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Fight borers when buying corn seed

It's the time of year when corn producers start making decisions about the seed they'll use for next year's crop, and LSU AgCenter entomologist Jack Baldwin says Louisiana farmers should consider variety selection as one part of their plans to manage corn borers.

“Corn borer pressure has been variable in recent years, but the potential for damaging infestations is a definite threat,” Baldwin said, adding, “Bt corn varieties with the Yieldgard Corn Borer technology provide almost complete protection from the corn borer complex — thus eliminating the threat of damaging infestations during the growing season.”

Baldwin said producers will pay a premium for Bt corn seed, but the advantages are that no additional control expenditures for pheromone traps, scouting or insecticide will be necessary for corn borers.

“The disadvantage, of course, is that the premium for Bt seed cannot be recouped if infestations are light this year,” he said.

Louisiana producers are fortunate to have several well-adapted Bt varieties to chose from, according to Baldwin.

Based on LSU AgCenter research at six locations around the state, nine Bt corn varieties are recommended for 2004 based on yield performance. The list includes Pioneer 31B13, DeKalb DKC 68-70, DeKalb DKC 69-70, Terral 2160 Bt, Terral 2155 Bt, Terral 26BR10n, Genesis 3214, Genesis 2A16 and N83-N5.

“The Bt technology — Yieldgard Corn Borer — in these varieties will control southwestern corn borer, sugarcane borer and European corn borer,” Baldwin explained, adding, “It also will suppress corn earworm and fall armyworm, but it will not control rootworms or cutworms.”

Producers should refer to LSU AgCenter Pub. 2827, “Corn Hybrids for 2004,” for other agronomic qualities of these varieties, Baldwin said.

In addition to those suggestions, Baldwin also stressed that producers are required to follow a resistance management program to preserve the benefits of Bt corn.

“In Louisiana, producers are required to plant a 50 percent refuge of non-Bt corn on every farm where Bt corn is planted,” he explained. “This refuge should be planted within one-half mile of the Bt corn, and it should be planted at the same time.”

Baldwin said there are several configuration options in which the refuge acreage can be arranged with the Bt acreage:

  • The refuge can be planted in a separate field.
  • Another way is to plant the refuge acreage as a block or blocks within the Bt field. These blocks of refuge corn should be large enough so that they can be easily treated with insecticide, if necessary.
  • A field can be strip-planted by splitting the planter so that four or more rows of refuge corn are alternated with four or more rows of Bt corn. The disadvantage of this configuration is that the refuge strips cannot be treated with insecticide separately. The advantage to strip planting, theoretically, is that the Bt strips may buffer the refuge strips or dilute the corn borer population in the field.

“But mixing Bt seed with non-Bt seed is not an allowable refuge option,” Baldwin said.

Tom Merrill is News Editor for LSU AgCenter Communications. (225-578-5896 or [email protected])

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