University of Minnesota Extension
http://www.extension.umn.edu/
612-624-1222
Menu Menu

Extension > Minnesota Crop News > Archives > May 2012 Archives

May 2012 Archives

FREEZE INJURY IN SMALL GRAINS

| Leave a comment

The last two mornings thermometers have dipped below 32oF 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

| Leave a comment

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 forecasting models to determine the risk for Fusarium head blight to decide whether an application at anthesis is warranted.

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

| 1 Comment

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.

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 E-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.

by Dan Martens, Extension Educator, Stearns-Benton-Morrison Counties
The link listed here provides Central MN Alfalfa Harvest Alert Scissors-Cut data through May 25. If we get additional information for May 25, it will be updated in the link posted here.

Alfalfa Harvest Alert Data 2012 May 25.pdf

Read more for some observations about insects, fertilizer, and a Forage Field Day and Dairy tour planned for June 15 near St. Anthony north of Albany in Stearns County.
 

Volunteer Corn - An Issue in Corn and Soybean

| Leave a comment

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?  
by Dan Martens, Extension Educator, Stearns-Benton-Morrison Counties
UPDATED May 22 5:30 p.m.
The link listed here provided Central MN Alfalfa Harvest Alert Scissors-Cut data obtained through May 21. Additional Information might be added to this report on May 23 later in the afternoon or evening. If so it will be edited here at this link. We will sample again on Thursday Morning, weather permitting.

It looks like finding a WEATHER opportunity may be the primary decision factor for a lot of the hay crop in this area now milk cow quality hay. There are some fields yet that are just starting to show some bud development and might have a little time to grow yet.

PAST HAIL. Good news for hailed off field on May 1 north of Albany. It is a very nice looking stand of 12 inch alfalfa now. Nearly every stem was broken at 3 to 7 inches by the hail.
 
Remember, for scissors-cut sampling, we like to have 3-4 samples that are 3 or 4 days apart to establish a trend line to gain more confidence in the numbers.

Alfalfa Harvest Alert Data 2012 May 21.pdf

ALFALFA WEEVIL RESOURCE. There a couple notes at the end of the posted report finding some alfalfa weevil larva in a field today... and a resource listing some threshold guidelines. Here's another:
AW trtmnt thresholds.pdf







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 reddish or purple coloration (similar to BYDV).

There have been several reports from the northern RRV of yellowing in small grains fields (see figure at bottom). While the primary symptom of Aster Yellows is yellowing leaves, it's felt that leafhopper populations have not been established in the northern part of the valley long enough for AY to be the cause of this discoloration. On the other hand, there's some indication that yellowing now being seen in the northern RRV is likely related to nitrogen and potassium deficiencies. Even in fields which typically have high potassium or good nitrogen levels, the dry soil conditions may be making these nutrients unavailable to the plants. So, yellowing may not necessarily be AY, but something else.

There have been a lot of questions about adding insecticide along with the next herbicide application in efforts to kill off leafhopper populations. Technically, not a difficult practice; almost any insecticide labeled in small grains will kill leafhoppers, and the small, thin crop canopy means there will be less of a deleterious effect of applying insecticides with the lower pressure and larger drop size you get from herbicide nozzles. But, as we currently have no data on the effect on grain yields of these high leafhopper populations, nor on how much AY is being transmitted in the field, we cannot provide a recommendation for or against this practice.

If you considering treating fields, there are a few points to keep in mind about your expected outcomes (you may need to modify your expectations):

1) AY phytoplasm is transmitted very quickly by the leafhoppers (just like non-persistent virus by aphids). If you have heavy populations of leafhoppers in your fields, plants may already be infected with AY. We know from experience that insecticides, both foliar and seed treatments, are not effective in managing quickly transmitted plant diseases (e.g. PVY in potatoes). In the time the insecticide takes to do its job, the disease can be transmitted. Consequently, don't be too surprised if there are AY infected plants in fields later this season after you had successful leafhopper control.

