MSU Extension Vegetables

Weather

Growers north of I-69 received easily over 3 inches of rain over the last 10 days, with some growers reporting 6 inches during Aug. 25–28, and additional rains over Labor Day weekend preventing field access for protective sprays. As a result, many growers are experiencing fruit rots and overall plant decline from saturated soils. Many are faced with the decision of harvesting at light speed to finish the planting before everything rots, or spraying to try and get another picking. The efficacy of a spray in the face of favorable disease conditions must be considered. Field access will be tough in either scenario with a sprayer versus harvest equipment.

If picking, focus on the cleanest areas first and move product to a dry environment. Keep an eye on them to remove spoiled ones throughout the week. Many fresh market growers do not have the labor storage capacity to rescue large volumes of produce from a bad field. In which case, they may choose to spray.

If spraying, choose the best product for the issue and tank mix with a protectant, like chlorothalonil, mancozeb or copper. Temporarily remove screens from nozzles to prevent clogs. Note, spraying for fruit rots with an expensive product this late in the game will not have the same effect it would have had four or five weeks ago. There is more surface area touching the ground now, which will a foliar spray will never reach. Systemic products only go so far to protect fruit, and are aided by natural resistance in certain varieties.

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. Note, some of the weather station links below were misdirecting. They have all been checked and fixed.

• Emmett
• Fairgrove
• Flint
• Frankenmuth
• Freeland
• Kinde
• Lapeer
• Linwood
• Munger
• Pigeon
• Romeo
• Sandusky
• Verona

Crops

I’ll start with something positive. Garlic growers are sizing and storing bulbs for replant later on in October. At least one grower expressed interest in planting buckwheat to follow a summer vegetable crop and before planting garlic. Buckwheat is a fast grower, which can crowd out weeds and mine nutrients. It does not share a plant family with any of our annual crops, making a safe rotational crop without many common diseases or insect pests. This is a good window for such a vigorous cover crop.  It would be drilled or broadcast/incorporated at 50 pounds per acre, and plowed in within two weeks of planting garlic. In most cases this would be a short enough period to prevent buckwheat from setting seed.

Pepper and tomato growers are reporting more bacterial issues with the recent rains. This is caused by Xanthomonas and Pseudomonas. See my Aug. 22 vegetable report for treatment options. The longer fruit remain in the field, the more this will spread. Due to the cost and availability of labor, I see more acres of untrellised tomatoes resting on the ground. The market price will often not justify the effort pawing through muddy ground-contact tomatoes that will rot in the box.

Hoop house tomatoes are experiencing heavy tomato leaf mold pressure. This is caused by a pathogen called Passalora fulva. This disease causes yellow spots on the leaf surface and on the leaf underside you will find discrete circle of olive green spores. Growers I’ve spoken with noted that these symptoms have been spreading rapidly. It can also cause flower abortions, but won’t attack any fruit that’s already formed. 

Tomato leaf mold thrives in hot humid temperatures and can reduce yield. The control window for this year has passed, but tomato leaf mold infections will leave behind sclerotia (think spores that act more like a weed seeds) that re-inoculate the hoop house next year. We recommend heavily picking remaining breaker fruit and removing and destroying infected plants. This will reduce the amount of overwintering sclerotia. 

If this is a perennial issue in your hoop house, choosing resistant variety is the best strategy to deal with this disease. Cornell has developed a list of both cherry and slicer type tomatoes that have performed well in New York, though we don’t know as much about Michigan populations of the disease to know if these varieties will be resistant to whatever strains of tomato leaf mold we have in Michigan. For an overview of tomato leaf mold and the varieties recommended in New York, see “Leaf Mold in High Tunnel Tomatoes.”

There are organic preventative products available, which vary in price but have performed similarly in trials in New York. Products trialed include Champ (Copper Hydroxide), Double Nickle (Bacillus amyloliquefaciens), Oxidate (Hydrogen dioxide), Regalia (Reynoutria sachalinensisextract) and Zonix (Rhamnolipid biosurfactant). Note, only certain copper hydroxide formulations are approved for organic use, including Champ WG and Kocide 3000-O. For more information on product trials, see “Managing Leaf Mold in High Tunnel Production.”

Vine crop growers across the region are faced with a combination of three issues: rapid powdery mildew defoliation, fruit rots and early ripening fruit. We are two weeks ahead with most crops this year. For more information on pumpkin management, see my article, “Pumpkin management in the final stretch.”

Sweet corn is under heavy corn earworm pressure. I caught 190 moths in five days last week. Trap catches have reached 400-600 moths per week in other areas of the state. Treatments should continue on green silk plantings on a tight 3-day interval.

Meetings

Sept. 7, 10 a.m. Late blight diagnostic training for growers and crop scouts at the MSU Plant Pathology Farm, 3735 N College Rd, Lansing, MI 48910. Contact Fred Springborn, springb2@msu.edu, 989-671-7460 for more information.

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.