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CROP WATCH

By Staff | Sep 11, 2009

The second week of September is upon us and it looks like an early frost is representing less of a threat that we earlier thought it would.

Just getting two more weeks without frost will allow most crops to reach maturity. Some of the proposed reasons for that are good and some are not so good. Conditions continue to vary around the state.

Early in the season planting date and soil types created most of the difference. Now moisture during August and disease causing conditions are the primary source of the disparities.

If you were to travel to these different parts and walk the fields you could see the crops in each and view for yourself what warts crop scouts have been seeing for weeks or months.

Harvest is creeping closer all the time. Most operators started the process of preparing their combines for this year’s season anytime from last winter to last month. It typically takes a few more days and parts than expected.

Most of the time, surprises with machinery are not good. Thus one good thing about last year’s increase in grain prices is that it allowed many farmers to update their harvest and grain handling equipment.

Last week’s crop news

In last week’s Farm News issue there was a front page story summarizing what various agronomists are expecting in this fall’s harvest.

It is difficult to sum up the entire state with one broad stroke of the brush. Thus it is tough for a person who has seen many of the warts during a very tough cropping season to be extremely optimistic about the corn and bean yields in every section of the state.

We can accurately state that corn will yield between 0 and 250 bushels per acres and soybeans between 0 and maybe over 100. The low ends of the range will come from one of the many hailed fields that have gotten zeroed out by Mother Nature and a hail adjustor.

The best crops otherwise will be coming from the southwest and northwest ninths of the state. Getting the crops planted on time, loosing a minimal amount of nitrogen, obtaining great plant stands and receiving adequate rainfall like they did is vital for good yields.

In the other ninths those conditions were not as common for the rest of the season.

As I mentioned earlier if you walk enough fields you see the deficiencies in them. Thus one begins to count the lost bushels that once existed in potential but now won’t reach the bin.

In the 1980s and 1990s top end yields were in the 180 bushels per acre range, thus 50 lost bushels dropped you to 130 Bu/A. In 2009 50 Bu lost from the 250 to 260 Bu/A top-end might still leave 200 to 210 Bu/A on better soils.

There will be fields that will produce disappointing yields that will be below the USDA expected 180 Bu/A and below where any profit margins exist.

Corn diseases

The number of Iowa corn acres receiving a foliar applied fungicide this summer was likely a record. There were a number of reasons. The crop was worth more, growers were better educated about which varieties were more susceptible, crop advisors were more keyed to making recommendations concerning fungicide applications, and more advertising was done concerning certain products.

This was the year to have more acres sprayed since it was a wet season with lots of inoculum remaining in the residue left from the 2008 crop. It was also easier to commit to spraying acres when other neighbors were doing the same.

Eyespot was the most obvious leaf disease during July and it was easy to spot. Next were the fairly obvious grey leaf spots that started small but grew in size. What were tougher to see at that time were the numerous small anthracnose lesions on the upper half of the plants.

Those and the root fusarium infections were major pathogens that invaded susceptible plants and played a role in many of the corn fields having turned yellow and brown over the past three weeks when they should have remained dark green and still filling.

A decade ago the plants stayed green until the kernels reached black. Then the husks browned, opened up, and drydown of the grain began. I checked the ISU publication entitled ‘How a Corn Plant Develops’ this week to make sure the R5, R6, and R7 stages matched what I had learned in college.

For the third year in a row a high percentage of the fields held plants yellowed up earlier than normal, even with the growing degree unit accumulation being about 300+ GDUs behind normal and weeks before the black layer stage was due.

What major thing has changed from today versus 10 years ago? Might corn yellow up in July next year right after blister? Fungicides are nice band-aids, but they don’t cure a gaping wound.

In 2008 the early disease onset led to a major stalk problem ending in flat corn in October. We don’t want that to happen again. If it does, what then?

It is interesting to see how satellite and aerial near and far infrared graphs picked up these color changes and infections sequences.

Now over the next week it will be good to wander into those fields to squeeze the stalks and twist the ears. The first will give us an early indicator of stalk quality problems. The latter will give an indication as to how complete or incomplete kernel and ear fill were before dry matter accumulation ended.

In a few weeks we will get to see how different treatments affected yields and what will be profitable to recommend next season.

Soybean yields, pod fill

It is still difficult to look at soybean plants, make counts, and accurately guess soybean yields. Thus far yields from the Delta states have been very good.

In Iowa most growers are seeing much lower pod and node counts. Most node counts are 25 to 30 percent below normal. Thus seed size will be an important component in determining yields.

One method that has commonly been used has been to count all of the two- and three-bean pods on a plant and assume that equals the bushels per acre. Another is to count nodes and then factor in any pods showing more than 3.5 pods per node.

Early season growth for most beans was extremely slow and most plants were two to three weeks behind in development, which led to delayed flowering.

Cold nighttime temps arrived during the normal flowering period and it looks like about one fourth of the normal flowering time was lost. Except for north central Iowa August rainfall was good and should have helped puff the seeds up in size.

In a May article I had mentioned that the best response to the cool season was going to be foliar phosphate and sugar applications. Beans that were foliar fed using the right products, such as Seed Set after more branches had been formed, at the proper timings look excellent.

SDS infections have been as bad this year as many have ever seen. Wet, rutted field traffic last fall coupled with saturated soils this season to create the perfect world to this root infecting fungus.

Thus the singed leaves first appeared on the headlands, along any compacted strips and spots where water sat and soils were compacted.

There are a few operators with fields and management programs where there is no SDS. We need to toss out the rules for managing the disease beyond thinking varietal variance is the answer.

Final aphid evaluation

Aphids played a big part in 2009 cropping programs with most growers having to spray once and a smaller percentage making a second stripped application.

Does their appearance in 2009, a supposed non-aphid year, signal that they will be with us every year, as has been suggested?

And how did the Rag 1 or Rag-bred resistant varieties fare in commercial fields? I did have one grower in the center of the aphid storm who had a quarter section field where there was no aphid population buildup and it required no treatment.

There was one product used that may have prevented the buildup of N03-N and simple sugars they were seeking. More on that issue later.

Enjoy attending the Clay County Fair.

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