Southwest Michigan vegetable update – May 22, 2019

We continue to be two weeks behind schedule.

Colorado potato beetle adult and eggs.
Colorado potato beetle adult and eggs. Photo by Wikimedia Commons: Adámozphoto.


The growing degree-day (GDD) units base 50 degrees Fahrenheit are at 206 for 2019 compared to 278 for 2018 and 326 for the five-year average. We continue to lag further behind each week in heat units. We had about 0.5 inch of rain over the past week. Temperatures ranged from 39-83 F.

Field activity

Drier conditions allowed for increased field preparation and planting activity. Growers continue to say they are about two weeks behind. Cloudy weather has also slowed plant growth in the greenhouse, so fortunately there is not too much pressure to move plants out of the greenhouse due to plant size.

Crop reports

Asparagus is at the 10–12 pick stage. Asparagus beetles have been found in some fields but is variable from field to field. Educate harvest crews on adult and egg identification.

Early potatoes continue to emerge, which means Colorado potato beetles cannot be too far away. They will be primarily in the adult and egg phase at this time (see photo) and will most likely be found on horse nettle. Planting also continues.

Sweet corn is 6–8 inches tall and generally poorly colored due to cool temperatures. Since below normal temperatures are still in the forecast, consider longer intervals between plantings so that early and later plantings do not significantly overlap in maturity.

Direct seeding of cucumber, yellow squash and zucchini continues. Emergence and growth of earlier plantings is slow even under low tunnels.

Transplanting of tomatoes, peppers and eggplant continues as weather and field conditions permit. Transplant shock is minimal, but so is growth at this time.

Imported cabbageworm adults were flying last week. They will mostly be in the adult or egg stage at this time but eggs should soon be hatching by the weekend. For those growing Brassica crops, scout your fields for the first signs of larvae and feeding. Early planted kale will be harvested this week.


Rain and delayed planting may make early nitrogen applications less effective. This may especially be evident in sweet corn. Consider increasing nitrogen levels at the first sidedressing. Plasticulture beds were shaped when soil was quite moist. Because of this, you can delay first irrigation for up to three weeks. This delay will encourage deeper rooting and lead to larger plants and greater yields. Wet, cool conditions may also decrease the effectiveness of chemical weed control. Therefore, do not be surprised if you see more weeds than normal in fields.

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