Many years ago, I was asked by a well-respected agricultural chemical company to find answers to a puzzling situation. Growers had been reporting to the company that their fungicides were ineffective and not performing as advertised. Despite following dosing instructions, crops were still succumbing to fungal diseases. The growers were understandably frustrated and angry, and this had the potential to blow up into a lawsuit against the company in question.
I conducted a detailed study of affected fields and their surrounding region, and found why the fungicidal products were failing: all the affected growers lived in a positive eddying zone.
Positive eddying zones are regions where, due to weather patterns and the structure of underlying geographical features, winds swirl in place. They collect and concentrate debris much as a swirl of wind crossing your porch on a windy day brings with it a pile of leaves and trash.
In Northern and Central California, winds tend to originate off the West Coast, funneling their way in through the Carquinez Straits west of San Francisco. These winds flow across the Central Valley until they run into the Sierra Nevada mountains. Here, the wind effectively splits, with some spinning off to the north, and others to the south. As these winds continue their journey, they lose speed, eventually dissolving into swirling eddies. It is at these points where they form positive eddying zones, where they not only concentrate dust and dirt, but also fungal spores and other disease-causing organisms.
But, why did the fact that these growers were located in eddying zones present a problem? Farms and vineyards in positive eddying zones face 2 to 3 times the normal disease pressure found in regions with ‘normal’ wind patterns. It’s the difference between sitting in a room with a couple sick people, versus 5 or 6 people.
Growers have long misconstrued product inefficiencies caused by environmental factors, instead blaming them on fungi and pests developing resistance.
In the case of the growers who found their fungicides ineffective, they needed to increase the rate and/or the frequency of applications. Once the effective dosage was increased to compensate for the increased levels of inoculum (disease-causing particles) in the air, the treatments took hold and repelled infection.
Pesticide resistance is not nearly as common as is popularly believed. For example, I have witnessed resistance in laboratory studies. But despite many years in the field, I have yet to see resistance shown in the real world, at field level.
There’s a good reason for this. An organism is susceptible to a pesticide due to the nature of how it works, and what makes it successful as an organism. In most cases, a mutation which confers resistance also undermines its ability to be successful in nature.
Consider the venom of most species of rattlesnake. Rattlesnake venom is hemotoxic, meaning it disrupts the ability of blood to clot, which leads to internal hemorrhaging and other issues. Now, imagine a person who, due to a genetic mutation, overproduced blood platelets. This person would have a natural resistance to rattlesnake venom, but at the cost of a serious propensity for blood clots that would likely prove fatal before they ever got the chance to pass this resistance along.
But even if a mutation isn’t inherently fatal, it typically puts an organism at a competitive disadvantage. Most fungicides work by inhibiting metabolic processes—how absorbed nutrients are turned into energy. A fungus might develop a subtly changed metabolism that drops the use of a protein or enzyme a fungicide typically acts upon, thus making it resistant. But this almost certainly results in a less effective metabolism as well, which extracts less energy and provides less fuel for growth and reproduction. The mutation is a short-term victory for the resistant fungi strain, but it soon finds itself crowded out by more nimble and fast-growing competitors.
As I said, I’ve seen resistance in the lab. But a laboratory is a gentle and kind environment ideal for fostering genetic innovation. Nature isn’t nearly so patient. Hence why I have yet to witness pesticide resistance in the field. When an organism gains resistance to pesticides, it generally loses viability in the long-term, and that mutation dies out.
This is why when a grower reports that their pesticides and fungicides are becoming ineffective in the field—as was the case with those aforementioned growers many years ago—a PCA’s first suspicion is that there’s a previously unsuspected environmental factor in play.
But for grower to recognize environmental causes for complications in the field, they need the assistance of a plant disease laboratory.
It can be challenging enough just to diagnose a disease in the field, let alone understand why a tried-and-true product appears to have lost its effectiveness. Perhaps symptoms are manifesting in such a way that you’ve misidentified the culprit. Or maybe you’ve made an accurate diagnosis, but disease levels are far more severe than is readily apparent. No pesticide, fungicide, or other agricultural product you pick up off the shelf is going to work if the situation isn’t what you think it is.
That’s where an agricultural laboratory like Sunburst Plant Disease Clinic comes into play. When you work with Sunburst, here’s what happens:
- Experienced PCAs can examine your fields and take soil, water, and plant tissue samples, and protect these samples so they don’t change from the moment of sampling to the time of examination.
- Lab technicians examine the samples, looking at the chemistry and biology of the water and soil samples, and scrutinize the plant samples for otherwise invisible evidence.
- Our scientists also take a step back and consider the bigger picture—the predominant wind patterns that run through your farm and the surrounding region, the nature of the previous crop and any difficulties it experienced, and the surrounding growers and their quality of farming—especially upwind growers.
- Other details examined may include water quality, history of herbicide use, characteristics of particularly difficult pockets of soil, the high and lows temperatures on your farm, and so on.
- Then, we summarize all the relevant particulars, and generate a state-of-the-art, season-long program that guides you through the entire year.
You will almost certainly be pleased with the outcome. Products that previously lacked effectiveness will suddenly work miracles, when applied in a way appropriate for your local environment and crops, and in combination with other necessary treatments and nutritional supplements.
Many of our customers are shocked at how much simpler things become. As the manager of one of our top distributors said, “When Dr. Tom and his team at Sunburst and Fusion came into our lives, they made farming fun again.”
If you’ve grown frustrated with farming, consider giving working with Sunburst PDC and Fusion 360. Leave the worrying to us, so you can focus on what you’re good at, and rediscover the joy it brings you.