Scouting Your Fields: What Lessons Can We Yet Learn From 1997?

September 10, 1997 4(24):140

Joe Lauer, Corn Agronomist

We are rapidly approaching the close of the 1997 growing season. Below are some things to check in your fields yet this year, and to consider in your plans for 1998.

Scout for corn standability. Fields that have lodging problems can be identified and targeted for the earliest possible harvest. Look for visible symptoms and test stalk firmness by pinching the lower internodes with your thumb and forefinger. Healthy stalks are firm and can't be compressed. If a stalk can be compressed or feels soft, it is rotted and is a good candidate for lodging.

Check the maturity of hybrids in your fields and relate back to planting and emergence dates. Following the rate of drydown using kernel milkline is a good way to predict the order fields should be harvested. In a typical year a common benchmark is that fields should be dented by the first week in September. It takes about 25 days to go from dent to black layer (physiological maturity); about 13 days to get to 50% kernel milk and another 12 days to black layer. Kernel moisture at black layer will average 32 to 35 percent. The tightness of the husk, thickness of the seed coat and daily weather conditions influence the speed of kernel drydown. After black layer formation several hard frosts followed by sunny weather with temperatures in the 80's and a slight breeze is the ideal drying environment.

Check for ear-tip fill. Incomplete ear-tip fill is not necessarily bad. If kernels are filled out completely to the ear tip, plant populations are likely too low for the environmental conditions of 1997. Expect about an inch of underdeveloped kernels at the ear tip when plant populations are at the proper level for optimizing grain yield.

Scout for pest problems. Hybrid differences for pest resistance and tolerance should be monitored and noted all season, but will be most apparent in the fall.

Resist eyeballing yield differences between corn hybrids - measure it. Make notes bout "ease of combining." Test weight and grain moisture can influence hybrid yield. There are "quickie" measures of potential grain yield, but you shouldn't expect much precision with these measures.


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