Southwest Michigan Field Crops Weather and Crop Update July 10

By Andi Anderson

Southwest Michigan experienced steady temperatures in the 80s last week. Scattered showers offered light rain until July 9, when some areas saw over an inch of rainfall.

However, other regions remained dry, adding to a seasonal moisture deficit of around 5 inches. More scattered rain is expected this weekend and mid-next week, alongside rising temperatures and above-normal evapotranspiration.

Soybeans are progressing from late vegetative to early reproductive stages. Some fields have already reached R3, marked by pods measuring at least 3/16 inch in the upper nodes. Fungicide applications for white mold prevention are most effective between R1 and R3. Current risk models show low white mold threats.

Cornfields are entering late vegetative stages, with tassels emerging in some areas. Select seed corn fields have begun detasseling. Tar spot, a concerning corn disease, was confirmed in Cass and Eaton counties on July 9.

While the current tar spot risk remains low, the best fungicide timing is between VT and R3-4 stages. As tasseling starts, watch for western bean cutworm moths by scouting for egg masses on the upper leaves.

Wheat is maturing, with most fields at Feekes 11.3 to 11.4 stages. Harvest began last week. Growers considering double-crop soybeans should refer to resources on planting after wheat, cover crop guides, and herbicide tolerance.

Potatoes are at risk of vine rot due to hot weather and dense canopies. Regular scouting for late blight, aphids, and Colorado potato beetles is advised. Aphids should be monitored by checking 20-25 plants in multiple field areas.

Water demand is increasing. Corn at tasseling uses about 0.20 inches of water daily. Soybeans in early reproductive stages require around 1.40 inches weekly.

Wheat, at maturity, needs less water, but soil moisture is key for second-crop planting. Farmers should watch for signs of water stress, such as leaf rolling in corn or leaf flipping in soybeans, and consider using irrigation tools to maintain optimal moisture.

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