Rhizopus oryzae as a causal agent of a head rot of sunflowers in Queensland

Abstract

The causal agent of a common head rot of sunflowers in Queensland was isolated and identified as Rhizopus oryzae. Field experiments were conducted to investigate the environmental and host conditions suitable for disease development, and control of the disease by the use of fungicides. The disease occurs in wound inoculated plants when atmospheric humidity is high. Dicloran is capable of restricting established infection, but wound inoculations made after the application of the fungicide avoid the protective barrier and are uninfluenced by it. The possible use of chemicals to control the disease is discussed.