(Radio Iowa) – Iowa State University Extension crop specialist, Joel DeJong, says northwest Iowa crops are showing signs of stress from the dry conditions. He says they need around 25 inches of moisture during the crop development stage. “We still need to have about 12 to 15 inches of rainfall during this season. You know, if we have slightly about average we’re probably going to reach that — otherwise, we are going to put some stress on our yield potential through the year,” DeJong says.

DeJong says stress is already showing up in the corn leaves.”If you take a look at the cornfields recently, you’ll see that almost every day we have a lot of cornfields rolling,” according to DeJong. “And it is an indicator that the root systems of those corn plants — even if there is water in that soil — the root systems right now aren’t deep enough to keep up with daily demand with low humidity and high temperature.” He says the rolling has been evident the last week in the afternoons and some mornings during the mid-90 degree days. DeJong says the humidity that we try to avoid is a good thing out in the field.

“It’s kind of unique to have 20 to 25 percent humidity and 90-some degree temperatures. That makes it seem a little more cooler for humans — but that is the opposite of what we want to see for a crop,” Dejong explains. “We want to see high humidity to go with those temperatures if they are going to be that high, because high humidity means less water demand in those plants.” The crops specialist says if the issue continues, farmers may see a drastic yield loss. The corn ear now is starting to fill in rows. “All this stress is probably reducing some of the rows we are going to have in some of those ears — might only be a few rows less, maybe it’s a few more. We still have the potential to continue to form the length of that ear all the way to the length of that corn. We’re still in that process,” he says.

DeJong says the next thirty days will be critical to the corn development as the corn begins to pollinate. He says soybeans are also showing some signs of stress, but soybeans have a way to delay the need for moisture until later in the year.