Zoysiagrass Genotypes Differ in Susceptibility to Bluegrass Billbug.

Zoysiagrass has few insect pest problems, but may suffer significant injury from extensive bluegrass billbug (Sphenophorus parvulus Gyllenhal) infestations. In this study, Meyer and DALZ 0102 zoysiagrass (both Zoysia japonica Steud.) and 18 experimental zoysiagrass progeny, which included crosses between Z. japonica x Z. matrella (L.) Merr. or Z. japonica x Emerald (Z. japonica x Z. tenuifolia Willd.) were arranged in a randomized complete block design with three replicates per zoysiagrass progeny. The zoysiagrass plots were maintained under golf course fairway conditions and experienced a natural infestation of bluegrass billbugs in 2009 and 2010 with injury apparent in June, and continuing throughout the remainder of the growing season. Overall, Meyer suffered the highest level of injury on each of six rating dates, ranging from 19% to 35% of the plot area affected. Among the zoysiagrass progeny, injury ranged from 0% to 35%, with the majority between 0% and 15%. Zoysiagrass progeny from the crosses associated with Z. japonica x Z. matrella or Z. japonica x Emerald were more tolerant to bluegrass billbug than Meyer.