By Nicolle Ritchie and Angie Gradiz
Weather
High temperatures and no precipitation made for a hot week with high water demand. Scattered showers forecast for the weekend will bring slightly cooler temperatures, with the next significant precipitation expected on Monday, July 20.
Crops and pests
Most soybeans are in reproductive stages, ranging from R1 (one open flower anywhere on the stem) to R4 (a pod 3/4 inches long at the fourth node down). Fungicide applications to prevent white mold should be applied between R1 and R3. The Crop Protection Network’s Crop Risk Tool showed high risk of white mold development on irrigated soybeans and low to moderate on non-irrigated soybeans in southwest Michigan for the past week.
More corn put out tassels this week. Detasseling of seed corn fields began in earnest. As corn enters reproductive stages, scout for tar spot by looking for small dark lesions on leaves. Make sure to add water and try to rub the lesion off. If it can be rubbed off, it is not tar spot, but insect droppings. Tar spot fungicides are most profitable when applied between R1 (silking) and R3 (milky kernel) in corn. According to the Tar Spot Map, tar spot has now been confirmed in Calhoun and Jackson Counties.
Watch for western bean cutworm in fields that are close to tasseling or freshly tasseled. Put the sun behind the leaves to watch for egg masses, which will appear as dark shadows on the backlit leaves. The threshold for western bean cutworm treatment is 5% of plants affected (cumulative week after week).
Source : msu.edu