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CROP WATCH

By Staff | Aug 26, 2011

D Day is approaching for the crops and farmers in many parts of Iowa. For the first part of the season we were staring skywards wondering when the rains would quit.

During the second half we’ve been looking skyward, hoping for clouds to move in and drop the same rains.

Getting the amount of grain fill is important for the corn. Even more important is receiving 2 to 3 inches of rain to continue filling the soybean pods.

The cropping advisors who have toured extensively are expressing serious worry about the size of the corn and bean crops.

High-priced grain is nice if you are solely looking at a one-year assessment of cash flow, but all of the expenses will catch up. That’s when we see just how important livestock and ethanol production are to Iowa’s economy.

Corn prices at current levels or even higher are needed to match input cost price increases, but they are not sustainable to most livestock producers.

Crop tour

It is time now for the crop scouting tours such as the one by Pro Farmer, where they walk randomly selected fields and make their calculated guesses as to the size of the two major crops in each of the major states.

Anyone who has been in the fields much in the past two months and has ventured beyond the outside six row knows that most of the USDA forecasts are too high in most areas. The projected bushels produced are likely to end up at lower levels than projected last March, last July and last week.

For instance, the Indiana crop is now forecast by Pro Farmer as being 24 bushels per acre less than last year. Down in Southeast Iowa a large farmer’s crop scout shrunk his farm estimate by 40 to 50 bpa in the past two weeks.

All of those forecasters do a good job of understanding weather and plant population. They do not understand how these new diseases such as Goss’ wilt or SDS affects yield and can shut down dry matter accumulation.

The best commodity forecasters are beginning to get a handle on those factors as they become introspective and review how they could be fooled so badly for the second or third year in a row.

There are reports now from southeast Iowa of some early planted fields producing under 75 bpa.

Those fields went through July and August without rain, so that was a factor. There were neighboring fields that will produce much better because those operators recognized that the challenges with plant diseases and micro-nutrients and overall fertility have changed, and they have changed their management to adjust.

My tour

I took a little crop tour in early July that took me clear west to Denver and see the crops through western Iowa and all of Nebraska. What I saw was a crop that was being limited by too much rain and possibly lost nitrogen.

It still looked very good and it appeared that with their irrigation capacity they may produce a higher yield than in Iowa.

I arrived back home on Tuesday after making a 1,300-mile trip from Ames to near Detroit to take daughter No. 3 to grad school.

The corn looked very spotty through eastern Iowa and northern Illinois. Lots of fields were exhibiting major problems with plant diseases and drought. It was easy to see that many fields were either all yellow, or yellow on top from anthracnose and browning from the bottom from fusarium, or were all brown from the Goss’ wilt disease chimera.

My return journey took the I-80 route and what I saw was not good. Through central Illinois all the way to Des Moines about two-thirds of the fields had a pukey yellow color, rather than a robust, dark green color as is considered normal and healthy.

In southern Illinois there are corn fields where the plants have all turned brown, with flipped down ears, and the kernels have only gotten a few days into forming the milk line. One of the debates is whether the plants will stand long enough to be able to harvest it.

Plant health

The final decline on the corn plant health seemed to have started about seven to 10 days ago. Affected plants turned yellow or brown in a matter of three to five days.

Whether the change was due to Goss’ wilt, top leaf anthracnose, fusarium moving into the roots and up the stalk, or general plant collapse due to drought and accompanying nutrient deficiencies can be debated, but the end result will be the same.

The trend to seeing Goss’-tolerant varieties that were sprayed once or twice with micronutrients looking much better and staying healthy is continuing.

It will be important to scout each of your fields and varieties to gauge stalk quality.

Farmers and crop scouts who have worked with Goss’ for years related that stalk rots in those fields can be severe with all root tissue rotting quickly.

Corn aphids

It is not possible to see high populations of the green corn leaf aphids in the corn fields. Though it is late August and most growers don’t want to make any more crop treatments and they are tired of spending money, it might be wise to be wary of this insect.

They suck sap from the plant that should be devoted to filling the kernels. During dry seasons the plants have no excess sap to give and these insects can cause yield loss.

There are hybrid differences, but no company or university has done any work to document which hybrids or genetic families are most infected.

What we saw 20 years ago in the Denison area and two to three years ago were some 20 to 30 bpa yield benefits to treating.

In order to minimize costs, I would consider stripping a chlorpyrifos product using aerial or high clearance.

Bean aphids, weeds

It is too early to forget about scouting for soybean aphids.

Again, with drier conditions and a high percent of the bean seeds left to fill, letting the insects consume the valuable plant sap is going to be damaging to yields.

Spraying this late seems obscene, but if the numbers are even getting close to 250 per plant, or perhaps less than normaleconomic threshold, it will be beneficial to spray.

Just as predicted, many bean fields have gotten quite dirty in appearance as the surviving waterhemp have grown taller.

That suggests that most growers will be making changes or adaptations to their weed control programs.

What worked in the past may not work for the future. So pay attention to new products that could be appearing for next season.

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

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