5 questions for 2012
1. Will my corn rootworm trait work?
In most cases, yes. Still, watch rootworm trait performance closely.
Last July, Aaron Gassmann, an Iowa State University entomologist, and other ISU entomologists confirmed resistance to the Cry3Bb1 protein in Iowa. This is the Bt rootworm-resistant trait found in Monsanto's YieldGard VT Triple and Genuity VT Triple PRO corn products. No resistance has been detected in Cry34/35Ab1 corn (Herculex technology offered by Pioneer and Dow) and the modified Cry3A Bt protein Syngenta uses in its Agrisure trait packages.
It's difficult to ascertain if resistance is widespread. Mike Gray, University of Illinois Extension entomologist, has received more reports of rootworm-damaged corn than in years past.
“That in itself doesn't confirm resistance, but simply suggests there is a performance problem in those fields,” says Gray.
If you had unsatisfactory root protection in 2011, consider these steps in 2012, advises Gray.
● Rotate to a nonhost crop.
● Use a soil-applied insecticide.
● Use another rootworm-resistant trait other than the one containing the Cry3Bb1 protein.
● Plant pyramided Bt hybrids that expressed multiple cry proteins targeted against corn rootworm.
Long-term, the best strategy is one using an integrated system using multiple controls.
“By keeping corn rootworm ‘guessing’ from season to season, resistance development to control tactics can be delayed or prevented,” Gray says.
2. Can refuge corn outyield insect-resistant traited corn?
It sure can. “One thing we've noticed with our refuge (without insect-resistant traits) corn is that sometimes it will come up quicker and have a better stand,” says Clarke Kelso, a Macomb, Illinois, farmer. “It depends on the year, but in some years, it's so much better (yielding) than some of the stacks for which you pay the big money.”
Many times, refuge corn contains the same base genetics as contained in triple-stack hybrids, says Bill Belzer, Pioneer Hi-Bred senior marketing manager for corn.
“Under low insect pressure, these products can yield incredibly well,” says Belzer. “A soil-applied insecticide can protect against moderate levels of corn rootworm.”
That changes, though, under heavy corn rootworm pressure, says Belzer. In many of these cases, rootworm-resistant traits still do a good job of fending off corn rootworm.
“Buying insect-traited corn is like buying hail insurance,” says Bob Jackson, product development manager for Wyffels Hybrids. “You may not have hail, but you can have insurance just in case you do. Insects are a lot more common than a hailstorm.”
3. Will planting corn-on-corn work?
For several years preceding to 2010, few agronomic problems accompanied corn-on-corn.