Before you spray pricklypear, be sure the spray solution won’t be intercepted by other vegetation. Coverage is critical for control.
You can control pricklypear with MezaVue® herbicide almost any time of year if you cover the cactus with the herbicide.
Repeat that last part for emphasis: if you cover the cactus with the herbicide.
“Coverage is critical to pricklypear control,” says Charles Hart, Ph.D., a rangeland ecologist and market development specialist for Corteva Agriscience. “The herbicide has to get into the plant through the pads or roots to work.”
That sounds elemental, but it’s something to think about as you plan. It’s possible for vegetation to intercept the herbicide before it reaches the pricklypear. Typically, that’s tree leaves or tall grass, and it’s more of a consideration for aerial application.
Many ranchers aerially spray pricklypear between Nov. 1 and March 31 when mesquite leaves are off to improve coverage. “But if leaves aren’t a factor, spray in late summer or fall,” Hart says. “That’s actually when pear is most susceptible to the herbicide.”
If an overstory of dense forage obscures the pricklypear, find a way to reduce it before you spray, Hart advises. One way is intensive grazing followed by spraying followed by rest. Or you can capitalize on heavy snow or ice that pushed down the forage to expose the cactus. Prescribed burning is another option. Burning also weakens pricklypear to aid control.
Ground broadcast applications and individual plant treatments (hand-spraying) with MezaVue typically post better — and faster — results than aerial applications.
“That’s primarily due to better coverage — more herbicide solution on the pear pads,” Hart says.
From aerial application of MezaVue at the labeled rate of 32 ounces per acre, ranchers can expect 65% to 82% control two years after spraying, based on trial results.
“That assumes good coverage and proper application, because both really matter,” Hart says. “That means you use no less than 5 gallons per acre (gpa) total volume [water and additives], and more is better. I like 7 or 8 gpa. Use a reputable applicator. If you shave the application volume or herbicide rate, control falls off pretty fast.”
In studies by Corteva Agriscience, ground-broadcast applications usually average 10 percentage points better control than aerial, Hart says. Ground applicators typically use MezaVue at 32 ounces per acre in 10 gpa to 20 gpa total volume.
Hand-spraying is even better. Individual plant treatment (IPT) has produced nearly 100% efficacy in trials.
No matter how it’s applied, MezaVue is faster than the old standard herbicide. Ranchers often see yellowing of pricklypear just four months after application, desiccation (significant drying) in a year and plant mortality in two years. For pricklypear treated with the old standard, all symptoms were slower to appear and pricklypear could take at least three years to die.
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