Diquat Water Weed and Landscape Herbicide (1 Quart) Diquat Dibromide 37.3% Diquat Herbicide is for weed/algae control in and around ponds, lakes, commercial greenhouses and nurseries, landscapes, industrial land, recreational land, residential lawns, and public areas. Diquat should be mixed at a rate of 1 gallon per surface acre (4' depth) or mixed at 32ounces per 100 gallons when spraying as a commercial weed killer.