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Conditions are Right for Fall Dandelion Control in Corn and Soybean

By Jeffrey L. Gunsolus, Extension agronomist-weed science
An early corn and soybean harvest and good weather conditions are keeping the window of opportunity open for fall dandelion control this year. Fall is an excellent time to target several herbaceous perennials including: alfalfa, Canada thistle and dandelion. A fall application is more effective than a spring application because systemic herbicides such as glyphosate, 2,4-D, Express, Basis and Synchrony tend to accumulate in greater amounts in a perennial plant's roots or rhizomes after a fall application. Movement to the below ground roots and rhizome buds increases herbicide effectiveness and possibly decreases winter hardiness of the plant.

Non harvested soybeans: Can you expect an extra N credit?

By Daniel Kaiser, Extension Soil Fertility Specialist
With the recent flooding or late season hail there may be questions on whether a credit can be taken from soybeans not harvested for the next year's crop. Soybeans are a high protein crop which means they can contain a large amount of nitrogen. Average values of nitrogen removed in soybean grain are reported at around 3.8 lbs of N per bushel (Source IPNI) for a total of 190 lbs of N in a 50 bu/ac soybean crop. In comparison corn grain would remove about 0.90 lbs of N per bushel and a total of 180 lbs of N in a 200 bu/ac crop.  Can all of this nitrogen be counted on if the soybeans cannot be harvested and are plowed under if they cannot be harvested?

Hot and dry summer conditions in Minnesota are favorable for corn ear rots and mycotoxin production

Dean Malvick, Extension Plant Pathologist
Not only have the hot and dry conditions and hail affected corn yields in Minnesota this year, these conditions have also favored development of ear rots. Reports of ear rots have been coming in from several different areas, and the quality of grain that comes off these affected fields may be reduced. Several different types of ear rots occur in Minnesota, and all are not equally important. Aspergillus ear rot and Fusarium ear rot may be of particular importance this year due to the hot and dry conditions in much of Minnesota.

Feekes 10.51: A Pictorial

The recommended timing for fungicide applications to suppress Fusarium head blight or scab is Feekes 10.5 in barley and Feekes 10.51 in wheat. At growth stage Feekes 10.5 the inflorescence or spike is completely emerged from the boot. Photo 1 shows the progress of the heading process in barley. The third kulm is at Feekes 10.5 and the correct growth stage to receive a fungicide to suppress FHB. Photo 2 shows the progressing of the pollen shed in durum wheat; in the first kulm no anthers are visible on the outside of the individual florets, while in the second kulm the anthers are only visible in the center section of the spike. As these anthers are still yellow, they likely shed pollen earlier that day. In the third pollen shed is complete as anthers are visible across the length of the spike and are bleached and desiccated. The second photo closely approximates Feekes 10.51. The progression in spring and winter wheat is identical to the progression in durum wheat.

Purple Auricles in Wheat

The auricles in wheat are defined as the clasping appendages or the claw-like projections that are located at the junction of a leaf sheath and the leaf blade. Auricles in combination with the shape of the ligules are two anatomical features used to distinguish grassy species from another, such has in this identification key.

The auricles on most of our wheat and barley varieties are pale green. A few recent releases have purple auricles. Below is a close-up picture of the auricles on the cv. 'Faller'. This coloring is the result of the presence of anthocyanins and is a heritable trait. Expression of the trait is, however, not stable and you may find different levels of coloring from year to year. There is no reason to be concerned about this coloring.


Photo 1: Purple auricles on the cv 'Faller'.

Late Season N in Wheat - The Cliff Notes Edition

Based on the number of phone calls I received in just the last few days there is a considerable amount of interest in late season application of nitrogen with the goal to improve the grain protein content of spring and winter wheat. This interest isn't surprising given the extremely low grain protein concentrations of last year's crop and the crippling discounts that followed. Foliar applications of N during the onset of kernel fill have shown to be able to increase grain protein. A review article and decision guide were published in 2006.

Risk of Fusarium Head Blight in Wheat on the Rise

Wheat crops in the flowering stage are now at risk for FHB infection across most of the state, with highest risk in the NW region of MN. Winter wheat either already flowered or is flowering now, while some of the first planted spring wheat is close to flowering.

Risk is highest for susceptible to very susceptible cultivars. The 24-72 hour forecast indicates that the risk will remain or even get higher in the next few days.

Control of Volunteer Soybean in Corn

By Jeff Gunsolus
This week I have received several inquires about the presence and potential impact of volunteer soybean in corn and cost-effective control procedures.  The scenario of volunteer soybean in corn is a fairly recent phenomenon due to the wide-spread use of the glyphosate-resistant technology in corn and soybean.  As a result, to my knowledge, data on corn yield loss potential as a function of volunteer soybean density is not available.  However, I do know of one NDSU study conducted by Dr. Richard Zollinger that does evaluate several herbicide options to control volunteer soybean in corn. You can find a general summary titled Control of Volunteer Roundup Ready Crops at:
http://z.umn.edu/ndweedguide and click on Weed Control Ratings.

