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CROP WATCH

By Staff | Jul 26, 2018

Late July is here and the summer seems to be flying by. Not having any spring produced a time crunch with all the early field work. Then the very warm May and first half of June sped corn growth so corn went from emerging to showing tassels in weeks shorter than normal. Now much of the corn has been tasseled for several weeks and in parts of southeast Iowa the first whole fields were tasselling by June 22nd.

If one was paying attention to the national weather and viewing predictions by noted weather groups, last Sunday night several groups were predicting a divergence in the jet stream where states in the great and southern plains were going to bake while we in cold country would see a cool down into comfortable temperature ranges. This Sunday parts of Texas and other points were basking in 110- to 111 degree temps while we saw near perfect weather and temps in the 77 to 84 range. That kind of warmth is going to cook many crops if they run short of moisture. Grain depth will be reduced and any shallow roots could subtract many bushels from their expectations.

The weather services got things right this time. It is rare to hear the prediction of heavy hail in a precise area of any state as they did last in an area around Cedar Rapids. This was the case last week, when Marshalltown, Pella and Bondurant were all hit by twisters. It is always traumatic for the people who lived through one, especially if they saw it and were in danger. Kudos to Vermeer to have their employees in mind when they fortified much of their new construction making it tornado proof. It could have been a very bad day for the 400 outside visitors and the town. Once you hear the train sound or see one close up, you never forget it. Been there, done that. Hanging onto a fence post is not the safest place to be.

The current corn and soybean crop status

I don’t think there are any averages in existence across Iowa and a few surrounding states. Here we will likely see many fields pushing 230 to 250 Bu/A, but just as many fields in central Iowa where large ponds that will affect 25 to 33 percent of the acreage of, dropping the whole field yields down closer to 140 Bu/A. If they happened to miss the saturating rains or had the slope allowing controlled run off, or great drainage, then the ponding is a non issue. Those ponds will be very visible from the air, but what will be tougher to extrapolate will be the damage done to the stalks or roots from sitting partially submerged or on saturated soils for three to four weeks. The acknowledgement by the USDA in their NASS statistics that the condition rating for soybeans drops a few points was likely an understatement and a similar move may take place next week as reports respond in small increments.

The soybean plants have gotten taller and bushier in the past two to three weeks in most fields, but there are some where the plants seem to lack the energy to develop new leaves and stems. It may take mixes involving minerals, sugar and growth stimulants to get the plants stimulated and growing at a rapid pace. The results from applying products like Seed Set have been very good. There is also a new product from AgriGuardian called NutraBoost, which contains a mixture of K, S, and Mg at the time when V2 has arrived or is approaching. When the champion bean grower from Ventura was experimenting with different spray mixtures, he found that the minerals he applied at the V2 growth stage provided double digit yield increases. These boomed even more when he included Humate products to boost cell intake and sugar production by the plants. The NutraBoost from AgriGuardian include those minerals.

The first aphids are now being found in NW Iowa. I looked at quite a few fields last week and found very few, but some. They are starting to blow in and surviving. Trial work done last year documented that a % of them in IA, MN and SD were no longer controlled by pyrethroid insecticides. If you see this in your fields, be sure to clarify if you first adjusted your water pH down into the 5.0 range or paid no attention to that recommendation. It is a requirement to that family plus with all SUs.

Lost N and actions

It is easy to find many fields where the corn has yellowed dramatically. Given the fact that it is only July and the corn needs to maintain a SPAD reading above 50 to come close to reaching optimum yields, these fields could be heavily affected. Because there are fewer farmer or custom applicators with the tall equipment to apply N to these yellowing fields, and most aerial pilots have switched booms to apply fungicides next that option is out.

I have one of the Minolta SPAD meters and it is coming in very handy to provide greenness readings. I like to test three to four points on the ear leaf on several plants. The generated numbers then allow field to field or stabilized to non stabilized comparisons. Now is when having one of those meters can pay large dividends, as being able to monitor N levels and respond as needed are critical.

