Southwest Michigan vegetable regional report – August 12, 2015
Remove cucumber fields as soon as possible after last harvest to minimize amount of downy mildew inoculum.
We finally experienced a period of “normal” weather with highs from 77 to 82 degrees Fahrenheit and lows from 59 to 68 F. Rainfall for the area ranged from nothing to 0.75 inches or more. These conditions have led to harvest of high quality fruit, especially from peppers, tomatoes, squash and cucumbers, but it has also increased the need for irrigation. We are near 1,925 base 50 growing degree days (GDD) compared to 1,750 GDD for 2014.
Watermelon harvest has begun.
Michigan State University Extension urges cucumber, cantaloupe and watermelon growers to remove their fields as soon as possible after the last harvest. Quick removal minimizes the amount of downy mildew inoculum. Reducing inoculum levels is critical in controlling spread to other fields.
Rust has been reported in sweet corn. Rust does best under cool (60 to 75 F), wet conditions – something we had a lot of earlier this year. Recent drier weather will limit spread, but control steps may need to be taken on younger plantings. Tissue prior to tasseling is more susceptible and that is when protective measures are more effective. If you are going to harvest next week, control is not necessary. Fungicides should be applied if leaves average more than six infected sites per leaf.
Phytophthora is also showing up in susceptible plants, especially peppers in low lying areas of fields. It would be best to avoid planting those areas.