Wisconsin Potato and Vegetable Growers Association

Vegetable Crop Update #14

August 3rd, 2022 | Posted in: Crop Updates, News


I provide this vegetable disease alert so that growers may be most proactive in preventatively managing this potentially destructive disease in cucumbers here in Wisconsin. Weekly, I summarize our Wisconsin risk for cucurbit downy mildew, and to date, we’ve had little to worry about with reports multiple states away with no forecasted spore movement.

In this issue, I share a report from Dr. Mary Hausbeck at Michigan State University which alerts growers to first symptoms of cucurbit downy mildew on pickling cucumber in both Muskegon and Allegan counties on July 25, 2022. Six counties in Michigan also had cucurbit downy mildew spores present in their air traps over the past 10 days which suggests a larger spore movement into their state during this past week.

The article below, by Mary Hausbeck and her collaborators Annika Peterson (UW Plant Pathology alumnus!), and Carmen Medina-Mora from the Department of Plant, Soil, and Microbial Sciences summarizes the situation well with appropriate fungicide recommendations for our state of Wisconsin.

The first symptoms of cucurbit downy mildew disease on pickling cucumber plants in commercial production fields has been found by the Hausbeck Lab in Muskegon and Allegan counties on the morning of July 25, 2022. The statewide spore trapping network to detect downy mildew spores in the air has positives for six counties from the sampling period that ended July 17.

It is very important cucumber growers use proven downy mildew fungicides (shown below in alphabetical order). These fungicides were effective in our 2021 research field plots and include:

  • Elumin + chlorothalonil or mancozeb
  • Omega (Orbus) + chlorothalonil or mancozeb
  • *Orondis Opti (chlorothalonil is part of the premix)
  • Previcur Flex + chlorothalonil or mancozeb
  • *Ranman + chlorothalonil or mancozeb
  • Zampro + chlorothalonil or mancozeb

The full article with pictures can be found here:

Downy mildew detected on cukes in Muskegon and Allegan, several counties have positive spores in air samples

In an additional update, eastern Ontario Canada has reported two counties (Prince Edward and Ottawa) with tomato late blight. No further strain type/clonal lineage information is available at this time.

Amanda Gevens
Chair, Professor & Integrated Extension Specialist
Interim Administrative Director of the Wisconsin Seed Potato Certification Program
Plant Pathology Department
1630 Linden Drive Room
University of Wisconsin-Madison
Madison, WI 53706

E-mail: [email protected]
Office: 608-890-3072/Cell: 608-575-3029

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