Glyphosate is the most widely used herbicide in history. It kills nearly all plants by inhibiting the EPSP synthase enzyme in the shikimate pathway - a metabolic process that exists in plants and microorganisms but NOT in animals. It is the active ingredient in Roundup and hundreds of generic products.
Nearly all annual and perennial weeds, grasses, broadleaf plants, and woody brush. Non-selective - kills virtually any green plant it contacts. Used for: driveway/patio weed control, fence line clearing, pre-planting field preparation, stump treatment, invasive plant management. Does NOT work as a pre-emergent - only kills actively growing plants.
Roundup (Bayer/Monsanto - the iconic brand), Ranger Pro, Compare-N-Save Concentrate 41% Glyphosate, RM43 (with imazapyr for total vegetation control), Rodeo (aquatic-labeled formulation), Hi-Yield Super Concentrate, hundreds of generic 41% glyphosate concentrates.
Low acute toxicity to mammals, birds, and fish. The active ingredient glyphosate has an excellent acute safety profile. However, the formulated products (especially those containing POEA surfactant) have higher toxicity than the active ingredient alone.
Application basics: Apply to actively growing weeds on a calm, dry day. No rain for 6 hours after application. Visible results in 7-14 days (it works slowly because it is systemic - traveling from leaves to roots). Do not mow for 7 days before or after application.
Concentration guide: For annual weeds: 1-2% solution. For perennial weeds (dandelions, quackgrass): 2-3%. For woody brush and stumps: 5-10%. Most consumer products are pre-diluted ready-to-use at appropriate concentrations.
The drift problem: Glyphosate kills ANY plant it contacts. Spray drift onto desirable plants, trees, and gardens is the number one complaint. Use a shield or cardboard barrier when spraying near valued plants. Never spray in wind above 5 mph. Foam markers help prevent overlap.
Non-selective means NON-SELECTIVE: It will kill your grass, your flowers, and your vegetable garden just as effectively as it kills weeds. For lawn weed control, use selective herbicides (2,4-D, dicamba) that kill broadleaf weeds but spare grass.