Cropping Issues in Northwest Minnesota

While corn maturity and harvest are still some time away, it is never too early to be aware of potential challenges to crop growth and development and harvest. Are you at risk of leaving some ears behind? As ears fill out and eventually begin to mature and dry down, corn plants become very top-heavy. Stalk rots increase the chance that plants will fall over (lodge) due to a combination of gravity and weather. In addition to being not-so-fun to harvest, lodged plants can significantly decrease harvestable yield by literally leaving some ears on the ground. Stress conditions favor stalk rots. The combination of mid-season environmental conditions that favor kernel-set followed by conditions that stress plants increases the risk of stalk rot. This year, weather conditions in much of Northwestern Minnesota were relatively mild during silking and pollen shed, favoring good kernel set. However, since then much of the crop has experienced abnormally dry or even moderate drought condition

Wheat stem sawfly adult female (P. Beauzay, NDSU) 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.

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.

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.  

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. Read more » Response of soybean yield to dicamba exposure: A Research-based report by Jeff Gunsolus, Extension weed scientist Xtendimax drift onto non dicamba-tolerant soybean. Photo: Liz Stahl As you continue to assess and document the impact of dicamba injury on soybean yield, I tho