Southwest Michigan vegetable update – Aug. 22, 2018
Time to increase protection against corn earworm and tomato fruitworm.
High temperatures ranged from 76 to 84 degrees Fahrenheit and lows from 61 to 67 F. There was spotty rain throughout the area Aug. 21. We received 1.3 inches at the Southwest Michigan Research and Extension Center, other areas received more and others less. The 50 F degree-day units are at 2,247 for 2018 compared to 2,178 for 2017 and 2,151 for the five-year average. We are probably five days ahead of last year and seven or so ahead of the five-year average.
Corn earworm and tomato fruitworm have increased on sweet corn and tomato fruit. These are the same insect, they just go by different names depending on where they are found. Trap catches of adults have exceeded 100 in some nights last week and with field corn drying down, females look for other hosts to lay eggs, with sweet corn and tomatoes being the most likely this time of year.
Aphid populations are also increasing, especially on peppers (see photo). High populations will make the plants and fruit sticky due to honeydew and increase the chances of virus disease transmission.
Plants vary in their response to nitrogen rates. Some plants are able to utilize higher rates and turn it into the marketable portion of the plant, whether that is a leaf, like lettuce, or a fruit, like peppers. However, other plants are not able to do that very effectively. Read “Vegetable crops and their response to nitrogen” from Michigan State University Extension for more information.