West central Michigan vegetables regional report – September 4, 2013

Protect cucurbits and tomatoes against disease if you will be growing them into September.

Asparagus growers have either already or are in the process of seeding a fall rye cover crop into asparagus. Some growers have also made their final fungicide application of the season. Common asparagus beetle larvae were active at one location yesterday (Sept. 3) and Japanese beetles continue to be present in some locations.

Cucurbits (cucumbers, pumpkins, summer squash, winter squash): Multiple diseases are now challenging cucurbits. Downy mildew continues to be present and has been detected in winter squash in Ohio. Symptoms on winter squash and pumpkins are less obvious than those on melons and cucumbers. If you suspect downy mildew is present, submit a sample to Michigan State University Diagnostic Services.

Note that products used to protect against powdery mildew will not protect against downy mildew. If downy mildew has been found in your county, consider including a product that is effective against downy mildew along with your powdery mildew material, applied at seven- to 10-day intervals. Examples of products effective against downy mildew recommended by Michigan State University Extension include:

  • Gavel 75WG (five-day PHI)
  • Presidio 4L (two-day PHI)
  • Previcur Flex 6SC (two-day PHI)
  • Ranman 3.6SC (zero-day PHI)
  • Zampro (zero-day PHI)

See a list of counties where downy mildew has been found in Michigan during 2013.

For pumpkins, protecting against powdery mildew into September will help maintain a good leaf canopy to protect fruit from sunburn and will also help maintain good handles on Jack-o-lantern varieties. Phytophthora capsici could also be a problem as we move into September. Read more information on Phytophthora and powdery mildew in pumpkins.

Late blight risk for potatoes and tomatoes is forecast to be high three out of five days during Sept. 5-9. If you are growing tomatoes into September, be aware that this month traditionally challenges tomato producers with elevated disease risk. Being on top of applications of fungicides for late blight will help protect tomatoes. If you have experienced Phytophthora capsici problems in the location your tomatoes are planted, there are a number of fungicides that can be used preventively to help reduce problems. Secondary infections of bacterial diseases could also occur in tomatoes.

In sweet corn, the corn earworm trap in Hart, Mich., captured 12 moths during Aug. 22-30. There is a low risk of additional migration over the next few days. The MSU western bean cutworm trapping network has been shut down after sustained low captures of this pest across Lower Michigan.

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