hello - a couple questions i have a very large vegetable garden and have...

Asked August 26, 2013, 10:08 AM EDT

hello - a couple questions i have a very large vegetable garden and have problems with downy mildew on my squash for the last couple years - what can i do this winter to get rid of it? i've heard it can live in the soil for 8+ years?? also - i've never planted a cover crop for winter - thoughts? is it worth it - i know my garden could use a nitrogen boost. I also have 3 large beds that i've rotated things in but thins year i seem to have various squashes everywhere! would a cover crop help the soil to recover before next year or should i plant somewhere completely different next year. also - squash vine borers - i don't want to till but am wondering if that would prevent some from coming back next year. thank you! you can also call me 763-205-3181

Hennepin County Minnesota cover crops downy mildew

1 Response

Hi, and thanks for contacting AaE.

First of all I have to ask if you are certain that your plants are being affected by Downy mildew, or Powdery Mildew. They aren't the same disease even though some of the symptoms and results may be similar. How you manage the disease will depend upon an accurate identification. The following information is about Downy Mildew.

Downy mildew is becoming more common in Minnesota. For those of us trying to grow cucurbit crops, this has been an especially hard year. This disease flourishes in cool, wet conditions...just exactly like the spring and early summer of 2013. Once established the mold can survive even if the weather turns hot and dry.

The mold does not overwinter in the soil here in the cold midwest, but is easily air-borne and it may be transmitted by newly planted infected plants, human activity (like gardening around infected plants and then moving into an uninfected area!), insects and so on. While this means that you don't have to worry about applying something to your soil this fall or spring, it doesn't solve the mold problem.
Here is a fact sheet from our University that will give you some information about this disease:
http://www.extension.umn.edu/distribution/horticulture/DG1172-12.html

Regardless of whether this is Downy or Powdery mildew, please consider planting disease resistant seeds or starts next year.

It sounds like you feel that your soil needs some amendments and/or fertilizing. While planting a cover crop won't do anything harmful, and may be a great idea, you should do a soil test before you plant again next year. Sometimes, if our plants are malnourished, they become more susceptible to disease and less able to fend off insect invaders. Here's a link that will tell you how to do a soil test, and what the test will tell you about your soil:
http://soiltest.cfans.umn.edu/

And here is one about cover crops:
http://www.gardening.cornell.edu/factsheets/ecogardening/impsoilcov.html

As far as the vine borers go, this is now a problem for next year (the larvae are done with their damage and have emerged as adults who simply want to lay their eggs). I'm not sure how you feel about insecticides, but some folks simply want to know what to use and when.
Here are somes links that will help you choose some insect controls for next year:
http://www.agrisk.umn.edu/cache/arl02957.htm
http://www.vegedge.umn.edu/vegpest/cucs/squabug.htm
http://www.extension.umn.edu/distribution/horticulture/M1262.html

I hope some of this information has helped to answer your concerns. Please contact AaE again if you have further questions.