One of the largest and least visible sources of nitrogen (N) for Iowa corn is the soil itself. Through N mineralization, soil microbes convert organic N into plant-available forms every day. In many fields, this natural process supplies well over 100 lb N/acre during the growing season. 

Corn fields around the state, if not tasseling currently, will be soon. Soybeans are mostly in the R2 to R3 stages. Overall, disease pressure remains low with reports of gray leaf spot and bacterial leaf streak being found in corn and bacterial blight, septoria brown spot and phytophthora being found in soybeans. Insects reported include Japanese beetles, grasshoppers, and corn rootworm beetles.

The hot and humid conditions last week really pushed the crops along. The week also brought heavy rainfall to parts of the state – including areas in central Iowa getting 12+ inches over a 3-day period. Corn fields are starting to tassel, and soybeans are fully in the reproductive stages now. Bacterial leaf streak, Goss’s wilt, weed escapes, Japanese beetles, and adult corn rootworm beetles emerging are some of the issues observed by ISU extension field agronomists this past week.