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Showing posts from May, 2012

Freeze injury in small grains

Jochum Wiersma, Small grains specialist
The last two mornings thermometers have dipped below 32°F in many places across Northwest Minnesota. Unlike the freezing temperatures we endured in April, these lows may have actually caused some damage as most fields are now at or past the jointing stage. Kansas State University has published an excellent bulletin about freeze injury in wheat that describes in detail what the damage looks like and what the yield impact can be. Simply follow this link: Spring Freeze Injury to Kansas Wheat

Understand that any freeze injury is probably localized to sheltered and low lying areas. You should also now that damage to the growing point may not be evident immediately. Leaf tissue that is damaged should show symptoms after a day or two.

Small Grains Disease Update

05/31/2012

Winter and the earliest spring wheat fields are heading across the State. While producers in the southern half of the State comment that their winter and spring wheat has never looked this good, the northwest part of the State suffered enough drought stress to impact the yield potential of the spring and winter wheat crops. The drought and last week's heat caused tillers to be aborted and crop phenology to advance rapidly, with some field moving from jointing to having the flag leaf fully emerged in just over a week. A few initial counts of the number spikelets per spike were disappointing.

There are confirmed reports of stripe rust across the state but there are no confirmed cases of leaf rust to date. More details scouting reports will be available as of next Monday morning.

Now is the time to scout the fields to assess yield potential and the presence of any foliar diseases such as tan spot and leaf or stripe rust. Keep an eye on the weather forecast and the disease …

Scouting Alfalfa Fields for Nutrient Deficiencies

By Daniel Kaiser, Extension Nutrient Management Specialist
The dry conditions in March and April have given way to extremely wet areas in some parts of Minnesota.  Since alfalfa stands got an early start this year there were a few concerns popping up early in the southeastern part of the state on areas of fields yellowing.  While there may have been some effects due to the cool weather in April a couple of nutrient could be of concern.

Potassium and Dry Soils

Daniel Kaiser and Jochum Wiersma, University of Minnesota Extension
Weather conditions have been extremely variable around the state of Minnesota this year. While some areas have experienced near record rainfalls others have still been in the midst of a drought. These differences have brought some interesting questions regarding management of potassium and soil testing in the midst of dry soil conditions.

Dry soil conditions can be challenging for crops to take up nutrients.  Elements such as phosphorus and potassium move to the plant roots via diffusion.  Diffusion is a process by which things move from areas of high concentration to areas of low concentration.  If you can think back to high school science if you open a bottle of ammonia at one end of the room over time you will smell the ammonia as it diffuses through the air.  That is a simplistic explanation of a more complex process in the soil.

When it rains, it pours! What is happening to my nitrogen?

John A. Lamb and Daniel E. Kaiser, Soil Fertility Specialists
Nitrogen is important for corn growth. This has been a concern on growers' minds since March. First concern was with the poor tillage conditions last fall. Did the nitrogen applied stay in the soil. We attempted to answer that question in a March 18 Crop News. At the time of that E-news, drought was the weather condition on everyone's mind. Now with the record rainfalls, there are concerns if nitrogen has been lost to leaching or denitrification.

Volunteer Corn - An Issue in Corn and Soybean

By Liz Stahl and Jeff Coulter
Growers are finding high populations of volunteer corn in their fields this spring. Factors likely contributing to this include lodging in many fields last fall due to poor stalk quality and drought conditions, and higher harvest losses due to low grain moisture at harvest. Other factors that can lead to high populations of volunteer corn the following year include storm damage and ear droppage. The question arises: When are populations of volunteer corn high enough to warrant control?


Figure 1. Volunteer corn in corn

Not all Yellows are Created Equal (or, more correctly, not all yellows have an equal creation...)

Ian MacRae (UMN), Jochum Wiersma (UMN), Janet Knodel (NDSU), and Bruce Potter (UMN)
Leafhopper populations are increasing in the northern RRV. Fields which held low numbers on Friday have significantly increased populations this week. These are all winged adults and so are likely the populations from the southern part of the state that are migrating north. We don't have any data on what impact on yield these higher populations of leafhoppers may have on small grains but sap-feeding leafhoppers generally don't impact yield. Having said that, leafhopper populations in typical years are much lower; in dry conditions, sap feeders have been known to exacerbate drought stress. Generally, leafhoppers are more important as vectors of the disease, Aster Yellows (AY). Caused by a phytoplasm, AY can infect wheat, and under the right conditions cause yield loss. Symptoms show up a couple of weeks after infection by the leafhopper and include yellowing of leaves, often accompanied with re…

Update on Aster Leafhoppers in Wheat

by Ian MacRae, Jan Knodel, Bruce Potter, Jochum Wiersma
High populations of Aster Leafhopper (also called 6-spotted Leafhopper) have been reported in small grains over the past couple of weeks. Starting in the south but now spreading to northern MN and ND. Aster Leafhoppers are greyish leafhoppers; the adults have clear wings and 6 spots between the compound eyes (Figure 1). Other than their coloration, the adults and nymphs both very much resemble potato leafhopper. The leafhopper uses it's piercing sucking mouthparts to feed on the plant's sap. The damage caused by Aster Leafhopper feeding is more localized than that produced by potato leafhopper. Feeding may produce localized necrosis or stippling (Figure 2), however, damage is much less than that caused by the Potato Leafhopper.

Alfalfa Hail Damage and Management Decisions

by Dan Martens, Extension Educator, Stearns-Benton-Morrison Counties

Hail did some damage to alfalfa fields as well as automobiles and homes on Tuesday afternoon and evening on May 1 at places  from out toward Padua in western Stearns County to Albany. In some fields nearly all stems in established alfalfa were broken as stripped of leaves. These will need to start again with new shoots from the crown. In new emerged alfalfa seedlings, stems broken below the leaves are done. I'll attach an article here written previously by Wisconsin Extension Specialist Dan Undersander that offers some discussions about decisions that might be made.
Hail Alfalfa Undersander.pdf

You can also check this article by Undersander and Krishona Martinson at U of M, also from a previous hail experience: Alfalfa hail damage and management decisions

On Farm IDC Management Strip Trials

Daniel Kaiser, University of Minnesota Soil Fertility Specialist
Research on Iron Deficiency Chlorosis (IDC) has been identifying methods to manage the problem for soybeans. Since 2010 research has been conducted using strip trials within farmers' fields. Currently we are looking for a 5 acre area to conduct a field study looking at the effect of Soygreen and oat cover crops on areas of the field that range from no-IDC to severe IDC. Our goal is to determine the economic benefits of the treatments on varying IDC severity within fields planted with two soybean varieties with varying tolerances to IDC.

Small Grain Disease Forecast System and Disease Commentary Online

The 2012 growing season is well under way. The spring planting progress has been at a record pace, a consequence of a very dry fall and winter and a very warm March. Winter wheat has very little winter injury and stands are generally very good.

The winter wheat crop is at or near jointing and some of the earliest spring wheat fields are not far behind. This means that it is time to start scouting for early season tan spot.

To aid in your decision whether a fungicide is needed to control early season tan spot you can go to http://mawg.cropdisease.com to evaluate the risk that conditions are favorable for tan spot to develop. Make sure to select the model for tan spot in the left hand model.

An overview article of control of early season tan spot can be found here:
http://www.extension.umn.edu/b-assets/efans/cropnews/2010/05/early-season-tan-spot.html.

Be aware that tank mixing fungicide with certain herbicides can result in temporary crop injury. See here for details here http://ww…