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CROP WATCH

By Staff | Aug 8, 2014

The summer months are rolling along quickly and seemingly faster than in previous years.

This year that may be due to the late planting season and the loss of two to three weeks when it kept raining. It seems like days and it seems like years since we began planting before, right around, and after Easter, and like always will have to wait until after harvest before we can conclude when the best time to plant – though all bets right now would be for the mid April time period.

Assessing the growing season is tougher since both major crops still have a ways to go to reach maturity versus other years. A high percentage of the soybean fields definitely show this. It would be very presumptuous to expect the extra three weeks of great growing conditions through mid-October like we had in 2013.

That makes it doubly remarkable how all the USDA and grain marketing people can expect to know exactly how yields will turn up this fall. But we have to remember what happened in 1994 and 2004 when a few of the weather events mirror what is occurring this season.

The biggest difference in the end may the weather making a sudden U-turn after July 5 – suddenly turning warmer and very dry.

We now have had a full month without rain just when the crops are entering the grain-filling stage. The earliest planted corn is in the later mild stage and the beans have formed pod and could capitalize on any future rains.

Weed control

Our final evaluation of the weed control issues still has to be formulated. There are still many waterhemp plants and other broadleaf weeds that can and will poke up above the different crop canopies.

That can be seen already with growers who did all they physically and financially could and still saw the bigger weeds survive and smaller weeds keep coming.

I recently had the chance to visit with some European growers and consultants who use row crop cultivators equipped with optic controls to cultivate within an inch of the plants at about 10 mph.

When they pair that trip with a post-plant, pre-emerge pass with a tined bar to dislodge any early emerged weeds they are ending up with weed free fields. There is also renewed work on potions that are being fall-applied to stimulate germination of all weed and grass seeds.

Where this blends in is that many of the big herbicide firms are now owned by life science companies who see larger returns on investment from their pharma divisions.

New products and new modes of action are expensive to develop and their medical counterparts are going to be commanding the research dollars leaving ag use somewhat orphaned.

With some of the protoporphyrinogen oxidase, or PPO, herbicides causing plant stunting and yellowing, rather than casting them aside we will have to figure out what environmental or carryover issues are at play as well as seeing if any P450 excitors can be paired with them.

Nitrogen programs

What nitrogen program will we judge to be the best after this season? After seeing many of the totally fall-applied N fields go yellow after standing in water, many growers will be trying to figure out what program will be most effective and still manageable.

While sidedressing is nice and has worked very well, it always brings up the question about how to manage the task if the weather is not agreeable.

The answer may depend on what new N stabilizers are in existenc, but have not been tested in the Midwest to the extent they deserve.

The old Soil Doctor, which was developed by NASA scientist Dr. John Colburn and depends on running sensored coulters on the N applicators to gauge N and ammonium, and expected N release from soil organic matter versus projected corn yields looks like the perfect tool now.

Maybe we will see Ag Leader pick it up and pair it with their optics equipment to really have a versatile tool.

While the optics are nice there is still an advantage with a more predictive model that does not have the two- to three-week time lag.

Soybean management

Sometime between July 20 and July 25 is typically the time when 30-inch soybeans are going to close the row making further field traffic difficult or impossible.

This year that rule will not apply as many fields will have to grow a lot during August to make that happen.

Several other things typically happen at the same time that may require action on the part of growers.

As the rows close, humidity levels climb and hours of leaf wetness increase enough that the fungus that causes septoria brown spot does its job and those lower leaves turn yellow and show black spots.

Those leaves will fall off cheating the plants of their ability to maximize grain fill. Fields south of U.S. Highway 20 – typically always – and fields south of Iowa Highway 3 – about 50 percent of the time – show a benefit to a strobe fungicide application.

So making that trip through the field one more time can be well worth it.

Another reason may be the appearance of aphids. If mineral levels are down, the plants accumulate nitrate as nitrogen and simple sugars which aphids are attracted to and like to feed upon.

So if aphids have chosen to dine on your plants and you don’t approve of their presence you may have to deal with them with an insecticide combo for quick and residual activity.

The current status of the soybean aphids seems to be that their populations vary tremendously and are spotty, with no apparent trend as to why they are following that pattern.

With most beans at R4 they will not be concentrated on the upper unfolding trifoliate leaves, instead finding good nutrition on all the leaves. Keep an eye on them.

And if you have followed Ray Rawson and his 95-plus bushel per acre fields you may know that he typically kept up the foliar feeding until the pods were completely filled to make sure his seed weight was maximized at around 2,100 seeds per pound.

So if you have a pet field you would like to experiment on you may want to apply another mix of Seed Set or Respire and minerals.

Leaf diseases

Now is when a good plant disease specialist is going to earn his or her keep. When there is lots of dew and the plants have dropped their immune system levels, they are prone to disease infection. Thus each grower should be tracking the levels of disease for both the incidence, which is the percentage of plants infected, and the severity, which is how bad each planted is affected.

In beans, the septoria is currently on the lower leaves and causing leaf drop, and cercospora sojina and kukuchi are expected. It is also time for sudden death syndrome to be appearing on susceptible varieties.

In corn, the plants range from being very healthy to having high amounts of common rust, gray leaf spot, Northern corn leaf blight, eyespot, anthracnose, and in some fields large amounts of Helminthosporim carbonum.

Does a person apply a fungicide now in hopes of preserving the yield potential? The correct answer will depend on the plants’ levels of immunity somewhat based on micronutrient levels and genetics, field topography, expected humidity levels and dew duration, and temperatures.

Where yield expectations and potentials are high it may be best to apply a fungicide as yields are made by the amount of green photosynthesizing tissue remaining on the plants.

Thus there are cases where even though spending any more on the declining value crop it will be best to do so.

In other cases choosing healthier rated hybrids and applying micros will do the job.

Good luck in scouting and taking note of the crop health.

The conference

While I seldom take time off in the summer away from Midwest fields, I accepted an invitation from a foreign government to a speaking engagement where about 30 of the top researchers, practitioners, soil scientists and medical specialists from many countries assembled.

Those leaders have taken note of the one- or two-decade long decline in human health in many countries and recognize the need to react.

It was extremely rewarding and interesting. I will be able to talk more about it with interested people in person at a later date.

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

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