Efficacy of methionine against ectoparasitic nematodes on golf course turf

Plant-parasitic nematodes are important pathogens of intensely-managed turf used on golf courses. Two of these nematodes that are common in the southeastern US are Belonolaimus longicaudatus and Mesocriconema ornata. Currently, there is a lack of effective treatments that can be used to manage these important pests. Turfgrass field trials evaluated DL-methionine as a turfgrass nematicide against B. longicaudatus and M. ornata. One trial was on a bermudagrass putting green, the other was on zoysiagrass maintained under putting-green conditions. Two rates of methionine, 1120 kg/ha in a single application, and 112 kg/ha applied twice four weeks apart, were compared with untreated control and fenamiphos treatments. Measurements collected included soil nematode counts, turf density, and root lengths. In both trials, 1120 kg/ha of methionine reduced numbers of both nematode species (P ≤ 0.1), and 112 kg/ha of methionine reduced numbers of both nematode species after two applications. Bermudagrass turf density responded favorably to both methionine rates and root lengths were improved by the 1120 kg/ha rate. Zoysiagrass showed short-term phytotoxicity to methionine, but quickly recovered and treated plots were improved compared to the untreated controls by the end of the trial. These trials indicated that methionine has potential for development as a turfgrass nematicide, but further research is needed to determine how it can best be used.