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Showing posts from May, 2014

Pay attention to black cutworm when scouting corn and other crops this spring.

It is too early to know if black cutworm will be a significant problem in 2014 MN crop production. However, captures in a cooperative pheromone trapping network indicate vigilance is in order. We do not have complete coverage of the state with this network and cutworm infestations are always variable from field to field so it is best to err on the side of caution. Pay close attention to any leaf feeding, wilted or cut off corn plants as you scout.

Heat Canker in Wheat, Barley, and Oats

The last couple days the weather has given us some dry sunny weather with high winds. This has been great to have fields finally dry off and make strides with planting the crop. Unfortunately this also exposed young small grain seedlings to same conditions. The daytime heat at the soil surface has caused heat canker. The tender young tissue at the soil surface basically has been 'cooked' and this appears as a yellow band that is slightly constricted (Photo 1). As the leaf continues to grow, this yellow band (1/8 - 1/4") moves upward and away from the soil surface. If the hot and dry weather last for several days, repeated bands should become visible. The damage is nicely depicted on page 81 of the second edition of the Small Grains Field Guide. Because of the high winds, the tips of leaves may break off at the yellow band and give a field a very ragged appearance. Damage from heat canker is temporary and should not affect further growth and development.


Photo 1 - Wheat s…

Early Season Scouting in Small Grains: Tan Spot

Madeleine Smith, Small Grains and Canola Pathologist

Tan spot is identifiable by the brown spots often
surrounded by a yellow halo that appear
Having experienced a very late spring as in 2013, we are also experiencing a similar start to the season when it comes to diseases in small grains as last year. Tan spot has made an appearance on wheat and barley around the state.

This may run together to form larger patches of yellowing and browning. Initial infections in young seedlings often result in yellowing of leaf tips as the seedlings react to the toxins produced by this fungus. Tan spot will be particularly prevalent on previous wheat ground. Be careful not to mistake nitrogen deficiency (see recent post to crop e-news by Dr. Jochum Wiersma on early season yellowing in small grains) or symptoms of BYDV for tan spot.

Early Season Yellowing of Wheat, Barley, and Oats.

Reports of yellowing in small grains have started to reach us. There are several reasons why young wheat, barley, or oat plants have a pale green/yellow color. Some of the common reasons for early season yellowing are:

Nitrogen deficiencySulfur deficiencyEarly tan spot infectionHerbicide injury

Switching to Soybeans?

Seth Naeve, University of Minnesota Extension Soybean Agronomist

As June 1 looms in the not-too-distant future, large areas of land intended for small grains or corn remain unplanted in Northwestern Minnesota. Likewise, there are localized areas in East-central and South-central Minnesota where the corn crop has not yet been planted. With recent rainfall, and a May 31 crop insurance cut-off date around the corner, some producers are considering switching to soybeans.

U of MN Launches One-Stop Shop for Crops Research Results

By Lizabeth Stahl and Lisa Behnken, Extension Educators in Crops
Access to results for many of the U of MN crops research trials conducted across the state has now become streamlined with the launch of the new, U of MN Extension Crops Research website.  This one-stop shop can be accessed through the U of MN Extension Crops webpage at www.extension.umn.edu/crops under "Research Reports".

The website contains results for small plot and on-farm crops research and demonstration trials conducted across Southern MN from 2003 to 2013.  You can also access research results for crops trials conducted at Research and Outreach Centers located across the state by clicking on the respective link.  Statewide results for weed science research can be accessed through the "Applied Weed Science" link, and results for the Minnesota hybrid and variety trials can be accessed through the "Minnesota Field Crops Variety Trials" link. 

The Research Reports webpage supplements …

Cool, wet conditions this spring may favor seed corn maggot

By Robert Koch, Extension Entomologist

Recent cool and wet conditions may increase the risk of seedcorn maggot infestation in some soybean and corn fields. Seedcorn maggots are small (1/4 inch long), white maggots (fly larvae) that feed on germinating seeds. The maggots can tunnel into seed, which may result in seed death, and can injure the emerging plant tissues, which can affect plant growth or lead to damping off. Such injury can result in stand loss or weakened plants. For example, if the growing point of soybean is killed, "Y-plants" can result when branching develops at the cotyledons. Yield from "Y-plants" may be reduced if competing with neighboring healthy plants. Seedcorn maggot injury can be difficult to distinguish from other problems such as Pythium and other seedling diseases.

Black cutworm traps pick up significant flights

Over the past couple weeks, cooperator-run pheromone traps indicate the potential for localized damaging populations of black cutworm in corn and other crops. Faribault, Lac Qui Parle, Swift and Waseca Counties have had significant captures. Cutting from the earliest of these flights is projected to occur after May 28.

Areas with delayed spring tillage and early season weeds are most attractive for migrant cutworms to lay eggs.

This does not mean insurance insecticide applications are warranted and insecticide rescue treatments work well where economic threshold populations occur.

