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ISSUE 9  June 28, 2001

 

TRIAL IT, YOU WILL LEARN TO LIKE IT

Do you consider the hybrids and varieties you chose for your farm this year to be the best? Odds, unfortunately, are that a complete stranger could pick a variety that would match or even beat your choice. A University of Wisconsin study that was run in 1992 may cause you to consider your hand in the hybrid and variety game.

A University of Wisconsin agronomist challenged 60 growers to each pick their best corn hybrid for their farm. Then, he picked a hybrid of the same relative maturity based on yield results from the universityís trials. The seed were then planted side-by-side in a field of the farmerís choice.

On 16 of the farms in the study, the agronomist and the growers picked the same hybrid, while on 22 of the farms the hybrids chosen by each (the farmer and the agronomist) had statistically similar yields. On the remaining 22 farms, the agronomist and the farmers were equally in the winnerís rings. Thus, the agronomist broke even on the showing.

This reveals that those small plots that universities replicate CAN predict what will happen in the field as well as that personal touch in your farm field determinations. In fact, small plots can be just as good or even better at predicting top-yielding hybrids and varieties than your own farm experience. The main point of the example is that picking seed based only on farm experience just isnít enough today. This is especially true with new hybrids and varieties popping up in the market each year. On-farm plots, including those conducted as sales plots with seed companies, often are not replicated and are only on one site. The information from these biased plots can skew results if one hybrid is planted on better soil than another. Even some replication will still be only on location for stand-alone farm trials.

Use of university data compared yields over large numbers of locations under a greater variety of soil, weather and management conditions and will provide more information that three years worth of date from one farm.

Consider looking at university trial data as well as company tests in your area. Both the farmer and university trials check the recommendations across soil types and thus provide the farmer with even more information.

On-farm tests, however, are still valuable. These trials are really good at checking secondary traits such as standability and drydown. Also, these trials will allow you to test maturity ranges of hybrids and varieties you want right where you can watch the entire season.

Rather than learning the hard way during a long, wet harvest season, try some trials on new varieties. This will allow you to move toward spreading out your risk by ascertaining which varieties are early (25% of your farm), which are adapted (50%) and which are later (25%). Donít have a year go by to remind you how trials will help you determine your farm needs. Visit the trials at your local university center or near your farm. Check the stands and health of the plants as well as the herbicide program being used now. . .especially after the winds and weather we have had this year. Try to check these same plots later in the season, just before harvest and ask for the harvest data. Donít bet your farm on a near guess, get as much trial data this year as you can in order to make better decisions next year.

 

WATSON, IS IT OR ISNíT IT HERBICIDE?

Later season cupping or wrinkling of soybean leaves can mean several different things. Depending on how good a detective you are out in your field, you should be able to identify the various symptoms. By using the cropping history and recent weather conditions, further narrow down the culprit(s) to the damage. When leaves are crinkled or disfigured with plants that may or may not be stunted, possible causes include: viruses (or other diseases), herbicide injury, insect damage, manganese toxicity, boron toxicity or just weather conditions.

Like here, the Midwest has had increasing calls on puckering symptoms on soybeans.

First, disease problems can cause wrinkling and cupping of soybean leaves. You need to carefully scout and observe any progress or elimination of the problem over a short period of time to determine if diseases have been prevalent in the area and show the symptoms you are seeing.

Second, check on the cropping history and the spraying that has been done in the area. Look at information on the soybean field with the problems as well s the surrounding areas. Do you see a pattern in the damage or any other field observation that might tie the cupping of the soybean leaves to herbicides? Donít jump to conclusions, check carefully. One of the first herbicides suggested, if it is herbicide damage, is Banvel of 2, 4-D. Use of either Banvel or Clarity nearby and volatilized can cause puckering of new soybean leaves, especially leaves that have emerged recently. This damage may last for several weeks and then disappear. Similarly, 2, 4-D will show wrinkling or cupping symptoms. Yield in minor damage cases is usually not compromised, especially if the soybeans are still in the vegetative stage. Another herbicide, Roundup, can cause leaf cupping on Roundup-Ready soybeans for a short time under the right weather conditions. Pursuit, Classic and Pinnacle can also give the appearance of wrinkled soybean leaves, if conditions are right. Again, continue scouting until the symptoms more clearly define the problem or they clear up.

Third, insects such as spider mites or leafhoppers can cause soybean leaf disfigurement. Check for the insects in the vicinity or other damage that indicates insects are promoting the problem.

Fourth, if you havenít had your soil sampled within the last three years, it might be worth your time to run an analysis. It could be the cupping-leaf symptom is simply a micronutrient problem such as manganese toxicity or boron toxicity. While these micronutrient problems are usually not found in this are, check back on the cropping history and determine what was put on the field in the last three years and if any major land changes were done on the field. . . is it reclaimed land from mining or a railroad crossing. . . has soil been brought in. . . have other changes occurred?

Fifth, and certainly not least, simply consider the weather. Has hot, humid conditions occurred for several days? Has cool conditions existed? Were the affected soybeans planted in a wet spot in the field?

Also consider a combination of the above problems. Hot, humid weather sure makes it possible to have more volatilization of herbicides and insect feeding can add to the puckering-leaf problem! Donít jump to conclusions, scout for insects, look at the weather that occurred the last week or so and narrow down the problems to make your final assessment on the field.

Denise McWilliams
Extension Crop Production Specialist
dmcwilli@ndsuext.nodak.edu

 

SENSITIVE SMALL GRAIN GROWTH STAGES

In the past week hot weather has resulted in very rapid growth and development of the small grain crop. This, following several weeks of continuous wet weather.

Most of the small grain crop is in the boot through flowering stages. The challenge this presents is, much of the small grain crop was not sprayed to control broad leaf weeds due to earlier wet conditions. I have received multiple calls this week that go something like this, "My wheat is heading, what can I spray to control Lambsquarters, Pigweed and Mustard?" Without injuring the crop, nothing.

Boot through flowering are the growth stages when a small grain crop is most sensitive to stress. Moisture stress while in the boot will cause spikelets to abort. Moisture stress combined with high temperature results in even greater spikelet abortion. The most sensitive time is just prior to, and during flowering. Hot temperatures and high humidity during this time can kill pollen resulting in sterility. When sterility occurs florets will open in an effort to intercept pollen making them more susceptible to certain diseases, particularly ergot.

Most have seen the readily visible effects of applying broad leaf herbicides during these sensitive growth stages. For example, growth regulators often result in curled/twisted heads and stems. What is not considered is the less visible effects of herbicide applications during sensitive times. These are the same as described for environmental stress, spikelet abortion and sterility.

Early boot through flowering are the sensitive stages, with the time just prior to and flowering the most sensitive. Remember barley flowers while in the boot just prior to head emergence while wheat flowers one to three days after head emergence. Any induced stress during this time can easily injure the crop.

Michael D. Peel
Small Grains Extension Agronomist
mpeel@ndsuext.nodak.edu


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