September 28, 2001
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Alfalfa Corn Diseases Forecasts/Climate Soybeans Reader Survey Other Agnews
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The possibilities of chemical weapon attacks or attacks on food and water supplies, coupled with recent FAA temporary bans on agricultural aircraft, are prompting a new awareness of proper pesticide storage and security measures. The actions of the past few days have created a need for a higher level of awareness and heightened responsibility among pesticide applicators, for reasons not seriously considered earlier.
For safety concerns now, as always, agri-chemical dealers, ag pilots, lawn care operators and exterminators should review management practices associated with their pesticide storage area and application equipment. These are simple, appropriate and justifiable steps to take.
I am reminded of a portion of new UNL Cooperative Extension Publication, Safe Transport, Storage and Disposal of Pesticides: "Regardless of whether it is a cabinet, room or an entire building, the pesticide storage area should be lockable to prevent unauthorized entry and should only be used for pesticides and pesticide equipment."
Keep the following points in mind when assessing your pesticide storage security:
For more information on pesticide responsibility, safety, and storage, visit the NU Pesticide Education Center.
Larry Schulze
Pesticide Education Coordinator
The Label newsletter,
September 2001
Green stem is an abnormal scenario which can significantly affect some producers. This results in plugged combines and difficulties at harvest. If you own a newer combine with reverse on the intake, this problem is not nearly as frustrating as for those with an older model.
Does frost cause green stem? No. Frost will result in defoliation and initially stems may be green, but the normal maturation process should continue. Plants with true green stem will have the condition after all the pods have fully matured and dried down. Frost may occur before all leaves have dropped and pods have changed color, but the stems should dry down normally after this event.
Several things can cause green stem soybeans at harvest. If plants are scattered throughout the field probably the most plausible cause is viral infection. Plant viruses are notorious for altering physiological events, such as the normal maturation process of the plant. Several viruses can cause green stem including bean pod mottle virus, tobacco streak virus, and tobacco ringspot virus also called bud blight. While all of these viruses are found in Nebraska, bean pod mottle virus is the most widely distributed. In most cases, I suspect scattered plants with green stem in a field result from an infection with this virus. There is a high incidence of bean pod mottle virus in many fields this year. (This is related to populations of the bean leaf beetle, the main vector for this disease.)
Recommendations
Don't worry about green stem unless you are considering holding over seed. Remember that licensing restrictions prohibit genetically modified seed from being held over so producers should make sure they follow the agreement.
If you are considering holding seed and are observing a lot of green stem this fall, you may want to have plants tested to potentially learn the cause of the problem. The viruses that affect soybean are not held over in the soil, but in some cases they can be held in the seed. For example, seed transmission for tobacco streak virus has been reported to be as high as 30%. Bean pod mottle virus, the most common soybean virus in Nebraska, has been shown to be seed transmitted at a very low percentage of 0.1% or less. Some researches have shown no transmission of bean pod mottle virus with seed.
Loren Giesler
Green stems in soybeans complicate harvest
Extension Plant Pathologist
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Much of Nebraska is likely to have a cooler than normal fall followed by a warmer than normal winter, if forecasts hold true. During the six-month period of fall (September to November) and winter (December through February), much of the state is also likely to see above normal precipitation.
Details of these forecasts are shown in the four figures for different sub-climate regions in Nebraska. These forecasts are departures from long-term (30 years from 1970-1999) seasonal average values of temperature and precipitation, which are given in Table 1 (below).
Figure 1 shows the temperature departures for fall 2001 in these regions. They call for 10% (3°F-6°F) below average seasonal temperatures, or a cool to cold fall in most of Nebraska. Colder temperatures of 15-20% (8°F-12°F) below seasonal averages are predicted for Region 2 (north central) and Region 7 (south central). Near average temperatures are foreseen only in Regions 4, 5, and 8. (Note: because forecasts were produced based on regions, the figure doesn't show smooth transitions from one region to the next.) In contrast to the below-average fall temperatures, winter temperatures, shown in Figure 2, are predicted to be 3°F-5°F above average, except for Regions 1, 4, and 7, where average seasonal temperatures are predicted.
