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By Staff | May 14, 2010

It’s mid-May and most of us in corn and bean growing country are wondering where our nice weather disappeared to. Those 75 degree days of mid- and late-April seemed so nice, and all of the plants and seeds responded so nicely to finally being in a warm place.

The lilacs are still blooming, the first rhubarb has hit the pie pan, and the major league baseball season is already over a month old.

So why have we gone back to wearing warm jackets and worrying about wind chill and strong winds that seem to blow every day?

Maybe we were rushing things a bit, due to expectations of a repeat of 2009, but having some of that haste perhaps coming back to bite us does not seem fair. Now we get to play a waiting game to see when conditions revert to being drier and warmer so we can make an educated guess as to when the final acres of corn will be planted – or replanted – plus when we can continue with soybean planting.

After surviving a weird 2009 weather year we were hoping for “normal” conditions to return. Hopefully in another week that will be the case.

Marketing the expected crop at decent prices is something that all farmers hope to do. Having the facts for your operations, plus facts from grain producing areas around the world, then coupling that information with grain demand from foreign countries always presents a challenge in understanding and assimilating accurately.

Knowing that many countries’ political classes like cheap food going into an election can mean that fundamentals might count little is where it is tough for us in farm country to guess the markets accurately.

The big news of frost

The first item to cover here is something that could affect many growers in the state dramatically or it might be history, depending on how things turn out. That item is the freezing temperatures that moved into the state last weekend.

The map that was circulated on Monday showed temps dipped below 32 degrees clear south of I-80 in eastern Iowa and south to Highway 30 in western Iowa.

In fact there were many areas where temps of 28 degrees were registered on thermometers on one of those mornings.

Depending on where they were located, farmers who did a fast tour of their emerged acres on Monday and Tuesday saw crops that either escaped the subfreezing temps or plants that ranged from just nipped by frost or had turned black/brown and were laying limp on the ground.

Making the determination as to which plants would recover and which one are, were, or will be toast is something that takes time. Typically after three or four 70-plus degree days there is going to be enough regrowth on the surviving plants that one can say that they will recover nicely and be productive plants.

With corn plants and their growing points staying below the soil surface until the plants are about 10 inches tall, they are a plant that can recover from freezing weather and yield normally.

However having cool and wet or hot weather during the few days until the sprouts are 1/2 to 1 inch tall leaves a time window when they can be infected by soft rot bacteria and decay. Then they would be lost.

Soybean plants can be a different matter. Just after emergence the small plants can tolerate colder weather than can small corn plants down to about 29 degrees. The cause seems to be cellular sugar levels.

Below that temp they are more vulnerable than corn plants to freeze damage. With the above-ground growing point they do not recover from freezing at all.

One other consideration to evaluating freeze damage is the amount of residue cover on the ground. This cover can act as a blanket to keep warm air in and minimize damage, but it can also act as an insulator that retains cold air and magnifies the amount of plant damage.

Things that are affected by the residue are air flow patterns, dark sky radiation, temperature retention, duration of the cold air and ground temperature.

As of Tuesday night most farmers and agronomists would have walked quite a few fields and tried to decide what course of action to follow, let things recover or decide that recovery would be minimal and replanting was the best option.

However the fields are too wet to permit any field traffic and the lack of heat has delayed any of the regrowing that will be needed to make a decision. Later this week when you are walking your fields alone or with an agronomist or seed person, keep all of those things in mind.

Back in either 2002 or 2003 much of the northern half of Iowa experienced freezing temps around May 4 and May 5. Farmers had planted early and the growing points were generally below ground, but it got cold enough to freeze the soil to a 1 inch or slightly greater depth. What we saw is that a number of hybrids known for being quick out of the ground formed the early root crown about 3/8 of an inch below the soil surface.

Those plants froze and did not recover. The opposite type hybrids, those having reputations for being slow emergers, formed that crown about an inch or so below the soil surface and they survived. Thus in making your evaluations there will be hybrid, planting depth, amount of tillage, residue amount, soil type and topography difference.

Pay particular attention to low areas where temps remained cold longer. Cold air acts like a liquid and it will flow along field borders or into any depression.


Given the fact that soil temps were quite warm through mid- and late-April stands are generally good. However there are a few reports trickling in from areas where farmers planted just prior to the cold rains of early May. The problems seem to be most prevalent in fields with poorer drainage and less aeration.

When soil temps are below 50 degrees and the ground remains saturated, the seed can simply decay without ever having sprouted.

There has also been research done in the recent past by plant nutritionists who have been exploring the link between low micronutrient levels and poor germination. In other words what happened in seed fields last year could have an impact on what happens in your commercial fields this spring.

A few people are currently gathering seed samples from end supplies to have them tested for about 10 micros to see what correlation, if any existed.

Last year there were a number of documented observations of sprouts that corkscrewed under the soil, acting as though there was a heavy crust, but there was no crust at all. Germ tests didn’t seem to answer the existing questions. Nutrient tests might do that.

By the way, bean leaf beetles could be found in fields southwest of Fort Dodge last week attacking volunteer bean plants. The models didn’t predict heavy feeding this season, but those models did not take into account the fact that the deep snow insulated the soils and insects from the severe cold.


Nationwide over half the bean crop still needs to be planted. In northern states earlier planting typically increases yield potential while in southern locations having pods filling during rainy periods rather than times of stress helps the most.

From what I am hearing from seed companies, and others doing seed treatments, is that still not every grower requested enough of the 2:1 or 3:1 return on investment input items to maximize yields.

About 75 percent of the bean growers are now using a seed-applied fungicide. This would have to be No. 1. Next for most growers, depending on soil type and yield goals, is the application of one of the newer inoculants.

Other new biological seed treatments that can be used on either corn or beans are continuing to appear. Gary Harmon, plant pathology researcher at Cornell University has developed a new radiation bred Trichoderma called Saber X. Trichodermas fill several roles, which include helping with phosphorus release, maintaining root health, and increasing nitrogen use efficiency.

In 2009, yield increases in corn were in the 8 to 13 percent range. We are also experimenting with a new pseudomonas that in 2009 gave several farmers a 5 to 7 bushels per acre yield increase in soybeans.

This is the third year where we are using Tropho-Max on beans. Results have generally been good where soils are active and yield potentials are high. Most of those items are inexpensively priced and give a good ROI.

We are seeing more companies, including some of the major seed treatment firms commercialize biologicals that boost growth or manipulate the plants physiologically to increase yields. Farmers in the U.S. are not in the lead in adopting such products.

A number of companies will be field testing their micronutrient foliar, or seed polymer applied, products to see what crop benefits are produced. These will be interesting to watch, given the fact that soil sampling for several micros, when they are rarely analyzed, has documented major shortages of several nutrients.

Field trials already completed in southern locations looked good.

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