Renewable Farming

August Vegetative index

Consultant Bob Streit’s crop update for week of Aug. 24

There is now a chill in the air that sure makes it feel like fall is not too far away. Now if that doesn’t send a shudder down your spine nothing else will. We all enjoy fall, with its pleasant days and brilliant colors. It’s what come later that we don’t look forward to. In previous years, much of the Midwest went into the fall with farmers thinking that if we could just get a good rain, the crops would be able to add bushels. Then those late rains never came in time. This year is different in that much of Iowa and some surrounding regions have received over 6 inches of rain with all of it soaking in. In some ways we are prepping for the 2016 crop at this point. Going into a new season with a full soil moisture profile almost guarantees a trendline crop.

Strange sights: For the second time in my life it happened this morning. This morning while heading home from 8 AM mass on Boone’s east Mamie Eisenhower highway, I came upon a 40 pound beaver which had gotten run over last night. What he was doing about five miles from the closest stream? He was not as big as the 60 pounder I saw up by Ft Dodge about fifteen years ago.

 Yield Potential: The Pro Farmer Crop Tour was conducted last week. There are groups of field scouts that cover the eastern states while the other half heads west. They stop at fields at predetermined distances, then enter the fields and make their corn and bean yield estimates. The latter is done via pod counts. What they found were state by state estimates which may make waves on the grain markets. They found fields that looked worse than the USDA has guesstimated in both halves of the country. That is qualified by acknowledging that the eastern states plus MO and KS ratings have been very low while the western states plus WI have been much higher in ratings.

The first clue to that might be what a marketing person in Illinois has been watching. He has noticed that the vegetation index for nearly all the states has been lower than in 2014. Those NDVI ratings typically don’t lie, and usually end up being reflected in the final yields.  Here’s the latest image for the U.S. compared to a year earlier. Brown means less “green-ness” than the same time a year earlier.

August Vegetative index
U.S. August 19 Vegetative Index compared with 2015


Corn Health: Over a four-day period last week it was very apparent that something bad was happening to many corn fields. In those fields, the plants went from very green to having a very noticeable percentage of leaves turn either yellow or brown. This all happened while there was no shortage of water to the plant. So how many growers were scratching their head asking what was going on, and thinking of how many bushels might that cost them? It appeared that fields which ran short of N showed great occurrence of that phenomena. How much will this continue over the next few weeks? Will it be such that local seed plots will be cut short when the varieties are embarrassing to show? Time will tell. Will it affect final yields as the plants will lose their ability to fill the kernels as deeply as they should have?

In some cases these fields received several applications of fungicides to maintain plant health. In cases it has been something outside of a disease causing pathogen like a fungus or bacteria that is causing the change in plant appearance.

What is also apparent is how different microclimates are making a big difference as far as how healthy one hybrid is along Hwy 3 versus Hwy 30. The first area was drier thru mid August than the latter. In grape and veggie country they will have sensors and programs set to alert growers to the need to apply their fungicides after a set number of dew hours based on humidity, temps and dew points. While we don’t have such sensors in place here, the diseases act by the same environmental rules.

The important question is what percent of the grain fill will have been completed before the effective healthy leaf area index drops below what is needed to complete grain fill plus maintain plant health.

Now that we have a name to put on those caramel colored lesions that have been showing up for seven years we can build on our knowledge of the disease and potential ways to manage it. So far the fields that have received the BioImpruv look very good. As of Sunday at 8 PM, I have one jug of the improved version to place. If the results look good and other trials verify its systemic activity, it offers the potential to apply early and manage/control late season disease problems.

Ear Size: Many corn growers who are scouting their fields are seeing that kernel row numbers seem to be lower than normal. What should be 16-18-20 is more likely in the 14-16 range. What might have happened? The kernel count is decided during the V4 growth stage. Having the cellular P content at .42 or higher at that stage was determined in Purdue research to be very important to getting the higher kernel diameter. With the conditions being very wet and cool in May, plant uptake of P may have been reduced via low uptake due to low ET or high dilution within the root zone. Planter applied fertilizer or early foliars can be very helpful in tweaking this level up.        

The other factor can be low zinc levels. A well respected nutrient expert recommends having Zn test levels in the 3 to 5 ppm range rather than the old 1 ppm standard.

Soybean Potential: On the Pro Farmer Crop Tour, the important observation was the large number of small pods and continued flowering that offered the potential for another 25 to 40 pods per plant that could still fill with seeds if the weather is conducive to filling them. We have the moisture available. The question will be available nutrition and adequate sunshine and heat. If one has to read their crystal ball, it appears the hint of fall in the air is causing the earlier planted fields to show the first signs of yellowing already. Optimum nodulation and sunny, warm weather will be vital for the potential to be realized. 

Ag Shows: The 3-I granddaddy Farm Progress Show is scheduled for Illinois next week. It is being held a week later than normal, likely because not enough corn was ready for demo harvest last year. The cool spring and slow growing degree day accumulation left the early RM corn still over 35% moisture.


Insects: And now, roughly six weeks late we are seeing the corn rootworm beetles appearing. They should have been emerging closer to July 5 along Highway 20. It sure suggests that through the continued use of granular insecticides and traits we have been selecting for the late hatching variants.

Several years ago there were efforts to label several liquid insecticides for a later season application using the Y-drops, so a product could be applied closer to the time of egg hatch. The research dollars and corporate support got pulled away for other uses, so the idea never got promoted. Maybe it is time to reexamine this practice in the heavy rootworm areas. Luckily the heavy pressure of a few years ago has been reduced by natural factors.

Bob Streit  Boone, Iowa   (515) 432-0907