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CROP WATCH

By Staff | Jul 29, 2011

After the first seven months of the year have been so erratic with one calamity after another, we have to wonder what might happen during August.

We can quit hoping for a bit of heat to push the crop along, as we have had enough. Most parts of Iowa and Nebraska still need rain to help fill the profile and meet crop demands during any extended rainless period.

After much of those states went two to three weeks without rain and enduring 95 to 100 degree temperatures in the humid fields, it feels like we have been walking on the edge crop wise.

This is all happening while the most ever attention has been paid to the status of the Midwest’s corn and bean crops. The nation seems to now acknowledge that food doesn’t come from the grocery store.

It gets coaxed from our rich soils via lots of hard work, plus a financial and emotional commitment from everyone involved.

How accurate are all the state and nationwide crop forecasts? With the widely varying conditions and the poor accuracy of forecasts seen in 2009 and 2010, why would anyone think they have improved?

It was about this time in the two previous years that the corn and bean crops began to fall apart under pressure from several different plant diseases.

Since most fields still have 35 to 40 days of grain fill ahead of them, and the moisture profiles in portions of the state are running low, there is no guarantee that maximum or even trend line yield levels will be reached.

The windstorm

The farmers who got blasted by the big wind of three weeks ago are still coping with the downed corn and damaged buildings. Where grain facilities got hit and destroyed the grain is being vacuumed and hauled away.

It will be a race to see if any cement work, bin repair and construction, installation of new legs, and then the wiring can all get done in time for this fall’s harvest.

You have to feel for any group that gets put in such a position and know they will do their best. But at a time when bin companies are not carrying huge inventories, can the job get done in time?

I was in some of the eastern Iowa fields this week and saw lodged plants that ranged from being 90 percent upright to being goose necked and having a 40-degree bend in them.

They are pushed over 10 inches beyond the neighboring row. The pollination looks good as the ears ended up vertical and able to catch pollen.

Corn conditions

The heat is pushing the corn crop along faster than expected. The ears in many parts of the Midwest are now in the late blister through milk stage. Next will be the dough and then dent stages.

If the temperatures cool down and moisture stress is not going to occur we expect the corn plants to need 35 to 40 days to reach the black-layering stage.

There doesn’t seem to be signs of any major problem with pollination, which is normal, but now is when stress conditions can cause major abortion of kernels.

Those tip kernels can just shrink back into the ear and essentially disappear. More rain is definitely needed in most areas.

Warm and sunny days with adequate moisture are what the plants want in order to maximize yield. The hot days don’t hurt yields during the vegetative growth period if moisture is adequate, but now that the plants are filling the kernels the hot days can shorten the grain-filling period, producing shallower kernels.

Having accompanying hot nights is a negative as a portion of the starch formed during the day is burned up during the dark hours

From now until the crop is finished cooler weather is beneficial to grain fill and does so by adding days to the grain-fill period.

For those with non-Bt hybrids, the first second brood moths have begun to emerge and are now hanging out in the grassy ditches.

In about a week crop scouts will have to start looking for their eggs on the corn plants.

Soybean conditions

Things are still erratic with soybeans. Because soybean plants are triggered into their reproductive processes via nighttime length we typically expect that fields of like maturities planted in the same week will be at the same growth stage.

This year it has been common to find fields at R1 right next to fields at the R3 stage. What is causing these differences and will these differences disappear or will they remain?

What is apparent is that the plants in many fields will be podded-node challenged. Since most plants are nearing the time when the last set of trifoliate leaves is extended, it is possible to count the nodes on the main stem and side branches.

While we typically hope and manage for 17 to 19 nodes, this year it looks like 14 to 15 will be very common with a limited branch number.

I did get into a field of an older 2.4 bean that had been sprayed with hormone producing PPFMs and we counted as many as nine side branches on the plants.

Some of those branches held as many as 12 podded nodes. If branch No. 1 has 12, then No. 2 has 11 and so on.

That gives a very high cumulative podded node count. If the grower can get more flowers to form and then held at each node the yield potential is quite high.

Bean growers are wondering about the need to spray and what timing they should be using. If they would bend the plants back and look at the lower leaves, if any of those leaves are turning yellow and developing black spots, septoria is the likely cause.

This typically requires a Strobe or Strobe mix to cure the problem. Aphid populations are still light, but present. Any cooler temps will be favorable to their populations’ increase.

Accompanying them are the first generation of the bean leaf beetle, several species of loopers and a few stink bugs.

Over sprays

One very common occurrence this year that most farmers are noticing are the many overlaps on the end rows of bean fields where it is apparent that a post-emerge herbicide was double applied.

In previous years the plants turned slightly yellow and then recovered. This year the plants in those spots are bright yellow and show little sign of returning to a healthy green color.

Field-long overlaps from two to four rows wide are also very common and have become very visible.

There are going to be growers who will be watching those spots and strips for disease appearance and for possible yield losses.

Corn, bean diseases

As in 2009 and 2010 what happens in the next 30 days could be one of the major stories of the season. Last year was one for Goss’ wilt and SDS. Will they cause problems yet in 2011?

There are verified reports from around Iowa and neighboring states of Goss’ bacteria and infections showing up on the upper leaves and on the stalks.

I have used up quite a few strips doing the testing and know of other labs and crop scouts doing the same.

Corn growers will have to hope that their varietal selection and fertilizer/micronutrient programs provide the plant protection to ward off this bacterial disease.

GLS and northern leaf blight are also common in many fields and their level of infection needs to be assessed by the cropping managers.

The micronutrient sprays really seemed to help and in many cases appear to have helped keep the plants healthy.

We have seen that SDS symptoms normally begin to appear after the last set of trifoliate leaves has reached full size.

That is when the plants becomes stressed and a physiological trigger is pulled.

We have to hope that the disease is not as bad as in 2010, but the soils were very saturated during June so the risk of the disease appearing exists.

We should know in two weeks. It cost many growers severely last year and they need much better answers than they received.

Stay cool and get the needed rains.

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

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