2) AY symptoms can be similar to those caused by a number of nutrient and other disease factors, including early-season tan spot, BYDV, nitrogen or potassium deficiencies. Removing the leafhoppers will not be effective in solving the underlying cause of yellowing.

3) The thin crop canopies make for a reduced expectation of insecticide residual. They allow UV light, wind, and any moisture available onto all the leaves. These are the environmental factors that break down the active ingredients in insecticides. The plants are also still relatively small, meaning more vegetative material is going to develop, none of which will be protected by insecticide.

4) Shorter residual means potential re-infestation by immigrating populations of leafhoppers. Keep scouting fields.

5) Early spraying may remove predator insects that can limit later populations of aphids. If we get aphids later in the season, sprayed fields may require re-treatment. If aphids infest local grain fields, keep a close eye on their numbers (85% stems with more than one aphid present).

6) Leafhopper populations in the south are decreasing so we may well see similar dynamics here in the next week or two.

Bottom line - we can't recommend spraying, we can't recommend not spraying - we just have no data. But even if a field is treated, you may have to modify your expectations.

- Ian MacRae (UMN), Jochum Wiersma (UMN), Janet Knodel (NDSU), and Bruce Potter (UMN)

AY or nutrient2.jpg

by Dan Martens, Extension Educator, Stearns-Benton-Morrison Counties
UPDATED MAY 18 9 PM
The link listed here provides Central MN Alfalfa Harvest Alert Scissors-Cut and PEAQ data obtained as of May 17. I expect to get a few more lab reports back on Friday and will aim to update the document posted at the link listed here sometime later Friday afternoon.

More buds - and more harvest decisions. As fields appear to meet harvest goals, farmers are making harvest decisions.

Remember, for scissors-cut sampling, we'd like to have 3-4 samples that are 3-4 days apart to establish a trend line to gain more confidence in the numbers. Thinking about a trend line takes out some of the "bounce" we see sometimes from one sample to the next.

Alfalfa Harvest Alert Data 2012 05 17.pdf

Check the notes at the end of the report for some discussion about why we might see better RFV in some fields this year. We'll find out in the feed bunk and for dairy herds in what cows are able to do with it.

CORN EMERGENCE - On another topic, we've had some calls in central MN this week about problems with corn emergence, mainly due to heavy rains around May 1 and 6. One key point to remember is that for corn that starts to leaf out underground, those plants will likely NOT make it to the surface. For some discussion about evaluating stands do a website search for "Minnesota Extension Corn Emergence" or go direct to:
http://www.extension.umn.edu/corn/emergence.html

Please continue to have a safe spring work season, hay harvest, and other things you enjoy in the spring.


by Dan Martens, Extension Educator, Stearns-Benton-Morrison Counties
UPDATED MAY 15 5 pm

The link listed here provides Central MN PEAQ and Scissors-Cut sample information from Monday May 14... and a list from past sampling days for each cooperating farm.

We will have more lab reports for Monday sampling on Tuesday and I will update the link listed HERE with new data as we get it. Remember, for scissors-cut sampling, we like to have 3-4 samples taken 3-4 days apart to consider a trend line to provide more confidence in the numbers. The can bounce up and down some based on the chance of what is clipped each day.
 
Alfalfa Harvest Alert Data 2012 05 14.pdf

Read more for some other observations and resources





by Dan Martens, Extension Educator, Stearns-Benton-Morrison Counties
UDATED MAY 11 about 10 PM
This is the information from PEAQ field notes and Scissors-Cut sample lab tests on May 10 for the Central MN Alfalfa Harvest Alert Project. We expect to get more sample information from today on Friday and we'll aim to update this posting here sometime on Friday night.

Alfalfa Harvest Alert Data 2012 05 10.pdf

The data for entries in the "height" column marked with an asterisk are still from a previous sample date.

Alfalfa at the Poppler farm near Waverly was CUT on Wednesday May 9. It was 24 inches on Monday. Some farms are considering harvest plans for next week, where the crop is ready for their ration targets. Things will likely change quickly if we get warm weather.

