Crop Consultant Streit emphasizes need to help crops deal with moisture stress

 

Crop consultant Bob Streit based in Boone, IA allows us to select and publish comments from his weekly updates to clients, primarily in Iowa. Today, Bob describes in detail that the 2021 corn and soybean crops face stress challenges.

June 8, 2021 We've also encouraged Midwest growers to provide "stress resistant" support to corn and soybeans, using Adaptive Symbiotic Technology's BioEnsure and BioTango. You can seed-apply these microbial endophytes if you have to replant corn or beans. Or you can foliar-apply them during vegetative stages. Endophytes are fungal and bacterial microbes which live inside your crop, between plant cells. They provide stress resistance against drought, cold and excess moisture. 

As we look at the 10-day forecast on the Weather Underground site, as of this date (June 8, 2021) we're in for hot weather with few thunderstorms through mid-June.

Renewable Farming works closely with Adaptive Symbiotic Technologies, and we are a Midwest distributor. Please see our earlier posts here and here for descriptions of how BioEnsure and BioTango can enhance the stress-resistance of your corn and soybeans. Get in touch with us for further details.

Now, here are excerpts from Bob Streit's description of how the Midwest season is shaping up for crops.

Early June crop observations by Bob Streit, crop consultant

The 2021 growing season is shaping up, and several challenges have already been imposed by nature: Lack of heat, shortages or excesses in moisture, late frosts, and now an excess in temperatures. The entire season seems to be one high-wire walk where each step and each week creates new challenges for crops and the people trying to grow them.

While about two-thirds of the crop-growing Midwestern states are in some stage of dryness and getting drier, growers in the other third are suffering from too much rain and muddy conditions — enough that some fields have been too wet and muddy to drive into. For them the optimum planting window has closed.

Consultant Bob Streit

 

Our Late Frost

The frost seen last week was a complete surprise for most of farmers touched by it. They say it was the third largest late May freeze seen in the Midwest since weather records have been kept, which is somewhere in the 1870s.

As an interesting side note, one ag researcher from Alexander, IA told me about two months ago that we would see a major late May frost this year. He did not know how far south it would go.

The ISU extension agronomist who looked at fields across N Central IA in an area from about Charles City to O’Brien County described it as a freckle frost. Damage was very patchy and irregular among corn and beans. The worst fields were those planted in heavy residue, no-till fields.

She theorizes that the residue cover prevented radiative heat released from the soil to warm the surrounding plants during the early morning hours. Now that 7 days have elapsed since the frost, it is more apparent as to which plants are dead and which ones survived. Replanting soybeans makes sense at this date as they are not always yield penalized from being planted late. What we learned in the wet 1991 delayed planting year is that planting corn after June 5 along Hwy 3 and north was often a losing exercise.

The best and only way to scout damaged fields is with a visual inspection to check out the different elevations within each field. Cold air acts like a liquid so it flows into low spots to damage the plants. People who were up early enough tell of the cold air moving like a fog flowing into the low areas.

As of Friday June 4, most of the corn plants showed 3 to 4 inches of regrowth and should recover. If they had not regrown that much, they're not likely to be productive. The best approach is likely to procure replant seed, load a 6-8-12 row mounted planter and replant the dead areas. As to running a field cultivator, that could be an option depending on the amount of residue.

The field inspection of soybeans should be similar. Regrowth of the new bud tissue should be visible. If, after a week, these new buds are not expanding, the plants’ growing points must have been killed. I know of farms where all of the no-tilled beans were killed while tilled fields a few feet away escaped damage.

When choosing your replant variety, pick one of a normal mid-maturity that has an increased ability to branch. Narrow the row width if possible and increase the seed population.

Moisture Use by Plants

Much of northern Iowa used to be marshy or swampy ground. Peat was actually in many of those low spots and is actually difficult to manage as to weed control and being more susceptible to late and early frost problems.

During dry years, the extra moisture held in the soil reservoir, providing those extra inches of moisture needed by the crops. Because that soil was known to hold 2.0 -2.2” of water per foot and corn roots typically were considered to penetrate to 60”, growers on the heavier soils knew their soil held 10 to 11” of total moisture.

The first 5 to 5.5” were readily extracted easily and took the soil down to 50% of field capacity. The next 3” were plant extractable taking it down to 20%. Below 20% it required oven drying to extract the final 2”. The wilting would begin to appear at the 50% range. At 20% they would succumb to the lack of moisture or if lucky and the soil was porous enough, grow as deep as 20’.

Much of the applied fertilizers are held in the top few inches of soil. As this profile grows progressively drier, movement of those minerals into roots decreases. Any additional nutrition must be supplied either thru a Y-drop or via a foliar application. In soybeans the belief is that the stem’s vascular system is not large or efficient enough to conduct the needed mineral nutrition from roots up to the leaves, where photosynthesis occurs.

The Corn Crop

Iowa corn generally reached the V3 to V5 growth stages the first week in June. A few of the very early fields are nearing row closure. With the expected heat, the plants will grow as fast as moisture reserves allow.

The projected heat of the next two weeks has growers reviewing their cropping program and seeing if any other applied product could help their plants tolerate the heat and dryness better.

We know that the improved soil biology, Protect+, Respite, and Mainstay Si are products that are important. Projected marginal or larger improvements that eke out substantial additional bushels could have a large economic benefit if the corn crop is reduced in size over the Midwest and grain prices move higher.

With the calendar moving to mid-June, we can expect corn rootworm egg hatch and root feeding to begin a bit later than in recent years. Experience tells us that plants under stress are less likely to form the normal amount of Bt toxin. Thus the traited plant could be less protected by the Bt traits than normal. Also, planting-time insecticides will likely be more degraded than is typical for most of the products. Corn-on-corn fields should be checked for feeding damage; a timing signal. to scout is when the first fireflies appear.

Many fields seemed to enter their ugly period when plants are on their own and have to procure their own mineral supply versus getting them from the attached seed kernel.

Other causes could have been the very dry soils which are not releasing the minerals as they normally do, or any applied herbicides which have chelated mineral nutrients needed to retain abundant chlorophyll. Poor uptake of nitrogen could have also been a cause.

There were many growers who noticed this and were seeking answers. If the slow rate of plant development was a shortage of energy, minerals or hormones, we were hoping the BioDyne ‘Advance’ product, applied as a foliar, would supply those three compounds. It did last year.

The Bean Crop

Soybeans are slower than normal in adding growth stages. In early June, most were still in the unifoliate to V1 to early V2 stage. They were very slow in germinating and emerging. Lack of moisture could be slowing their ability to form new leaf tissue.

Beans typically form new leaves every 3.8 days, and they have to reach V5 before they can enter the flowering or R1 stage. It appears that early planted beans have not grown as fast as they have in previous years. Thus, beans may not show the usual increase in podded nodes and total nodes per plant. Managing for additional branches could be important to producing higher yields. We like to see cytokine-producing bacteria or Impulse applied the young plants to stimulate more branching.

While the bean plants have been slower in developing, pigweeds don’t seem to be handicapped this spring. I have seen some in the 3" to 4” tall stage, which is the height at which control begins to get more difficult due to the additional growing points which form on the main stem.

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