Warm temperatures, scattered rainfall and advancing crop development marked the past week across southwest Michigan as corn entered pollination, soybeans progressed into reproductive stages and winter wheat harvest wrapped up.
Temperatures began the week on the mild side before climbing into the mid-80s. Storms early in the week delivered rainfall across much of the region, while forecasts call for similar temperatures over the coming week with additional precipitation expected near the weekend. Otherwise, conditions are expected to remain dry and sunny.
Soybean development continued, with more fields reaching the R5 growth stage while others remained in the R3 and R4 stages. Agronomists noted that R3 is the final effective growth stage for applying preventative fungicides against white mold. The Crop Protection Network's Crop Risk Tool indicated a high risk of white mold in irrigated soybeans and a low risk in non-irrigated fields across southwest Michigan during the past week. Although disease pressure remained lower in non-irrigated fields, some soybeans showed drought stress symptoms, including flipped or rolled leaves after several days of mostly dry weather.
Double-crop soybeans planted after wheat also made strong progress during the week.
Most corn across the region has entered pollination, with some fields advancing into kernel development. Male row destruction has begun in seed corn production, while detasseling operations are nearing completion.
Farmers are encouraged to continue scouting corn for tar spot by checking leaves for small, dark lesions that cannot be rubbed away. Current disease pressure remains low, with confirmed infections reported only in Calhoun and Jackson counties. Cooler temperatures and irrigation can increase the risk of tar spot development. Fungicide applications are considered most effective between the R1 and R3 growth stages.
Western bean cutworm scouting also remains important in fields approaching or just entering tasseling. Treatment is recommended when cumulative scouting finds egg masses or larvae on at least 5% of plants.
Winter wheat harvest and straw baling concluded over the past week, and growers have begun planting cover crops following wheat. The early harvest provides favorable conditions for establishing warm season cover crops and diverse cover crop mixtures.
Potatoes remain in the tuber bulking stage, with vine kill beginning on early russet varieties to prepare for harvest. Fresh chipping potato harvest also started this week. Growers are advised to continue monitoring full-season and storage potato fields for aphids and late blight, with disease risk ranging from low to moderate.
Water management remains a priority as corn, soybeans and potatoes enter periods of peak water demand. Corn from tasseling through early dent and soybeans from R3 through R6 each require about 1.3 inches of water per week. Potatoes in the tuber bulking stage need about 1 inch of water weekly.
Recent rainfall met crop water needs in some areas, but growers are encouraged to account for effective rainfall when scheduling irrigation to avoid overwatering. Irrigated soybean fields also face a greater risk of white mold during periods of frequent or extended leaf wetness.
Extension specialists recommend using irrigation scheduling tools that incorporate crop stage, weather and soil conditions to improve irrigation efficiency. They also highlighted the benefits of establishing late summer and fall cover crops to help protect soil and conserve organic matter following wheat harvest.
Source: Michigan State University, "Southwest Michigan field crops update – July 30, 2026"