There's still time to foliar-apply a "final fill" as corn and soybeans head for the finish line

Here's the latest field report and season-ending management suggestions from crop consultant Bob Streit, based at Boone, Iowa. 

August 23, 2021  By Bob Streit

Now that the end of the growing season and month of August are drawing to a close, our opinions and evaluation of the crops and grain production carry more value. Potentials and estimates will become realities as we measure the yields when harvest starts.

Through July and August the common refrain was that the major crops looked a lot better than they should have, as scant moisture supplies were gradually reduced to that 20% level at which plants can no longer extract additional moisture. Heavy dews from the higher humidity levels of June and July turned into small amounts of rain that ran down the stalks every evening to give the plants a small drink.

Incremental steps such as paying attention to root architecture, applying drought tolerating microbes to the seeds or plants to become more heat and drought tolerant appeared to do their thing. Monitoring tissue test levels to increase mineral levels increased drought tolerance and were beneficial to the crops. Paired with multiyear programs to increase soil health and organic matter levels, these were steps that paid off. We will know to what degree as fields begin to be harvested.

In general, the best-looking crops in the state as of the end of July 30 were those north of Hwy 30 and in northeast Iowa. Then hot weather and 3 weeks without rain caused a major decline for them.   

 

Iowa on Display

For people who love Mom, apple pie and lemonade, the game of baseball is ingrained in America society. I used to listen to my dairy farmer grandfather tell us stories about the great players of his day before we got into countless Sunday afternoon ball games.

He had been a good player on their local town team. The popular movie ‘Field of Dreams’ over the years has produced enough intergenerational warm feelings among fans and league officials to consider holding a Major League Field of Dreams baseball game at the site near Dyersville. It got canceled in 2020.

As you likely know the 2021 version was held two weeks ago, complete with ceremonies that drew non-politicized attention of tens of millions of baseball fans to the state of Iowa and its culture. In past years, several baseball players from Ft. Dodge acted as White Sox ghost players coming out of the corn during organized games. All the players in the 2021 game made their grand entrance through the rows of corn, as did MC Kevin Costner. The rolling landscape and green fields of NE Iowa served as the perfect backdrop and were often mentioned in the telecast.  The grandeur will be repeated in 2022 with a contest between the Cubs and Reds.    

 

Corn near Fort Dodge, Iowa,
foliar-fed at V6 with Impulse
from Spraytec.
Photo by Drew Ewing

Crop Development

The ProFarmer Crop Tour was conducted last week. The overall term they used to describe the Iowa crop was "highly variable." Being lucky enough to catch a passing shower when neighboring fields did not catch any often meant having crops that looked good versus having plants under severe stress. Their summary was that many of the states east of the Mississippi have very good 2021 crops but those to the west have large areas where rainfall was often short for long periods of time and the crops suffered from non-recoverable yield losses.

Having been in many fields across four states I have commonly seen where 8 - 14 rings of kernels were aborted at the tips to reduce ear length, while the rings of kernels around were commonly 2 - 4 less than normal.  The overall kernel count is reduced with kernels depth to be decided yet. Driving home four hours from NW IA on Friday allowed me to observe the very common brown and dead plants in the majority of fields.  

It is easy to conclude that these observations will translate into lower than trendline yields in these areas. The reports out of parts of MN, SD and ND tell of very low bean counts and places where the corn was chopped for silage a month ago. Part of the yield loss will come from lack of moisture to keep the plants turgid, and part from poor nutrient release because of dry soils. Almost no bean plants contain terminal clusters and final grain fill of pods will depend on rain arriving this past weekend.

Bug and Crop News

Corn rootworm damage to corn roots was mentioned a lot this summer as root lodging appeared in many areas when winds accompanied rain. A few things can explain these failures of both planting time insecticides and traits which were not providing CRW control. One thought is the plants were under so much stress that they did not have the extra energy to form the protein-based endotoxin.

Kevin Steffey,  an Iowa State PhD entomology student under Jon Tollefson, my former classmate in Ent 370, served as the Extension Entomologist for the U of Illinois. In a research plot at the U of Illinois, he found the toxin level among CRW-Bt hybrids varied tremendously. He discovered that a low percent of the hybrids never produced enough endotoxin to be effective.