Early season tan spot

Early season tan spot can be readily found across the Red River Valley. Especially in wheat on wheat situations the disease can readily be found. One of the characteristic symptoms of these infections at the 2 to 3 leaf stage is a yellowing discoloring of whole leaves. This is a more extreme expression of the same the yellow halo that surrounds the tan spot lesions in more mature plants. Be careful not to mistake this yellowing for a nitrogen deficiency.

High Temperatures, Spikelet Counts, and Yield Potential

Much of the earliest planted wheat in the Red River Valley is approaching the 5 leaf stage. At this time the initiation of the head has begun. After the number of tillers that were initiated over the past three weeks, the number of spikelets is the second the three yield components that ultimately will determine yield. Like tillering, the number of spikelets is also greatly influenced by temperature. The figure below shows what happens as the average maximum temperature increases from 65 to 85; the average spikelet counts declines almost by a third from 17 to 13.

Corn Stand Evaluations

Dr. Jeff Coulter, Extension Corn Agronomist, and Bruce Potter, SW Minnesota IPM Specialist
An unfortunate weather event
The frost on the morning of May 9, 2010 has some corn growers and those who advise them a bit nervous. The frost damaged corn plants I looked at on Monday all had firm green tissue from the soil surface and below and should come through the frost well. The injury stopped at the soil line and after the recent rainfall the green tissue is now above the soil surface. The cold, wet weather since the frost has added another level of stress which, by itself, might reduce stands slightly. There is some potential for these two situations may create a situation favorable for stand reducing pathogens. Warmer weather is in the forecast and frost injured corn plants will begin shooting new leaves soon. In fact, many fields have recently begun to improve in appearance. An idea of the extent of stand loss, if any, should be visible by May 18. To avoid unnecessary wear and tear on…

Spring Frost Damage to Early-Planted Corn

By Jeff Coulter, Extension Corn Agronomist

Figure 1. Early-planted corn off to a vigorous start.
The unusually warm and dry spring has facilitated some of the earliest corn planting dates of all time in Minnesota, with an estimated 63 percent of the state's corn crop planted and 1% emerged by April 25. This early start to the growing season should allow the corn crop to pollinate and fill grain earlier than normal, hopefully under more favorable soil moisture levels. From 1966 to 2009 at the University of Minnesota Southwest Research and Outreach Center in Lamberton, plant-available soil water to a depth of five feet averaged 5.22 inches on July 15, compared to 4.32 inches on August 15. Early corn planting dates should also allow kernels to fill when day length is longer, reduce the risk of a fall freeze before crop maturity, and allow increased time for grain dry-down prior to harvest.

An Interesting Observation: Spring Wheat Volunteers that Survived Winter

I have received reports and observed it myself - there is a lot of volunteer spring wheat that has survived the winter and is happily growing right this moment in some fields in the region (Photos1 and 2). Interestingly, it appears to be limited to certain varieties. The HRSW variety 'Faller' has been positively identified as a variety that is showing this survival. I'm interested to hear whether you have fields in which volunteer spring wheat survived the winter and which varieties, other than Faller, are in those fields. Simply e-mail (wiers002@umn.edu) me or call me (218-281-8629).

Photo 1. Stand of volunteer spring wheat that survived the 09/10 winter near Crookston.
Photo 2. A few volunteer spring wheat plants that survived the 09/10 winter near Crookston.

Sulfur for Corn: 2010 and Beyond?

By: Daniel Kaiser, University of Minnesota Soil Fertility Extension Specialist
With spring almost upon us there have been questions regarding sulfur application for corn for the upcoming year.  Our current Minnesota recommendations focus on sulfur application to sandy soils that are low in organic matter.  This is mainly due to the fact that sulfate-sulfur is mobile and may leach out of the soil, and that the organic matter is a large storehouse of sulfur and through mineralization this sulfur can become available for uptake in plants.  In the past sulfur was added through atmospheric deposition, applied (but not accounted for) with other nutrients in some commercial fertilizer sources, and in animal manures.  Over time most of these indirect additions have lessened and it is reasonable to assume that there may be deficiencies showing up more prevalent today then in the past.  However, a large research focus has been placed on determining how widespread this problem is and if only cer…

Low Protein Wheat in 2009: What Happened?

By Daniel Kaiser and Jochum Wiersma
Decisions about the amount of nitrogen to apply in wheat and barley are challenging each and every year, as the return per acre is not simply a function of the price of the commodity but also on the quality (grain protein%) of those bushels. There are opportunities to capture premiums for protein but more often than not producers are faced with discounts as the grain protein percentages fall below the market's 14% threshold.  While this was already an issue in 2008 with high yields in Northwest Minnesota leading to lower protein, it was greatly magnified in 2009 with producers reporting grain protein percentages of 10% or less.

This issue is not new since it has been long noticed that yield and protein are inversely related. The amount of grain protein produced per acre appears to be relatively constant over years. In high yielding years the extra starch produced  simply dilutes the total protein produced per acre, leading to smaller percentage…