Abstract

St. Augustinegrass, S. secundatum (Walt.) Kuntze, a widely used turfgrass in the southern coastal states, has 2 major limiting pests, southern chinch bug, Blissus insularis Barbar and St. Augustine decline strain of Panicum mosaic virus (PMV-SAD). gamma-Ray-derived mutants of Floratam, a very coarse cultivar which is resistant to both pests, were evaluated for stability of resistance and turf characteristics. All mutants retained resistance of PMV-SAD and all except 14 caused higher antibiosis to the confined bugs than the susceptible Florida Common St. Augustinegrass (22%). Mutant 6 produced 76% mortality of the confined southern chinch bugs at 7 days which was significantly greater than the mortality produced by four of the other mutants. None of the mutants was significantly more resistant than Floratam (65% mortality). Egg deposition was significantly less on Floratam and all mutants (from 4 to 13 eggs/stolon) than on the Florida Common (average of 23 eggs/stolon). One of the mutants had a faster rate of establishment and all mutants had shorter internodes than Floratam, all were immune to PMV-SAD, and only on had lost its southern chinch bug resistance.