Wash Roundup from affected plants by using a steady stream of water for about 30 to 60 seconds. Do this immediately after the plants were exposed to Roundup. Roundup is completely rainproof, or waterproof, after only 30 minutes. So the longer you wait, the less effective this counteractive measure becomes.
Sprinkle soil on the affected plants as soon as possible after Roundup was applied. Soil absorbs some of the product's chemical, reducing its affects. Wash the soil and Roundup off the plants as soon as possible, however, for the best control.
Prune the affected leaves and limbs if you waited too long to use a different method to counteract Roundup. After Roundup is absorbed by a plant's foliage, it travels to the roots, where it kills the plant. Annuals show signs of Roundup's effect two to four days after the product's application, and perennials show the effect in seven to 10 days. Therefore, selective pruning may stop plant roots from becoming afflicted with the product's chemical.