Tri-County News

White mold management 2020


By Nathan Drewitz, U of M Extension

It is hard to believe that we are only a few short months away from the start of planting. Hopefully, many of you are prepared for the upcoming planting season with your crop, nutrient, and chemical management programs completed or close to completion. This is also the point in the season where I start putting together articles based on what were agronomic problems from last year’s growing season. I hope that you consider these articles and use them to review the details of what you have planned. While the past couple of year’s climatic conditions have made us question having field plans, I hope this doesn’t deter you from having a plan in place for this next growing season. Having a plan B or C may not be a bad idea either, at this point.

One of the best things of teaching Private Pesticide Applicator recertification workshops is that I get to hear from everyone what problems they had during the growing season. As it turns out, beyond the water issues this last season we also saw a lot of white mold issues. This makes a lot of sense with the wet conditions that we had plus the cooler temperatures around flowering of this past season. High fertility can also help contribute to the environmental conditions needed for this disease. Keep in mind that manure applications can contribute to high fertility conditions that can lead to worse white mold issues. Higher plant populations can also create a favorable environment for white mold issues to develop.

Something that I noticed this last year was the increased weed management issues, especially around areas where water was sitting and/or crops were planted later and had yet to canopy. Many weed species can play host to white mold and need to be managed to help prevent white mold issues.

Management of white mold starts with finding the resistant varieties to plant in those white mold-infested fields. Keep in mind there are no varieties that are completely resistant to white mold. To find these resistant varieties, talk with your local agronomist and look at yield trial data to help determine which varieties will work best in those fields. Using multiple sources for varietal selection could help with selecting the proper varieties. Reducing planting populations can help with reducing white mold issues. Remember that lower plant populations may still maximize yield, but can carry with it higher risk of yield losses if stand establishment is poor. Wider row spacing can help, but that may be more difficult with different planter set-ups and may also lead to lower weed control. Speaking of weed control, following our best management practices (BMPs) when making weed management programs can help eliminate weeds that are hosts for white mold. If your white mold issues are at a point where the above management options are no longer working, considerations for biological and chemical control may be warranted. Remember to always look at the costs of your management options and weigh them against the yield loss due to white mold.

It should be clear that white mold management decisions can be made prior to the start of the growing season. I would also encourage tracking the white mold in your fields to check the effectiveness of your management.

If you have any questions on white mold or would like more information, please feel free to call me at (320) 968-5077. I would also encourage you to fill out the needs assessment survey at z.umn.edu/TriCountyCrops so I know what you would like to hear more about in the future.

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