Corn+Soybean Digest

Ask The Experts

Will I get a consistent return to CRW Bt corn hybrids?

(SAX) This is a question that's difficult to answer definitively. This isn't as easy a decision as choosing to plant Bt corn to protect against European corn borer.

Will CRW corn reduce root feeding by corn rootworm larvae? Yes. Will that reduction in feeding translate to a yield improvement? It won't every year in every field.

Data from the past three years does show a consistent reduction in root feeding. However, that reduction doesn't always translate to an increase in yield.

Research has shown that we can tolerate a certain level of feeding from rootworm larvae before a yield reduction is measured. Thus, complete root protection isn't required to prevent yield reductions.

CRW corn is truly a risk management tool. Planting CRW corn will reduce your risk of having yield loss from rootworm larvae feeding, but it won't guarantee improved yields. Even if CRW corn has root feeding, it will most likely be similar or less than the level of feeding where a rootworm insecticide is used.

(HARMS) We are in an area of very heavy pressure from rootworms. The CRW Bt hybrids have given adequate control in light to moderate infestations but have not provided the control that I had hoped for in severe infestations. They seem to be doing too much damage before they are controlled.

In these areas of high infestation, the first step is to pick hybrids that have good root systems and good root regeneration. Don't shave rates and keep a close watch on root feeding.

You may be able to use a rescue treatment in some cases if there is a problem and it is caught early.

At this point, I'm not ready to jump on the CRW-resistant corn bandwagon. I don't feel comfortable with its effectiveness in heavy infestations, and as I understand it, the cost is about equal to the cost of an insecticide.

What are the actual cost benefits from a swath/guidance system?

(SAX) The financial returns a farmer can expect from a swath/guidance system appear to be related to the following areas:

  • Time savings

  • Time management efficiencies

  • Reduced fertilizer and pesticide costs

  • Reduced hours of wear on equipment

Benefits in time savings may be derived from the concept of reduced overlap. If you're not overlapping an extra 2-3 ft. with each tillage pass, you'll make fewer passes across the field and spend less time on tillage.

The same is true for application equipment — less overlap equals fewer passes and greater time savings.

Another means of saving time is the ability to end one pass and start another at the right location more quickly.

Time management efficiencies may be realized by being able to do a tillage or application pass at a time you wouldn't normally accomplish this task.

For instance, you might spray field borders during the daylight and spray the rest of the field at night.

Reduced input costs. This area may not be a major return.

However, every savings is an extra return to owning and operating one of these systems: more hours per gallon of fuel, extra acres per container of pesticide and extra use efficiency from the application of fertilizer.

(HARMS) A guidance system should reduce the overlap and skip problem with most fertilizer and chemical applications. This should allow for optimal use.

In addition, it may result in time savings since you'll not have to count rows or try to follow a marker across the field. Don't expect a big cost advantage.

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