Response of Summer-Dormant and Summer-Active Type Tall Fescue with and without Fungal Endophyte Infection to Plant Parasitic Nematode Exposure.

Summer-active (continental) tall fescue (Schedonorus arundinaceus) is adapted to regions with annual precipitation greater than 889 mm. Continental types possess drought avoidance mechanisms but re-grow with summer rains, reducing persistence in the southern plains. Mediterranean basin origin summer-dormant tall fescues (Mediterranean) invoke dormancy in response to increasing day length and temperature and may expand regions of tall fescue adaptation. Continental persistence is enhanced by presence of an ergot alkaloid producing endophyte Neotyphodium coenophialum (wild) conferring resistance to insects and drought but causing fescue toxicosis. Non-ergot alkaloid producing strains of N. coenophialum (novel) have been identified and placed into tall fescue selections. Some novel strains in continental tall fescue confer resistance to plant parasitic nematodes but others, do not. Resistance to nematodes by novel endophytes in Mediterranean tall fescues is uncertain. This study sought to compare effects of four nematode types on wild endophyte-infected continental tall fescue and novel endophytes in continental or Mediterranean tall fescue. This greenhouse study was conducted with two continental varieties; Kentucky 31 (wild); and Texoma MaxQ II (novel) and the Mediterranean variety Flecha AR542 (novel). Endophyte-free plants of each variety served as controls.  Plants were established from seed, endophyte presence verified then transplanted to 19 cm pots. Pots were inoculated with high and low levels of stunt (Tylenchorhynchus spp); ring (Criconemella spp.); spiral (Helicotylenchus spp); and lesion (Pratylenchus spp.) nematodes. Study length was seven months then nematode populations determined. Lesion populations were near zero in all plants. Texoma MaxQ II populations were similar to wild for stunt and spiral but higher for ring. Ring populations were higher for Flecha AR542 than other variety by endophyte combinations. Flecha AR542 stunt populations were higher than either endophyte-infected continental line. Results indicate that AR542 increases host suitability of Flecha summer-dormant tall fescue to nematodes.