Fight Fungicide Resistance With Seasonal BMPs

Jan 09, 2015


From United Soybean Board News


Soybean farmers have recently been finding that one of the fungicides they use frequently is starting to lose its effectiveness. That’s because the diseases that this fungicide is meant to control have built up resistance to it.

In his recent Focus on Soybeans webinar, Hollier provides U.S. soybean farmers with seasonal best-management practices to manage and prevent one of the pathogens that cause fungicide-resistant diseases. The pathogen, Rhizoctonia solani, is responsible for various diseases such as seed, root and stem rot.

Hollier offers a year-long plan of attack for this pathogen.

“Not any single suggestion will eliminate the pathogen,” said Hollier, “All of these must be used together in order to have a management system that would reduce the amount of loss associated with the disease.”

Before planting, Hollier emphasizes the importance of understanding pathogens and how they spread. When dealing with R. solani, a soil-borne fungus, variety selection and seed treatment become especially important. Follow these pre-planting recommendations to control R. solani:

  • Plant tolerant or the least-susceptible varieties.
  • Use a seed treatment that provides solani control.
  • Rotate to crops that are less affected by solani.
  • Use recommended fertilizer rates. Over fertilizing can adversely affect the incidence and severity of disease.
  • Plant at the recommended seeding rates.
  • Clean equipment between fields to prevent the spread of pathogens.

Managing R. solani during the growing season involves scouting and the full-rate use of non-strobilurin fungicides. Hollier also suggests applying a second non-strobilurin fungicide to fields where conditions are especially conducive to the disease. Follow these recommendations during the growing season:

  • Apply a non-strobilurin fungicide for management of solani.
  • Strobilurin fungicides may still be needed to manage other diseases.
  • Scout early! Do no wait for the disease to spread.
  • Apply fungicides at the full-rate. Using more or less than the recommended rate can promote fungicide resistance.
  • Make a second application of non-strobilurin fungicide where conditions are especially conducive to disease development.

After harvest, destruction of crop residue is especially important for R. solani control. In some conditions, fallowing may be the best option to control R. solani. Hollier’s other suggestions for post-harvest disease management include:

  • Rotate to a less-susceptible crop.
  • Clean equipment with a pressure washer after every tillage operation and move from one field to another. This prevents the spread of inoculum from field to field.
  • Clean the combine after harvesting each suspect field.
  • Clean any land-leveling equipment or other equipment that moves in suspect fields before entering or leaving a farm.

The soy checkoff provided financial support for Hollier’s research. Focus on Soybean webcasts are provided through a partnership between the soy checkoff and the Plant Management Network.