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CROP WATCH

Scout fields for stalk quality and soybean disease

September 8, 2017
By BOB STREIT , Farm News

September has arrived and in a few weeks the fall harvest season will begin. A very safe bet is that there will be a lot few loads of grain coming out of each field in the southwest three fourth of the state. This is in spite of the seemingly official claims that we did not have a drought this season. We shall see which parties were correct in their assessment of the season.

The national news of the week centered on the devastation from Hurricane Harvey. From now on having four or five inches of rain in a week or two will seem trivial versus their 50+ inches that fell. Water always runs downhill, but when the rivers are full, it has to go somewhere. We had our most similar experience back in 1993 when parts of the state recorded nearly 60 inches total in the month of June, July and August. Getting around the state for travel or seeing fields often averaging in single digits was something that we never wish to see again. I guess the take home message is the no matter when you live Nature is always has some disaster then can send in your direction. Tornadoes, earthquakes, mudslides, blizzards, hurricanes, wildfires and floods have always been with us. Where we build can tempt nature and make other question peoples' decision. Pick your poison.

From the roads

Over the past week and especially over the weekend I had lots of messages and texts from growers and lay people who noticed the now rapid decline in the appearance of both major crops. This is something that astute growers and ones who have been around enough to not believe everyone who says it is normal for the crops to die or turn brown before Labor Day or when the first freeze hits. It is not something that is bred into the corn or a new gene to hasten drydown.

A little story to illustrate the happening was told to me by a noted plant path professor. He had a colleague at a Midwestern University who had a pet project developing new sweet corn varieties. His goal was to develop earlier and earlier varieties. After 15 to 20 years of work he did a full assessment of his progress and pronounced all he had done was select for the most Fusarium susceptible varieties.

A few columns ago I mentioned ten different qualifiers that have to be examined for each field that range from looking green yet with nice sized ears and intact lofty yield goals, down to fields that began to go downhill around mid-July when they took on a yellowish hue and are likely brown with the ears flipped down already and grain fill is over with. Last year 90 percent of the corn died on September 6th, which was the first Tuesday in the month. It was a day that hit 90 plus degrees with a strong south wind and low humidity. In 2014 a high percentage of the fields died the weekend before the start of the Farm Progress Show. Again weather conditions that created high moisture and nutrient demands in the upper part of the plant exceeded the ability of the plants' vascular system to meet those demands. So they died. Therefore the 11th qualifier that should be examined would be to gauge the degree of vascular plugging occurring in each field and with each variety or genetic family. It is very apparent that there are vast differences between genetics this year and in the last nine years. There are also vast differences between fields with good soil health and good microbial activity versus those which would have low Haney scores. All the articles about soil health and cover crops will hit home for many growers as they run the combines and watch the yield monitors during the next two months.

Many spots in Iowa received rain about two weeks ago. Some got 5-plus inches. Others got 1.0 1.5-inches. The crops used the latter amounts up in about a week and are under moisture stress again.

Microbial packages

One side that is having a tougher time controlling weeds in soybean fields me believe that more second year corn will be the case next year. Then those who see a big yield difference between their corn following beans versus second year corn will believe the opposite.

What would make second year corn easier to manage would be a good microbial pack that would speed the decomposition of corn stalks into soil building humus, which releases minerals to the new corn plants and serves as a sponge to hold moisture for crop used during the drier summer months. From what I am hearing there are many new biological products with merit that will be showing up sooner rather than later.

SDS

So far SDS has not appeared in fields in severity like it did in 2010, 2014 and 2016. Conditions were too dry and oxygen levels in the fields were high. The same applies to more other fungal diseases as long dew hours create the conditions conducive to pathogen invasion.

There are areas where white mold has begun to appear at levels great enough to cause yield losses. It is late for its initial appearance but with the beans running about two weeks behind in development it does not surprise people. Doing anything to combat it is basically impossible since the invasion took place weeks ago.

So if the beans are running two weeks behind in development, why have so many fields turned yellow already? At first the yellowing spots were those where moisture stress would have been worse. Now whole fields have turned color. The last two weeks in July and first ten days in September was supposed to be when the beans would take advantage of late August rains and fill the pods more. That won't happen this year.

Scouting

If you have fields that are giving up the ghost already it will be beneficial to begin visiting those fields and rating them for stalk quality. If the stalks fail the pinch tests done in mid September early harvest may be recommended.

Field days

Over the next two weeks there are likely to be local field days where you can visit local plots and start learning about hybrid performance in your area. Whether conditions in 2018 are anything like those experienced this year we don't know yet. But building a data base using your own judgment will be beneficial.

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

 
 

 

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