Figures 3 and 4 show the precipitation forecasts for fall and winter. According to the forecasts, we anticipate 10-15% above average precipitation in most of Nebraska this fall, except for Region 5. Larger departures of up to 25% of the seasonal average precipitation are expected in north central and northeast Nebraska. Average fall precipitation is predicted for Region 5 (east central). Winter precipitation also is predicted to be above normal for most regions in the state. Departures are 10-15% of the seasonal average values. Near seasonal average precipitation is expected in central and southern Nebraska in Regions 4, 5, and 7.
Finally, the reliability of the forecasts -- the chance or probability for the forecasts to occur in reality -- is 74% for fall and 69% for winter. Although a forecast can never be 100% sure, it offers a much higher probability, e.g., 74% and 69% in this case, then a blind guess with a 50% chance. In other words, correctly using climate forecasts and predictions will improve your chance to make a successful production plan.
Q. Steve Hu
Assistant Professor and
Agricultural Climatologist
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We have online reports summarizing 2001 corn insect control studies for corn rootworm, wireworms, and first generation European corn borer. The reports, from research based at the NU South Central Research and Extension Center, are located at:
http://screc.unl.edu/Entomology/
Data from past year's trials are also available at this site.
Bob Wright
NU corn insect control reports
Extension Entomologist
South Central REC
Rains may lead to increased molds in corn
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Grain mold development may become an issue where grain was stored on the ground and not covered before the rain began. In some areas four to five days of continuous rainy conditions have occurred. Grain mold development also may become a problem where grain is harvested early to avoid harvest complications from stalk rot induced lodging. When harvested at higher than ideal moisture, grain should be dried to less than 16% moisture within 48 hours, if possible.
Not only are these molds a concern for grading, but the potential also exists for mycotoxin contamination of the grain. Some molds produce compounds, called mycotoxins, that can be toxic to farm animals, wildlife, or humans; however, the presence of mold does not indicate contamination of the grain with mycotoxins. Only certain strains of certain species produce these potentially harmful compounds. Grain molds occur in Nebraska every year to varying degrees. The fungi that cause grain molds are found throughout Nebraska; however, they are not usually considered a major constraint to production or marketing of Nebraska corn.
The most striking external symptom of grain mold is the presence of the mold itself. The degree of growth on and between the kernels and the appearance of the mold (e.g., color & density) varies with the mold species and the environmental conditions in the field and in storage. Temperature and relative humidity are the two most important environmental factors regulating mold growth. Most grain mold pathogens become associated with the kernel in the field but can grow within the colonized kernel and even spread to adjacent kernels during storage if grain moisture and relative humidity are not adequately controlled. It is imperative to dry down the grain as soon as possible.
Some producers will be deciding whether to let the grain dry in the field and risk stalk rot-induced lodging or harvest at higher moisture and dry the grain postharvest. In Nebraska no fungicides are labeled for postharvest application to corn for the management of molds or mycotoxins. For more information and photos see NebGuide GOO-1408 Grain Molds and Mycotoxins in Corn.
Jim Stack
Extension Plant Pathologist
South Central REC
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Proper combine adjustment and operation gets more beans in the bin and reduces damage. Harvest losses often approach 10% of the yield according to several university studies.
Read the combine owner's manual to become a combine operator not just a driver. Be prepared to change settings during the day or even on-the-go when passing through the field. Following are a few reminders:
For more details on adjusting combines, check the archived Crop Watch story on the web.
Paul Jasa
Extension Engineer
Timely rains during the past two weeks have substantially increased soil moisture reserves at most monitoring sites across the state. Soil moisture readings are now approaching levels seen at the end of April, just prior to the heavy May rains.
As long as normal precipitation falls prior to ground freeze, we would anticipate that soil moisture levels will be more than sufficient to alleviate concerns about inadequate moisture reserves next spring. Certainly soil moisture recharge is off to a better start this fall than has been seen for several years.