Leaf diseases

With the recent warm weather and near constant overnight dews, the stage is set for heavy disease pressure. If and when you are scouting your fields for diseases be sure to focus your efforts on field that tissue or soil tested low for Mn, Cu, Zn and Bo, as deficiencies in those minerals leads to a greater susceptibility to root, stalk and leaf diseases. Low zinc creates leaky root tissue while low Mn lowers the plants’ ability to wall off an infection peg from a fungus trying to gain entry into a plant. The use of a popular non-selective herbicide lowers the population of one major protective bacterium in the soil.

In nearby states several well known leaf and stalk diseases are being diagnosed. These include Southern Corn Leaf Rust, as warm and wet conditions favor its development after spores blow in from the south. Bacterial leaf streak is also appearing. Diplodia leaf disease has also been diagnosed. That one is new to many. The rust can do major damage quickly as many spores are produced and it can be on both sides of the leaf. Tebu does a good job on it. The New Goss’s caramel colored lesions are now much more visible and will need to be reckoned with for growers who want their corn to have a long grain fill period.

Be sure you get a chance to read the Goss’s article by Dr. Alison Robinson where she lists several of the implicating factors on this disease. It is always good to learn about a disease’s biology to get into the mindset that diseases can often be minimized by limiting its causal factors rather than mindlessly try to control it thru ‘after the fact expensive’ curative products. There is a place and need, but prevention can play a big role.

Signaling compounds

This is a new term that is worth learning, and more so in the future. Another reference would be an ‘elicitor compound’ as it refers to a compound produced by microbes, plants, insects or an outside source that causes a treated plant to react to the stimulus.

Examples are the product called Take Off. It was discovered in cactus plants by a lady chemist at Los Alamos national lab. It instructs the plant to scavenge for as much N and other minerals as it can find in the neighborhood, then pull it in, and use it as wisely as possible. Another well researched product that has hit the marketplace from several differed companies is chitosan, which instructs soil microbes or plants to produce the enzyme chitinase, which dissolves insects, nematode parts and several plant pathogens. It can be quick, clean and harmless to non target organisms. We checked out several fields last week where it had been applied and it seemed to destroy fungi which had already invaded the plants’ root systems. This provides insight into what constitutes a ‘disease suppressive soil.’

An open field day

Over the past few years I have mentioned a research farm down by Guthrie Center owned and run by Dave Schwartz, a farmer and manager with Verdesian Life Sciences. We have discussed having a field day the week before the Farm Progress so people can see the no-till corn on corn and view the results in person.

Different trials in place include the use of stabilizers in an area where separate tile systems were installed where the actual effectiveness of the produces are demonstrated. There are different demos where several newer products are being tested in a stair step approach. Because much of the land is highly erodible and soybeans would increase the chance of serious erosion, the ground is mostly planted to continuous no-till corn.

BioDyne 501 was applied last fall behind a stalk chopper and it worked like a charm. One area is dedicated to an NCAA corn yield contest for the corn on corn, no-till, non-irrigated category with a goal of 400 Bu/A plus. Based on the current appearance and multiple ear counts, if the field avoids late season hail it has a high chance of achieving that goal. It currently has plants that are black green, quite tall, contain many multiple ears, and shows no sign of being diseased. Maintaining the disease free status is the job of the applied minerals and the BioEmpruv. Last year the corn was dark green until late October and showed perfect standability. Each ear was filled clear to the tip with zero tip back and very little to no dent. The actual soil test data show low moderate P and K levels. The Haney and regularly tested PLFA scores are being measured and recorded.

Right now mark Aug 20th as the date of the field day. Please reserve your spot. We are inviting speakers to this event, many of whom spoke at the March 3rd meeting this past winter. There will be some additional speakers from new companies we are now working with. We think it will be an informative event.

Call Carol at 515-231-6710 or log on to our website to register www.centraliowaAg.com .

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

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