AVENGER Organic Weed Killer, biodegradable, non-toxic - Concentrate 32oz Avenger Organic Weed Killer Concentrate is a non-selective, post-emergence herbicide that quickly and effectively kills weeds, grasses and broadleaves The active ingredient d-limonene (citrus oil) naturally strips away the waxy plant cuticle, causing it to dehydrate and die. University and independent testing results prove that Avenger Weed Killer is as effective Approved for Use in Organic Gardening by the U.S. Deptartment of Agriculture's (USDA) National Organic Program (NOP) Rule Small annual weeds: For the control of annual weeds less than 6 inches tall, use a 1:6 ratio (1 part of Avenger Weed Killer into 6 parts of water). Larger annual weeds: For the control annual weeds above 6 inches, use a 1:4-1/2 ratio (1 part of Avenger Weed Killer in 4-1/2 parts of water).