Dithiopyr

Dithiopyr is a pre-emergent herbicide used for the control of certain types of grasses and broadleaf weeds. It is a member of the pyridine family and is commonly used in both residential and commercial settings, including lawns, golf courses, and other types of turf.

Chemical Structure and Properties

Dithiopyr is a yellow crystalline solid with a slight sulfur odor. Its chemical formula is C19H22N2O4S3 and its molecular weight is 442.58 g/mol. It is not soluble in water and has a low volatility. The compound is stable under normal temperatures and pressures, but it can decompose when heated.

Mode of Action

Dithiopyr works by inhibiting the growth of newly germinated weed seeds. It interferes with the plant's cell division process, specifically in the roots and shoots, preventing the weed from growing. This makes it an effective pre-emergent herbicide, as it can control weeds before they emerge from the ground.

Usage and Application

Dithiopyr is typically applied in the early spring, before the targeted weeds germinate. It can be used on a variety of turfgrasses, including Kentucky bluegrass, perennial ryegrass, tall fescue, and bermudagrass. It is not recommended for use on certain types of grasses, such as St. Augustine grass, due to potential injury to the turf.

Safety and Environmental Impact

Dithiopyr has a low toxicity to humans and animals. However, it can be harmful if swallowed or inhaled, and it can cause eye irritation. It is not considered to be a carcinogen.

In terms of environmental impact, dithiopyr has a low toxicity to birds, fish, and bees. However, it can be toxic to some types of aquatic plants and invertebrates. It is not likely to leach into groundwater due to its low solubility in water.

Regulation

In the United States, dithiopyr is regulated by the Environmental Protection Agency (EPA). It is classified as a General Use Pesticide (GUP), meaning it can be purchased and used by the general public.

See Also

• Herbicide
• Pre-emergent herbicide
• Pyridine
• Environmental Protection Agency

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