Don’t let warmer temperatures and the longer, sunny days of late spring or early summer tempt you into spraying brush before it’s ready. A little patience will pay off in better results when you hold off on foliar applications on woody plants.
No matter how badly you want to rid your pasture of that greening multiflora rose or the locust sapling threatening your fence line, it’s too early to make foliar (leaf-spray) applications on awakening woody plants.
“Patience is critical for foliar brush applications,” explains Jodie Crose, an Oklahoma-based field scientist with Corteva Agriscience. “Two things must happen for success. Target plants need enough leaf area for herbicide uptake, and once the herbicide is in the plant, it needs to translocate throughout for more complete control.”
Neither can happen this early in the growing season. During spring greenup, nutrients are traveling up through the plant and pushing out new growth. A foliar application that’s too early won’t adequately translocate throughout the plant, leaving the root system alive and intact. By late spring, trees and other woody species might appear to be fully leafed out. Most likely, they still are pushing out new growth. Hold off on spraying until new growth ceases.
“A plant can appear to be leafed out, but until new spring growth is complete, it is still pushing out new growth, which inhibits herbicide uptake and movement into the plant,” Crose says. “Once that new growth is complete, the plant will then begin moving nutrients — and the herbicide — to the roots.”
Treatment timing for foliar applications depends on several factors, including geography and the type of spring. The window for these applications opens earlier in southern regions and progresses north. An early spring can allow for earlier spraying, but as a general rule, hold off on foliar brush treatments until late May. Waiting until late June or July is even better, especially in northern regions.
“A preventive approach to brush control is always the best choice,” Crose says. “But you also want the best results possible. If warm spring days have you itching to get the jump on brush, you have options. Low-volume basal and basal cut-stump treatments perform year-round and can tide you over until plants are fully leafed out.”
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