East Michigan vegetable update – Aug. 1, 2018

Vegetable disease reports have increased across the region.


The dry weather was holding most diseases at bay. This week I’ve been contact by growers across the entire Bay and Thumb area to look at spots, rots and wilts. It makes sense if you think of the disease triangle. We’ve had the hosts (crops) all season, and the diseases have probably been dormant or blown in but couldn’t establish without the right environmental conditions in our fields. But, now we have the right environment with rain, fog and dew almost every morning for the last two weeks.

Click the links below to view maximum and minimum air temperatures, as well as degree-day and rainfall accumulations from Jan. 1 through the last 14 days. 


All heading brassica harvest continues. Remember that for swede midge prevention, destroy crop residues as soon as possible. Growers are reporting satisfaction with head size using 16-inch in-row spacing.

Red beets have experienced heavy pressure from spinach leafminer this year. They are commonly found infesting lambs quarters. Good weed control in rotation crops can help reduce their population before planting beets, spinach or chard.

Vine crops are getting powdery mildew across the region. There are great products out there for this disease, which include Quintec, Torino, Rally, Merivon, Vivando, Luna Experience and Luna Sensation. This is most important in pumpkins, which benefit from a nice, healthy handle at the marketplace. All vine crop fruits will experience sunburn if powdery mildew is left unchecked, but the hard squashes can tolerate a heavier infestation because their stems and handles aren’t as important for marketing as in pumpkins.

Pumpkin fruits are just setting, with the largest about the size of a softball. Acorn, butternut and spaghetti squash are close to their market size, but are still ripening. 

Pickling cucumber harvests are rolling. Downy mildew reports are coming in from the Thumb and southwest Michigan. It is a good time to use Ranman or Orondis Opti on new and older crops.

In onions, thrips pressure has been heavy this year, and some stemphylium and bacterial leaf blight symptoms are now showing up in onion crops. There is a known association between thrips pressure and stemphylium. 

Late blight in potatoes and tomatoes has not yet been detected in Michigan. Some table stock potatoes are going to market. Disease pressure is now increasing, with some bacterial and fungal pathogens colonizing the leaves closest to the ground in field and hoop house plantings.

Pepper harvest has begun. If you are a commercial pepper grower who regularly uses copper and are detecting leaf spot, please let us know (email me at phill406@msu.edu). The MSU Vegetable Pathology Lab is testing isolates for copper sensitivity.

Sweet corn is now under attack by birds and raccoons in many areas. Over the last week, my trap in Lapeer, Michigan, caught zero corn earworm moths, zero fall armyworm moths and 11 western bean cutworm moths. Scout for western bean cutworm eggs and treat if you find one egg mass per 100 pre-tasseled plants. The drought has staggered the silking periods in field corn across out region, and earworms are likely focusing their egglaying there. Once field corn is done silking, we should see higher moth pressure on later plantings of sweet corn. 


Aug. 2, 8:45 a.m. – 4 p.m. Soil: Your Silent Business Partner at Lee Thelen’s farm, 3077 W. Hyde Rd, St. Johns, MI. Event registration $10 per person or $20 for a group of four (lunch included).  

Aug. 13, 9:30 a.m. – 1:30 p.m. Variable Rate Seeding Focus Group at the MSU Agronomy Farm, 4450 Beaumont Rd, Lansing, MI 48910. Seeking focus group participants about seeding rate decisions. Participants will be paid $80. Contact Manni Singh at msingh@msu.edu or 517.353.0226.

Sept. 19, 8:30 a.m. – 1:30 p.m. Organic Management Field Day at the MSU Kellogg Biological Station, 9701 N 40th St, Hickory Corners, MI 49060. Lunch is included.

Sept. 26, 9:30 a.m. – 4 p.m. The Midwest Mechanical Weed Control Field Day at PrairiErth Farm, 2073 2000 Ave, Atlanta, IL 61723. See in-row cultivation tools demonstrated on vegetable crops, with a trade show, and grower experiences with mechanical cultivation. Event registration is $20 (lunch included). Check it out on Facebook

Need your water tested for the Food Safety Modernization Act (FSMA)? Check out the Michigan Ag Water Lab Map.

Please contact me at phill406@msu.edu or 616-901-7513 with questions, concerns or to schedule a farm visit. You can also send plant materials to MSU Diagnostic Services.

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