Answers are from the Indiana certified crop adviser panel: Danny Greene, Greene Crop Consulting, Franklin; Bryan Overstreet, soil conservation coordinator, Rensselaer; Dan Quinn, Purdue Extension corn specialist, West Lafayette; and Dan Ritter, Dairyland Seed agronomist, Plymouth.

 

I haven’t noticed strong corn rootworm pressure in at least five years. However, my son insists on planting hybrids with rootworm protection. Is that necessary?

 

Greene: After several low-pressure years, it’s smart to question whether rootworm protection is still paying off. Rootworm risk depends heavily on field history, rotation frequency and local populations of the pest. If you’re rotating crops, pressure often drops significantly.

 

With tight budgets, it can pay to know the value of each protection method: traits, seed treatments or in-furrow insecticides. Work with your agronomic adviser to test your questions through on-farm strip trials. Track yield differences and costs to calculate return on investment. In basic terms, ROI equals yield advantage in bushels per acre times grain price per bushel minus treatment cost per acre. 

 

If possible, repeat the comparison over multiple fields or years before making broad changes. Also continue scouting for adult corn rootworm beetles. If counts stay low, you can have more confidence in scaling back trait use.

 

Overstreet: Rootworm numbers have been down significantly over the last few years. However, there are still areas where they have caused issues. If you have corn after corn, consider that ground more prone for issues. 

 

For planning for the future, scout fields next summer to see how much pressure you have. If you are finding, on average, more than 0.5 adult per plant, consider an insecticide the next year in continuous corn. If you put out sticky traps in your soybean fields, the threshold is two adult beetles per day of trapping. 

 

Quinn: Indiana is currently at historically low levels for corn rootworm pressure. Therefore, it may be a viable option now to implement hybrids without rootworm protection. However, be mindful that this should only be done in fields that are rotated with soybeans, not in continuous cornfields. 

 

In addition, if you make this move, monitor for rootworms through adult sampling with sticky traps or for larvae by digging roots. This will allow you to adequately monitor and track corn rootworm pressure levels. It can still be risky to move away from hybrids without rootworm resistance, even if you have not seen any pressure in a long time. 

 

Ritter: Shop for the best genetic fit for your farm first. That could be corn rootworm corn, or it could be corn with only aboveground insect protection. In Indiana, there are good options for corn rootworm control other than CRW-traited seed. Those options may include seed treatment and soil insecticide. 

 

In other areas or states, CRW is serious enough that protection is an absolute necessity, like in an all-hands-on-deck situation. I have seen an increase in CRW populations on the western edge of Indiana. So, if you are in that area, give it strong consideration. It certainly merits monitoring beetle populations, at a minimum.