From Landscape Alert Newsletter
Vol. 21, No. 1, June 23, 2006
Bert Cregg
Horticulture and Forestry
Let’s face it. Most of us can’t imagine keeping weeds out of our lawns, gardens and flower beds without herbicides. But several of the products we rely on most, such as Round-up (glyophosate) and Weed-b-gone (2-4-D) can wreak havoc if they drift onto trees and shrubs. Both products are contact, post-emergent herbicides. That is, they kill plants by entering through the leaves and interfering with the plant’s metabolism. Glyphosate is a non-selective herbicide. When spraying Round-up around your yard, act as though anything green you spray it on will die, because it likely will. 2-4-D is a selective, broadleaf weed killer. It will kill dandelions but not your turf grass. It can, however, also kill your shade trees, shrubs and bedding plants.
One of the keys to using herbicides safely around the home is reading and following the label directions. One the most important cautions on contact herbicide labels is to avoid drift. Here some ways to help keep herbicides on the intended target and avoid collateral damage.
Use the Weather Channel
Professional pesticide applicators carry wind speed gauges to determine if wind speeds are within acceptable limits. Most homeowners don’t have an indulge but you can check out your “Weather on the 8’s” to get local wind speeds. There is no magic number for wind speed though ten miles per hour is a common rule of thumb as a limit for spraying. Remember winds are highly variable, especially around buildings and trees. Even through the general wind speed might be acceptable, you can sometimes have wind tunnel effects between buildings or between your garage and a tree windbreak.
Spray early in the day
The is usually calmest first thing in the morning and picks up as the day wears on. Try to schedule your spraying as an early Saturday or Sunday morning activity.
Use Weather.com
In the local weather section of Weather.com you can select the ‘Hour by hour’ feature, which includes predicted wind speeds, to plan your weekend spray activities.
Back off the pressure, man
Reducing the pressure on your sprayer can help reduce drift by increasing droplet size. Since most homeowners use pump-up hand sprayers, this means pumping up the sprayer a little more often, but with fewer strokes.
Adjust your nozzle
Again, larger droplets mean less drift. Avoid fine mists to help keep herbicides off of unintended targets.
Herbicide injury is a common problem in many landscape plants. Avoiding drift is they key to avoiding accidentally frying your prize azalea. Everyone’s time is limited on the weekends. Plan ahead and get your spraying done when the wind is down.