Can wetting agents improve the post-application persistence of entomopathogenic nematodes in turfgrass?

Entomopathogenic nematodes (EPNs) can provide a highly effective alternative to chemical insecticides in many cropping systems.  However, their use is limited in most systems due to their expense and poor post-application persistence.  Soil moisture may be the most important factor influencing EPN population dynamics as it is critical for survival and movement towards hosts.  Turfgrass wetting agents (soil surfactants) were tested for their ability to improve the persistence or movement of two species of EPNs in turfgrass rootzones during the seasons when they would be most appropriately timed.  The density and spatial distribution of Steinernema carpocapsae was assessed in short-mown bentgrass during early summer when the ambusher nematode would be employed against several early-season, surface active insects.  The ability of wetting agents to move Heterorhabditis bacteriophora into the soil profile was assessed in late summer in rough-cut Kentucky bluegrass plots with moderate to high thatch content.  The abundance and distribution of EPNs, and spatial association between EPNs and soil moisture was analyzed by Spatial Distances by IndicEs (SADIE). The findings and their implications will be discussed.