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CROP WATCH

By Staff | Jun 27, 2014

Just a few short weeks ago, crop farmers in the western half of Iowa and points north and west were still paying attention to the Palmer Drought ratings for their respective areas.

Decent summer rains had been scarce since 2011, and we all knew that the subsoil supplies were very slim.

Thus any dry spell accompanied by intense heat was going to mean trouble for the 2014 crop.

A few of the meteorologists we are familiar with did their best crystal ball work and saw in their prognostications a good chance for rains beginning in mid- to late-June and they were right.

In fact, within the Browning June Newsletter, they spent time discussing atmospheric rivers.

These were described by physicist Dr. Louis Frank, who served as assistant under Iowa’s James Van Allen, as air currents that become saturated with moisture poised to dump heavy rains if a strong signal is given by a colliding cold front.

With areas north and west of Storm Lake and Spencer receiving 10-plus inches of rain it looks like one of those atmospheric rivers delivered the rain.

The crop ratings for most of the Midwestern crop growing states tell of the major two crops looking very good.

Both of those crops grew tremendously quickly in the past week and are approaching a good normal for this time of year.

The warmer days, warm nights, and long hours of sunshine are all factors in this rapid growth and it sounds like those will all continue for the upcoming week.

Summertime foggy conditions are unusual, but have been happening this week.

Supersaturated conditions and cool early morning temps have been perfect for that occurring. Lots of lush plant growth releases a tremendous amount of water evaporation that ends up as dews on our cool mornings.

While those are great now, they can present perfect conditions for disease development if plants are nutritionally deficient and susceptible to leaf and stalk diseases near their reproductive stage.

Corn growth

In heat like we are going to have during the next week, we can expect the corn plants to add about 2.5 leaf stages.

Assuming most of the hybrids will form 18 to 19 total leaves, the corn plants now in the V8 to V9 growth stage should be tasseling in one month.

Corn plants generally add 2 to 2.5 leaves per week depending on growing degree unit accumulation.

Then from silking to black-layering will be 55 to 60 days. Then if we take an aggressive and, perhaps Pollyannaish, view that the corn will stay alive like it did 10 years ago, the corn plants will be safe from frost through the Sept. 15 to Sept. 25 time period.

One thing the strong winds did when the big rain came last Monday night was push many acres of corn to some degree of flat.

The question by many growers was if the plants were going to right themselves and produce normally. In this case, the ground was softened by the rainfall and the plants were simply pushed flat.

Those fields looked bad initially, but within three to four days the brace roots were establishing themselves and ended up righting the top growth. Shallow planted corn is sometimes at a disadvantage performing this task as their brace root number is reduced.

Yield loss and actual bushel loss should be minimal if anything from this event.

Soybean growth

In comparison, the growth soybean plants put on last week seems soil type and topography dependent. Bean plants typically grow another set of trifoliates every 3.8 days with normal temps.

There were fields that advanced from V2 to mid-V5 while others put on about only made it to late-V3. The first of them began to show flowers on June 17.

More are flowering now, which is typically triggered when the longest day of the year occurs, or June 21.

Nutrient status

We received the first batch of tissue sample results from the Midwest Lab late last week. What I had sent in were entire plants that were showing the streaking indicative of nutrient deficiency. What the tissue analyses numbers showed is that most plants included in the sample group were deficient in one or more minerals.

This was evidenced by plants that turned yellowish and/or streaked in lighter soiled areas of the field or all across the fields.

The deficient minerals included boron, zinc, molybdenum, manganese, magnesium and copper.

A number of farmers followed the recommendations, which were to apply a nutrient mix in a foliar application, as a way to bring the tissue cells back to normal and make them physiologically less susceptible to root, stalk and leaf pathogens.

There are several guide pamphlets that show the color and pattern of the symptomology, plus give guidance as to which minerals are mobile or less so.

Every grower needs to learn this as crops’ health depends on it.

While everyone is commenting on how good things look, one crop and marketing analyzer is paying attention to USDA-NASS figures for crop appearance and production.

What he is seeing in satellite photos is a lowered vegetation score that does not mesh with excellent crop size forecast.

Is this discrepancy an indicator of troubles that are brewing now or just an anomaly that will be explained away in time?

One item to ponder is that Goss’ wilt was initially diagnosed near June 10 in 2013. Being we are beyond that date has anyone found it already, is it just waiting to be found, or has it disappeared as a problem?

Right now the top corn growers already have their plan of defense set and ready to implement.

The earlier in the infection cycle one battles it, the more likely that operator is going to win. Here is where a good plan takes into account mineral status of the plant, the use of the copper compounds in multiple mini-doses and Procidic.

Nitrogen loss

Whenever crop advisors and farmers sit down to map plans for the coming crops one big item is always nitrogen use and nitrogen use efficiency.

Too much or too little available nitrogen will carry a cost to the grower.

Now that we have warm and saturated soils the risk of losing 3.5 to 5 percent of the N, as University of Illinois research suggests, is real.

Rate your fields for the number of days where the water sat, expected N usage and applied amount.

Sidedressing is, or was, a good way to fill in any gaps. Before blindly applying more N, run a tissue test to see if the Mg, Zn or Cu levels are low and poor N use efficiency is the problem.

Now that more retail fertilizer places offer high clearance equipment and tall sidedressing is more available, make use of that equipment if a good analysis of your fields’ status suggests additional N is needed.

Consider what form or forms of N you used offer leaching protection, or did you use a stabilizer that has worked in the past?

Weed development

It is time to keep track of weed development in each field, what the populations are as well as stage of growth.

Be more vigilant of any weed control breaks that are occurring due to the high amounts of rainfall that could have leached the herbicides down or enhanced degradation.

With nearly all broadleaves, the earlier you apply a control product the more likely the success rates.

CRW hatching

A week ago the reports out of Bloomington, Ill., area told of the corn rootworm larvae being found.

Thus growers here who are raising second-year corn have to be alert, looking for the small, black-headed larvae.

A bucket float test or salt water examination test is helpful to do, or wash select roots off to look for feeding or scarring.

The $64,000 question is then what to do as a rescue treatment since the insecticides that were available are no longer registered for that use.

Then the question is what application equipment do you have available to you, such as a dead-on-dribbler setup, a broadcast boom, or a 2/3 nozzle bander.

Several available insecticides can work as can the biologically safer Safe-Strike.

Good luck in getting all the tasks done.

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

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