How to Use Weed Killer

Dandelions are lovely but invasive.

Most lawns contain at least a few weeds, but when they overrun the grass or crops in a farmer's field, most people reach for a herbicide to kill them. Choosing the right weed killer is important but the proper application of herbicide can be just as essential to its effectiveness.

Things You'll Need

• Herbicide
• Sprayer, spreader or applicator
• Measuring cups and spoons
• Buckets for mixing (if necessary)
• Garden gloves
• Garden shoes or boots
• Eye protection (goggles or safety glasses)

Instructions

1. 

   Match the herbicide to the task. Weed killers are labeled with the names of the weeds they are formulated to kill. If you're aiming to kill a few dandelions, you may be able to use a hand sprayer or pump with liquid. If your problem is more widespread, choose a granular form that can be dropped from a lawn spreader. Methylchlorophenoxypropionic acid (MCPP), 2,4-D and dicamba are common post-emergent broadleaf weed herbicide components. Pre-emergent crabgrass systemic root and seed-killing poisons include benefin and trifluralin. Glyphosate is a common systemic poison; good for killing just about anything that grows---including grasses, ornamentals and woody plants.

2. 

   Use the right applicator. Dilute liquids according to package directions using measuring cups and spoons and containers that are used only for garden use to avoid cross-contamination with food. Pre-mixed sprays come in their own bottles but dilute sprays should be mixed in sprayers designed for herbicide use. Use a drop fertilizer spreader rather than a rotary or broadcast spreader for granulated herbicides---particularly in small areas where over-spread may land on ornamentals. Ask for help when purchasing applicators if instructions are unclear or if you've never used weed killers before.

3. 

   Mix liquids according to directions and set drop applicators for the number of pounds per foot indicated on the packaging. Lighter concentrations may not kill weeds and heavier concentrations may burn out surrounding plants or leave residual chemicals in the soil, affecting future plants. Always wear gloves, shoes (or boots) and eye protection reserved for gardening use when using herbicides. Spray or drop herbicides only when the wind is calm to control application. Mix only as much solution as will be use--you can always make more.

4. 

   Drop or spray pre-emergent killer early in the spring before plants start growing so it can work on roots and seeds in the ground. Apply broad-leaf weed killer when weeds are actively growing so that the chemicals can be absorbed into the plants' systems. Avoid over-spray with liquid herbicides and drop granular herbicide following a regular pattern going back and forth in two directions for even application. Spray or drop post-emergent herbicides when leaves are wet; in the morning when dew lies on them or after rainfall or watering.

5. 

   Clean up when application is complete. Rinse empty containers and applicators. Dispose of extra herbicide according to procedures for hazardous chemical waste in your community--many operate waste disposal programs or participate in Clean Sweep programs. Wash hands and face with lots of soap and water. Wash garden clothing and gloves and boots after using herbicides to avoid tracking weed killer where it's not wanted. Dispose of rinsed containers in the trash and store unused chemicals in a secure cabinet with their contents clearly marked.

Tips & Warnings

• Groundskeepers that handle herbicides and pesticides use special coveralls, rubber (or nitrile) gloves and eye protection and may wear respirators for sprayers and open-air granulated spreaders. Residential applications may require less personal protective equipment. Keep clothing for the garden that can be easily cleaned to keep poisons out of the house. Weed growth is often merely a symptom of deeper problems. Check for soil compaction, poor drainage, low nitrogen levels, improper pH or shallow watering; each can create an environment that favors weed growth. Before resorting to the use of chemicals, diagnose and correct cultural problems.

• If there's no list of species a herbicide is effective on, put the package down--labeling is required by the government. Never empty containers of herbicides down drains. Whether dumped in a sanitary or storm sewer, they will upset the environment as they work through the system into lakes, rivers or water tables.

References

• Weed Control for Home Lawns
• Application Methods

Resources

• Types Of Herbicides
• Woody Plant Control
• Weed Control for Home Lawns