Southwest Michigan vegetable update – June 20, 2018
Harvest has begun from direct-seeded zucchini and yellow squash. Harvest has also begun for low tunnel-grown cucumbers.
Low tunnels do not have the desired effect this year. Their biggest advantage is during sunny, cool weather, and we have experienced a lot of cloudy, cool weather. The hot temperatures over Memorial Day weekend also proved to be a problem in tunneled plantings by aborting flowers in some fields, even though the tunnel was open.
No significant insect or diseases have been reported. However, weather conditions have been ideal for disease spread and development, which could easily show up later in the season. We have had several mornings and days of high humidity and periods of significant leaf wetness. We have also experienced several hard, driving rains, which move diseases from soil to plant and then within the plant—even in a raised bed, plastic mulch system.
We have also experienced cloudy, windy, cool conditions, which are ideal for spread of cucurbit downy mildew and other wind-borne diseases. Be sure your plantings are adequately protected and do not try to get extra days out of your spray program. Stretching spray intervals is not wise under these conditions—it only works with dry, sunny weather.
West central Michigan vegetable update – June 20, 2018
For cucurbits, planting of processing zucchini was ongoing in Oceana County, depending on the timing of grower contracts. There was an outbreak of cucurbit downy mildew in Maryland recently, which is earlier than normal.