Because of the tremendous VARIATION we see in fields this year for a lot of different reasons, it's even more important for farmers to check their own fields and to have a clear idea of their own feed needs related to quality and yield. Some fields are ready now, some might not be ready for 10 days to 2 weeks. Along the way, everyone can wrestle with what they can count on from the weather.

Please note cooperating agribusiness and Extension people who are working with this project as noted at the end of the report, the Central MN Forage Council and cooperating farmers.

Please Plan and Prepare for a SAFE hay harvest.

 

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.
While they may overwinter as eggs in parts of MN, the sudden arrival of large populations of adults, together with the lack of nymphs present, indicates they arrived here from somewhere else. Like many other snowbirds in this area, part of the northern plain's populations overwinter somewhere warmer and return to the north when the weather once again becomes bearable! Once active in the region, Aster Leafhoppers feed on a wide variety of grass and broadleaf plants, crop and non-crop alike. Adults may move between host plants and follow what's green and available.
Disease Vectors - These insects can be economically important in wheat when they vector of Aster Yellows (AY). Feeding injury of aster leafhoppers is less important than disease vectoring. AY has a very wide host range and causes economic losses in several vegetables and ornamentals. If you have seen purple coneflowers with green distorted flowers, you have seen the aster yellows plant disease. Aster yellows is caused be a phytoplasm; an organism similar to a bacterium but without cell walls. When AY infects wheat, it produces symptoms very similar to Barley Yellow Dwarf Virus (BYDV).
Research has shown that heavy infections of AY can cause yield loss in susceptible wheat varieties. There are anecdotal observations from wheat varietal plots in northern Minnesota, which indicate that AY symptoms may be more severe, or that the disease is aggravated under wet conditions.
Aster leafhoppers acquire the phytoplasm by feeding on an AY infected plant for a minimum of 30 minutes. Acquisition of the phytoplasm increases with longer feeding times. The AY phytoplasm requires another two weeks, to incubate within the aster leafhopper before the leafhopper can transmit the disease to new plants. Consequently, immigrating aster leafhoppers, arriving already infectious for AY, are more likely to vector the disease into fields than the smaller overwintering populations which have to acquire and incubate the phytoplasm before they can infect plants. However, once it acquires the phytoplasm, a leafhopper remains infectious for an extended period of time. Although the acquisition phase may be long, it takes a very short feeding period by the leafhopper to transmit the disease to uninfected plants. Generally speaking, the more disease vectors that are present, the greater the potential for that disease to spread.
Feeding Damage - Other than vectoring AY, there is little data on the impact of very high levels of aster leafhoppers. In most years the populations of aster leafhoppers are lower and their feeding injury has little or no impact on wheat yield. We have no data indicating if this is the case with very high populations of aster leafhoppers such as we are seeing this year.
Management -Unfortunately, there is no clear cut answer as to whether treatment of an individual field is warranted; we have no action thresholds for this insect as it is rarely a problem (the only mention we can find of treatable levels is from a 1935 paper that refers to clouds of leafhoppers at one's feet). There are a number of factors to be considered before making individual decisions.


  • High numbers of vectors increase the chances of disease spread

  • There is little data indicating that direct feeding damage causes wheat yield losses. There is no treatment threshold (clouds not being a very useful term).

  • The rapid transmission of AY may mean that fields with heavy populations of aster leafhoppers may contain plants already infected with the disease, so killing aster leafhoppers to avoid AY may not be effective.

  • There's not yet a canopy, plants are small, rapidly adding new leaves and have maximum exposure to wind, sun and moisture, meaning insecticide residual is going to be shorter than later in the season. So there's no guarantee that treated fields may not become re-infested with aster leafhoppers.

  • Treating with a broad spectrum insecticide will kill beneficial organisms and may lead to higher aphid populations and BYDV. Bird-cherry oat aphids are already present in southern MN and BYDV is a more serious threat to wheat yield than AY. Populations of aphids in the field would favor treating the field and influence the insecticide used.

