Abstract

'Floratam' and 'FX-313' St. Augustinegrasses (Stenotaphrum secundatum) were compared in a time-course experiment for host suitability and susceptibility to the lance nematode, Hoplolaimus galeatus.  Nematode densities were determined in the soil and acid-fuchsin stained roots 42, 84, 126, 168, and 210 days after pots containing 230 cm^-3 of autoclaved native Margate fine sand/pot were infested with 104 + 9 nematodes and maintained at 25 + 2 C in the laboratory.   'FX-313' was a more suitable host for H. galeatus.  Numbers of H. galeatus reached a maximum at 210 days after inoculation, with 5,550 and 4,120 nematodes (adults plus juveniles)/pot for 'FX-313' and 'Floratam,' respectively.   Root and shoot dry weights of both grasses were not affected by H. galeatus throughout the experiment.  Three polyploid, 2n = 30 to 32 ('Floratam,' 'FX-10,' and 'Bitterblue') and three diploid, 2n = 18 ('FX-313, 'Florida Common,' and 'Seville') S. secundatum genotypes were inoculated with H. galeatus (99 + 9/pot) and compared with uninoculated controls 210 days after inoculation.   St. Augustinegrass genotypes differed as hosts of H. galeatus.   'FX-313' and 'Florida Common' represented the high and low extremes, respectively, for nematode reproduction (9,750 and 5,490 nematodes/pot or 4,239 and 2,387 nematodes/100 cm^-3 of soil).  However, differences in root and shoot growth were not detected 210 days after inoculation with H. galeatus.