homepage logo


By Staff | Jul 15, 2016

Our typically hottest month of the year continues and will it live up to its billing. Will it continue to be hot and dry, or switch to cool and wet, or some combination of the above?

We need rain as the silking and reproductive phase of the corn plant continues and the early grain period arrives. Cooler nights with bright sunny skies create the optimum conditions. Soybeans aren’t quite as picky with their longer flowering time.

I did have the chance over the weekend to see the Illinois crop from north to south and saw a very good one. They were short on moisture like we were, but have been blessed with widespread rains the last two weeks.

We walked a few fields and what as most noticeable was their corn plants were about two feet taller than normal, while ours are about two feet shorter than normal. Like us, timely rain through July and August will be needed.

Crop ratings

The high crop ratings given for the corn and bean crops according to most Iowa farmers seems too high. Is that because we know the warts and shortfalls? We saw the fields early and know the stands are far from perfect and that emergence in many fields was during a few weeks rather than within a few days. We also know getting out too early with the planters in early April happened, but seemed necessary.

Early planting the past few years seemed the right thing to do. This year it is common to see both corn and soybean fields planted after the late April cold spell and when the temps warmed a month later catch and even pass those planted earlier.

Only time and the final yields will determine which dates were the best for planting.

Nitrogen changes

This was maybe a watershed year in that a higher percentage of the growers were conscious of the need to be as prudent as possible with their N applications.

Losing a sizeable portion of the nitrogen they paid for was something they consciously hoped to avoid.

Two things made things easier. The first was that the nitrogen industry shifted slightly in that urea was priced the same as 82 percent and more retailers were geared up with higher clearance dry spreader equipment. Thus custom after-planting application was easier and quicker.

The second advance was that the Y drops have been well accepted among corn growers. Making applications to taller corn is much easier.

The other advance that needs to be mentioned is that kit that measures plant-available soil nitrogen. Those are now scattered among retailers, distributors and equipment dealers and available for use to help growers measure and then calculate the current crop needs for additional nitrogen.

Growers have to recognize that nitrogen in irrigation is tracked down to 30 inches and can be present in the nitrate, ammonium or organic matter as measured by the Kjeldahl test form. There is more recognition that soil nitrogen can be a living and biologically functioning phase.

Last year, with the much higher-than-normal rainfall totals we did see some cannibalization of proteins in the top part of the plants as they scavenged for any form of nitrogen.

It was responsible for some of the late-season yellowing of the top leaves, but not the major cause.

Disease comments

The issue, discussion of and the salesmanship of fungicides for diseases is more common than a dozen years ago. In the Midwest it began with the news and preparation for the possible invasion of Asian rust in South America and possibly North America.

Having personably seen tens of millions of acres of soybeans wiped out in the early years in Brazil those us who spent many days down there recognized that farmers needed to build their knowledge base.

In parts of Mato Grosso they will spray one bean crop up to 11 to 13 times or it dies.

Within the educational system it still needs to be stressed that plant diseases are a function of varietal susceptibility, environmental factors (names humidity and hours of leaf wetness) and nutritional deficiencies.

During the 2016 season so far there have been many fewer hours of dew and leaf wetness, thus the disease pressure should be much less than last year.

Just as over-use and repeated use of same action site herbicides has backed us into a corner and given us weeds that are increasingly resistant to products that used to kill them, the same thing will happen to fungicides.

Fungi are plants that lack chlorophyll and can’t form their own sugar. Fungicides are herbicides against those plants. In Brazil, Argentina and other South American soybean producing countries they are now using only three-way mixes in the hopes of lengthening the effectiveness of the carboximide family.

With no new families of fungicide families near commercialization what is now being sold has to be used longer. What is good to see is that the top pathology and mineral people in South American and in this country are collaborating to recognize and teach that mineral deficiencies in plants are often the main cause of disease susceptibility.


For the rest of July farmers and crop advisors will be busy looking at fields for early signs of insects in the major crops. Knowing the life cycles and IDs of the different major pests and being alert to the populations moving into the areas they cover will be important for the scouts to be effective in their work.

I think I mentioned last week that an Extension specialist found soybean aphids already near Kanawha. That isn’t too surprising, though they are usually spotted further north and west early. So bean growers need to be watching their fields and making counts.

There continues to be small lesions of gray leaf spot, northern corn leaf blight and anthracnose. Varietal ratings and tissue analysis levels give clues as to which varieties will be affected the most.

People doing the scouting should be carrying their scouting guides and know what the treatment thresholds are for each pest or disease. They also need the education and vision of the potential that each pest or disease can do and how fast they or it can multiply and spread.

So growers have now put in the efforts and expense to get their crops this far.

It take vigilance through July and August to help them realize their potential. Best of luck in that work.

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