Puccinia araujae, a promising classical biocontrol agent for moth plant in New Zealand: Biology, host range and hyperparasitism by Cladosporium uredinicola

Abstract

The rust fungusPuccinia araujiaeis proposed as a biological control agent for moth plant (Araujiahortorum) in New Zealand. This pathogen completes its life cycle on this host, it has the capacity ofdamaging it by producing premature foliage senescence and defoliation, and, it is only known frommembers of the Oxypetalinae (Apocynaceae).P. araujiaewas found to be heavily hyperparasitised bythe fungusCladosporium uredinicolain the field in Argentina. The mode of action of this hyperparasitewas investigated and efforts are currently being made to completely eliminate it from a culture of the rustthrough a combination of superficial disinfection and multiple sequential inoculations. A protocol wasdeveloped for long term storage of teliospores of the rust at very low temperatures. Stored spores wereshown to maintain their ability to germinate and produce infective basidiospores for up to 12 months.The possible effect of the hyperparasite on the performance of the rust as a biological control agent,should it be introduced into New Zealand, is discussed.