East Michigan vegetable update – Aug. 22, 2018

Benjamin Phillips<benp@msu.edu> - August 22, 2018

Excellent yields in cantaloupes and a great looking pumpkin crop ahead. Aphid reports are increasing on many crops.

Thrips feeding craters and scars broccoli leaves. The high population also left a lot of frass. These combined symptoms, and the lack of thrips from an effective insecticide treatment, created the illusion of a foliar disease. Photo by Ben Phillips.

Weather

The bulk of our region received about 1.5 inches of rain over the last three days. This was a good thing for many growers in Livingston, Genesee, Lapeer, Tuscola, Huron and Sanilac counties. Those areas were officially classified by the U.S. Drought Monitor as experiencing a “moderate drought” as of Aug. 16. However, drying onions and potato vines is harder with rain. I would expect some fruit split in field grown tomatoes and cantaloupes as well.

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.

Crops

All heading brassicas harvest continues. Some buyers at the auction were wondering about some broccoli leaves that appeared to be diseased at first glance. Their undersides were brown and covered with a dark fuzz. Upon closer inspection, the cause was apparent. Thrips were living on these leaves in such high numbers that the fuzz was actually their frass. It looked like a bygone civilization. The leaves were thoroughly pitted and scarred from feeding thrips, causing a brownish background. Few living thrips remained; washed away by rain or killed by a thorough insecticide application.

Pepper growers are reporting more incidences of bacterial leaf spot. This is caused by Xanthomonas. Treatment options have traditionally consisted of foliar applications of copper. Tank mixing with mancozeb products, Serenade (Bacillus subtilis) or Tanos (famoxadone + cymoxanil) can improve control. I have been asked whether there is a drip irrigation treatment for this disease. Actigard 50WG is a newer product that can be applied through the drip, and has shown some efficacy in trials when used this way. The rate must be increased as plant canopy grows, and is compatible with other foliar products. However, it is not labeled for bell peppers.

Bacterial leaf spot preventative fungicides
Product	Mode of action	Rate	PHI/REI
Kocide, Champ, others Copper hydroxide	M1	Various rates depending on formulation.	0 day/48 hours or see label depending on formulation.
Manzate, Koverall, others mancozeb	M3	Various rates depending on formulation.	7 days/24 hours or see label depending on formulation.
Tanos famoxadone + cymoxanil	7 + 9	8 – 10 ounces per acre	3 days/12 hours
Serenade Opti Serenade Max Bacillus subtilis QST 713	44	Opti: 14 – 20 ounces per acre Max: 1 -3 pounds per acre	0 day/4 hours
Actigard 50WG acibenzolar-s-methyl	P1	0.33 – 0.75 ounce per acre. Start low and increase rate as canopy grows. Can be applied as drip.	0 day/12 hours

Melons are being harvested in Bay County with great quality and quantity. Disease pressure has been light this year and rain on the clay soils has not drowned plantings.

Pumpkin reports have been favorable, with some growers expecting a record year. Pumpkins have a prolific root system and the clay ground held enough moisture through the dry spell to keep them going. Pollination has been excellent and we have seen few abortions. If your carving pumpkins are ripening now, cut them from the vine, let them cure for about a week in the sun and store them in a shady dry spot or a barn until sales time.

Sweet corn is under heavy corn earworm pressure across much of the state, but populations are spotty. Traps in Oceana and Lenawee counties caught 30-50 moths in three days. However, traps in Lapeer and Mecosta counties caught very few moths over the last week.

Meetings

Aug. 27. Curious about using drones in agriculture? Attend the Tri-State UAV Field Day in Ohio. Contact Ricardo Costa at costasil@anr.msu.edu or 573-639-8971 for more information and registration.

Sept. 19, 8:30 a.m. – 1:30 p.m. Organic Management Field Day at the MSU Kellogg Biological Station, 9701 N 40^th 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.

Oct. 4, 10 a.m. – 4 p.m. Fert, Dirt, & Squirt: Nutritional Monitoring of Greenhouse Crops Workshop. MSU Diagnostic Center for Population & Animal Health, 4125 Beaumont Rd, Lansing, MI 48910. This hands-on workshop emphasizes in-house nutrient monitoring for beginning to advanced growers. Event registration is $80 advanced, $100 on site (lunch included).

Dec. 4-6. It is never too early to make accommodations to attend Great Lakes Fruit and Vegetable EXPO in Grand Rapids, Michigan. Hotel blocks are open and tend to go fast. The combination of grower-focused, research-backed presentations and an exhibit hall featuring a diverse set of vendors make it a can’t-miss event.

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.

This article was published by Michigan State University Extension. For more information, visit https://extension.msu.edu. To have a digest of information delivered straight to your email inbox, visit https://extension.msu.edu/newsletters. To contact an expert in your area, visit https://extension.msu.edu/experts, or call 888-MSUE4MI (888-678-3464).