Drought conditions have been eliminated across eastern Nebraska, with only the extreme southwestern corner still classified as under moderate drought conditions. The real problem in this region has been the lack of adequate inflows into the reservoir systems to overcome the precipitous drop in lake levels the last two years.
Most reservoirs in southwestern Nebraska are running an average of 4 feet higher than at this point last year. Unfortunately, these systems are still 20-30 feet below capacity. Normal to above normal snowfall this winter will be needed to bring these systems back to normal.
Much of the Panhandle and western Sandhills have been designated as abnormally dry. A couple of timely precipitation events in the 0.50- to 0.75-inch range over the next few weeks will eliminate these short-term problems. The abnormally dry designation does not mean this area is experiencing a drought, but that it needs to be watched. Our primary concern for this region is ensuring that enough surface moisture is present to provide a sound foundation for spring wheat germination.
We have noticed a distinct change in the atmospheric pattern since early August. Very intense lows have been moving into the northern Rockies every two to three weeks. With each successive low, minimum temperatures have dropped an average of 10-15oF per event. If this continues, expectations are that a hard freeze would occur before mid October.
These systems have been much stronger than we would expect for this time of year. In fact, they resemble patterns typically not seen until late fall or early winter. Rainfall has been generous, so a continuation of this trend would bode well for additional soil moisture recharge; however, it also may result in harvesting delays if we don't receive adequate surface drying between events.
Al Dutcher
State Climatologist
Agricultural Meteorology
A few weeks ago, I discouraged cutting alfalfa while it was winterizing because of potential winter injury; however recent rains have changed the outlook.
By mid-October the growing season is pretty much complete. Many folks received some late season rain and some areas have had light frosts that left alfalfa plants pretty much unaffected. So, you might have a substantial, high quality alfalfa crop remaining in your field.
Alfalfa that has had at least six weeks of growth in mid-October since the previous cutting will have developed adequate winterhardiness for all but the most severe winters. It also has begun to go dormant naturally because of shorter days and cooler temperatures. As a result, harvest will not reduce winter reserves, nor is it likely to jeopardize stand persistence.
Hay harvest, though, can be difficult because alfalfa dries and cures very slowly in October. If you do try to cut hay, be extra alert to weather reports, use a conditioner to speed dry-down, and consider using a preservative that will protect hay that's baled at higher than normal moisture levels.
Often it is better to harvest alfalfa as haylage in October. Less drying is needed, and since drying is slower, haylage can be made at a more uniform moisture content than in summer. October alfalfa also tends to preserve well as haylage.
Grazing is another option now, but be a little cautious about bloat. Also avoid grazing on wet soils, or stand damage could occur.
Good alfalfa in mid-October doesn't have to be sacrificed to maintain winter-hardiness. Just be sure you had adequate time to develop winter-hardiness, and then select a good harvest method.
Bruce Anderson
Extension Forage Specialist
Late summer plantings of alfalfa tend to have fewer weeds than spring plantings; however, this year weeds are a problem in some fields. Select a control option, based on the type of weed and how dense it is in your alfalfa.
Doing nothing is best when weeds are annuals like foxtail, crabgrass, and pigweed that will be killed by frost, as long as the weed stand is thin enough to permit plenty of light to reach new alfalfa seedlings.Clipping tall weeds is another option. This works best on thick stands of tall broadleaf weeds, but be careful not to cut or smother the seedling alfalfa.
Herbicie options are limited. If herbicides are used, spray this fall because spring treatment usually is not effective. For grassy weeds, especially winter annual grasses like downy brome, cheatgrass, and volunteer wheat, use Poast Plus or Select herbicides before grasses are 4 inches tall. If your weeds are broadleaf weeds like pennycress and mustards, spray Buctril or Butyrac while weeds are small this fall. If both grasses and broadleaves are a problem, Pursuit can be used, but this is more expensive.
By selecting the best method of weed control, you can help your alfalfa be clean and productive for many years.
