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CROP WATCH

By Staff | Apr 26, 2013

We are still waiting for spring-like weather to arrive. There was still snow in the forecast on April 16 and every radio station was still mentioning the wind chill temperatures that could be expected.

We all know it has to be due to global warming. Currently warmer temps are expected for the weekend, which would be great, though it will take some time for the soils to warm enough to feel comfortable about planting seed in the 50 to 52-degrees range.

However if having cold temps were what we had to pay for receiving the 2.5 to 7 inches of rain that fell across the state, it was likely worth it.

There is still time to get the crops planted and expected trend line yields if the rainfall amounts and timings are agreeable with what they require.

Growers were so hoping for any rainfall that any will be accepted no matter how it falls. If the penalty for receiving it is a slightly delayed planting season, so be it.

Until about three weeks ago we really weren’t sure if there was enough moisture below 12 or 18 inches to allow the roots to follow it deeper into the soil.

More will be needed on a regular basis through the summer to hope for a decent crop. If the old indicator of “watch the rainfall amounts in Arkansas to see what Iowa will be receiving in four to six weeks” prove true, we may have a chance.

Now we just need enough heat to raise the soil temperatures to where they need to be to provide a nice warm seed bed so the small corn and bean sprouts have a nice environment in which to germinate and form root systems.

Speaking of how spring moisture is shaping up across the upper Midwest, here are a few items to be aware of. Duluth has received 51 inches of snow since March.

In North Dakota they have had a huge amount as well. One Minnesota farmer said that their neighbors to the west now have a snow cover of 2 feet to melt.

On top of the ice are 2 to 6 inches of water that will have to flow downhill once the snow and ice melt.

This has not begun yet, so their expectations are for record floods. Right now meteorologists are predicting severe flooding for the Red and James rivers that could make 2.5 to 3.5 million corn acres disappear.

That is where most of the new 2013 acres were supposed to be planted.

Rainfall and irrigation

Several universities and tillage groups have been commenting about the lack of good soil structure in many of the fields. It seems as many of those reports are accurate. Last fall the ground was so dry that the soil dug during tiling was just powder.

That situation allowed the ground to be packed tighter than normal with little pore space and to become somewhat moisture repellant.

Granted last week’s rains through Iowa, Missouri and Illinois were heavy, but the amount of runoff was very high. Most of the streams and major rivers jumped out of their banks.

Rain that should have been stored in the profile for use later in the season ended up going down the Mississippi instead.

In flood-irrigated country, farmers often begin their irrigation runs by sending a quick stream of water down each furrow to slick off the surface and to break the surface tension.

This pre-wetting opens up the surface where it then will allow more of the following stream to soak in the full length of the field.

It does appear that the high amount of tillage done last fall when the ground was super dry was a negative. Fields with good residue cover or a cover crop retained more of the moistures that fell.

An extra 2 inches of retained moisture could translate into an extra 20 to 24 inches of yield if drought conditions return. The fields now growing a cover crop appeared to retain the most rainfall and should allow for a perfect seedbed to be formed.

Many tons of soil were lost during those heavy rains, as evidenced by the gully and sheet erosions that took place in both hilly and mostly flat fields.

The key there is to have as much of the kinetic energy held by the falling raindrops captured by surface residue.

It also helps more of the rain to infiltrate the soil surface making its way into the deeper profile rather than run downhill.

Current weed control

Surveys from different herbicide retailers reflect the current switch by many growers to return to using residual herbicides to achieve more consistent grass and weed control.

In cases where growers were using half rates of residual products, they are now using three-fourths or full rates in hopes of not having to make a second trip or simply acknowledging that they will be using a one-two punch and are now preplanning their post-emerge application.

Dr. Bob Hartzler, of ISU, recently wrote two herbicide articles. The first was about the parameters of post-emerge spraying and the potential of having a degree of tissue burn or phytotoxic symptomology occurring.

In the old days we used to talk about how differential metabolism allowed one species of crop plants to escape with no damage while the weed crop escaped unharmed.

In one situation that degree of difference in metabolism between the crop and weeds was large.

A good example might be when there were lambs-quarters in a corn field where we were using Banvel or Callisto. In a second field, the crop may be soybeans and the weeds are now pigweeds.

With pigweeds being C4 plants and the soybeans being the less physiologically efficient C3 plants, the beans are less tolerant of many herbicides than are the weeds.

Therefore finding effective weed control products with no chance of leaf burn gets more difficult and often more expensive.

The second Hartzler article dealt with the new Zidua and Fierce herbicides which were recently approved for use in soybean fields.

Growers have been interested in these two products along with the companion Anthem due to their longer residual times and greater ability to control small-seeded broadleaf weeds.

This new KIH 485 offers longer residual due to its lower water solubility, yet offers good soil sorption.

Saftener use

Plant physiologists have long known there were two different physiological breakdown systems present in corn plants. They are the GST (Dual, Surpass, Harness) and the P450 cytochrome (SU, ALS, HPPD, and PPO) systems.

The later system is also present in mammals and serves as the major system involved in their immune responses. If you don’t have it operating at peak efficiency, due to cool weather of lack of sunshine, we have seen more phyto damage done.

We’ve seen lower levels of saftening occurring when lower micronutrient levels were available to the plants. This happened when and where we saw corn plants bleach lightly to severely under stress conditions in recent seasons.

The answer was recently sleuthed out by several chemists and that information is available in the article that you can obtain by typing “Entropy Cytochrome” in a search engine.

With the return to more conventional herbicides and some organophosphate insecticides every grower will have to get educated on the P450 activity.

Lessons learned in the library or at the desk are less expensive than those learned in the field.

It used to be a hot potato topic among seed and herbicide companies with no one taking ownership of a problem. That has not changed and too often problems get ignored until lots of acres are affected.

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

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