Southeast Michigan vegetable update — Aug. 16 2017

Much of our area received an inch of rain or less in the last month. The dry conditions have hindered disease development, but kept irrigation systems working overtime.

Relatives of Japanese beetles, Asiatic garden beetles spend the day underground and the night feeding on foliage. Photo by Mike Reding and Betsy Anderson, USDA Agricultural Research Service,
Relatives of Japanese beetles, Asiatic garden beetles spend the day underground and the night feeding on foliage. Photo by Mike Reding and Betsy Anderson, USDA Agricultural Research Service,


Things are dry! There are predictions of thunderstorms across the region for Thursday, Aug. 17.

The table below presents rainfall in inches for the Michigan State University Enviroweather stations in southeast Michigan with the amount of change from last week reported. Growing degree-days (GDD) starting March 1 are calculated using the Baskerville-Emin Method.

Rainfall and GGD totals as of Aug. 16


GGD base 50

Five-year GGD average base 50

Rainfall since April 1 (inches)


1,832 (+132)


12.25 (+0.35)


2,116 (+144)

Not available

12.38 (+0.15)


1,896 (+129)


13.29 (+0.08)


Asiatic garden beetles have caused problems on some small farms. This is a newer pest in Michigan, and while this pest is well-known in the turfgrass world, less is known about it in other systems. The larvae feed on roots and live in the soil, and the adults spend their days in soil while feeding on foliage at night.

According to “Western bean cutworms and Asiatic garden beetles are emerging in field crops” by MSU Extension, entomologists in Ohio and Michigan have noted Asiatic garden beetles seem to be very attracted marestail and have found large number of larvae and adults in the root zone of the weed. The best control strategy for small farms is probably handpicking the beetles at night when they are active. Row covers may not be effective as the larvae and adults may be living in the soil under the row cover.


Downy mildew has been found on basil in Ohio. This disease causes yellow areas on the upper leaf surface and a carpet of fuzzy, gray-black spores on the leaf underside. If infected plants are found, remove these plants to prevent the disease from spreading to other plants and plantings.

Muskmelon is being harvested.

Pepper harvest continues. The dry weather has hindered phytophthora development. If the weather takes a turn towards rainy, applying protective fungicides to fields with a history of this disease before conditions change can hamper disease development.

Recommended products include the various formulations of Orondis and Ranman. For a full listing, see the “Midwest Vegetable Production Guide.” A good overview of cultural practices to prevent this disease is in the MSU Extension article, “Phytophthora can blight your peppers and your profits.”

Potato tops are being killed and harvest is underway.

Pumpkins and winter squash are sizing up nicely. I’ve seen bacterial symptoms as well as edema in fields. Isolated incidences of viral infection are also evident. For more information on recognizing and dealing with viruses, see my MSU Extension article, “Viral infections can lead to traditional pumpkin varieties taking on a new appearance.”

Sweet corn harvest in ongoing, though weather is likely to blame for some production gaps. Corn earworm populations continue to be low, with my trap in Monroe County capturing five moths in the last week. The rain predicted for Aug. 17 may bring a new batch of moths in with it.

In fields without consistent spray programs, western bean cutworms can be found feeding in many ears. The caterpillars I’ve seen have bored directly through the husk and have fed on small patches of kernels throughout the ear.

western bean cutworm csu

Western bean cutworm is a newer pest of Michigan corn. The key characteristic for larval identification is the dark area with thin, white stripes behind the head. Photo by Frank Peairs, Colorado State University,

European corn borer caterpillars are also feeding in some ears. Fall armyworm is being reported in west Michigan—this is typically the time of year this pest makes it to Michigan, so I would not be surprised if it was in our area.

Staked tomato harvest continues. Late blight has been reported in north central Ohio in the last week, and as long as weather conditions remain cool, conditions are conducive to disease development. The dry weather encourages spider mite development, so keep an eye out as this pest’s activity may increase.

Processing tomatoes harvest has begun.

Watermelon is being harvested. As the dry weather persists, keep an eye out for spider mites.

Contact me any time at 517-264-5309 or for pest and disease sampling. I make updates regularly on Twitter at @SoutheastMIVeg.


Growers with greenhouse and floriculture aspects to their farms may be interested in attending the 2017 Greenhouse Production, Plant Health, and Marketing Conference Sept. 13 in Lansing, Michigan. A wide range of topics will be covered, with a focus on increasing plant quality, safety and sales. For more information, see “Register now for 2017 Greenhouse Production, Plant Health and Marketing Conference.”

The Midwest Mechanical Weed Control Field Day is Sept. 26 at the MSU Horticulture Farm. This meeting will feature mechanical weeders from the U.S. and Europe, as well as the experiences of farmers who use these tools. For more information and registration, see “Midwest Mechanical Weed Control Field Day.”

Hotels are filling up for the Great Lakes Fruit and Vegetable EXPO, Dec. 5-7 in Grand Rapids, Michigan. The combination of grower-focused, research-backed presentations and an amazing exhibit hall make it a can’t-miss event.

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