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Monday, July 24, 2017

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.

Estimating final yield in May and June in an individual field is fraught with a much larger error than at the aggregate level of a whole state. Once the crop, however, has headed and the grainfill has started it get much easier to estimate the final yield.  Rather than just predicting the final grain yield, you can actually quantify the number of stems per unit area and the number of kernels per spikelet or panicle.  This means that when you multiply this with an average kernel weight you can have a more accurate estimate of grain yield. The formulas for wheat, barley, and oats are:

Wheat: Grain yield (bu/acre) = (kernels per spike x spikes per 3 ft of row) x 0.0319
Barley: Grain yield (bu/acre) = (kernels per spike x spikes per 3 ft of row) x 0.0389
Oats: Grain yield (bu/acre) = (kernels per spike x spikes per 3 ft of row) x 0.0504

The multiplication factor for each crop is a function of bushel weight, average kernel weight, and row spacing.  To adjust the yield estimate for other row spacing, simply divide the estimated yield by your row spacing (in inches) and multiply the product by 7.

A word of caution is that you need to have sampled a representative length of row and that the average kernels weight used in these formulas are the same as the eventual kernel weights. The first source of error can be addressed by taking multiple samples in a single field; the second source of variability is a bit more challenging to deal with. As calculating seeding rates have taught you over the years, the number of seeds per lbs. can vary considerably, not just between varieties but also from year to year.  

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.

Friday, July 21, 2017

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.  

Thursday, July 20, 2017

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:

Wednesday, July 19, 2017

Herbicide Mode of Action and Crop Injury Symptoms at the University of Minnesota Field School for Ag Professionals

by Dave Nicolai, IAP Program Coordinator

This year at the Field School, participants will have two opportunities to learn, re-learn or fine-tune their skills in linking visual symptomology to the common herbicide modes of action commonly used in corn and soybean and gain in-depth knowledge of growth regulator herbicide movement and symptomology in soybean.

Weed management has changed dramatically in recent years. The large number of herbicide options—new products, old products with new names, new formulations of old products, premixes, and generics—can make weed control appear to be a difficult and confusing task. Knowing and understanding each herbicide’s mode of action is an important step in simplifying and selecting the proper herbicide for each crop, diagnosing herbicide injury, and designing a successful and durable weed management program for a farmer’s production system.

Tuesday, July 18, 2017

Lunch and Learn Webinar: Managing Ash Content in Hay

Krishona Martinson - University of Minnesota

On Wednesday, August 23, 2017 from 12:00 to 1:00 pm (central time), the University of Minnesota will host a free webinar titled “Managing Ash Content in Hay”. Dr. Marvin Hall, Professor of Forage Management from Penn State University, and Abby Neu, Extension Educator from the University of Minnesota Extension, will present the webinar.

Hay Rake Impacts Ash Content in Alfalfa Hay

Abby Neu, Craig Sheaffer, Scotty 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.
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