  • Both Aster Yellows and Barley Yellow Dwarf must be transmitted by insects (aster leafhoppers and aphids respectively). If you see discoloration in the absence of these insects, it isn't AY or BYDV, look for some other cause!


The bottom line is this will have to be an individual's decision and is a field by field situation, please use the facts that we've mentioned above and make the best decision for your production system.
AL_wheat.jpg

by Dan Martens, Extension Educator, Stearns-Benton-Morrison Counties
UPDATED MAY 9 about 9 PM - Added report from Maus farm near Freeport
The link listed here provides Central "MN Alfalfa Harvest Alert" scissors-cut data and PEAQ readings for May 7 and previous dates.
Alfalfa Harvest Alert Data 2012 05 07.pdf

Some fields are looking about ready, depending on goals, weather and soil conditions. Some fields may be 10 days to 2 weeks later.
Read more for other resources.



Alfalfa Hail Damage and Management Decisions

| Leave a comment
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. Here
by Dan Martens, Extension Educator, Stearns-Benton-Morrison Counties
The link listed here provides Central MN Alfalfa Harvest Alert Scissors-Cut data obtained as of May 5. Addition information might be added to this report on May 7. If so it will be edited here. Remember, for scissors-cut sampling, we like to have 3 or 4 samples that are 3 or 4 days apart to establish a trend line to gain more confidence in the numbers.
Alfalfa Harvest Alert Data 2012 05 03.pdf

For more information about scissors-cut sampling or PEAQ go to  http://www.extension.umn.edu/forages
Or search for Midwest Forage Association

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.

Alfalfa Scissors Cut Project Starts for 2012

| Leave a comment
by Dan Martens, Extension Educator, Stearns-Benton-Morrison Counties    
       The Central MN Alfalfa Harvest Alert Scissors-Cut and PEAQ Sampling project has started for 2012 with data collected in Carver, Scott, McLeod, Meeker, Wright, Stearns, Benton and Morrison Counties.
      Data from fields measured and sampled on April 30, 2012 are posted at
 Alfalfa Harvest Alert Data 2012 April 30.pdf
       There could be a lot of variation between fields based on soil moisture conditions, any earlier frost damage, how late fields were cut in the fall, how much growth was on fields in the fall, hail damage, and other factors.
      Some questions have been asked about whether the hay crop will be more mature than height and maturity would indicate because it came out of dormancy so early. The numbers from the first three fields sampled would seem to indicate this won't be much of an issue, but we'll get a better look at that as we see more field and lab results.
       More sampling sites will be started on May 3 and perhaps a couple more next week. Results will be posted here as the information is put together.
Read Further for more information.

Sauk Centre Hay Auction April 19, 2012

| Leave a comment

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

This information is from the Sauk Centre Hay Auction held on April 19, 2012. I am posting three reports:

Apr 19, 2012 SC Hay Auction.pdf ...  A list of all tested hay lots and bedding materials sold ... grouped by kind of hay, RFV and type of bale ... cost per pound of dry matter and cost per RFV point are calculated.

History of Selected Lots 2011 2012.pdf ... A summary of auctions held this year: Medium Square Alfalfa 101 to 200 RFV divided in 25 point groups, and bedding material.

Graph SC Hay Auction 2001-2012.pdf ... A line graph of auction seasons from 2001 to 2012

Read further for a couple observations about the auction and a resource for evaluating hail damage on alfalfa.

The last two auctions of the season are scheduled for May 3 and 17.

You can look at USDA Hay Market Reports at http://www.ams.usda.gov/AMSv1.0/LSMNpubs and a "hay wanted" and "hay  for sale" Minnesota Hay List at www.haylist.umn.edu 

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 seaon 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://blog.lib.umn.edu/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://www.plantmanagementnetwork.org/sub/cm/research/2011/mixing/ and http://blog.lib.umn.edu/efans/cropnews/2011/06/early-season-tan-spot-and-risk.html

  • © 2014 Regents of the University of Minnesota. All rights reserved.
  • The University of Minnesota is an equal opportunity educator and employer. Privacy