Field Insights

Scouting Tips for Powdery Mildew in Sugar Beets

Keep an eye on the weather and your fields to catch powdery mildew before it’s too late.

Powdery mildew remains an annual issue for sugar beets. This yield-robbing disease is caused by the fungus Erysiphe betae and overwinters on Beta species, including sugar beets or swiss chard. The fungus grows over the surface of leaves and produces spores which give it a powdery appearance. These spores can be carried by wind over considerable distances and infect other plants.

The disease prefers dry, warmer weather: temperatures of 60-86oF. Temperatures exceeding 100oF can arrest disease development. If left untreated, it can yellow and kill leaves, reducing the plant’s photosynthetic capabilities which can threaten yield and sugar content. Infected leaves are also more susceptible to light freezes. Growers have seen as much as a 35% loss in sugar yield in infected fields.

It’s important to scout for the disease to catch it before it is too late. Leaves can become entirely covered in the fungus’ spores within a week of infection, so frequent scouting is key. The infection has a higher chance of taking hold and spreading during summer months, particularly in late July and early August. Here are a few tips on scouting for powdery mildew:

  • Keep the sun behind you/over your shoulder.
  • Scout the edges of the field, as this is where it typically first appears.
  • Start with the lower leaves of the canopy.
  • Pull a leaf and wrap it over your finger.
  • Look for leaves with a white to silver-gray color and the noted powdery appearance – this is how the infection first appears.
  • A musty basement-type odor in a field may be present in severely infected fields.

If you notice signs of powdery mildew, review the susceptibility of your beets to powdery mildew and recent or upcoming weather. If your beets are rated as moderate to sensitive and you’re experiencing ideal disease development temperatures, prevent powdery mildew from spreading in your field with Inspire® XT fungicide on a 10-day schedule using alternating modes of action. If your beets are resistant to powdery mildew or weather conditions are unfavorable to the disease, you can go up to a 21-day interval. Your local Syngenta sales rep can help you find the right solution for your crop.

March 2024 | By Syngenta Thrive
  • Powdery mildew is an easily recognizable disease that poses an annual threat to sugar beets.
  • Frequent scouting is key because leaves can become completely covered by spores within a week, impacting yield and sugar content.
  • Fungicides like Inspire® XT help protect susceptible sugar beet varieties even in ideal disease development temperatures.