Bruce Anderson
Extension Forage Specialist
Not surprisingly for this season, there has been an increase in the number of plant samples submitted for disease diagnosis. The following diseases were diagnosed by the UNL Plant and Pest Diagnostics Clinic Aug 13 - Sept 21:
Alfalfa -- rust (Colfax County), spring black stem (Keith County), summer black stem (Colfax County);
Corn -- charcoal rot (Lancaster County), fusarium stalk rot (Dodge and Lancaster counties), Goss's bacterial wilt (Chase, Cuming and York counties), gray leaf spot (Furnas and Nance counties), Northern corn leaf spot (Nance County);
Soybean -- anthracnose (Phelps County), bacterial pustule (Lancaster County), bean pod mottle virus (Johnson County), brown stem rot (Dodge and Holt counties), cercospora leaf spot (Clay County), charcoal rot (Burt, Clay and Dodge counties), fusarium (Buffalo, Clay and Hall counties), Phytophthora (Hall County), Pod and Stem Blight (Dodge and Phelps counties), Pythium (Buffalo and Clay counties), Rhizoctonia (Buffalo, Clay, Greeley, Hall and Lancaster counties).
Jennifer Chaky
Coordinator
Plant and Pest Diagnostic Clinic
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Corn condition rated 5% very poor, 8% poor, 24% fair, 43% good and 20% excellent. Irrigated corn was 79% good to excellent while dryland corn was 41% good to excellent. The crop was mature on 69% of the acreage, compared to 91% last year (drought conditions) and 63% average.
Soybean condition rated 7% very poor, 13% poor, 33% fair, 39% good, and 8% excellent. Plants were turning color at the same rate as the five-year average -- 94%.Most Nebraska soybean acres are at R7 (50% of leaves yellowing) or beyond. Many fields that are fully mature and nearly harvestable have a high percentage of green-stemmed plants remaining in the field. With normal soybean development, once physiological maturity is reached, the plants should continue the maturation process and stems should dry down.
A variety of commonly used Farm Service Agency (FSA), Natural Resources Conservation Service (NRCS), and Rural Development (RD) forms are readily accessible online 24 hours a day. Just visit their site at: http://forms.sc.egov.usda.gov/FormSearch.asp
The site includes instructions for completing the forms and submitting them to your local office.
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Dear Readers,
This week's Crop Watch includes a readership survey, designed to help us learn more about how you use information in the newsletter and how we might improve the newsletter. Please take a few moments to consider the depth and range of stories in this year's issues (more than 250 stories so far) and complete this survey. We have fine-tuned the questions and the format this year to make it easier and quicker to complete.
Responding to the survey will provide even more direct benefits to some of our readers. Several of the contributing authors have donated prizes to be used in a drawing of survey respondents. Readers interested in entering the drawing should include their name and address, which will be separated from the survey and entered in the drawing before responses are analyzed. The prizes, which are listed below, will be drawn from those names submitted from both the print and web versions of the newsletter before Oct. 15.
One half-price reduction in the registration fee to an Integrated Crop Management Winter Program available at the NU Agricultural Research and Development Center near Mead. (Value not to exceed $50)
Free registration to the NU Crop Protection Clinic of your choice. (Value of $25)
One copy of the Crop Management and Diagnostic Clinic Reference Book (Value of $50)
Three copies of the new NU Agronomic Crops of Nebraska Nutrient Management Guide, a 176-page book addressing in depth the nutrient needs of the state's major agronomic crops. (Each prize valued at $25)
Ten pairs of chemical resistant gloves. (Value of $25)
$25 toward the purchase of your choice of any NU Cooperative Extension publication(s).
Three prizes, each of which is a free diagnosis from the NU Plant and Pest Diagnostic Clinic. (Each prize valued at $10)
Lisa Brown Jasa
Crop Watch Editor
Paul Hay, Extension Educator in Gage County: Harvest is slowly resuming following the rains. Corn stalk rot does not appear to be a great concern with averages below 25% (most in the low teens) for all but one variety in the Southeast Nebraska Corn Growers dryland and irrigated trials. Lots of reports that the last bit of grain in bins had weevils. Don't forget to clean and treat bins before harvest. (See the Aug. 31 Crop Watch for details on grain bin preparations.)
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