New Mulch Could Control Weeds

Researchers at the Ohio State University have developed a combination of mulch and pre-emergent herbicides that reportedly can control weeds for nearly a full year with just one application. The combination could translate into chemical and labor savings of 88-93 percent for nursery and landscape professionals.

Researchers selected the top 10 herbicide-mulch combinations from the university’s container trials and tested them in the field. They analyzed the efficacy of those combinations after 30, 60, 90, 120 and 350 days. Researchers used a single application of different combinations (mulch under herbicide, mulch over herbicide and pretreated mulch) and then compared their performance to direct chemical sprays and untreated mulches for a total of 38 treatments.

The mulches tested were pine nuggets and hardwood bark. The liquid chemicals that were tested were Surflan (oryzalin), SureGuard (flumioxazin), Harness (acetochlor), Casoron (dichlobenil) and a combination of oryzalin and flumioxazin.

Twenty of the 38 treatments provided commercially acceptable efficacy ratings of seven or higher after 120 days – all but one of the treatments was a herbicide/mulch combination.

After 350 days, four treatments were still providing commercially acceptable weed control: Surflan/SureGuard pre-treated pine nuggets, Casoron applied over pine nuggets, Surflan/SureGuard applied over pine nuggets and Casoron applied under pine nuggets.