USA
September 2016
Source: C.O.R.N. Newsletter 2016-29
By Anne Dorrance
Soybean variety selection is the crucial first step to a successful year and bountiful harvest. In Ohio, we face many challenges and some of them were quite apparent in different parts of the state. Frogeye leaf spot, sudden death syndrome, white mold and even more surprising, Phytophthora stem rot. To add to this soybean cyst nematode (SCN) can now be found at detectable and higher levels than 20 years ago. There is very good resistance to all of these pathogens in the soybean cultivar line up of all companies. We sometimes just get the wrong genetics in the wrong field or in the wrong region. So it is time for folks to take these things seriously and know what fields these pathogens are in and how much damage they are causing. A good scouting at the end of the year will give producers a handle on if:
- The variety they purchased had the right resistance package for Ohio’s plethora of pathogens.
- Pathogens are present – what resistance packages will be needed in future years – aka drop that variety in that field
Key for Phytophthora, the Rps genes will only go so far, and what is critical for Ohio conditions is the quantitative resistance portion of the package (seed companies market this as tolerance, partial resistance).
Resistance to SDS has come a long way: In our trial this year (North Central Soybean Research Program), only the susceptible checks developed symptoms, very impressive! Be sure you also have the SCN portion of the package.
How long have you been growing SCN resistant varieties with PI88788 and do you now have SCN? If the answer to this is a long time and a lot- you are past due for a genetic change to Peking sources. These aren’t easy to find, so start your search now.
Frogeye seems to be a recurring theme for a disease that really was never a problem before 2005. With lower soybean prices, it is time to get away from depending on the sprays and moving towards eliminating this disease by planting more resistant varieties. I have had side-by-side trials of resistant and susceptible varieties the last 2 years at Western – Resistance is winning hands down.
White mold – we have had a similar pattern with this as well. Check out the OSU Soybean Pathology facebook page for a gorgeous picture of resistant vs susceptible – side by side plots. The resistance is there so for those regions where this disease is now an annual occurrence (even in a dry humid 2016), choose varieties with higher levels of resistance.
These are all good things to ask the seed companies next week while you are at Farm Science Review!
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