ACREMONIUM ISOLATES FROM STIPA-ROBUSTA

Endophytic Acremonium isolates were obtained from 43 of 50 plants of S tipa robusta grown from seed collected from 10 locations in New Mexico and Colorado. Hyphae in the lower 2-3 cm of seedlings grown aseptical ly from infected seed were intercellular, about 2 mu m in diameter, mo stly straight. Coarse sinuous or convoluted hyphae were produced in cu lture to some extent by many isolates and conidia were seen in all cul tures. Observations of fungal structures were easily made on water aga r. When first cultured, mean conidial lengths of individual isolates v aried from 5.9 to 8.7 mu m Considerable variation in conidial shapes o ccurred and average spore lengths of most isolates did not conform to described species, but were intermediate between A. starrii and A. coe nophialum. The most common type of spore was too short for A. coenophi alum and too long for A. starrii, and no isolate even faintly resemble d A. chisosum. Spores of most isolates were dead in cultures 60 days o ld at 22 C. Serological analysis demonstrated the relatedness of the i solates to endophyte isolates from a broad range of other grasses.