Back

CROP WATCH
July 6, 2018

Share

After one of the most severe monsoon seasons in recent years the farming natives in the northwest three-fourths of Iowa have to be wondering what is next in store for them.

About three weeks ago the noted, and often deadly accurate climatologist that most people have never heard of, Simon Atkins, came out with his world weather prediction for the next month from his healing center in the middle of a eucalyptus forest just west of Punta del Este in southern Uruguay, and said parts of the Midwest were set up to potentially receive up to half of their normal summers' total rainfall in the next two to three weeks. He makes his predictions by tracking solar cycles and celestial gravitational pulls to determine how and where the mineral filled magma inside the earth's crust will flow, thus setting up magnetic lay lines that steer the solar winds, atmospheric rivers and storm tracks.

That is pretty darn accurate. That should make more of you think about signing up for his subscription service. (We visited him down at his place a few years ago while we were in AR and UY and found out he was also extremely psychic, such that you would never bet against him).

Meanwhile our friendly USDA and NASS are predicting record crop yields for Iowa. Rain makes grain. Farmers finally got most of their intended corn and soybean acres planted and those are all going to produce 49 Bu/A yields right. All of that rain has produced so many ponds in some many fields and beside the actual area involving each pond the effect typically spreads out 100 to 200 feet beyond the edges of the pond. By now many of us saw that internet picture of the corn plant from north central Iowa where the root was about three inches in depth and had turned brown already. Sadly the worst result from the ponding ended up becoming true. The hot air temps warmed up the water and the minimum predicted survival period for the corn and soybeans ended up becoming true and plants in most of those ponded areas died. In most cases the ponds filled up two or three times and never got dry enough to replant. Sadly if those ponds don't grow crops they grow weeds, and those weeds produce seeds.

The gauntlet

So as we move into the month of July it has to feel that we and our crops are entering a weather gauntlet. While the NW three-quarters of the state and the portions of the surrounding states are either drowning in similar amounts of water, or facing extremely dry conditions, our corn crop has progressed to the point where much of it in the southern half of the state could be in the tasselling stage in the next two weeks. Mr. Atkins is predicting extreme heat, especially at night, will begin appearing on July 9th. High temps during the day typically don't harm the corn plants if they have sufficient moisture, which they definitely do. But temps above 65 or so and into mid to high 70s don't allow the plants metabolism to slow down and they burn up a portion of the starch they formed during the day. I think it is called the 'dark period photo respiration cycle'. This phenomenon occurred during many of the days during the summer of 2012 and when combined with the drought caused reduced corn yields. Interestingly enough the nighttime temps during the 2011 growing season were also quite warm and some stories relate were even hotter. Astute observers remember seeing midnight temps in the 80s that season.

Root rots and leaf

diseases

The excessively wet soils combined with warm weather are increasing the incidence and severity of the root rots or so-called slime molds in the Oomycete family. There are several that occur in the Midwest that most farmers are acquainted with.

If the corn or bean plants are lacking the minerals most important to plant health and a fully functioning immune system, manganese, zinc, copper or boron the chances of that happening are increased. Applying micronutrient mixes could have or still could improve the overall disease status of each field is the levels of those minerals are low.

The situation in soybean fields could turn serious. A windshield survey of fields across the state where rainfall has been excessive in the last two weeks tended to find that yellowed beans were very common in 50 to 66 percent of those fields.

Now the yellowing could have been due to the anaerobic conditions the roots and the nitrogen fixing bacteria in the nodules on the roots had to tolerate. But I remember recognizing the color shift from green to yellow in many fields back in 2010, 2014 and 2016 and many of those fields had the same yellowed spots erupt with Fusarium caused SDS in August.

We know from USDA research that application of a certain non-selective herbicide will kill off the Pseudomonas fluorescence bacteria which serve as the natural control agent to the Fusarium vulgiforma fungus.

In that case is there any product that might work to help minimize the Fusarium population? Based on the observation of astute growers there may be one safe compound that has produced good results when used in such situations. I wish we had a year's worth of experience in this state.

Leaf diseases can become detectable in corn plants very early in their growth cycle, but typically become more advanced as the corn plants move into their reproductive phases. The long hours of leaf wetness and dews help to create conditions favorable for soil or airborne fungal spore to float around and germinate on the leaves or stalks of corn plants or the leaves of soybeans plants.

Low manganese conditions inhibit the plant from walling off the infecting pegs of the fungus that are hoping to penetrate the outer cuticle of the plant. Low zinc levels create a thinner and more porous root system more prone to soil borne fungal organisms.

A quick examination of the leaves of corn plants in this wet and heavy dew season will find many small to medium sized lesions already present. There are many different field guides that you could carry with you or have available at the shop where you could take your leaf samples to in order to be examined.

If you are going to devote time to scout your fields it would be beneficial to have one of several pictorial guides that will guide you in the ID process. What would come in handy would be an instrument that you could point to an infected plant part and the instrument could compare the visual symptoms to a known library of common diseases. Also try to have a seed company guide that lists the genetic ratings of each hybrid.

In soybeans there are also a few leaf and stem pathogens that can be found now. Rhizoctonia and Frogeye are two of them. Again leaf hour wetness and saturated conditions are perfect for infections to occur. Be ready with a fungicide that can control Septoria near row closure, which on 30-inch rows is near R3 or July 20th to 25th.

Goss's Wilt

A new research paper written by plant path researchers at ISU and UNL giving details on Goss's Wilt in at least ten and likely many more states was recently published. In a number of PNW states it has not been officially recognized because it is not supposed to be there. It is amusing how that works. In the paper the authors discuss what factors seem to be correlated with its appearance, incidence and severity.

I had mentioned in a previous column that the very young and very small lesions could be found around June 12th in central Iowa. Now it is possible to see plants where the entire lowest internode is showing the presence of the brown, stinky slime. If it goes unchecked and we get the 90-plus degree days with strong south winds and low humidity the plants could be dead well before the Farm Progress Show, just as they were in 2014.

That year the harvest demos were canceled because many of the infected fields showed severe stalk lodging and would have been an embarrassment. Remember that a fungicide application will not control it. Only two products have shown the residual and strength to boost plant health so it does not cause damage.

Lost nitrogen

Knowing that saturated soils above 50 degrees will allow 5 to 7 percent of the nitrogen per day to disappear is scary because of how many days have existed so far this season.

The challenge lately has been how to identify how much of the original N has been lost and then how to apply any additional N.

We are seeing the best of the stabilizers are doing their job and that the Azotobacter free living N fixing bacteria in the BioDyne products are also doing their job. As to the drop dead date for adding mid or late season N? The latest research seems to show that applying N through early dough stage can benefit yields.

Insect news

The invasion of Japanese beetles has occurred. The nasty ravenous beasts have been gorging on their twenty favorite plants further north each week and reached the Hwy 30 line this past week. While mowing lawn on Saturday I saw they had found my red raspberry patch. I quickly had a sprayer loaded with a chitosan based product and spayed the plants and neighboring fruit trees. Within 20 minutes they had left. Apparently they could detect the change in the plants' immune system. A neighbor had seen the same thing happen in his trees and gardens. The stuff seems to work like a charm and is based on a natural and completely safe product. A solution finally exists and was made from a natural source.

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

Share

Regular Size Farm News