INCIDENCE AND VIABILITY OF ACREMONIUM ENDOPHYTES IN TALL FESCUE AND MEADOW FESCUE PLANT INTRODUCTIONS

Assessment of the infection status and viability of endophytic Acremon ium spp. in USDA plant introductions (PI) of Festuca spp. would aid in identifying potentially desirable endophyte strains for improving pas ture and turf species. The PI collection of tall fescue (F. arundinace a Schreb.) and meadow fescue (F. pratensis Buds.) was screened to dete rmine Acremonium infection rate and viability. For tall fescue, 20 see d from each of 565 regenerated seedlots were microscopically examined for endophyte. Seventy-nine accessions contained endophyte with an ave rage infection frequency of 67.4%. Leaf sheaths of seedlings from the infected accessions were then examined to determine endophyte viabilit y. Fifty-five of the 79 infected accessions contained viable endophyte at an average infection frequency of 41.2% in the seedlings. The decl ine in the number of infected accessions and in their infection freque ncy suggested that loss in endophyte viability may have occurred in st orage. More intensive analysis of 15 tall fescue accessions showed tha t endophyte infection declined from 68.4% in originally collected seed to 42.7% in regenerated seed to 23.6% in the seedlings from the regen erated seedlots, indicating diminishing endophyte occurrence and viabi lity between the time of deposition of seed in the germplasm system an d release of regenerated seed for general distribution. In meadow fesc ue, 29 of 198 accessions contained endophyte at 42.4% infection freque ncy in the seed and 31.6% infection frequency in the seedlings, indica ting a proportionally lesser decline in endophyte viability than in ta ll fescue. While existing germplasm collections of Festuca spp. can pr ovide Acremonium germplasm for study, newly collected Festuca germplas m will offer a greater diversity of Acremonium genotypes.