Southwest Michigan vegetable update – July 19, 2017

Harvest of most crops is well underway.

July 19, 2017 - Author: Ron Goldy, Michigan State University Extension


Temperatures are slightly below normal for the week, with highs ranging from 72 to 84 degrees Fahrenheit and lows from 53 to 66 F. We have fallen behind 2016 in growing degree-days by approximately 147 hours, but are near the five-year average.

We received 2.5 inches of rain across the area for the week. Much of the rain (1.3 inches) came in one event on July 12.

Field activity

Early squash and cucumber fields are being removed and either replanted or sprayed with herbicide. Final plantings of cucumbers and summer squash are being made. Harvest continues or will begin over the next week for all crops except watermelon.

Crop reports

Sweet corn harvest continues. Volume is increasing as more fields come into production. European corn borer and corn earworm are present, so Michigan State University Extension advises protecting susceptible plantings.

There are no reports of downy mildew on cucurbits in the area, but we are getting close to when it will show up, so scouting efforts need to increase. Downy mildew has moved into the Bay City, Michigan, area and if it follows its normal pattern, it will be here within the next few weeks. To keep track of progression, go to MSU Downy Mildew News.

Phytophthora symptoms are showing up in vine crops, especially in low areas of fields. Symptoms began shortly after the heavy rain on July 12. Powdery mildew is showing up on several cucurbit crops. Weather will be favorable for powdery mildew development from now until the end of the season. Powdery mildew is favored by heavy dew and high humidity prevalent during late July, August and into September. We are at the end of squash vine borer season, but I would still apply at least one more protectant.

Tomato, pepper and eggplant harvest has begun mostly for local sales. General harvest of larger volumes will begin in the next seven to 10 days. No serious bacterial diseases have been reported.

Potato and limited onion harvest has begun. Onion harvest is mostly sweet onions for local, farm market sales. Colorado potato beetles are present, but seem to be in low numbers.

Tags: agriculture, asparagus, celery, cole crops, cover crops, cucumbers, msu extension, onions, organic agriculture, peppers, potatoes, pumpkins, squash, sweet corn, tomatoes, vegetables

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