Some were effective at V4 but not at V9, and a portion were very effective at V4, but marginally effective at V9. Then, include the fact that planting time insecticides often are degraded before the GDU associated egg hatch is complete. The end result is we have selected for the late hatching and feeding larvae. Witness the larvae that can now be found on tasseled plants.     

We had two growers experiment with a program involving an attractant, a newer insecticide, and a medical grade polymer called Argosy which prevents wash-off to extend the residual life of many pesticides. We are continuing to monitor the fields. So far the results look exceptional. If we get 21 - 42 days elimination of egg laying adults, as verified by sticky trap catches, we will continue to work with the attractant. Those growers made changes with nozzles and screens, but things worked as good or better than we hoped for.  

A related note: The EPA asked the manufacturer of Chlorpyriphos two years ago to present new data that clearly showed it was a safe product. That data did not exist. Dow was the original developer & manufacturer and they are no longer making or selling it. Thus the registration will be canceled six months from the Aug 18, 2021 date. There are two closely held reasons for its cancellation. In its place for  aphid control is BASF’s Sefina. For spider mites there is a Ivermectin analog that is labeled for use.   

Escaped waterhemp in soybean fields has been a major issue this season. This was not due to lack of effort or expense spent by farmers. Nothing seemed to work. The problem now is the surviving tall plants are flowering and shedding pollen, which is attracting 200-300 hungry rootworm beetles. The swollen and gravid (highly pregnant) females will likely stay in the SB field to lay those eggs. We are likely to see spotty and potentially heavy root feeding in first year cornfields in 2022.  

Speaking of waterhemp: A farmer friend from South Dakota sent me a picture of a pigweed growing in a field where he had seeded a cover crop. He noticed the long seed head and was asking if those long seed heads indicated it was Palmer amaranth. One look confirmed it was. He will need to rogue the field and physically remove each plant for drying and incineration. Whether it can tolerate the South Dakota cold is still in question.

The same waterhemp growing above the canopy is a strong competitor for sunlight and moisture. A few growers are making use of the weed zappers now being made in Missouri or by Lasco. A few of those fields in NW IA can be spotted and have a very distinct look with all the tall, dead weed carcasses. They are not the total answer but can lessen the in-plant competition.

In spite of having a dry season, there was enough moisture during August to spur the appearance of White Mold in low lying, thick canopied bean fields. The leaves of affected plants turn a lighter green color visible thru binocs. There is supposed to be no product that can be sprayed on plants once the infection occurs or whitish growth appears. We are testing two products to see we can change that notion.  

 

High Yield Beans

Does a grower aiming for very high soybean yields quit spraying foliar minerals by Aug 20th? Not if the grower intends to set yield records. Just like a livestock man does not quite feeding his cattle or hogs when they hit a certain size, plants will keep filling out if given the proper feed.

Whether a ground rig or plane is required depends on whether any early and mid-season applications of sugar and P were applied to shorten the internodes. Ray Rawson, Jimmy Fredricks, Bill, Dan and Keith typically made several extra trips with the realization they are buying those last bushels. With $13 to $15/Bu beans and expected shortage of beans in the industry, this is likely the year to find the best recipe and capitalize on the prices.

Applicators need to use a mix of minerals known to increase bean size and to increase stem strength to facilitate easier harvest. Having several new amino acid chelated minerals that act and move systemically should be a boom for bean growers. Growers have had to identified the role of each mineral in the plants’ grain production process.  They will also have to learn facts about the importance of water quality, water pH, EC, energized minerals, radiation use efficiency (RUE), and nozzle selection.   

Silica

There are increasing numbers of crop acres in Iowa that had Silica applied to them, either foliar or soil-applied. Silica promotes 33% improved water use efficiency (WUE), and provides better abiotic stress and radiation use efficiency to corn and bean plants.

Its application should show up as improved yields this fall. A number of plant scientists who interacted with Einstein and Reams have touted its benefits for years. This year we have growers in dry areas of South Dakota who applied silica and have great looking corn and beans next to neighbors’ fields that succumbed to drought.

The main negative with it in the past was its tendency to lay down a film in the sprayer equipment and hoses if the sprayer sat. A few gallons of apple cider vinegar will liquify any film that formed. In 2018 we saw a 30 Bu/A increase in corn yields. For a $7/A investment its use was justified. 2020 trials on soybeans, in the Midwest showed 7.3 and 8.4 Bu/A increases presumably thru stress mitigation.   

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