homepage logo


By Staff | Jul 15, 2011

This is one year where it seems we need to be very careful about what we wish fo, because:

  • Hoping for a bit of rain brings us a deluge.
  • Hoping for warm weather brings us two weeks of extreme heat.

Someone on Sunday must have hoped for a slight breeze. And so this wacky weather continues.

Even though the USDA agencies are continually predicting huge corn and bean crops, those in the field see lots of different challenges and are trying to avoid counting their chickens and bushels too early.

That currently seems to be the correct strategy.

The big windstorm

We wondered when a portion of the state was going to get slammed in some sort of storm that was as destructive as one of those seen in recent years.

That answer came early on Monday morning when 100 mph winds moved from across central and east central Iowa, clear across Illinois and Michigan. Now all of the affected growers and businesses get to pick up the pieces and see what is recoverable.

I have to get over into the Marshalltown area yet today to see how the crops fared. Early reports have told of corn that was flattened to some degree. A large question connected to the issue is what can be expected with the corn from this point on.

Back a few years ago we saw major windstorms near Carroll and Marshalltown. In the first case, which was in 1987, the rest of the summer was hot with some moisture stress and not too much wind.

Those tipped planst cooked and yields were decreased significantly.

In the second case corn fields were flattened near Marshalltown and the weather in the months after the storm was cooler with slow rains and gentle breezes on many days.

That fall, harvest was slow in those downed fields, but yields were very good yet.

In the past week I have been in fields in other parts of the state where greensnap has occurred and spots exist where up to and over half the stalks have snapped.

Yields are likely to be negatively affected.

Many of us have seen the news clips about the big windstorm that occurred near Phoenix two weeks ago. I can’t remember the name of that downburst event. The one that hit us was called a “derecho.”

A few of us were calculating the potential market impact. The path, according to farmers who have toured the area, tell that it was 20 to 25 miles wide and stretched for 500 miles.

That encompasses 10,000 square miles. Assuming 600 crop acres per mile and the rotation being 55 percent corn acres, that could that 3.3 million corn acres could have some degree of crop loss.

In a year when both acres and yields are expected to be down, it will affect supply and price.

Temperature extremes

How will we have the next two weeks play out weather-wise? Will we cool temps like on Tuesday or will it be 90-plus degrees? If so, what will the effect be on the corn and bean crops if the projected 12-day long hot spell hits?

Typically, the corn does OK if it has plenty of moisture available and the roots can access it. A good way to tell if the plants are stressed is to walk into a field and feel the leaves.

If they still feel cool on a hot day, they have enough moisture. If they feel quite warm, moisture is short and they no longer have the moisture supply needed to transpire and cool itself.

Questions arise as to the potential damage to the corn crop that has to tolerate hot temps during pollination. What happens when it gets hot and dry is that viable pollen is not shed for as many hours each day.

That is not a major problem unless the plant cannot recharge its cells with water during the nighttime hours.

With older hybrids in previous droughts much of the problems occurred because viable pollen shed hours were reduced at the same time that silk emergence was delayed.

Soybeans are more meant for dry conditions. Moisture stress can cause flower and small pod abortion which can subtract from yield; but because the plants flower for about six weeks they have more ability to compensate for weather extremes.


As to newly developed insect information growers need to be alert to the continued presence and feeding of Japanese beetles that eat on corn tassels and silks as well as soybean leaves.

If enough leaves are consumed they need to be controlled with labeled products.

Aphids are now being found in Iowa. Near Fort Dodge, they have been found near timbered areas. I was finding them in Plymouth and Cherokee counties this week.

It was the big sows and their offspring that I was finding. Their presence shows that the winged ones have blown in already and dropped their offspring.

Weed control

It is also the time when growers have gotten the opportunity to see what weed control program or products has worked or which ones failed.

A general thought lately has been that the waterhemp plants have become very difficult to control.

One big supplier that I visited with said about 70 percent of his customers were relating that they were having a very difficult time trying to control those plants, and they were about out of options on how to proceed.

Some have hoeing teams lined up to go into the smaller fields to physically remove them.

That sounds a lot like the Delta State stores about the difficulties controlling waterhemp that those famers faced in 2010.

Good luck with any final field work and stay cool.

Bob Streit is an independent crop consultant and columnist for Farm News. He can be reached at (515) 709-0143.

Please Enter Your Facebook App ID. Required for FB Comments. Click here for FB Comments Settings page