East Michigan vegetable regional report – July 27, 2016

Continued hot and dry weather is impacting pickling cucumbers. Irrigated fruiting vegetables are ripening quickly before putting on size.


The table below includes rainfall (inches since April 1) and degree-day (base 50 degrees Fahrenheit since March 1) accumulations to date from Michigan State University Enviro-weather stations in the region.

Rainfall and degree-day totals as of July 27, 2015



5-year average


5-year average















































First plantings of cabbage will be picked through the end of the week and then will be shutting down if they haven’t shut down already. Fall-harvested plants are at various stages. Some are still being transplanted.

Winter squash and pumpkins are setting fruit. Some are 9 inches in diameter.

Summer squash and cucumber harvest continues. Plants are looking healthy in most places, and even organic cucumbers are hanging on well. However, cucumber beetle damage has left many scarred fruit in the cull piles.

Pickling cucumber harvest has been low. Truckers at sorting stations have reported covering more acres per load than usual, indicating low yields. Some plantings have large plants that are wilting under the heat, while others are putting out stress-induced and bitter fruit without a lot of top growth.

Downy mildew has been confirmed in St. Clair, Bay, Midland, Gratiot, Arenac and Tuscola counties. Growers in those counties should be on a four- or five-day schedule on new plantings when conditions are overcast and mornings are dewy. Growers outside those counties should be on a seven-day schedule. MSU Extension recommends rotating between Gavel 75WG (five-day pre-harvest interval), Presidio 4FL (two-day pre-harvest interval), Tanos 50WG (three-day pre-harvest interval) or Zampro 4.4SC (zero-day pre-harvest interval) and tank-mix with broad-spectrum protectants like Dithane (five-day pre-harvest interval), Bravo (zero-day pre-harvest interval) or Zing! (zero-day pre-harvest interval). Save *Previcur Flex 6SC (two-day pre-harvest interval), *Ranman 3.6SC (zero-day pre-harvest interval) and *Orondis Opti (zero-day pre-harvest interval) for high pressure and favorable mildew conditions. View a special 24(c) label for Orondis Opti.

Cantaloupe and watermelon harvest has just begun on some farms. Size and quality are good. Gummy stem blight has been occurring at low levels in some fields. Fusarium wilt is just starting to become easy to spot in fields that have it. Melon growers need to be vigilant with downy mildew as well. See the recommendations for pickles above.

Fresh market tomatoes and peppers are being picked from the greenhouse and field. The prolonged dry heat has caused tomatoes and bell peppers to start ripening before getting very large. Late blight has been confirmed in Branch and St. Joseph counties.

Sweet onions will be harvested in more volume in the next two weeks. Keep in mind that once the leaves fall over, the bulb can still grow.

Sweet corn picking is going strong most places.

Hop growers can take advantage of a new Section 18 label for Presidio. It cannot be used on hops intended for the export market. Michigan growers may make up to three applications of Presidio 4SC at a 4-ounce-per-acre rate. The pre-harvest interval on hop is 24 days. Presidio should be tank-mixed with another downy mildew product (e.g., Forum, Curzate, Revus or Ranman) and applied at 10-14 day intervals, not in consecutive applications. The current weather pattern across much of the state remains favorable for downy mildew development, so limiting disease will be a challenge. Read the label before applying any pesticide.

Disease trend tools

Just because we are experiencing a drought does not guarantee a disease-free field. Anytime you have more than six hours of leaf wetness, or 10-20 hours of humidity over 80 percent and temperatures between 60-80 F, disease can spread. There are a few ways to determine how the conditions in your area may contribute to disease outbreaks. The weather factors that are important to downy mildew are important to late blight as well. The downy mildew model on Enviro-weather tracks cloudiness, humidity, temperature, rainfall and the number of wet/humid hours every day. The late blight forecasting map of Michigan is another tool for predicting the favorability of a disease spread. This map uses Enviro-weather stations to calculate a disease severity value (DSV) that then changes the color of a pin in the map. The color corresponds to disease infection risk, and whether late blight has been found. Certain management options are recommended based on those criteria.

Criteria for changing spray recommendations

Risk level

Factors affecting late blight spread

Management actions


7-Day DSV total ≤3, and season total <30, and late blight not seen

Lowest labeled rate of protectant fungicide recommended. Minimum 7 day application interval


7-day DSV total ≥3, or season total >30, and late blight not seen

Highest labeled rate of protectant fungicide recommended-- minimum 7 day application interval. Add Supertin (potatoes only) at 2 oz/acre if near end of season at early senescence


7-day DSV total ≥21, or isolated outbreak in county in fields <500 acres

Highest labeled rate of protectant fungicide recommended. Minimum 7 day application interval. Add Supertin (potatoes only) at 2 oz/acre if near end of season at early senescence.


DSV values no longer relevant when isolated outbreaks in county occur in fields between 500-1000 acres

Systemic fungicides recommended at full application rate or protectant fungicide plus Supertin (potatoes only) at 3 - 3.75 oz/acre. Minimum 7 day application interval


DSV values no longer relevant when widespread outbreaks in county occur in fields >1000 acres

Systemic fungicides recommended at full application rate or protectant fungicide plus Supertin (potatoes only) at 3 - 3.75 oz/acre. Minimum 5 day application interval

Special events

Agritainment growers who invite more of the public to their farms and markets than your average grower may be interested in a pollinator planting workshop. Visiting customers may wonder what you are doing about bees. A small planting near the parking area or a large one on your property could be a selling point. The same plants that help pollinators also help natural enemies combat pests in the crop. Come to the Aug. 2 workshop, Supporting Beneficial Insects with Flowering Plants, at the Clarksville Research Station to learn more.

MSU’s Dan Brainard is hosting an in-row cultivation workshop in Milan, Michigan, on Sept. 8 at Zilke Farms. Contact Dan at brainar9@msu.edu or Vicki Morrone at sorrone@msu.edu for details.

Reserve your hotel early for the Great Lakes EXPO in Grand Rapids, Michigan, Dec. 6-8! Registration is not open yet, but hotels often fill up before then. Anyone can access educational session summaries from the Great Lakes EXPO at the website. View the session summaries.

Please contact me at phill406@msu.edu or 616-901-7513 to grab any suspected disease samples from your farm, or send the diseased plant parts to MSU Diagnostic Services.

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