Spring officially arrived at 5 PM on Sunday afternoon. In central Iowa the weather was 45 to 50 degrees, so it felt like spring. Earlier in the week in way NW Iowa and SE South Dakota the single digit wind chills and the snow banks being 4 ft high and snow piles made when lots had to be cleared off were 8 to 10 feet tall, it felt more like winter. So gradually the temps will warm, with one noted meteorologist predicting below normal temps being the rules until April 15th. Though that will slow any progress being made in the fields it is much preferred to conditions for the past few months out in California. Several weather forecasters were predicting one to several of those storms to hit the west coast, but few of them could read the weather clues that a total of twelve of them would drop enough water and snow on the state to place 30 million of their inhabitants under flooding threats.
While flooding problems happen a long way from the Midwest we will feel the effects since a high percentage of our winter and spring vegetables are produced in several of their valleys. For instance, a major portion of strawberry supply usually comes from the Watsonville, CA area. Last week a levee in that town broke and many people had to be evacuated. In their high mountains where they were in a historically severe drought, the snow pack in places is 187 inches. The only good thing is that the extra water should fill most of not all of their reservoirs.
The Final Crop Meetings
We had the late winter meeting with the Iowa Crop Consultants Group. We heard from a major pesticide firm as to what new products have been mixed so they can launch a new three or four-way mix in an attempt to throw more modes of action at our troublesome weeds. It has become common to every season to hear that a once dependable herbicide is now having weed breakthroughs and can no longer depended upon the product to provide acceptable control.
In an associated note the crops site at the Univ of Wisconsin, Madison gave the details on a research project being conducted to rate the control data of how complete the waterhemp control was when planted into a crimped or rolled cereal rye was. So, this grad student had sizeable rectangular plots where they placed mats of rye grass on the ground representing increasing rates 500 lbs/A, 1,000 lbs and so on of dry rye straw to those plots and then measured the degree of water hemp control the residue provided. They used thermometers and light meters to detect the influence the straw had on waterhemp emergence thru limiting sunlight hitting the soil, lowering topsoil temps and competition for sunlight. Given the fact that Wisconsin researchers have identified degrees of tolerance or resistance of waterhemp to both Authority and Flexstar, such knowledge on the value and ability of cereal rye to minimize waterhemp pressure could be increasingly important.
In that research work they found plants that required a 3X rate of Authority to give acceptable waterhemp control. As to the rate of Flexstar needed to give acceptable control the herbicide rate had to be at 10x of normal.
Growers have grown to be totally dependent on weed control in a jug. Resistance to herbicides was always something that was talked about in the Delta states of in Australia. Now it is here in Midwest. We are not alone as we attended the Big Agro-Expo down in Argentina a few years ago and they were tracking where such resistant weeds were being found in South America.
Tar Spot
At this consultant meeting we heard all about Tar Spot and their recommendations for managing it. My contribution was to ask what his company had found when they did tissue analysis for mineral levels in the leaves. It was a deer in the headlights look. In a lengthy power point covering a five- decade time period I had assembled to use in meetings to describe our major crop diseases and on different approaches to minimizing the cost or potential losses from them. I pointed out how modern disease control in human and plant disease management has gone off the track.
In modern medicine the doctors are told to see as many patients per hour or per day and generate as many admissions or possible plus write as many prescriptions as possible. If they don’t follow the rules they may not keep their job. Now as to how crop advisors or most agronomists go about their job is to use a microscope and a pictorial guide to do their diagnostic work. The next step is typically to decide which chloride or fluoride fungicide should be applied, what rate and how many applications need to be made. Recognize that those two halide compounds kill living things, including beneficial microbes. A person hoping to improve soil health has to recognize the conundrum of his or her disease control situation has to develop a revised approach and see what other products are available.
I have not mentioned this before. I found out that a group of seed growers in Iowa are now applying a non-selective systemic herbicide to their seed fields up to five times per season. Three times for weed control and twice to kill the tassel on the female plants. Each year more of the product is accumulating each season, as the primary metabolite of the herbicide is even more toxic than the original product. The net effect is that a number of the mid major and micronutrients in the soil that should normally be available for use by the plants to stay healthy. The herbicide chelating action interrupts this availability. Detecting this tie up and distinguishing between available vs tied up minerals can only be done using a nuclear collider or synchrotron. Until now rapid degradation of this herbicide was not possible. As of this spring a new microbial mix which includes several ancient lactobacillus bacteria were found to be capable of degrading the secondary metabolite. It was developed by a lady microbiologist/biochemist from Colorado and Kentucky named Martha Carlin. Based on what top people think and current knowledge applies, growers who have had major losses from Tar Spot will have to stop the chelating action of the residual herbicide to allow the availability of the immune response of the plants.
New Old Sprayers
Be aware that progress has been made using the idea of electrostatic sprayers. The boom put a positive charge on the small spray droplets. These particles were attracted to all surfaces of the plants, tops, sides, and undersides of the leaves. One degreed engineer has figured them out and is building small models to be used for demo trials. The amount of product used was reduced and there was little off spray. Several sprayer companies in western Europe were building and selling them in the mid-70s to early 80s.
I was made aware of one small company that has been building such sprayers and selling them for grower use. I hope to get more of the details on this company and their products. What is known is that the amount of carrier recommended is greatly reduced and the positive/negative charges of the plant and spray ensure that the spray coats the leaves.
Now that the gardening and production season is approaching it may be beneficial to know that a new non-selective, safe herbicide was developed by a German chemist over in Australia a few years ago and given the green light for application in the U.S. It is called Terminator 20 and is made by Contact Organics. I applied it to Canadian thistle a few years ago and it fried them in four hours. A few notable places and institutions using it for vegetative control include the campus of Harvard Univ and the top golf course where the Masters, the National, is played. I am not a golfer, but golf courses receive heavy doses of pesticides to keep the course looking as green as possible. It has been pointed out that greenskeepers and professional golfers have troublesome health records.
In an era where the first U.S. made commercial sized optical sprayers were used in vegetable production fields out in Arizona in Feb of 2022 in corn fields in Nebraska later in the summer it will be interesting how we integrate these products and application equipment in the near future.
The Major Insect Problems
The one on-going insect problem in corn has to be the corn rootworm. We have seen soil applied insecticide and genetic traits fail due to selective pressure for insects and the microbes in their GI tract which can evolve and become resistant. So, what might the answer be to CRW feeding? Most educated guesses include several forms of biological control or the development of attractants which can be used for adult control. Three of these are on the near horizon. Let’s hope we see them.
Nematodes and their damage remain a mostly hidden problem that is not recognized or acknowledged. There are several biological control products currently awaiting EPA approval. Why does it take so long for their staff to act?
Bob Streit is an independent crop consultant and columnist for Farm News. He can be reached at (515) 709-0143 or www.CentralIowaAg.com.