Renewable Farming

Sept. 15 crop update from consultant Bob Streit

Over the next few weeks, corn harvest will begin in earnest across much of Iowa and surrounding states. Progress will be patchy due to a wide range in planting dates and rainfall events that halted planting and affected crop development.

Already, growers are visiting with friends and acquaintances who have made the early plunges with their combines in their early fields, and results seem to be a mixed bag. It would be a safe bet to expect that trend to develop. While the crop forecasters and crop survey participants make the counts and field observations, they always make the assumptions that the season from that point on will be normal.

Instead we have seen this quick-dying corn crop turn brown more than a month early. An interesting observation as published in the NASS figures: They had the corn crop in Iowa 10% mature as of Sept 6th and 26% mature by Sept 13. Those figures sure make it sound like the percentage of the corn crop dead by those dates exceeded the percentage that was mature.

What most people south of Highway 20 saw was likely about double the number of fields that were dead; those would have been rated as “mature.” Dead plants don’t accumulate much dry matter — never did, never will.

Field Observations

This would be a good time to enter any of those early dying fields and do the quick push test where you push the plants at chest height to a position that is roughly 29% from vertical. If the stalk collapses and does not spring back, the plants are going to be very prone to stalk lodging prior to harvest. It may be best to try to get to such fields earlier than planned to avoid have plants that have toppled over and could be difficult to get the snouts under.

I was checking a few fields on Monday planted to varieties that had disease problems not addressed either by micronutrient applications or by any curative treatment, and it was common to see 25% to 80% of the plant stalks were already soft. The milk lines in kernels were close to being completely down, but no true black layer had formed.

Years ago, stalk rot was simply considered the result of attack by a certain pathogen. Then Dr Jim Dodd of Cargill Seeds trumpeted his creed that any interruption in sugars by the plant weakened the plant and made it susceptible to fungal attack. A stalk suffering from attack is prone to cannibalizing itself. It turns out he was correct in forming that theory and proposing it in the court of public opinion. This year there were many stresses that cheated the plants from nutrients they needed, or caused several excesses that could be deemed a stress.

Making Plans for 2016

Since harvest is soon going to be here it is time to be making plans with your local agronomist or fertilizer dealer to have soil samples pulled so you could stay on your normal rotation. Changes that you might make would be to request that 25% to 30% of your samples be analyzed for micronutrients.

Then consider having a few select fields that you have had or will be farming for a long time and think about getting a soil biological or the Haney test run on them. Since more top people feel that the better performing crops will be produced on the higher scoring fields, getting your favorite fields tested in this manner would let you establish a base to compare to as and when you add new management tools or products to your program.

It might be a new biological, it could be moving to strip till, and it could be changing your nitrogen program or adding cover crops to the mix. A wise person says that you can only change what you can measure.

So far in the fields I have seen the Haney test results from are generating readings from 2.0 to 23.6 on the 1 – 50 scale. Unfortunately most of the fields are giving results closer to 1 than to 10 and even 5. In other words it is likely to cause wholesale examination of many of the fertilizers and some of the pesticides currently being used. If more people get on cultural programs where they can achieve higher scores we would like see none of those flash droughts. Building a deeper root profile and having higher organic matter to serve as a bigger sponge would help prevent such a problem.

Compaction Detection

A common problem after wet springs and falls is soil compaction. That has been a problem the last few years in much of the state except for NW Iowa. It would also be a good time to get a good person with a compaction probe to test sections of your fields to see if an inline deep ripping or some sort of strip till pass could alleviate the problem.

Weed Slip-Ups

Now that more soybean fields are at or near the leaf dropping stage, the many waterhemp, marestail or giant ragweed plants remaining dark green are sure noticeable. Because weed researchers have found that a large waterhemp plant can easily produce up to and in excess of one million seeds it is sure easy to see how fast a weed problem can get out of control.

When those one million seeds from a single plant, or multiply that by hundreds or thousands, there are huge contributions to the weed seed bank. What has also become very noticeable is how many pastures and patches of thistles (Musk, Bull or Canadian) and marestail were green and healthy thru the entire season. Years ago more people seemed willing to mow, chop or spray those patches.

The county weed crews seemed to be out spraying those patches oftener and earlier. Now as those plants flower and begin to produce their windblown seed, we can expect the problems seem likely to spread and multiply. It sure looks like the good neighbor policy on this issue needs to be applied again.

A New Disease

And somewhere, some fungicide company has invented a ‘new disease.’ Actually they think that Tar Spot for some reason moved into and was discovered in Indiana this summer. Interestingly enough it can be caused by two different organisms (how does that work?) with the version found here not being of the damaging type. That is bound to change once it gets adapted to our rotations and climate. There are pictures and stories about it on the Purdue website. 


In the past two or three weeks, as many fields of corn have died early, the predators such as ladybugs that depend on aphids and soft bodied insects for their diet are having to move to other plant as a food source. The same should happen with the small assassin bugs which can be a nuisance on fall afternoons. We are seeing the same thing with CRW adults which are flocking to any green plants, especially those which might still be producing pollen.

By Bob Streit, Boone, Iowa 50036  515-709-0143

Published Sept. 15, 2015