CENTRAL ILLINOIS (WCIA) — With the return of hot temperatures this week and without rainfall expectations, the corn crop in east-central Illinois is going to deteriorate.

Hot temperatures are talking a toll on your corn fields says crop physiologist Fred Below at the University of Illinois

“It is awful hot for this time in June, and corn can be heat stressed,” said Fred Below, crop physiologist at the University of Illinois. “The problem is that along with heat stress is usually drought stress. Those things usually go hand in hand. The corn plant can cool itself in the daytime as long as it has enough moisture. When that moisture gets limited, now that crop starts to heat up. That’s what we’re seeing here in Central Illinois.

So it needs moisture as a coolant. That’s a new one on me.

“It is. That corn plant transpires water, and for every gram of water it transpires, it takes 540 calories of heat out of the leaf,” Below responded. “It’s the same way we cool ourselves. It can cool itself in the daytime if it has enough water. But if it doesn’t have enough water, that is when the heat stress occurs.”

What happens to that corn plant when that happens?

“Everybody knows the corn plant likes heat. 86 would be the optimum temperature,” Below said. “Anything over 86, that plant is stressed and respiration goes up. That means it’s burning up energy in respiration instead of using that for growth and yield. It grows slower. When you see the corn plant rolled, it’s sort of taking the day off and not growing much.

So at this point, we’re not putting on kernels, but we’re really shutting down the opportunity to close the canopy so we can capture more sunlight.

“We are. You know the longest day of the year is right around the corner here. We’d surly like to have leaves over the ground canopy by the 21st of June,” Below responded. “When the crop rolls, that’s a defense mechanism to conserve water. It’s not photosynthesizing; it’s just sort of treading water. So it’s waiting for later, if you will. It’s a good survival tactic, but it’s not a very good practice for increasing light interception and yield.”

Mark you calendar for the Crop Physiology field day on August 4 at the Crop Science Research Center on South First Street