Susceptibility of Diploid St. Augustinegrasses to Belonolaimus longicaudatus


  • Philip Busey
  • Robin M. Giblin-Davis
  • Charles W. Riger
  • Edna I. Zaenker


A fine-textured, dwarf St. Augustinegrass (Stenotaphrum secundatum (Walt.) Kuntze) genotype, FX-313, was severely damaged in plots in the third year of evaluation in sandy soil in southern Florida. Damage was associated with numerous ( 40/100-cm³ soil) sting nematodes, Belonolaimus longicaudatus Rau. Damage was ameliorated (P 0.05) by fenamiphos applied broadcast at 2.2 g a.i./m², and B. longicaudatus numbers were reduced (P 0.01), compared with untreated plots. Root dry weights of four diploid (2n = 18) St. Augustinegrasses--FX-261, FX-299, FX-313, and Seville--were reduced (P 0.001) by B. longicaudatus in a temperature- and light-controlled experiment. Estimated daily transpiration, an indicator of plant health, was reduced (P 0.001) after 112 days to 3.32 g/pot for inoculated plants, compared with 5.10 g /pot for uninoculated plants. Genotypes did not differ in nematode number per pot (mean 551/215 cm² soil) 128 days after inoculation, but differed (P 0.05) in nematode numbers on a root dry weight basis, with FX-313 and Seville representing the extremes, 12,300 and 4,000 B. longicaudatus/g root dry weight, respectively. The diploid St. Augustinegrasses evaluated were good hosts for B. longicaudatus, but field data and controlled inoculation demonstrate genetic variation in susceptibility. Key words: Belonolaimus longicaudatus, breeding, fenamiphos, nematode, resistance, St. Augustinegrass, Stenotaphrum secundatum, sting nematode, turfgrass.