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Early assessing Iowa’s 2015 crops

By Staff | Jul 10, 2015

The 4th of July holiday mark was reached and most of the corn was at least knee high by that date.

Now we have to see if the rest of the month and the growing season are favorable to growth and crop development.

It is a time when we like to pass judgment on how kind or cruel nature has been to our major crops and the valiant efforts most growers have devoted to them.

Are things up to par and on track to meet trend line forecasts or have they been derailed? Were there any glaring issues that should be discussed or solutions proposed? What else should be done as proactive treatments?

Crop Condition

As to how the crop development is being rated, it is a very mixed bag. There is a strong east versus west of the Mississippi River split between bad and good crops. Wisconsin comes in as the one eastern state that has very good rated corn and beans.

All of the other eastern states have the two major crops drop significantly from a few weeks ago, as their percent of corn acres dropped into the low 50 percent range. The big three west of the river states Iowa, Minnesota and Missouri had corn GE in the high 70s.

In the past week, I saw and walked fields in many parts of the state on my way into Missouri, Nebraska and very near Minnesota as well as in Iowa.

As to how the corn crop looked: from the road it might be the first time that 80 percent or more of the acres were V12 or beyond by July 6. That puts tasseling on a schedule to have begun about Monday and with the majority doing so by July 20. In recent years where crop development is advanced and moisture levels stayed adequate the rest of the season, yields ended up being very good.

To the contrary, farmer friends who fly tell that from the air the crop is very uneven, and uneven crops typically do not produce record amounts of grain. Thus it appears more that the 2015 crop may draw the carryover amounts down if usage and exports stay good.

The bean plants in about two thirds of the fields seemed to take advantage of the heat and finally seemed to grow into their V6 growth stage.

They remain behind schedule by two to three weeks and are still trying to play catch up with flowering, early pod set and overall growth pace. Flowering which should have started June 20 appears to be occurring closer to mid-July due to this delay.

It might be the year where a foliar application to prod the beans into flower initiation could be very beneficial. It was apparent by last weekend that different bean fields planted in late April or early May that are finally reaching V7 to 8.

Weed management

Escaped weeds are ending up to be a formidable problem in many fields. Their height difference makes them stand out. The noted survivors are lambsquarters, giant ragweed, waterhemp and marestail.

The evidence suggests those survivors were plants dislodged by the field cultivators but were revived when watered by the next rain, and they found themselves transplanted.

Most farms saw moisture fronts march through every three or four days, and the larger diameter stems survived.

Add to it the dilution of the residual herbicides and there are more weed problems in front of us.

Think of all the tolerant weeds that grew within the corn canopy and likely cross pollinated with distant resistant weeds to produce seed for this year’s bean fields.

What to do about those transplanted weeds is still a question that has operators thinking about bean bars and possibly pulling out or rebuilding old bean riders, rope wicks and weed rollers.

It appears the right time for doings so and filling those rigs with different systemic mixtures good at affecting taller plants.

Rye cover crops

Given the fact that we now have much wider weed germination windows and now only older herbicides to work with, a number of growers are experimenting with planting into a standing or knocked down rye cover crop.

Some rolled the rye before planting and others sprayed the cover plants to terminate it prior to planting. Two colleagues are experimenting with mixtures of surfactants plus P or S fertilizers as means of termination, rather than using a regular herbicide.

At this point, the results look encouraging. The soybean plants in those fields were planted later than normal and are adding height now in a greatly reduced weed population environment. It is an ongoing experiment those growers hope to learn from and build upon.

It also helps to control erosion from those May or June gully washers. A similar strategy is used throughout Brazil where they typically plant into wheat supply or standing millet.

It appears that soil dwelling critters that also love the rye cover crops are little organisms such as slugs, snails and millipedes. Are these going to be a regular problem?

Will the value of rye roots serving to break up compaction far outweigh any negatives? Add in the value of less weed competition and these innovators are optimistic this cropping will become much more common.

Plant diseases

The old plant disease triangle says that when one has the inoculums, the right environment and susceptible plants, disease can occur. Those requirements have been met in many fields and operators who scout their fields regularly began to see many leaf diseases two to three weeks ago.

A complex of three to four common diseases began to appear in many fields, particularly those which showed lots of leaf streaking and those with genetic weakness toward specific pathogens.

I have beaten on the drum enough already about disease symptomology for one disease situation which is not officially recognized, but one which has been the biggest yield reducer since 2009. It produces caramel-colored, slimy lesions which are appearing just above ground level in nearly all fields again.

Try not to ignore them, as we have found that there are several products that have been tested at UNL and proven to boost plant health enough to help the plants fight the causal bacteria.

If you see those symptoms in your fields and wish to use a high clearance rig to test one or several of those products, it could help you increase yields dramatically, politics be damned.

Those plant health promoting products include 42 PHI, Procidic and a new one called Bio-Impruv. Each has done a very good job when tested in previous years by corn growers who recognized that something was destroying plant health by mid-August.

The Bio-Impruv is a new bacterial extract which has proven very effective in controlling the systemic CMM in other crops and should do the same in CMN in our midwestern crops.

In corn, all the management so far has been used to build yield potential. Now is the time to save that potential by preventing diseases or insects from robbing the same.

In soybeans, there are also a few diseases making an early appearance. The most troubling and yield-reducing one is the Septoria brown spot showing up in V8 to V10 narrow row beans.

It is seen when lower canopy leaves begin to turn yellow and then drop onto the soil. It is caused by a fungus that loves a moist environment. The result is lowered yield as the beans stay smaller in size.

A strobe or strobe mix is required to control the Septoria fungus. If you do spray, remember that a single strobe should never be applied twice in the same season. Instead a strobe mix containing a triazole should be alternated to help prevent resistance from developing.

I hope you are able to scout and get any work done to improve your crop potential.

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

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