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This stuff goes on sale every year beginning around May. That's because using it in temps above 85 degrees, WILL KILL YOUR LAWN, as well as the weeds. Even if you think, hmmm, I'll just apply it late in the day when it's below 85 degrees, that won't work, becuase the next day when the temps go back up, your lawn will begin its slow death march. HIGHLY recommend you read the label CAREFULLY before you apply. The best case for buying it is to pick up enough when it's on sale for a couple of applications to be used in the months / seasons when temps are down.
It's 2-4-d, dicamba, and some other salt. Basically broad left post-emergent. It's not roundup or non-selective so just for spot spraying easy to kill common weeds
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from IvyCharizard
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Roundup is awful for people and the environment.
I spot treat with this and I am happy with the results.
Fwiw:
The product you're viewing — Spectracide Weed Stop For Lawns Concentrate — contains four active ingredients: 2,4-D, Mecoprop-p (MCPP), Dicamba, and Sulfentrazone. Here's a breakdown of its toxicity profile:
Environmental Toxicity
Spectracide Weed Stop For Lawns:
Aquatic life — Moderately to highly toxic to fish and aquatic organisms. The label explicitly prohibits application within 25 feet of rivers, ponds, lakes, streams, reservoirs, marshes, estuaries, bays, and oceans
Soil — The active ingredients are water-soluble and can leach into groundwater, especially on sandy or permeable soils
Beneficial plants — Dicamba is notorious for vapor drift, capable of damaging nearby non-target plants (gardens, trees, shrubs) even when applied correctly
Bees/pollinators — Low direct toxicity to bees, but can harm flowering weeds that pollinators depend on
Birds — Low acute toxicity at normal use rates
Breakdown — 2,4-D and MCPP break down relatively quickly in soil (days to weeks); Dicamba persists slightly longer; Sulfentrazone can persist for months
vs. Roundup (Glyphosate):
Glyphosate is a broad-spectrum, non-selective herbicide — it kills nearly all vegetation vs. Spectracide's selective broadleaf targeting
Glyphosate has lower acute toxicity to mammals and birds than 2,4-D, but has faced significant scientific debate over long-term cancer risk (IARC classified it as "probably carcinogenic"; EPA maintains it is not)
Glyphosate is more toxic to aquatic invertebrates (especially via surfactants in Roundup formulations) but less prone to vapor drift than Dicamba
Overall: Spectracide Weed Stop has higher drift/neighbor-plant risk (Dicamba); Roundup has broader kill radius and more controversy around chronic human health effects
Toxicity to Pets & Animals
Spectracide Weed Stop:
Dogs & cats — Mildly to moderately toxic if ingested or skin-exposed while wet. Primary risk is gastrointestinal upset (vomiting, diarrhea, drooling). More serious with large doses
Re-entry — The label recommends keeping pets off treated areas until the spray has dried completely (typically 1–2 hours)
2,4-D specifically — Has been linked to malignant lymphoma in dogs in some studies at repeated/high exposures — though this remains debated scientifically
Dicamba — Low acute toxicity to mammals but irritating
vs. Roundup (Glyphosate):
Roundup's POEA surfactant (in older formulations) is more acutely toxic to pets than glyphosate itself
Both products carry similar "keep pets off treated area until dry" guidance
Neither is considered highly acutely toxic to pets at normal use rates, but repeated lawn exposure is an area of ongoing research for both.
Bottom line: Spectracide Weed Stop is meaningfully less risky than Roundup in terms of broad environmental kill and human health controversy, but its Dicamba component poses a higher drift/neighbor-plant risk. For a more eco-conscious alternative, products using iron-based herbicides (e.g., Ortho Weed B Gon with FeHEDTA) or corn gluten meal are significantly safer for animals, aquatic life, and the broader environment.
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I spot treat with this and I am happy with the results.
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Our community has rated this post as helpful. If you agree, why not thank slickernsnot
I spot treat with this and I am happy with the results.
The product you're viewing — Spectracide Weed Stop For Lawns Concentrate — contains four active ingredients: 2,4-D, Mecoprop-p (MCPP), Dicamba, and Sulfentrazone. Here's a breakdown of its toxicity profile:
Environmental Toxicity
Spectracide Weed Stop For Lawns:
Aquatic life — Moderately to highly toxic to fish and aquatic organisms. The label explicitly prohibits application within 25 feet of rivers, ponds, lakes, streams, reservoirs, marshes, estuaries, bays, and oceans
Soil — The active ingredients are water-soluble and can leach into groundwater, especially on sandy or permeable soils
Beneficial plants — Dicamba is notorious for vapor drift, capable of damaging nearby non-target plants (gardens, trees, shrubs) even when applied correctly
Bees/pollinators — Low direct toxicity to bees, but can harm flowering weeds that pollinators depend on
Birds — Low acute toxicity at normal use rates
Breakdown — 2,4-D and MCPP break down relatively quickly in soil (days to weeks); Dicamba persists slightly longer; Sulfentrazone can persist for months
vs. Roundup (Glyphosate):
Glyphosate is a broad-spectrum, non-selective herbicide — it kills nearly all vegetation vs. Spectracide's selective broadleaf targeting
Glyphosate has lower acute toxicity to mammals and birds than 2,4-D, but has faced significant scientific debate over long-term cancer risk (IARC classified it as "probably carcinogenic"; EPA maintains it is not)
Glyphosate is more toxic to aquatic invertebrates (especially via surfactants in Roundup formulations) but less prone to vapor drift than Dicamba
Overall: Spectracide Weed Stop has higher drift/neighbor-plant risk (Dicamba); Roundup has broader kill radius and more controversy around chronic human health effects
Toxicity to Pets & Animals
Spectracide Weed Stop:
Dogs & cats — Mildly to moderately toxic if ingested or skin-exposed while wet. Primary risk is gastrointestinal upset (vomiting, diarrhea, drooling). More serious with large doses
Re-entry — The label recommends keeping pets off treated areas until the spray has dried completely (typically 1–2 hours)
2,4-D specifically — Has been linked to malignant lymphoma in dogs in some studies at repeated/high exposures — though this remains debated scientifically
Dicamba — Low acute toxicity to mammals but irritating
vs. Roundup (Glyphosate):
Roundup's POEA surfactant (in older formulations) is more acutely toxic to pets than glyphosate itself
Both products carry similar "keep pets off treated area until dry" guidance
Neither is considered highly acutely toxic to pets at normal use rates, but repeated lawn exposure is an area of ongoing research for both.
Bottom line: Spectracide Weed Stop is meaningfully less risky than Roundup in terms of broad environmental kill and human health controversy, but its Dicamba component poses a higher drift/neighbor-plant risk. For a more eco-conscious alternative, products using iron-based herbicides (e.g., Ortho Weed B Gon with FeHEDTA) or corn gluten meal are significantly safer for animals, aquatic life, and the broader environment.
Join The Conversation
Share information with the community. Please follow our Community Guidelines and be kind!