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August 2013 Archives

Dean Malvick

The unusual weather this season in Minnesota has created favorable conditions for various diseases in corn and soybean crops. Some diseases have been appearing since June due in part to delayed planting and crop growth and abundant rainfall in many areas. This article focuses on diseases that have been recently been confirmed and have raised concern. In corn fields, above average levels of common rust are being reported and Goss's wilt was confirmed in two fields. In soybean, Phytophthora root and stem rot and the less important but often noticed leaf diseases bacterial blight and Septoria brown spot are widespread. This is a good time of the year to scout fields for crop diseases.

The Art of Swathing

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Swathing or windrowing of wheat, barley and oats were, at one time, the default operations that signaled the beginning of harvest. The primary purpose of swathing is to speed up and even out the dry down of the crop. Swathing always posed a risk as grain in the swath is more prone to preharvest sprouting if threshing is delayed due to adverse weather

Therefore, most wheat and barley is now straight cut in large part because modern varieties allow for it. Preharvest applications of glyphosate have further reduced need to swath wheat. In oats swathing remains more common place.

Swathing is becoming, however, something of a lost art. First, you have to decide when the crop is ready to be swath. The optimum time to swath is when the crop has reached physiological maturity. This is the same time to consider the application glyphosate. This is the point in the development when the crop has reached its maximum dry weight and the grainfill period has come to an end. Moisture content of the grain will vary but the ranges from 30 to 40 percent. In the absence of a moisture meter, there are other cues that signal the crop has reached physiological maturity. One of the easiest is to look at the color of the uppermost internode, or peduncle. The upper most portion of the peduncle, just below the spike or panicle, will have turned very light green to yellow when the crop reaches physiological maturity. There still may be some green in the canopy below or in the glumes but the least mature kernels will no green left in them, when threshed out by hand, .

Swathing before the crop reaches physiological maturity will result in yield and test weight losses and green kernels in the harvested grains. The losses get progressively worse the earlier you cut the crop. Research at NDSU in spring wheat and durum showed that swathing the grain at 45% moisture caused a 1 to 2 lb reduction in test weight and about a 10% reduction in grain yield. Swathing after physiological maturity increases the risk of shattering and will equally cause yield losses but no losses in grain quality. Shattering losses can be reduced by swathing in the early morning or late evening when some dew is present in the crop.

Protect pollinators while trying to protect your crops


By Robert Koch & Marla Spivak, Extension Entomologists

Honey bees and native bees forage in and near soybean and cornfields, especially during dry weather. When treatment decisions are being made for pests of these crops, it is important to consider minimizing the risk to these pollinators. Bees are the most important pollinators of our fruits, vegetables and crops like alfalfa hay that feed our farm animals. Honey bees and the thousands of native bee species all rely on the flowers they pollinate for good nutrition and health. Bees are being pushed to the tipping point by various factors, such as disruption of natural habitats, diseases and parasites, and widespread overuse of pesticides.

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