Bye-Bye Corn Borer
Where did all of the European corn borers go? The "late-night-driving-down-country-lanes windshield moth test” should have been a clue that something was up.
University of Illinois Extension entomologist Mike Gray confirms that there were very few corn borers found in the state in 2009, especially compared with the year prior to Bt use in the mid-1990s.
"The result of our 2009 statewide survey is stunning,” Gray says. "Only 1.2% of the corn plants in the study showed any sign of corn borer injury. The number of second-generation European corn borer was reduced to fewer than one [0.6] borer per 100 corn plants.”
Gray says no borers were found in 23 of the 48 counties sampled. The highest record in the past 11 years for the state was in 2002, when 49% of plants were infested and samplers found 95 borers per 100 plants.
Surveyors didn't distinguish between refuge and nonrefuge corn acres. Fields were chosen at random.
"European corn borers have been unable to survive, thanks to Bt corn,” Gray says. "As refuges decrease in size and additional Bt hybrids with pyramided genes expressing multiple Cry proteins come to the market, European corn borer densities will likely continue their decline.”
He expects the spring 2010 moth flight to be quite low. "These numbers suggest that this once prominent insect pest of corn has been reduced to nearly an insignificant threat,” Gray adds.
Think Safety With Safeners
How does a herbicide know to spare the crop and kill the weed? The latest answer in selective weed control technology is the use of safeners.
"These substances selectively protect crop plants from herbicide damage without reducing activity in target weed species,” says Jeff Springsteen, Bayer CropScience selective corn herbicide product manager. "When added to a herbicide formulation, the safener allows the crop to metabolize the herbicide fast enough to avoid injury but doesn't extend the same benefit to the weed.”
Balance Flexx (isoxaflutole) debuted in 2009 with a new safener (cyprosulfamide) that helps avoid some of the crop injury problems linked with earlier formulations. This year, farmers will get a look at Capreno, which uses two active ingredients (tembotrione and thiencarbazone-methyl) with a safener (isoxadifen).
The road to discovery with a safener is just as complex and regulatory-intense as finding a new active ingredient, Springsteen says.
Bayer began working on safeners in the 1970s and, with the acquisition of Aventis CropScience, has become the world's leading supplier of safener products. You can find Bayer's isoxadifen safener in DuPont's Q product formulations.
Springsteen notes that what the company calls CSI (Crop Safety Innovation) comes at an important time, when growers struggling with weed resistance issues need more nontrait-specific control options. So far, the technology is specific to corn herbicides, but the search is on for compounds to protect dicot crops.
"Safeners are also allowing us to go back and re-evaluate herbicides that were not developed because they caused injury to the crop,” Springsteen adds. "By including the new safeners, many of these products are now gentle on the crop and eliminate weeds at the same time.”
Go Post on Pigweed
Soybean and cotton growers struggling with Palmer amaranth and tall waterhemp get a new postemergence product for their toolbox this spring. Monsanto Company hasn't officially named the herbicide yet, but the new encapsulated formulation of acetochlor will be marketed for 2010 as MON 63410.
The Environmental Protection Agency approved the product for use as an early postemergence herbicide. Upon receipt of state registrations or approvals, it will be introduced primarily in the Southeast, mid-South and Midwest where growers have experienced resistance or control problems.
"We continue to work on weed control solutions from both the crop protection and seeds and traits perspectives,” says Kerry Overton, Monsanto selective herbicides marketing manager. Although MON 63410 contains the same active ingredient as corn herbicides Harness and Degree, Overton says the new formulation provides greater crop safety in cotton and soybeans. The product was tested in 2009 under experimental use permits.
Can You See Corn Growing?
On hot humid days in the Corn Belt, it's said, the corn grows before your very eyes.
University of Kentucky scientist Lloyd Murdock says he had heard that statement so often that he decided to head to the field to see if it was true. He chose one plant within a field that had good fertility and moisture conditions. The field was planted on April 20, 2008, at 28,000 plants per acre.
"Even I was surprised at the results,” Murdock says. The corn plant grew between 1.5" to 5" per day. It grew an average of 10% of its height each day during the V6 stage. The plant grew faster at later growth stages, but the percentage change in height each day was not as great. Measurements were made to the lowest point of the whorl.
Individual leaves grew even faster than the plant. From V6 through V8, leaves grew 2.5" to 4" per day—that's 0.10" to 0.15" per hour!
This gee-whiz trial wasn't precisely scientific. It wasn't replicated, and measurements were taken on only 18 of 32 days of the trial, beginning June 3. So growth stages may not be exactly to the day, but it does point to why you can pass a field one day and visibly notice a difference the next.
- March 2010