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SCN developing resistance?	4/11/2007 3:41 PM
I have been reading about SCN strains developing resistance to SCN bean varieties. Is this becoming a widespread problem causing economic loss? How do I manage bean varieties that will slow down this evolution, or at least continue to effectively control SCN in my fields?

Answer

4/25/2007 3:03 PM

I don’t believe that it is a widespread problem, but we have found a few cases in IA that we are investigating extensively right now. As soon as we know more we will release the information.

The best way to slow this evolution is to use the ISU SCN management recommendations which are based on rotating host crops and rotating different sources of SCN resistance. As long as you start managing SCN early (as soon as you find them in your field) you should implement the ISU SCN management plan. I don’t see any evidence that there is a yield drag between SCN resistance and SCN susceptible varieties and would not hesitate AT ALL to use SCN resistant varieties. The threshold for managing SCN today should be 1 egg per 100 cc since there is no yield drag between SCN resistant and susceptible varieties. 

One of the biggest problems that we have is that 97% of the SCN resistant varieties have the PI 88788 source of resistance. If we continue to use the same source of resistance and especially planting the same variety then it can cause a shift in the nematode populations. Alternatives to PI 88788 would be Peking and Hartwig. As long as we use good land stewardship and rotate sources of resistance, and start implementing a SCN management plan early, we can slow down this evolution. New sources of resistance are currently being developed and should be on the market in a few years.

Palle Pedersen (4/19/2007)