Many people use weedkillers, but may be unaware of the range of formulations available for different garden situations.
Information about chemical constituents and mechanisms
Spot treatment
Ready-to-use spray guns
These often have a range of spray width options, from a narrow direct jet, to a dribble, to a fine mist-like spray. Twisting the nozzle allows you to adjust the spray width to your requirements. Spray guns are an easy and quick way to spot-treat patio weeds.
If a paint-on gel proves difficult to obtain, it is possible (with caution and accuracy) to use the direct jet setting of a spray gun to spot-treat weeds in garden borders.
The foaming aerosol formulations for glyphosate (Advanced Glyphosate Spot Weeder for Paths & Patios and Advanced Glyphosate Spot Weeder for Beds & Borders) are also worth using for spot treating perennial weeds.
Treatment of tree stumps
- These are best treated by applying weedkiller directly to the stump, concentrating it in the outer ring of live tissue just beneath the bark. This is where all the tree’s transport mechanisms are located, and chemicals applied here will be taken down into the stump roots to kill it off entirely.
- Weedkiller is best applied to fresh stumps, as live tissue is needed for its uptake. If the stump is only a few weeks old, you may be able to expose live tissue by cutting the top off to expose a fresh-cut surface.
- The best time to apply stump killers is from autumn to winter. Avoid treatment in spring and early summer when the sap is rising.
- Stump and root killers containing ammonium sulphamate were withdrawn from sale in 2007 and can only be stored and used until 22 May 2008. Replacement products containing glyphosate (Roundup Tree Stump & Rootkiller and Deep Root Ultra Tree Stump & Weedkiller) are now available, along with the existing stump killer SBK Brushwood Killer (containing triclopyr).
To apply them, follow the manufacturer’s preferred method. This may involve treating the entire cut surface of the stump, drilling holes around the living edge of the stump to pour the granules into, or using a chisel or axe to make wedge-shaped incursions around the edge of the stump, prising the bark off the living tissue without removing it completely. These notches can then be filled with granules or brushed with the liquid weedkiller. Finally, cover the whole top of the stump with secured plastic sheeting, to prevent the weedkiller being washed away by rain.
Always follow the dosing, application and health-and-safety instructions given on the label of the product concerned.
Please note: Although it is not a legal requirement to wear protective clothing when handling and using amateur/home pesticides, you may want to wear gloves, Wellington boots and other protective clothing to be on the safe side.
Using weedkillers safely and effectively
Maya Albert