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CROP WATCH

By Staff | Jun 3, 2010

The second full week of summer-like weather is upon us and the crops seem to be capitalizing on it.

Much of the corn crop is shooting up in height and putting on lots of top growth.

The accompanying bean crop is also developing nicely with more and more fields now emerged and progressing through its early growth stages.

Just like the planting season seemed to arrive in spurts, the heat unit accumulation and growth seems to be doing the same.

In the past two weeks several meteorologists relayed the information that our friendly El Nino has now done an about face and turned into La Nina.

This switch is typically followed in two months by warmer and drier weather. Will that occur here or will conditions not follow any trend and do something no chart calls for?

In South America that switch arrive in early May as it turned into a winter which has been very warm and completely dry.

Their weather changed from one of the wettest ever to one of their driest summers ever.

Most corn planted after May 1 is now expected to be extremely low yielding.

What makes these developments confusing as that credible weather predictors still say that conditions could still suddenly switch back to cooler-than-normal.

Given the fact that we have already seen a 70+ growing degree unit advantage disappear in two short weeks, anything seems possible.

Crop observations

There seem to be many differing opinions as to how the corn and bean crops look across the Midwest.

In much of northwest and southwest Iowa the crops look about as good as they did a year ago, when things turned out excellent.

In central Iowa growers began planting early and that seems to be an advantage as the 14- to 17-day warm spell gave the early planted corn a chance to germinate, sprout and develop ahead of the normal pace.

Most of the corn in this area is looking good with an occasional wart.

The eastern part of the state seems to be having problems related to saturated soils and a slower pace of field activity.

The impact is still an unknown as quite a few stands are being reduced by Fusarium infections and other root rots.

I had to make a quick trip to St Louis this weekend and got a chance to see the corn along The Avenue of the Saints from Ames to Cedar Falls and south.

Due to the southeast portion of Iowa and northeast part of Missouri receiving 300 to 400 percent of normal rainfall in the last month, much of the corn crop in Missouri was a brilliant yellow color.

Much of the corn crop that was not drowned out is going to need to be supplemented with nitrogen to have a chance to yield up to expectations.

Along my route it was common for many of the fields to have 60 percent or more of their acreage to have already been lost to standing water.

Root rots

Growers and other crop people continue to look at cornfields that are experiencing growth problems.

That ranges from corn seedlings that succumbed to bacterial soft rots after the freeze to small plants that are still dying down or have already turned brown due to fungal or bacterial diseases.

Typically the corn seed attached to the seedling supplies nutrition to the seedling for about four weeks, which is typically long enough for the seedling to emerge and open the whorl.

This year those four weeks was not enough and led to frosted seedlings unable to have a source of nutrition to recover and grow.

Crop scouts working in the eastern portion of Iowa, especially the southeast, are continuing to see stands get thinner due to Fusarium root rots.

That disease was a major fungus affecting corn plants the past two summers and the inoculum population has to be very large in the soil.

Now, with saturated soil conditions, it is easy to find stressed seedlings that are wilting down and turning brown as their roots die.

Nothing can be done for those brown rooted plants except to boost drainage or replant heavily affected areas in those fields.

What we are wondering is what percent of the plants that are infected, but not showing enough symptoms to be detectable, will have problems later in the growing season?

Field warts

Depending on soil types and fieldwork activity there are now more fields showing their warts.

Two of the most common are yellowed plants due to lost nitrogen and plants that are trying to grow and develop a root system on compacted soils.

In the most recent IPM Newsletters crop specialists from several states devoted space and verbage to the wet soils in their states and the expected losses of nitrogen.

Having the soil profile saturated for three to four weeks after the soil temps warmed above 50 degrees contributed to loss of nitrogen out of the profile, depending on the form of N used.

The second most common problem is that of plants that are shorter and yellower the other plants within the row.

One common cause is that of unrotted residue over the seed trench that either kept temps lower or released its organic acid leading to allelopathy problems.

The second cause would be where there is a serious compaction problem about two inches deep in the profile.

Too much weight on wet soils either this spring or last fall caused a problem that has disappeared yet.

Black cutworms

The notice went out that Black Cutworm activity was expected to begin appearing last week across the state. Thus far damage has been minimal in the areas that I scout.

What has been documented and can serve as a guideline is to devote scouting time to no-till fields that supported a population of mustard plants.

Those plants are very attractive to the in-flights of moths as they blow in from their wintering sites in Texas and Mexico.

Weed scouting

In the next two weeks most growers are going to be working on controlling weeds in their fields.

They might be depending on one of three possible programs, total post, a two pass, or hoping for a successful one pass.

All depend on scouting those fields and identifying each weed properly if it is a new one.

The information you picked up by reading those farm magazines over winter could now be valuable if you have to face a new weed or one which has become tougher to control.

One weed that seems to have spread dramatically in recent seasons and could become problematic is Kochia.

It is a weed that has moved in from the west and can be tough to kill with a number of normally effective products. Be alert to it.

Foliar feeding

There are several things that can be done over the next two weeks to boost yield potential and speed up crop development.

It has been shown that one of the best ways to improve bean yields is to increase the number of branches on each plant.

Is everybody ready to do that during the vital V3 to V4 growth stage and ready to use the right product mix and rules?

In 2009 I saw cases where the application of a product called Soy Soap (now Wake Up) eliminated the aphid infestation in treated bean fields.

Will that success be repeated for growers who experiment with the product this year?

I wish there were more trials by more growers in northern states to see if those results can be repeated.

The proper timing of the application is at the V2 to V3 stage, which will be very soon.

Good luck in getting all your work completed.

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