Renewable Farming

Patches of premature soybean yellowing offer management clues

An Aug. 31 windshield cruise around northeast Iowa showed many yellowing areas in otherwise still-green soybean fields. 

Uniform yellowing and leaf drop indicates maturity, but the patchy areas can offer signals of nutrient deficiency, too much or too little moisture, or disease symptoms. 

A current and knowledgeable report on how to read the signals was recently posted by Michigan State University extension agronomist Bruce MacKellar.  Here’s the link.

We’ve seen crop observers’ comments that the upper 80-degree days forecast for the Midwest this week could “push” corn to early shutdown. That raises a question: Since we’ve observed many fields dying down in September the past several years, has this become something which appears normal? 

A late-season warm stretch, with abundant moisture, should be a gift from nature, helping add test weight. The goal at black-layer maturity is a green stalk, with an ear hanging down securely in a snug, white shuck. Not a dying stalk.