Research Summary Abstract
Several good herbicide products are available to manage weeds in and around nursery crops. Because growers produce many different plant species and cultivars and because many new crops are grown every year, this research was undertaken to expand the three pre-emergent herbicide labels: Pendulum 2G (pendimethalin), Pennant Magnum (s-metolachlor), and Snapshot 2.5TG (trifluralin + isoxaben). This report covers only Pennant Magnum. The rates chosen for this research were 2.5, 5.0 and 10.0 pounds active ingredient per acre (lb ai per A) as the 1X, 2X and 4X rates. Sixty-seven different species were examined. Of these, sixteen exhibited no or minimal transient injury after application at all three rates. Twelve crops require further research because of unclear results. Sixteen crops exhibited no phytotoxicity at 2.5 lb ai per acre, but did have some injury at the higher rates. Twenty-three species exhibited phytotoxicity at even the 2 lb ai per acre rate.