Southeast Michigan vegetable regional report – May 7, 2014

Field operations continue in Southeast Michigan. Growers should scout vegetable transplants in the greenhouse for diseases.

Bacterial spots in cabbage seedling. Photo credit: Lina Rodriguez Salamanca, MSU Extension

Bacterial spots in cabbage seedling. Photo credit: Lina Rodriguez Salamanca, MSU Extension

Current weather

In the past week, rainfall recorded at the Petersburg Enviro-weather station was close to 0.0625 inches. Since the beginning of the year, we have had a total of 5.5 inches of rain.

Air temperatures in the Southeast have ranged from 31 to 54 degrees Fahrenheit with an average soil temperature of 52 F for both 2 and 4 inches deep. This allows cole crop, potato and sweet corn planting operations to begin.

Based on the Petersburg Enviro-weather station, we currently have reached 119 growing degree days base 50 F (GDD50). See the current and forecasted GDD at MSU Enviro-weather.

Weather outlook

Temperatures tomorrow, May 8, will range from 60 to 80 F. The next chance of precipitation is forecasted for Friday, May 9, followed by a dry weekend with low precipitation chances.

Vegetable crops

Cole crops planting, including cabbage, broccoli and cauliflower, began in April and will be completed soon. The current GDD for cabbage maggot are 272 GDD43 with peak flight expected at 300 GDD43.

Sweet corn in plastic and bare ground has emerged and planting continues. Seed corn maggot adult peak flight occurred on May 2. First generation adult is expected at 456 GDD39 – currently we are at GDD39 384.

In the greenhouse, pepper transplants with damping off symptoms were confirmed to be caused by Rhizoctonia through MSU Diagnostic Services. Cabbage transplants with leaf spots were confirmed to be bacterial, caused by Pseudomonas.

Tobacco mosaic virus has been problematic this spring in ornamental plants in the greenhouse. Growing vegetable and ornamental plants in the same greenhouse is not a good practice as it may result in an increased risk of some pathogens with the ability to infect ornamentals and vegetables. Tobacco mosaic virus can infect tomato and pepper transplants.

As vegetable transplants continue to grow in greenhouse, Michigan State University Extension recommends implementing integrated pest management tactics for effective disease management in the greenhouse by:

  • Reducing the risk of introducing pathogens by using certified seed and disease-free transplants (learn to recognize diseases on vegetable transplants in the greenhouse).
  • Selecting crop varieties with resistance to problematic pathogens when available.
  • Monitoring and scouting transplants to detect symptoms early, practicing sanitation and, when needed, rogueing diseased plants to minimize the spread of diseases.
  • Using pathogen-free irrigation water and avoiding overwatering (see irrigation and disease management tips). Allow appropriate air flow and ventilation to avoid humidity build up in the greenhouse.
  • Getting an accurate disease diagnosis (see a checklist for submitting samples to a diagnostic lab) as one is required to implement effective management. Control strategies differ by pathogen as fungicides are often specific to a particular type of pathogen.

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