Crop tour provides close look at research trials
By Heather Thorstensen
hthorstensen@agrinews.com
Date Modified: 07/29/2010 9:46 AM
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Rochester, Minn.— Producers, crop consultants and agribusiness staff came to Rochester earlier this month to hear the latest updates from the University of Minnesota on crop management.
"What we try to do is show new things, new possibilities that farmers can implement on their farm, not this season but next season," said Lisa Behnken, Extension educator in crops based in Rochester.
Traveling on flat bed trailers, participants made five stops around the U of M research site located east of Rochester Community and Technical College's main campus. Visitors may return to monitor changes in the trials.
Extension and U of M's Southern Research and Outreach Center hosted the tour. The sponsor was West Central, Inc.
Herbicide drift impacts
Dave Nicolai, Extension educator in crops from Hutchinson, showed plots of soybeans given one-tenth, one-one hundredth and one-one thousandth of a normal rate of the corn growth regulator herbicide, Status. The purpose was to show how tank contamination or drifting spray affects plants.
The plot given one-tenth the rate had twisted leaves, brown stems and an expected significant yield loss two weeks after spraying. The one-one hundredth rate plants were stunted compared to a plot without any herbicide and probably would always be shorter. Yield loss is projected to be five to 10 bushels per acre.At the one-one thousandth rate, leaves showed cupping and malformation of tissue. The plants were expected to grow normally.
Others were given ammonium sulfate and non-ionic surfactant and had some cosmetic distortion of leaf surfaces that wasn't expected to be yield limiting.
Different nozzle styles were demonstrated on a sprayer, including two new styles: twin nozzles, which can spray to the front and to the back, and air induction nozzles.
Droplets smaller than 200 microns will likely drift, said Nicolai. This is approximately the diameter of two strands of human hair.
Strategies to reduce drift include selecting nozzles to increase droplet size, using lower pressure and avoiding application on windy days.
Crown rust control
Ryan Miller, Extension educator in crops based in Rochester, gave an update on a study looking at control of crown rust in oats. Crown rust is particularly common in southeast Minnesota.
Research is comparing a susceptible oat variety, Kame, to a moderately resistant variety, Souris.
Without fungicide, both had crown rust, but Kame showed significantly more. The fungicide Stratego reduced rust for both varieties, but Kame still had higher levels.
A main question is whether the fungicide gives Souris a greater yield and test weight. If so, the combination would be a good resistance package.
Stratego was chosen because it can be used when oats are under-seeded to alfalfa, a procedure of many growers.
Early planted corn
Corn was planted weekly at the research site from April 9 to May 4. Frost hit the area May 9. It didn't cause stand loss, but 50 percent to 60 percent had injury, said Miller. An additional planting took place May 19.
For each planting date, one plot was allowed to continue growing while another plot was tilled and replanted after the frost.
The study will determine it's more profitable to let injured corn continue growing or to replant.
Indications so far are that the injured corn will perform the best. Re-planted corn was significantly shorter.
Studies in Minnesota, Iowa and Wisconsin have shown the optimal corn planting window is April 20 to May 5 for best stand and yield. Because of good April weather, some growers planted earlier, running the risk of frost and the decision of replanting after the optimal dates pass.
Glufosinate-tolerant soybeans
Due to developing weed resistance to glyphosate, a study is focusing on LibertyLink soybeans, which are glufosinate-tolerant. This is the second year producers are able to use them.
The herbicide used with LibertyLink soybeans is Ignite 280. Both products come from Bayer CropScience.
"It's one additional, or new, option for farmers to use in their fields as far as herbicide goes," said Behnken.
These trials consist of a set of pre-emergent herbicides followed with Ignite compared to total post-emergent systems. The post systems were Ignite partnered with another herbicide as a tank mix; Ignite followed by Ignite in two weeks; Ignite plus an Ignite application in three weeks; and Ignite followed by Ignite in four weeks.
The pre/post systems exhibited more weed control than single tank mix application. The double Ignite applications also looked good, Miller said, but it's too early to tell which of them looked best.Ignite has no residual effects at all, Behnken said.
A pre/post herbicide program is recommended for growers, she said.
Weed management trials
Jeff Gunsolus, Extension weed specialist, gave a tour of southern Minnesota corn and soybean weed management trials. These target giant ragweed, common lambsquarters, common waterhemp and grasses. The trials are being replicated in Waseca and Lamberton. Results are provided during winter Extension meetings.
Gunsolus would like growers to have their weed control finished by July 4. After that, they face bigger weeds that are harder to control, more likely to cause crop damage and able to produce more seeds that will grow into weeds the following year.
Both soybean and corn plots evaluated pre-emergence/post-emergence herbicide programs compared to total post programs.
The pre/post program is showing good weed control, said Gunsolus. Pre-emergent herbicides control the first flush of weeds, giving growers early control so they can more easily handle those that grow later in the season.
On corn, the best pre-emergent herbicides used with glyphosate for giant ragweed control were Lumax and SureStart.