EFFECT OF BELONOLAIMUS LONGICAUDATUSON ROOT PARAMETERS OF ST. AUGUSTINE GRASS CULTIVARS

Abstract

In Florida, St. Augustinegrass (Stenotaphrum secundatum) is the most commonly used turfgrass species. Sting nematode (Belonolaimus longicaudatus) is recognized as a limiting factor to St. Augustinegrass in Florida, where ‘Floratam’, a polyploid, is the predominant cultivar; although the use of new diploid cultivars is increasing. The objective of this study was to evaluate the root response of three cultivars, Floratam, and two diploid cultivars
‘Palmetto’ and ‘Captiva’ grown in plastic pots containing 650 cm3 of sand in a greenhouse to inoculation with 0, 50, or 300B. longicaudatus/pot. Ninety days after inoculation, nematodes were extracted from the complete soil volume of the pots and counted. Roots were washed clean of soil, scanned, and root lengths, mean root diameters, and mean root volume were measured. All cultivars were good hosts for B. longicaudatus, ‘Palmetto’ supported higher population densities than the other cultivars at the 50 nematode inoculation rate only. There were differences in reproductive factor (Rf) among the inoculation rates, where the 50 nematode inoculation rate (Pi) had an Rf of 0.52, and the 300 nematode inoculation rate had an Rf of 1.84. At Pi 300, the non-infested
treatment had greater root lengths than inoculated for all cultivars, demonstrating that B. longicaudatus has a significant effect on St. Augustinegrass root development. Root diameter and volume were not affected by inoculation with B. longicaudatus. Root diameter and volume were higher for Floratam than for Palmetto or Captiva. Palmetto had greater root length than the other cultivars.