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CROP WATCH

By Staff | Sep 6, 2013

The last month of the growing season is here.

It is typically the time of the year where we drive past and walk into the great-looking fields to view the size of the ears or to count the number of pods to guesstimate how high the yields will be.

Then our thinking process starts to calculate the dollars that will be generated per acre and what debts can be paid or what new machine for our operation can be purchased.

Growers are apprehensive about what they will find when they actually nose their combines into each field. It was somewhat the same way last fall when extreme heat and drought affected the crop, but different because late August rains came in time to help grain fill. This year those rains still have not arrived in many areas.

We have all heard the different yield estimates that are circulating about the size of the crop, and most of us have our extreme doubts because most of the guessers have never set foot in the fields or because the expected normal grain fill period has been anything but normal.

We know the least ideal scenario for getting good grain fill would be to set the immature plants in a blast furnace, and that is what happened in the last two weeks.

Signs of that were visible from the roads finally as field after field turned a scorched brown.

Browned plants

By now we have all seen many fields that turned brown or white last week. In a portion of them the stalks were browned from the ground up to the tassel, with the ears hanging down like it was mid-October.

In another portion the plants had the tassels and a few top leaves turn yellowish to brownish, but the center part of the plant and husks were still green and alive.

In a smaller percentage the plants were staying a dark green color and didn’t seem to be hurt much by lack of moisture in the ground.

The plants in the last two categories have a chance of surprising us to the plus side.

If the fields were sandy underneath with low organic matter it was obvious they simply ran out of moisture.

Without sufficient moisture the high temps and excessive evapotranspiration exhausted the plants’ moisture supply. There are many fields with good cation exchange capacities where the plant’s top leaves began to turn yellow about a month ago. It was barely visible unless one was looking for it, and even then it was faint to even the trained observer.

That was the sign that the plant had a problem with one or more diseases in the pith tissue down in the root crown region.

Goss’s wilt was likely there from the start, and the tissue was brown even as a seedling. A number of growers and crop scouts were seeing it early and expected this to happen. In those fields if susceptible hybrids were planted, or if nutrient levels of minerals such as manganese, zinc, boron, copper and a few others were in the deficient category, the plants could not keep the disease from moving up the stalk and clogging the water conducting tissue.

With enough blockage the water and nutrient flows were squeezed or halted and the plants were starved for water and minerals. The minerals are also needed to form enzymes, run the plant at peak photosynthetic efficiency, and form sugars to power the plant and fill the kernels.

One of the organisms involved in the new Goss’s wilt serves as a type of plaque very similar to what clogs human blood vessels, causing a number of serious health issues when the blood flow is interrupted.

Remember that few leaf symptoms of the traditional Goss’s wilt ever showed up this year. So what has contributed to kill so many plants?

We are also seeing that heavy rates of hog manure have again been the kiss of death for a number of fields.

From the air you can spot the fields around a large hog CAFO from miles away. Actually around one small town north of Ames a recent immigrant from the Middle East could see a few weeks ago that the corn crop was dying. What can he see that so many people can’t?

Why this is all troubling is that the crop was planted in spurts with much of it being planted three to five weeks later than normal. It was slowed by cool weather in June and late July. Now the crop is dying early for the fifth time in the last five years when many of the ears are only in the milk to mid-dough stage.

Kernel depth is being greatly reduced and along with it final yields and nutritional content.

Currently, there are fields that have taken the heat surprisingly well. Good disease resistance along with good fertility and root development have to be credited. A rain or two at some time in July and August have also done wonders, but when you see an extreme of crop conditions side by side, you have to wonder what else has set the stage for such disparity.

It may be a good idea to get plant samples gathered for examination under a high-powered microscope later.

Soybean expectations

August is typically the time when the soybean pods are filled and the grain is made. With only the Sioux City, Mason City, and Dubuque areas being the locations receiving close to 3 inches of moisture along with a few rural areas in northern and northwestern Iowa receiving more than an inch in July the soybean crop is not heavily podded with plump seeds.

Though it was not publicized one producer who went on the eastern leg or the Pro-Farmer Tour remarked that his pod counts through those states were 50 to 70 percent below previous years.

With a number of bean fields beginning to yellow the chance of them suddenly filling the pods is very slim, especially with no rain in the seven-day forecast.

The reality of that situation influenced many growers along, and north of, U.S. Highway 20 who should have sprayed for aphids that appeared in heavy numbers over the last two to three weeks, but why spend more money on a below-insurance level crop?

That explosion in aphid numbers developed in the northern one-third of the state at seemingly impossible odds. Based on past experience and knowledge entomologists have gained, aphids were not supposed to hang around and multiply after sub 50-degree nights and above 90-degree days.

But their numbers did climb to treatable levels in certain areas on darker colored varieties that were in the mid-R4 to mid-R5 growth stage.

That is the development time frame when the leaves are supposed to provide the best nutrition to the sucking insects.

What is visible is that growers who put extra management into their soybean crop have bean plants that have developed a deep, heavily nodulated root system with lots of branches and pods.

Those plants’ chance of producing decent yields was increased, especially if rain ever falls.

New weed

Oh great. The presence of Palmer amaranth, the monster pigweed that typically possesses multiple resistances to our major herbicide families, was confirmed in western Iowa a few weeks ago.

Once it was documented in states to our west, south and east it was just a matter of time until birds, manure or machinery brought the seed in.

CRW testing work

This year we are conducting field trials of the Invite watermelon juice application as a means of rootworm beetle control.

With Penncap and all encapsulated insecticides being eliminated by Environmental Protection Agency actions we needed to find a compatible insecticide partner.

We are trying several and hope that a new product known for systemic activity, long field life, reduced risk rating and safety to beneficials shows the ability to kill beetles.

If this works then the ability for corn growing farmers to eliminate much of the rootworm beetle egg-laying to give traits, liquids or granules a chance to succeed will be maintained.

If plans continue as thought the Invite product will be fully available for use in 2014.

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

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