Influence of Selected White-Rot Fungi and Topdressings on the Composition of Thatch Components of Four Turfgrasses

In a pot-culture experiment with four highly-thatched turfgrasses [bermudagrass, Cynodon dactylon(L.) Pers.; centipedegrass, Eremochloa ophiuroides; Kentucky bluegrass, Poa pratensis L.; and St. Augustinegrass, Stenotaphrum secundatum (Walt.) Kuntze] we examined the influence of selected white-rot fungi and topdressings on the degradation of thatch components. Cores of each turfgrass were placed in pots and inoculated with one of four species of white-rot fungi (Polyporous giganteus, Coriolus versicolor, Phebia gigantea, or Phanerochaete chrysosporium). Pots were reinoculated with the appropriate fungus 14 days after the initial inoculation and after the 6 month sampling. Subplot treatments of the split-plot design were three topdressings (none, 0.31 cm sand, and 0.31 cm sand containing 4% colloidal phosphate). Samples of thatch were collected 6 and 12 months after inoculation and analyzed for cellulose and lignin by the acid detergent fiber procedure. Total oxidizable organic material and C and N were also determined. The cellulose content of bermudagrass and centipedegrass thatch was significantly reduced by Phebia gigantea, but no fungus significantly reduced the thatch cellulose content of St. Augustinegrass and Kentucky bluegrass. Coriolus versicolor significantly reduced the lignin content of thatch from all turfgrass species and the total oxidizable organic material of bermudagrass and centipedegrass. It appears to hold some potential for decomposing accumulated thatch. Topdressings with sand or a mixture of sand and colloidal phosphate significantly reduced the cellulose and lignin contents of thatch from most of the turfgrass species. Adding colloidal phosphate to the sand did not significantly increase the decomposition rate of the thatch. Kentucky bluegrass thatch contained the lowest quantity of lignin, and St. Augustinegrass thatch the least cellulose.