APS Abstracts of Presentations

Colonization of bermudagrass roots produced from stolons by Ophiosphaerella herpotricha
Presenter: N. Walker, Oklahoma State University
Co-Author(s): S. Marek, Oklahoma State University; C. Taliaferro, Oklahoma State University
Phytopathology 95:S107

Spring dead spot (SDS), caused by O. herpotricha, is the most damaging disease of bermudagrass (Cynodon dactylon L.) in Oklahoma. The objective of this study was to evaluate an in vitro assay system for the infection and colonization of roots produced from bermudagrass stolons by O. herpotricha. Stolon segments of the bermudagrass cv. Tifway 419 were surface-sterilized and plated on potato dextrose agar (PDA). Stolons free of contamination were transferred to culture tubes (60 ml) containing water agar and wrapped in aluminum foil. Tubes were placed in a growth chamber at 25°C to promote root growth. Single roots from six plants per replicate were inoculated with hyphae of O. herpotricha. Inoculated plants were maintained in a growth chamber at 17°C with a 12 h photoperiod. The study was replicated two times and non-inoculated plants were used as a control. After 21 days, roots were surface-sterilized and plated on PDA. After 4 days, the length of root colonized was measured. Using this assay method, forty two percent of the root length was colonized by O. herpotricha. Results suggest the usefulness of this method for evaluating differences in root colonization and, ultimately, SDS resistance among clonal lines of bermudagrass cultivars.

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