and Ian McRae

Wheat stem sawfly (WSS) are being found at significant levels in Polk County. Field surveys were conducted from August 14 to 18, 2017 to learn more about the levels of infestation and the possible size of the area impacted. 

The inspected fields had infestations on the field margins ranging from a low of 0 to a high of 15 WSS/row foot. Every field inspected had fewer infested stems as sampling moved further into the field. Edge effects are pretty strong with this insect as they overwinter in stubble and migrate to nearby wheat the next year.

Your Guide to Profitable Sulfur Fertilization in Spring Wheat

Dan Kaiser, Extension Soil Fertility Specialist

The major cause of sulfur deficiencies in crops is a lack of mineralized S in the soil. Research and recommendations in Minnesota have shown well-documented yield increases for corn with the application of sulfur, but what about wheat? Recent research funded by the Agricultural Fertilizer Research and Education Council and the Minnesota Wheat Research and Promotion Council shows us that sulfur applications can benefit wheat yield and protein concentration. Here are some tips and recommendations for sulfur applications in spring wheat based on that research.

Plan to attend the Strip-till Expo on September 6

Jodi DeJong-Hughes, Extension educator

Plan to attend this year’s Strip-Till Expo on Wednesday, September 6th at the University of Minnesota - North Dakota State University Tillage Research Trials, west of Fergus Falls, MN.

A hallmark of the day will be the side-by-side field demonstrations in the afternoon. Eight strip-till implement manufacturers will demonstrate their equipment, including Dawn, ETS, Gates Mfg., Kuhn Krause, Orthman Mfg., Schlagel, Twin Diamond, and Yetter.

Factors influencing dicamba volatility

Jeff Gunsolus, Extension weed scientist

Earlier Crop News articles focused on dicamba’s potential routes of injury, injury symptomology, soybean sensitivity and yield loss potential. In this article, I would like to explore in greater detail the factors that could contribute to dicamba volatility's role as a potential route of injury. I will be working off the assumption that the primary cause of dicamba volatility is due to degradation of the new dicamba formulations to dicamba acid, dicamba’s most volatile form. A 1979 Weed Science publication by Behrens, R. and W. E. Lueschen titled "Dicamba Volatility" will serve as my reference (Weed Sci. 27:486-493).

Target weeds after small grain harvest

By Jared Goplen, Tom Peters, and Dave Nicolai

Waterhemp in a wheat stubble field in Ottertail Co., Minnesota. Photo: Dave Nicolai

One of the many benefits of including small grains in crop rotations is improved broadleaf weed control and breaking up weed lifecycles. Although freshly harvested small grain fields have a clean look, they often have weeds hiding in the stubble. The most prominent weeds in stubble fields are often late-emerging weeds like waterhemp and other pigweed species that emerged after early season herbicide applications were made. Control escaped weeds now to prevent seed production and weed seed bank replenishment.

When good butterflies go bad

Bruce Potter, IPM specialist and Bob Koch, Extension entomologist

Photo 1. Thistle caterpillar leaf feeding and webbing. Photo: Bruce Potter

The second 2017 MN generation of thistle caterpillars continue to cause concern in some soybean fields. Most of the reports of Minnesota high populations are from SW, SC, C, and the WC part of the state.

Adults and egg-laying are now tapering off but more than two weeks of painted lady butterfly egg-laying activity means that there is a wide range of larval sizes out there.

Wheat Stem Sawfly Causing Problems in Polk County Wheat Fields

Prepared by Phillip Glogoza, Jochum Wiersma and Ian McRae

Figure 3. Wheat stem sawfly cut stems were so extensive, the cut stems could be picked up as a bundle on the edge of this wheat field west of Crookston, MN.

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.

Farmers have noticed lodged stems, particularly on field margins, where in some cases plants are 100% lodged for 50+ feet from the edge inward. In those cases, the cut stems could be grabbed and picked up in a bundle (Figure 3) and the stubble below was all cut (Figure 4). As we inspected the interior of these fields, the percent lodging, declined, but there was still evidence of Wheat Stem Sawfly damage.