In this week’s Boots In The Field Report Ken Ferrie covers reasons for seeing so much top die back in the corn.
1. Disease issues like anthracnose top kill will be on sporadic plants in the field, show black spores on outside of stalk on full dead plants, and behind the leaf sheaths on top killed plants. Can be hybrid and stress related.
2. Insect issues like corn borer. Will have dead tops, maybe even broken over from wind and with tunneling into nodes.
3. Heat Stress. More consistent across all plants in field not just sporadically. Doesn’t show the black spores or discoloration in the stalk like the disease top kill has. More prevalent in short corn or fields that struggled to close the row.

The early planted corn that had tassels out when the June 29th storm was already done growing, but the corn planted after May 10th was still 3-5 leaves from tasseling allowing it to utilize the rain and add height to the plant to capture more sunlight. Ken is finding the narrow rows and more pendulum hybrids are showing less damage due to the heat. Ken advises growers to start doing push test in the fields with disease and insect top kill in about 10 days to stay on top of how the crop is deteriorating.

Ken also covers how to do yield estimates in fields with variable ears and to be on the lookout for the movement to the greener corn or to soybeans from late season rootworm beetles as some of the fields start to die early.