Southwest Michigan vegetable update – May 30, 2018
From cool and wet to dry and hot, what’s a plant to do?
The weather has made a big flip over the past week. Within six days, the high went from 60 degrees Fahrenheit on May 22 to 96 F on May 28. Lows ranged from 44 to 68 F. Soil temperatures are averaging near 70 F. The 50 F growing degree-day (GDD) units are catching up with last year and the five-year average at 466 GDD for 2018, 497 GDD for 2017 and 472 GDD for the five-year average. The area only had 0.03 inch of rain.
Lack of rain allowed growers to catch up on field activity and transplanting. Some fields are experiencing dry soil conditions in some areas while there is standing water in others. High temperatures and light conditions have put extra stress on new transplants.
I am going to take a different approach this week and not report on individual crops, but issues to consider based on the unusual weather we have had this spring.
Transplants. Many transplanted crops over the past several days were set in the field under high temperature and sunlight conditions. Growers delayed transplanting waiting for better weather or for fields to dry out. When good conditions arrived, they planted as much and as quickly as possible, only to have the transplants experience three days of over 90 F temperatures, causing significant stress to some plantings. This is most notable in transplants grown in 128 cell trays compared to those in 72 cell trays. It is also more noticeable in peppers than in other crops. Transplants should be well-watered before transplanting.
Weed control. Expect weed control to be less effective this year. Cool, wet weather hampered application in some early-planted fields. If applied, control may not be what is expected. Reapply with caution and pay careful attention to product label directions, especially noting rates and any rotation restrictions that could affect 2019 crops.
Fertilizer. Do not expect to get as much benefit from pre-plant nitrogen applications that went on before all the rain in early May. Cool temperatures delayed crop emergence and growth, so plants could not utilize nutrients as effectively and excess rains may have leached nutrients away, especially nitrogen. Additional applications later in the season may be required.
Diseases. It was easy to identify low and poorly drained areas of fields. Avoid planting in these areas this year and take steps to increase drainage for the future. These sites are prime areas for development of root, water-borne diseases such as Phytophthora. Many transplants were removed from the greenhouse and kept in close proximity outside before field planting. This makes watering easier, but also encourages spread of diseases. Take extra care to control diseases once the plants are set in the field.