Southeast Michigan vegetable regional report – August 20, 2014

Rain events brought some relief to non-irrigated crops; more rain is forecasted. Continue protecting crops as the epidemic of tomato and potato late blight and cucurbit downy mildew continues and other disease can ramp up quickly in fields.


In the last two weeks, drier weather has been predominant. Four out of the past nine days had some precipitation, with 0.15 inches of rainfall recorded at the Michigan State University Hudson Enviro-weather station and 3.26 inches of rainfall recorded at the Romeo Enviro-weather station. The average for the southeast stations was 1.87 inches.

Based on data from the Petersburg Enviro-weather station, air temperatures ranged from 46 to 80 degrees Fahrenheit, with mostly sunny days. However, 14 to 17 hours of rain was recorded in the last two weeks, and up to 10 humid hours were recorded in dry days. Based on the five-year average, we currently are behind 278 growing degree days (GDD) base 50.

Rainfall and regional GDD for the southeast region via MSU Enviro-weather

Enviro-weather station

Rainfall total (inches)









Commerce Township















Average for the region





Weather outlook

Temperatures are forecasted to range from 63 to 90 F over the next week. Rain is in the forecast with chances ranging from 45 to 86 percent for Aug. 21-27.

Vegetable crops

Pumpkin fruit continue to develop, while vines are showing nutritional deficiency K and Mg associated most likely with the lack of adequate soil moisture. Some pumpkin fields have spots on the fruit, most likely from the bacterial pathogen that causes angular leaf spot splashing from the foliage to the fruit.

Powdery mildew pressure has increased and is now widespread in the area. Effective powdery mildew management requires a combination of resistant varieties and appropriate alternation of fungicides with different FRAC groups to avoid resistance build up. Fungicides with high risk of resistance are in FRAC groups 1 and 11, among others.

As watermelon and muskmelon harvest is in full swing, aphid and mite populations have increased in pumpkins and watermelon, respectively.

Cucurbit downy mildew has been confirmed in cantaloupe. Continue protecting cucumbers and melons from cucurbit downy mildew as weather in the following week is forecasted to be conducive for this disease. Keep in mind cucurbit downy mildew can also be problematic in other vine crops, and symptoms differ to those observed in cucumbers.

Potato and tomato harvest continues. Bacterial diseases continue to be challenging for tomato growers, fresh and processing. The epidemic of tomato and potato late blight is ramping up with confirmed reports in 10 counties. Weather in the following week will be conducive for disease development. Michigan State University Extension recommends continuing protecting crops with appropriated fungicide sprays for tomatoes and potatoes, scouting and reporting symptoms.

Banana pepper and bell pepper harvest is ramping up. Pepper varieties with resistance to bacterial spot can easily be told apart. Bacterial spot severity is minimal on those as opposed to other varieties without resistance.

Thrip populations have increased some in pepper and cabbage, but remain low compared to drier years, such as the 2012 growing season where thrip populations built up and caused damage in pepper fruit and cabbage heads. Cabbage harvest and planting of fall cole crops continues.

Sweet corn harvest continues, while trap counts for corn earworm, European corn borer and western bean cutworm moths remain at zero. The risk for western bean cutworm continues to be forecasted as moderate in our area, according to

For more information on commercial vegetable production, contact Lina Rodriguez Salamanca at 517-264-5310 or .(JavaScript must be enabled to view this email address).

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