Can Treflan Be Sprayed on Daylilies?

Purpose

• Treflan is a pre-emergent herbicide designed to keep annual grasses and broadleaf weeds at bay. Its main component is trifluralin. According to a University of Tennessee panel of experts in daylily care, Treflan is one of the many herbicides available for controlling weeds among daylilies. Treflan does not harm these ornamental plants because it is a selective herbicide, targeting specific offenders while leaving other vegetation alone.

Application

• Pre-emergent herbicides are applied before weeds germinate, which is typically in spring to early summer, and then again in early fall. Pre-emergents do not kill existing weeds, so don't use a pre-emergent on established weeds. Treflan is typically available in granular form, a dry substance sprinkled on an area Apply it directly to the soil at a rate of 3 oz. per 100 square feet. Water the area thoroughly immediately after application. When used correctly, Treflan provides 30 to 60 days of protection from new weeds.

Concerns

• Many individuals are concerned about the toxicity of chemicals used in farmlands and gardens. According to the U.S. Environmental Protection Agency, there is not much information available about the effects of trifluralin-based products on humans. Some defects, such as skeletal malformations and tumors, occurred in laboratory mice and rats that ingested trifluralin. Other animal studies showed subjects that inhaled the chemical and/or had direct contact on their skin developed less serious effects, such as decreased weight. Because of the tumors, however, the EPA warns that trifluralin may cause cancer in humans.

Alternatives

• Gardeners wanting to avoid using chemical-based weed control have other options. Pulling weeds by hand is one method, although it is physically demanding. Mulching around plants stifling weed growth is another solution. Laying landscape plastic or fabric directly on the soil and around existing plants, and then spreading mulch on top controls unwanted growth.