Purdue University doesn’t do fall corn borer counts any more. Is that because they’re no longer a threat to Indiana’s corn crop?

The Indiana Certified Crop Advisers panel dealt with this question. The panel includes Betsy Bower, Ceres Solutions, west-central, Indiana; Steve Dlugosz, Harvest Land Co-op, east-central Indiana; and Dan Ritter, Brodbeck’s Seeds, based in Rensselaer.

Question: Since Purdue entomologists no longer issue fall corn borer counts, does that mean I can forget about corn borer? Do I still need corn borer -resistant hybrids?

Ritter: The broad adaptation of corn borer- resistant traits in hybrids mad it difficult to find conventional corn to sample. Over time the level of infestation dropped as there were fewer fields to feed on and reproduce in.

European corn borers are by no means extinct. They are still out there and can be found in refuge areas. The 2015 growing season could have more conventional acres as growers strive to cut input prices. That means more acres for corn borers to feed on and reproduce, increasing the potential for infestation. So we could have a spike in the corn borer population in 2015. If resistant hybrids were a viable option for your operation in the past, I would continue to use them.

Bower: Just walk into any non-GMO field or any field with non-BT hybrids and you can still find evidence of corn borer damage. You should still consider using corn borer resistance, especially if your corn will be V6 or later in early June. The V6 stage means there are six leaves with collars on plants. This is likely when the first generation of European corn borers infest plants if corn borers are present.

There is also a second generation. It normally infests the plant from the V-12, or 12-leaf stage, through the early part of the reproductive stage, usually R 2. This means possible infestation can happen anytime between mid-July and mid-September depending upon the stage of growth and maturity of the corn in the field. (In some years there can even be a third generation if the growing season extends long enough in the fall.)

Duglosz: European corn borer is still a concern across the Corn Belt. Just ask some growers in southern Indiana who grew non-GMO corn to this past summer. Many who grow it have a market that will give them a premium for non-GMO corn. But the corn is subject to corn borer infestation and damage.

Choosing a non-resistant hybrid which does not have the Bt trait for corn borer control to save seed costs is a terrible idea!

(Editor’s note: Danny Greene of Greene’s Corp Consulting, Inc., Franklin, works with several farmers who grow non-GMO corn. He notes that signs of corn borer damage were higher than normal in many of these growers’ fields in 2014. In some cases treatment was warranted. Greene is also a CCA and member of the pool that makes up the Hoosier Bug Beat and Crops Corner panel.)

Corn borer was here! Here are typical signs of first generation corn borer feeding, known as shot-hole damage, where larvae chewed through the whorl.