The sod webworm (SWW), Chrysoteuchia topiaria (Zeller) is a common and damaging species in grass seed, turf, and lawns in western OR. Sod webworm is a persistent but sporadic pest in perennial ryegrass, tall fescue, bentgrass, and orchardgrass; however, the extent of damage is worse and more frequent in older fine fescue stands. Damage is usually first noticed by failures of fall regrowth. Larvae feed on and in crowns and roots of most grasses, and can seriously injure established stands wherever grass is grown for seed. Insecticide options are available, but they are soil active; it is challenging to achieve good efficacy due to the lack of sufficient and timely rainfall that allows the insecticides to reach the targeted pests. A replicated field trial was set up in fall 2020 to evaluate the efficacy of new chemistries against sod webworm; data on herbivory damage, severity, and natural enemy abundance etc. is being collected until spring 2021. The results from this study are expected to generate information for the execution of more accurate chemical management plans. Insect choice and no choice tests were conducted for better
understanding of the sod webworm’s host preference behavior; data are currently being analyzed to determine if the varietal difference in herbivory preference were indicative of differences in plant endophytic associations. Survey results for indigenous entomopathogenic nematode species associated with field-collected sod webworm populations confirmed the presence of an infective strain of Steinernema carpocapsae in at least one field site in OR.

Choice test using grass cultivars
Field collected sod webworm population