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Showing posts from July, 2017

Uncovering dicamba herbicide's wayward ways

by Jeff Gunsolus, Extension weed scientist Leaf cupping symptoms of dicamba injury in soybean. Photo: Fritz Breitenbach Dicamba injury to non-target soybeans has been widely reported in south central and southwest Minnesota. Symptoms range from cupping and strapping of newly emerged leaves to height reduction and injury to growing points. At low dicamba concentrations, symptoms were slow to emerge, showing up 14 to 21 days after exposure. The big unknown, of course, will be impact on soybean yield, which will require negotiations now to determine the most accurate in-field yield comparisons later.

Estimating Grain Small Grains Grain Yields

The USDA-NASS' July 1 yield forecasts for barley, oat, and spring wheat were 67, 71, and 61 bushels per acre, respectively.  This would mean a new state record for spring wheat, while the forecast for barley and oats are 10 and 7 bushels off the records set in 2015. To estimate yield the USDA-NASS collects farmer's assessment of yield prospects throughout the growing season, i.e. the USDA-NASS asks producers to predict their final yield. At first glance, this may seem a bit unscientific and not very accurate. The statistical methods that are used to crunch the collected data and have it confess a forecast, however, are robust and because enough producers are surveyed, the forecasts have been proven predictive at the aggregate level.  This is, in a way, a testament that you each know you crop and operation pretty well. The completely methodology can be found here .

Luxury Uptake of Boron: How Much is Too Much?

By Dan Kaiser, Extension Soil Fertility Specialist The ultimate goal of nutrient management is to ensure that the plant has enough nutrients to produce maximum potential yield. This involves monitoring soil nutrients and crop uptake, and often supplementing nutrients that the crop is lacking. But what happens when the plant takes up more than enough of a certain nutrient? That’s called luxury uptake. Though it isn’t usually a problem for crops, it can become an issue if a nutrient reaches toxic levels in a plant. In Minnesota, the main concern is with Boron in soybeans and other broadleaf plants.

Soybean aphid infestations and reports of failures of pyrethroid insecticides to control soybean aphid

Robert Koch (Extension Entomologist), Ian MacRae (Extension Entomologist), Bruce Potter (Extension IPM Specialist), and Phil Glogoza (Extension Educator – Crops) By now you should be scouting your soybean fields for soybean aphid on a regular basis. Soybean aphid can be found in most fields throughout the state and populations have reached economic threshold (250 aphids per plant) in some fields in northwest Minnesota and have require insecticide application to protect soybean yield. In northwest Minnesota (especially around Norman County), applications of pyrethroid insecticides are failing to adequately control aphid populations in some, but not all, fields. This is the third year in a row that we have received reports of failures of pyrethroids to control soybean aphid in Minnesota. In 2015 and 2016, field-level failures of pyrethroid insecticides were reported (Figure 1) and pyrethroid resistant populations of soybean aphid were confirmed in Minnesota, particularly in parts

The Dicamba Dilemma: Facts and speculations

Used with permission by Aaron Hager, University of Illinois Dicamba injury to soybeans in a southwestern Minnesota field. Photo: Stephan Melson Dicamba injury to non-target crops has dominated Extension discussions this week. Non-tolerant soybeans are extremely sensitive to this chemical and damage has been reported in a number of fields throughout the state. The following article by Dr. Aaron Hager at the University of Illinois echoes observations we have been making in Minnesota and summarizes injury symptoms on soybean, possible routes of exposure, and potential yield effects. His article is reprinted in its entirety:

Hay Rake Impacts Ash Content in Alfalfa Hay

Abby Neu, Craig Sheaffer, Samantha Wells and Krishona Martinson, University of Minnesota; Marvin Hall and Dan Kniffen, Pennsylvania State University; and Dan Undersander, University of Wisconsin. Summary: Using a hay merger or sidebar rake to combine swaths resulted in less ash content compared to a wheel rake; however, rake-type rarely resulted in differences in forage nutritive value. In addition to wide swaths, cutting heights ≥2 inches, and flat mower knives, the use of a hay merger or sidebar rake can be added to the list of best management practices to reduce ash content in alfalfa hay.

Pre-harvest Management of Small Grains

To save time and money most of you prefer to straight cut your wheat, barley, rye or oats.  The allow for straight cutting the crop has be evenly ripe across the field and the straw and grain has to be dry enough that it will feed through the combine. Waiting for a whole field to dry down poses a risk for the portion of the field that is already harvest ripe, including sprout damage, straw breakage and lodging. To even out dry-down and/or speed up dry-down you have two basic options. Swathing or windrowing, at one time, was the default operation that signaled the beginning of harvest.  A second preharvest option is an application of glyphosate at the hard dough stage. Glyphosate is labeled as a harvest aid to control late emerged weeds that may interfere with harvest. The RoundUp PowerMax II  label doesn't define it as a desiccant. Research has shown that glyphosate applied with or without ammonium sulfate may hasten drydown of the wheat crop if conditions for drydown are adver

White Heads

Jochum Wiersma, Ian MacRae, and Madeleine Smith Is not the reincarnation of the Detroit rock due the White Stripes but a phenomenon that often can be seen this time of year in wheat fields are they are starting to ripen.  The causes of these premature ripened heads are varied and a diagnostic key can be found here . People of commented that especially the wheat stem maggot is more prevalent this year and my travels to the different field trials across the state confirm this. The seemingly high numbers of wheat stem maggot may be related to the mild winter conditions.  Several insect pests that overwinter in Minnesota have had comparatively high and early populations this year. Incidence will generally be worse along field edges and taper off as you walk further into the field.

4 Steps to More Effective Tissue Sampling

Daniel Kaiser, Extension Soil Fertility Specialist For over 50 years, the practice of plant tissue sampling has been used to determine the status of nutrients in crops. More recently, there has been a movement to use tissue sampling to determine “hidden deficiencies” in the crop. While tissue analysis represents just one tool in the toolbox for managing nutrients and should be viewed like a report card, it can provide useful information in diagnosing problems when done properly. Here are the 4 things you need to make the most out of tissue analysis.

Field Studies: Setting up a Trial

Josh Coltrain, Kansas State University; Sara Berg, South Dakota State University; Lizabeth Stahl, University of Minnesota; John Thomas, University of Nebraska Lincoln Photo 1. Example of an on-farm trial. Higher yields, greater efficiency, reduced environmental impact!  This may sound like a used-car dealership sales pitch, but it could represent the objectives that make an operation sustainable. Increasingly, farmers are generating on-farm research data that encompass a wide-range of practical topics.  However, setting up those experiments so that the data is statistically valid is not necessarily common knowledge.

Short(er) Spring Wheat Crop = Lower Grain Yield?

Some of you have noticed and commented that the spring wheat crop is shorter when compared to the last few years and subsequently questioned its yield potential. A few weeks ago, Dr. Joel Ransom wrote a nice article in the Crop & Pest Report explaining why the spring wheat crop was shorter and whether its yield potential had already been reduced.   The physiology of grain fill has been well researched and we have a good understanding how temperature and droughts tress affect grain fill and grain quality. Table 1 summarizes the results of one of the published studies that illustrates how daytime and nighttime temperatures affect the length of the grain fill period and ultimately yield. The bottom-line is that higher nighttime temperatures are more detrimental than the maximum daytime temperatures. Just in the last two days has the grain fill suffered some heat-stress, as maximum temperatures had not yet reached above 85F in the two weeks prior while minimum temperatures we