It is the beginning of the dog days of August where the night time temps are dropping below 50 degrees and a lot of the corn fields are acquiring more yellowing leaves. At this point any additional field applications have to be made by high clearance sprayers, airplane, or now an increasing number of drones.

Why that may be crucial to a large number of soybean producers north of U.S. Highway 20 is that the breezes came from the north during the cool two-week time period and it has become apparent that a large influx of winged soybean aphids were carried on those breezes and ended up dropping out of the sky onto unsuspecting soybean fields and reproducing rapidly enough that the aphid counts are high enough on the leaves, stems and newly unfurled leaves are often sticky to make walking into those fields a sure thing to have to change clothes after the scouting task more uncertain. I am hearing that some growers between Iowa Highway 3 and U.S Highway 20 are now finding the higher populations in their fields.

One pertinent topic among farmers and aerial applicators is how to differentiate between aphid populations that are susceptible to pyrethroids and those that are resistant to that family of chemistry. You can find out by yourself by seeing if the bugs live or die quickly after an insecticide application. From what I have read, there are confirmations of this resistance in much of northwest Iowa. The jury is out as to the geography of the problem. What we already knew is that insects don’t read the book and will always surprise us. The first pyrethroids were extracted from chrysanthemums in Europe during WW II.

The first synthetic compounds were commercialized in the late 1970s and they totally changed our insect control programs in that they were safer, had longer residuals and were applied at very low rates. They replace much more toxic products such as Furadan, Toxaphene and many of the Ops. Since their use has been so broad and insects, or their Gut biota can mutate so quickly with one or a few seasons, it was only a matter of time before we saw broadscale resistance.

That left many applicators who scouted their bean fields in the last week north of Iowa Highway 3 or U.S. Highway 20 finding populations up to and well over the treatment threshholds of 250 per plants. The lesson we learned in 2003 is that if moisture is short, the small sucking aphids can cause yield losses of 10 to 30 bushels per acre.

Checking around, there seemed to be shortages of products labeled for uses on aphids in soybean fields. There were a few distributors who could find small quantities of a generic chlorpyriphos. The next product, which was attractively priced and was deemed effective yet safe to beneficials, was Sefina. Since each company has to project the quantity they envision needing in the upcoming season and since it has been four or five years since we have seen treatable populations of the small, green sucking insect, they used German mentality and prefer to sell out each season, so it was a hard product to find. It is typically priced under $6/A.

The last candidate to consider using is Transform from Syngenta at $11.30. The use rates are very low.

The soybean crop status

Once we began to have warmer nighttime temps the plants put on additional growth. Many of the later planted fields in areas where the ground stayed saturated are still short and a long way from closing the rows. Morning fogs were common for about two weeks and the two most common fungal pathogens showed up. Septoria was No. 1, and No. 2 was, or is, Downey Mildew. They form small, yellowish, irregular shaped spots which have silvery hairs growing from them when examined using a hand lens. This Cercospora species is in the same family as Frogeye leaf spot.

A portion of the state had gone approximately three weeks with no rain and the plants were exhibiting moisture stress. This would have been the demand for the nutrients needed to fill the seed. If that matches what you are seeing in your area, the best course of action is to respond with an application of a multi-mineral product such as Foliar Blend or Ingrained.

Status of the corn crop

Back in 2015 by the time of the Farm Progress Show, about 80% of the corn crop was dead and heavily lodged, to the point that the harvest demos were abandoned due to the fact that it was embarrassing to the seed companies.

The status of the corn crop is much different this year. However enough corn acres have turned from a dark green color to various shaded of yellowish green. This change is greatest in the areas where it rained every three or four days. I took my Minolta Spad meter with me last week to take readings of the plants to see if the plants tested higher than 50. The 50 reading marks the lowest level we ever want to see the nitrogen (N) level at. In this case, we had applied two species of the Gluconoacetobacter, or ‘Envita,’ foliarly in the hopes of fixing more atmospheric N and not have to deal with applying gallons of a liquid product. When using the meter you have to shut the jaws tight until it gives you the reading sign and then shut the jaws at 3 or 4 locations of the leaves to take 3 or 4 locations on the leaf.

All fields averaged above 50 but not as I would have liked. I would have liked each field be above 60. A few did that, especially if manure had been applied.

In pulling the husks back, I saw kernels denting ahead of schedule and more inches of tip back than I had seen in previous seasons. The cause could have been too hot of temps, low sunlight and resulting low levels of photosynthates formed, or soils that went many days with low 02 levels in the soil. It would not surprise me if the same thing shows up in a high percentage of the fields.

Fish as plant food

A newer fish fertilizer by the name of Tidal Grow is going to make its presence in the Midwest better known. We have all read how a Native American Indian named Squanto showed the colonists how to plant a seed right next to where they buried a fish. My first thoughts when hearing about using liquified fish again was that it may never catch on in the product high OM soils.

Larry Eekhoff took in few totes of the TNT fish and was hoping to get at least a few corn growers to apply a bit of it.

Well one well-known farmer was curious about how it might work and spent the money and applied it on 80 or 160 acres of corn.

How it stimulated the corn plants versus no fish was so impressive that he spent the money and applied it to all of his corn acres. They are taking weekly leaf samples for mineral analyses, and now that the ears have filled, they are measuring ear size and ear counts. It is still early and more fill is evident but the scale weights so far tell of a 72% increase in grain weight and a large increase in second ear.

On some of his acres they have only applied 60 pounds of N. They will be summarizing the results at winter meetings this coming winter. Now if the 60 pounds of N match or beats higher rates of N, they will have to develop new field trials to see what additional steps could be added to return ever higher ROIs.

Tar spot

As expected, there are more reports of tar spot appearing in different parts of the state and in more states.

I just took a call from a client near Monroe, Wisconsin. It is appearing in only the one field which received 6,500 gallons of dairy manure, which would have contained the normal amount of Gly, which would be .75 pounds/1,000 gallons manure. We now know that an application of Paleo Biotica’s microbial mix may need to be applied to degrade the herbicide residual in the soil prior to planting a conventional hybrid in 2025.

The Big Farm Progress Show

The days of the big show are getting closer. There has been lots of activity at the site in preparation of this biannual show. We just hope it stays sunny at 76 to 78 degrees and a light breeze.