Buying a bag of corn seed once was a relatively simple chore, but my how times have changed.
“Now, it’s full genetic traits, it has different seed treatments on it, and it’s becoming more and more complicated. In fact, I would say buying seed corn is more complicated than almost any other crop we deal with, including cotton,” said Dave Buntin, University of Georgia entomologist, speaking at the recent Georgia Corn Short Course held in Tifton.
The traits in cotton seed are relatively simple compared to those in corn, he says, because they’re concerned only with caterpillars and herbicides.
Corn seed also is becoming more expensive, adds Buntin, causing growers to ask if they’re getting value for the extra cost.
“There are many changes this year in terms of seed treatments,” he says. “Poncho/Acceleron 250 is the standard product as far as fungicides go, or Cruiser Extreme 250 also is on a number of varieties. If you get it in early enough, you also can order a 1250 rate if you have a high-risk situation like late-planted corn or reduced or no-till corn, or if you’ve had severe problems in your fields. You can also get it treated with nematicides.”
Also, says Buntin, imidacloprid insecticide is registered and can be put on seed at the dealer or on your farm, if you have the proper equipment and want to bump up the rate beyond 250.
All of these products target different pests, he says, and it’s difficult to tell ahead of time which insect pests you’ll have.
Most corn insect pests in Georgia are made worse by reduced-tillage and wet, cool conditions, with the exception of lesser cornstalk borer, which favors hot, dry conditions in conventional practices, he says.
Issues with sugarcane beetle
“Generally, over the past 10 years, the Poncho and Cruiser products are very similar in efficacy.
In recent years, we’ve had some issues with the sugarcane beetle. We had a number of reports from Georgia and across the South,” says Buntin.
Adult sugarcane beetles emerge from grass and pastures, moving into corn in April, he explains.
“This is one exception where there is a noticeable difference between the seed treatments. Poncho is a bit more effective against this insect. If you have high pressure, sometimes you’ll need a higher rate than 250, and rescue treatments aren’t effective. The worst cases I saw last year were in sweet corn with no treatment on the seed.”
This past year, says Buntin, was probably the lowest stink bug year seen in Georgia in the last decade. “Southern green stink bugs disappeared last year and brown stink bugs were hard to find. Cold conditions last winter probably had something to do with it.
“With a warm, dry winter this year, this trend probably won’t be repeated.”
Looking at thresholds for treating stink bugs, it has been determined that ear development before tasseling is the critical time growers need to be looking for stink bugs and applying insecticides. During R1 and R2, the insects will feed on the kernel.
“For brown stink bug, the best product is methyl parathion. There aren’t really a lot of other good choices, and methyl parathion will be removed from the market next year.”
As for Bt corn this year, Buntin says there’s a move to stacked or pyramided products with more than one gene in them.
Many hybrids now contain Bt caterpillar trait, a Bt rootworm trait plus herbicide tolerance in a three-way stack. Products with stalk protection, root protection and herbicide tolerance include Agrisure 3000GT, Herculex XTRA and YieldGard VT Triple.
Genuity VT Triple PROTM, Genuity VT Double PROTM contain two traits for caterpillar control, the same one in YieldGard VT Triple plus a new trait (Cry2A).
The combined traits provide good control of stalk borers and fall armyworm in the whorl, but also provide good levels of control of corn earworm in the ear.
Triple PRO also contains a gene for rootworm control but Double PRO does not have rootworm control.
Genuity SmartStax and SmartStax by Dow is an eight-gene combination and contains all the traits in Genuity VT Triple PRO plus all the traits in Herculex EXTRA.
Trait for corn earworm control
Agrisure Viptera is a new product series that contains a second new trait (Vip3A) for caterpillars, especially corn earworm control.
Specific Viptera products have a number designation which for Southern hybrids will be 3110, 3111 and 3220. Depending on the product, it also may be stacked with one or two traits for corn borer and corn rootworm control as well as tolerance to glyphosate and glufosinate herbicides.
Optimum Intrasect by Pioneer is a new product for the Southern U. S. It contains the two original corn borer proteins, in YieldGard-CB and Herculex 1, but does not contain a rootworm trait.
This product provides very good to excellent control of corn borers and fall armyworm in the whorl, says Buntin.
It also provides partial reduction in kernel damage by corn earworm similar to that of YieldGard-CB. Optimum Intrasect XTRA also has the rootworm trait in Herculex XTRA.
For 2012, says Buntin, there will be several Bt products marketed for the Midwest corn belt that have a reduced 5 percent or 10 percent non-Bt refuge that is mixed or blended in the bag of a Bt product.
They include Genuity SmartStax RIB Complete, REFUGE ADVANCED Powered by SmartStax and Optimum AcreMax (several products).
These products will not be marketed in cotton areas of the Southern U.S., but if grown in cotton areas, they will still require a 20-percent non-Bt structured refuge.
Insecticide resistance management (IRM) is required for all Bt traits in corn and includes structured refuge of non-Bt corn, says Buntin.
Refuge requirements are different for the Northern Corn Belt and the Southern cotton-growing areas of the United States. Refuge requirements also differ among hybrids with one or more Bt traits.
“Single above-ground trait products require a 50-percent non-Bt refuge.
Most multiple above-ground trait products require a 20-percent non-Bt corn refuge. Starting in 2012, seed bag tags will have details about product IRM requirements, refuge amount and refuge placement options.”
The National Corn Growers Association has produced a refuge configuration calculator that can be downloaded to any computer.
It covers Bt traits for all of the types of Bt corn sold in the U.S. and can be found at www.irmcalculator.com. You can look up the type of Bt product you have, enter the state and the acreage, and the program will tell you how many acres of Bt and refuge non-Bt are needed and options for how it can be planted.
(Even though corn seed is becoming more expensive and hybrid selection decisions are more difficult, the higher prices for corn are making insect control more critical. For a discussion of that topic, see http://southeastfarmpress.com/grains/rising-prices-make-corn-insect-control-more-beneficial . On another subject, the sugarcane beetle does seem to be emerging as a pest in corn crops in the South. For a look at that situation, visit http://southeastfarmpress.com/grains/sugarcane-beetles-causing-problems-alabama-corn-growers ).