The strongest weed killer is sodium chlorate, produced in dust, spray and granule forms. When used as an herbicide, sodium chlorate is toxic to green plants and kills them when it is absorbed through the roots or through leaves and stems.
As this chemical makes the surrounding soil sterile, it is used mainly in non-crop areas to control vegetation around roadsides, fences and ditches. Sodium chlorate is toxic if ingested by humans and can be explosive if mixed with other substances, such as sugar. Commercially available chlorate weed killers contain approximately 50 percent sodium chlorate mixed with a fire suppressant. Its use as a weed killer is banned in the European Union.
The full strength variety of Remuda is one of the strongest weed killers available. The product kills both broadleaf weeds and the grasses that somtimes grow with various weeds.
Bayer Advanced is also a powerful weed killer. The product can eliminate up to 200 varieties of weeds and takes less than an hour to become rain-proof.
Another strong weed killer is Round-Up Weed and Grass Killer in the Extended Control variety. This weed killer not only gets rid of harmful plants in a lawn or garden, but protects plants for up to four months; this provides a protective barrier for crops for a whole season.