Using Herbicides? Try Precision Spraying!

by Lon Drake

There’s been much debate – sometimes heated – over whether to use herbicides in weed control. What I’ve found is that folks who are responsible for more than an acre or two of land usually resort to herbicides as part of their conservation management program. The challenge then becomes how to use these sprays, while taking into consideration the concerns brought up in debate.

How do you accurately apply the spray – with almost surgical precision – to take out only the bad guys? For me, the key has been to use a backpack sprayer, which is suitable for operating at very low pressure. This allows me to spray small drops, which respond quickly to gravity, rather than creating a mist that drifts about on the slightest breeze. This is accomplished by squeezing the trigger first, with no pumping pressure, and then gently pumping up to just enough pressure to produce small drops, before any mist starts forming. With just a bit of practice, I can easily maintain this pressure with one hand, while directing the wand with the other hand. I’m usually able to aim with precision of less than an inch, while walking slowly.

But what happens when I encounter that tall alien? When a tall alien is beside a desirable native, I will try flattening it with my boots and then spray it. But don’t bend over while wearing a backpack sprayer! Most sprayers have vent holes in the top of the tank to prevent a vacuum from forming as you pump out the contents, and these holes will leak and drip herbicide down your back if you bend over to manipulate a plant with your hands; so use your feet.

My experience is limited to water-based glyphosate herbicide and oil-based herbicides may require some other adjustments. But doing your best to minimize drift – with precision spraying – will help reduce your collateral damage.

Photo caption: A low pressure/small drop demonstration, spraying onto pale, dry gravel so that the wetted pebbles provide dark contrast. I am following the edge of a 1.25” wide orange ribbon, held down with pebbles to keep it from moving in the light breeze. Applied at the pace of a slow walk.