FUNGI ASSOCIATED WITH SPRING DEAD SPOT REDUCES FREEZING RESISTANCE INBERMUDAGRASS

Although the effect of cold winters on the severity of bermudagrass (C ynodon dactylon Pers.) spring dead spot (SDS) has been studied, inform ation is needed concerning the effect of infection by fungi associated with SDS on the host's freezing resistance. A-22 bermudagrass was ino culated with Leptosphaeria korrae J. Walker & A.M. Smith and Ophiospha rella herpotricha (Fr.) J. Walker & A.M Smith. Differential thermal an alysis was used to monitor exotherm temperatures of healthy and O. her potricha- and L. korrae-infected A-22 bermudagrass at 10-day intervals during 90 days of acclimation in cold chambers. Healthy bermudagrass crowns supercooled to an average of -6.7C and fungi-infected crowns su percooled to an average of -4.8 and -4.4C, respectively. Healthy crown exotherm temperatures were significantly lower than those of fungi-in fected bermudagrass crowns on all nine sampling dates. This result ind icates that fungi-infected plants are more susceptible to cold damage.