Biological control of Eutypa armeniacae. II. Studies of the interaction between E. armeniacae and Fusarium lateritium, and their relative sensitivities to benzimidazole chemicals

Abstract

Fusarium lateritium, a saprophyte sometimes associated with apricot trees, inhibits in vitro germination and growth of Eutypa armeniacae. The amount of inhibition increases with the age of the F. lateritium colony and in the presence of nutrients. The inhibitor is non-volatile, diffusible and produced in amounts proportional to the age of the colony. In the field, F. lateritium sporulated abundantly at the pruned sapwood surfaces of apricot trees a few days after inoculation. Application to pruned surfaces of suspensions containing 104 macroconidia per ml, or more, gave significant protection against E. armeniacae. Growth of F. lateritium was mainly restricted to a zone of sapwood within 2 cm of the pruned surface. The tolerance of F. lateritium to benzimidazole chemicals in vitro is about 10 times as great as that of E. armeniacae, and its macroconidia germinate and produce sporulating colonies on sapwood of excised apricot stems when these are inoculated with spores in water suspensions containing up to 400 ppm benomyl or thiabendazole.