Corn maturing too early, may reduce yields

This summer?s oppressive heat has caused local corn to mature almost a month sooner than normal. Iowa State University Crop Specialist Jim Fawcett said the corn in southeast Iowa is showing signs of ?denting,? which refers to the divot left in the kernels at the end of the ear.

?You see divots in the kernels that are exposed because the heat is causing it to dry and shrink,? Fawcett said. ?We?re experiencing warmer than usual temperatures, and that is causing the corn to advance rapidly.?

Fawcett said corn normally matures in September and occasionally in early October. He said this year?s crop might mature by late August.

Last year?s hot summer reduced corn yields for area farmers. Fawcett is afraid the same thing will happen this fall.

?I think we?ll have lower than normal yields,? he said. ?They will definitely be lower than their potential a few weeks ago.?

Fawcett said Iowa?s temperatures have been well above what corn plants want and need to produce their grain.

?We would like to see temperatures below 70 at night,? he said. ?Corn needs cooler nights. Corn likes 80s in the day and 60s at night. If we have 90s in the day and 70s at night, that is not good.?

Hot nights force corn plants to deplete the energy they stored to grow grain.

?If it?s hot at night, the corn is just trying to stay alive,? Fawcett said. ?The corn is eating its own reserves to stay alive rather than saving them for the grain. The hotter it is, the more it takes to keep the plant going.?

Fawcett said July is the key month for corn. He said that, ordinarily, there are things farmers can do in early August to improve their yields. The only trouble is that, this year, the corn plants feel as if they?ve reached late August.

?It?s not too late to prevent further losses, but we?re not going to get back what we?ve lost,? he said. ?I know planes are still spraying. Some fields may benefit from fungicide application, but we?re getting towards the end of that because of the stage of the corn?s development. The weather is still the most important part.?

Considering the hot days and hot nights corn has suffered through, Fawcett said it?s a wonder the crops are not in worse shape.

?It?s surprising how good things still look,? Fawcett said. ?Today?s hybrids can take the stress a lot better.?

Fawcett said some areas of the state have received little rainfall this year, and that, too, will likely hurt yields. At the same time, he said that even in those areas where there has been plenty of moisture, the heat has reduced the number of days for the plant to grow its grain.

Iowa farmers saw a great yield two years ago, when the temperatures were normal. The only downside that year was that it rained so much in the fall that farmers had to spend money drying their crops.

?This year, there shouldn?t be much artificial drying,? Fawcett said.