By Andi Anderson
Weather Overview
Scattered rainfall across southwest Michigan this week brought varied amounts—some areas received over 2 inches, while others received less than half an inch.
High temperatures and humidity persisted, but temperatures are expected to drop today, July 31, and over the weekend. However, mid-80s temperatures will return next week. No significant precipitation is forecast for the next week, but humidity will remain high, potentially affecting crop health.
Crop and Pest Update
Soybeans are transitioning from flowering to pod production (R4 stage), with pods on the fourth node measuring 0.75 inches. At this stage, fungicides are less effective against white mold, which is a major concern for irrigated fields.
Some fields have entered the R5 stage, with a pod seed size of 0.125 inches. Frog-eye leaf spot risk is moderate, and white mold risk is high on irrigated fields but low on unirrigated fields.
Corn has reached tasseling (R1) and entered corn ear stages. At R2, kernels are filled with clear liquid. Seed corn detasseling is nearly complete. This week, tar spot was confirmed in several Michigan counties, including Branch, Kalamazoo, and St. Joseph.
Tar spot risks are higher in areas with increased leaf wetness and moisture. Fungicide applications are most effective between VT (tasseling) and R3 (milk stage). Western bean cutworm moth flights have been low, with peak flight likely last week. Freshly tasseled or near-tasseling corn is most vulnerable.
Potato and Wheat Harvest
Winter wheat harvest has been completed, with many fields now planted with cover crops or double-crop soybeans. The harvest of fresh chip potatoes began the week before last, and vine kill on early-harvest tablestock potatoes continues.
The late blight risk for potatoes is now at medium, with pockets of high risk due to persistent precipitation. Farmers should prioritize scouting for late blight in wet areas and along field edges.
Irrigation and Water Use
Crop water use has decreased this week thanks to the recent rainfall, but both corn and soybeans remain in critical growth stages. For corn, the most critical period occurs between VT (tasseling) and R3 (milk stage and early grain fill). Soybeans are most sensitive to water stress during R3 to R6 (pod development through seed fill). Irrigation Scheduling Tools can assist in estimating water needs and determining the right time for irrigation.
If irrigation is necessary, larger amounts should be applied less frequently to prevent disease progression. It's essential to consider local weather conditions, growth stages, and soil properties when making irrigation decisions.
Photo Credit: getty-images-elhenyo
Categories: Michigan, Weather