2014 University of Minnesota Cooperative Black Cutworm Trapping Network newsletters with further information on cutworm biology, scouting, thresholds and control as well as maps of trap captures and cutting predictions can be found at: http://swroc.cfans.umn.edu/ResearchandOutreach/PestManagement/CutwormNetwork/index.htm




Late Planting of Small Grains

Jochum Wiersma, Small grains specialist
Wheat, barley, and oat are cool season annuals and are most productive when they grow and develop during cool weather. The yield potential of a crop is largely determined by the 6 leaf stage. Cool temperatures during this period are particularly important for the development of a high yield potential. For example, the number of tillers that ultimately produce grain at harvest declines as planting is delayed (Figure 1). The number of spikelets per spike is determined during the 4 to 5.5 leaf stage (Figure 2). Spikelet numbers are negatively correlated with temperature; spikelet numbers are greater when temperatures during the 4-5.5 leaf stages are cool.

Crusting and Emergence Problems

Last week's heavy rains have caused widespread crusting problems. Dr. David Franzen , NDSU Extension Soil Scientist, summarized the options available to you in an article more than a decade ago. It has been reprinted here as a refresher.

Crusting results from rains breaking down soil aggregates into particles that cement into hard layers at the soil surface when drying occurs rapidly. In soils that have not been seeded, the crust prevents further soil drying by sealing off the underlying soil from the air. The crust also reflects sunlight, in effect insulating the soil and maintaining cooler soil temperatures that further slow drying.

Evaluating Winter Wheat Plant Stands

Jochum Wiersma, Small grains specialist
One of the hardest decisions with growing winter wheat is evaluating the amount of winter kill and making the decision whether to keep a stand. Winter wheat is planted in the fall and develops in the spring during relatively ideal conditions for tiller development. Therefore the optimum plant stands of winter wheat can be less than that of spring wheat. A stand of 900,000 - 1,000,000 plants/acre or 21 - 23 plants/ft2 will be enough to maximize grain yield.

Some winter kill is to be expected in Minnesota. This past winter was cold even by Minnesota standards. The extreme cold, combined with little snow cover in parts of the state, and that the fact some of winter wheat was planted on prevent plant acres that had little or no standing stubble to collect the limited snow that fell, means that winter kill is very likely this year. Roots are generally less winter hardy than crowns and regrowth may be very slow, even if roots and shoots appear dead.

Tebuconazole Resistant Fusarium Head Blight Isolate Found in New York State

Researchers at Cornell University recently discovered an isolate of Fusarium graminearum (the organism which causes Fusarium head blight (FHB)) with greatly reduced sensitivity to tebuconazole. Tebuconazole is the active ingredient (A.I.) in fungicides such as Folicur and one of the A.I.s in Prosaro. These fungicides are routinely used to control both leaf diseases and also for FHB suppression.

The researchers conducted a study to examine the sensitivity of 50 isolates of Fusarium to tebuconazole and another A.I , metconazole (the A. I. in Caramba). They found one isolate out of these 50 (designated TEB-R) so have such a reduced sensitivity to tebuconazole, they deemed it tebuconazole-resistant.

Better Long-Term Weed Management Demonstrated by the "PRE Challenge"

By Lizabeth Stahl, Extension Educator in Crops
Benefits of a preemergence (PRE) herbicide application in soybean were demonstrated through the "PRE Challenge" - a series of on-farm research and demonstration trials conducted across southern MN in 2012 and 2013. In these University of Minnesota Extension trials, made possible through financial support of the Minnesota Soybean Research and Promotion Council, cooperators compared a postemergence-only herbicide program to a program that included a PRE herbicide application.

One benefit observed with a PRE application was a significant reduction in weed densities early in the season.  Although the cooperators were able to make timely postemergence applications in these trials, this is not always possible in each field every year.  Crop yield can be reduced when weeds are left to compete with the crop for too long early in the season.  How long is "too long" depends on factors such as weed density, weed species, enviro…

April Showers Brings May Flowers, or Cover Crops.

by M. Scott Wells - Forage and Cropping System Agronomist
mswells@umn.edu

Being new to this state, I have been curious about how this spring compares to the previous year as it relates to precipitation. This time last year, much of Minnesota reported below normal precipitation (Figure 1a). However, across Southern Minnesota this year there has been greater than normal precipitation reported with some areas departing more than 6-inches from the normal (Figure 1b).






Figure 1.Minnesota Monthly Departure from Normal Precipitation for April 2013 (a) and 2014 (b). NOAA - Advance Hydrological Prediction Services. http://www.noaa.gov

Hold your Current Soybean Varieties

Seth Naeve, Extension Soybean Agronomist
The continuous rainy weather that we've been experiencing can take an emotional toll on a farmer. It's easy to feel a little helpless looking out at those soggy fields. The common response is to keep active and begin to make contingency plans. Some producers are beginning to get nervous about their variety choices and are calling on their seed dealers to inquire about sourcing earlier maturity soybeans.

While this is a very normal response to the situation, it's important to remember that soybean maturities need not be adjusted for some time. The standard University of Minnesota recommendations state that soybean maturities should not be adjusted until a target planting date of June 10 is reached. We will have MANY good working days before then.