Off-target movement of herbicides carries a risk to your own crops, your neighbour’s crop and your insurance premiums.
Particularly with the arrival of Group 4 and Group 9 herbicide technologies, there may be a perception that weed management has become simpler. But resistant weed biotypes are confounding that notion and are challenging growers and their advisors with tank-mix solutions and the importance of application timing.
Why it matters: Agronomists say industry and farmers need remedial training in off-target movement as seed technology and herbicide resistance increases.
Read Also
Staging slip leads to corn damage after Dicamba spray
The Ontario Weed Tour at the Elora Research Station discussed how plant staging accuracy, timing and weather conditions can significantly impact crop health, yield and limit potential herbicide application injury.
The underlying factor in this scenario is off-target movement, where herbicides end up on crops outside the target field and result in poor neighbour relations and loss of yield for crops intolerant of the spray.
Chad Anderson, a certified crop advisor with Anderson Agronomy Services near Brigden, has been calling attention to this issue for years. Instead of differentiating between 2,4-D and dicamba, he identifies it as a Group 4 challenge.
“I worry that as Enlist acres increase, the incidence of dicamba drift will increase, since soybeans are so sensitive to it,” he says.
“Before an Xtend grower need be concerned about conventional soybeans next door, now they will need to know if their neighbour is planting Enlist or Xtend, as well as be able to manage their applications.”
That means applying dicamba as early in the season as possible, when soybeans have yet to emerge or are just out of the ground.
Enlist technology is enticing to growers who want to wait until later into the season to address fuller weed flushes. Yet this is where the opportunity for off-target movement increases the risk of more severe damage and crop loss, even though soybeans are more tolerant to 2,4-D than dicamba.
“The worst drift scenarios I have been involved with have been where conventional soybeans were initially hit with a dicamba drift and followed by a 2,4-D drift,” says Anderson.
“The soybeans just seemed to quit growing, especially in a year like (2022) where we suffered so much compounding stress from the dry June and July we had.”
Definitions for everyone
Another part of the challenge is a proper understanding of terms. Just as some in the industry use “varieties” and “hybrids” interchangeably, many in the industry find it hard to differentiate “drift” from “volatilization”.
Shannon Bieman believes everyone in the industry has confusion about various terms.
“Absolutely, there’s not enough of an understanding,” says Bieman, a certified crop advisor and head of market development for Western Ontario with SeCan.
“We have to educate ourselves in the industry to do a better job of helping growers. We need to talk about the weather, sprayer tips, record keeping and having those conversations with neighbours. Ninety-nine per cent of growers want to get along, so we need to keep the lines open.”
Bieman took that challenge to heart by enrolling in Peter Sikkema’s weed science course last year.
Among other things, she learned there are few days in a growing season without a thermal inversion. And she learned the fallacy of the statement, “I can spray: there’s no wind!”
Needed education also includes optimal use of herbicide-tolerant seed technologies and understanding the “why” as much as the “what” of the purchase.
“What chemistry do you need to address the problem?” asks Bieman. “Is 2,4-D more important? What weed spectrum are you going after, and why? This is no longer a variety issue.”
Anderson agrees that growers often miss important messages about chemical technology. It’s troubling that some are unaware that they’re required to spray dicamba with an extra- to ultra-coarse droplet size.
This becomes an even greater concern when it comes to liability insurance deductibles.
“Private insurance companies use your liability insurance to cover one field when they drift on another,” says Anderson. “The thing is, they have to be negligent – making the application off-label, wrong tips, wrong wind direction or too windy, too calm. If you’re a multiple offender, you will see premiums rise but normally these policies carry no deductibles. This is starting to change because the amount of claims has become very worrisome.”
