Viability of Acremonium coenophialum in Tall Fescue Seed after Ionizing Radiation Treatments

Planting tall fescue (Festuca arundinacea Schreb.) seed free of the endophyte Acremonium coenophialum Morgan‐Jones & Gains allows establishment of swards free of the fungus. Eradication of the fungal endophyte from infected tall fescoe seeds containing 130 g kg−1 moisture using ionizing radiation was investigated. Three sources of radiation were used: gamma rays (60Co source), neutron particles (252Cf source), and a thermal neutron beam. The percent germination of tall fescue seeds among gamma doses did not differ significantly (P < 0.05) from the control treatment and did not show a significant negative response (R2 = 0.41) to increasing levels of gamma radiation. At 250 Gy of gamma radiation, percent germination after 14 d was still =90%. Percent seed germination of tall fescue and high levels of radiation were negatively correlated for both sources of neutrons. Gamma radiation was shown to reduce (P < 0.01) the percent of the viable endophyte to =10% of control. The 2s2Cf and thermal neutrons reduced the percent of tall fescue infected by the endophyte to =30% without deleterious effects on seed germination.