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Monday, March 30, 2009

Seeding Rates in Hard Red Spring Wheat

Jochum Wiersma, Small Grains Specialist, University of Minnesota Extension

Each year questions arise about the correct seeding rate for hard red spring wheat. ‘Is a bushel and a peck enough?’ is a question I have been asked more than once.  Research in the mid nineties demonstrated that - on average - an initial stand of 30-32 plants/ft2 maximized grain yield. As planting was delayed past the optimum, the initial stand needed to be increased by ~ 1 plant/ft2 for each week of delay to maximize grain yield. With this number in mind and assuming a stand loss between 10-15% one can calculate a seeding rate using the following formula.


Repeated research, however, has demonstrated that the optimum seeding rates differ for individual varieties. To determine this optimum seeding rate the variety in question is tested at a wide range of seeding rates. The seeding rate for maximum grain yield can be derived from the parabolic response curve of grain yield versus number of plants per unit area, which increases quickly to a maximum and slowly decreases at higher plant densities.

Fungicide for corn? The influence of agronomic factors in 2008

Jeff Coulter, Extension Corn Agronomist

In the past few years, the use of foliar fungicide on corn has gained considerable attention. In 2008, with generous support from the Minnesota Corn Growers Association and BASF, research was conducted in southern Minnesota at Lamberton and Waseca to determine how planting date impacted corn response to foliar fungicide. In these trials, corn followed soybean at 32,400 plants per acre, and the hybrid was DKC52-59. At both locations, there was little to no foliar disease at the time of fungicide application. The same was true at the early dent stage, regardless of whether fungicide was used. Nonetheless, yield was generally 3 to 4% (5 to 6 bushels per acre) higher when fungicide was applied, regardless of planting date or location (Figures 1 and 2). The exception was the early planting date at Waseca, where foliar fungicide resulted in a 6% yield increase (Figure 1). However, these numerical yield increases were not statistically significant, even at the 10% probability level. In other words, additional replication is needed in order to ensure that these differences are actually due to the treatments imposed, rather than random variability in soil productivity from one plot to the next.

Monday, March 23, 2009

Think Carefully About Corn Plant Population to Maximize Profits

Jeff Coulter, Extension Corn Agronomist

Field work is just around the corner, and now is the time to re-evaluate agronomic decisions related to corn planting. With support from the Minnesota Corn Growers Association and others, we have been able to conduct a number of trials to determine how corn yield responds to plant population for various situations in Minnesota.

In 2008, research was conducted at Lamberton and Waseca, MN to determine how planting date impacted optimum plant population. In this study, the economically optimum plant population was not consistently influenced by planting date (Figure 1). However, yield potential was greatest with early planting, and the optimum plant population with the early planting date was 2,400 plants per acre higher than that with the mid-May planting.
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