Management of three newly recorded asparagus diseases in Queensland will require adoption of new production strategies

Abstract

During March 2000-March 2001, three fungal diseases were recorded for the first time on Asparagus officinalis in Queensland, Australia. Rust (Puccinia asparagi) was restricted to a single farm initially. The property was quarantined and although the affected asparagus crop was destroyed, rust has since been recorded on most properties within a 250 km radius of this initial recording. The disease has been found on all cultivars currently being grown in Queensland but pathogenic specialisation has not yet been determined. The fungicides myclobutanil, difenoconazole and mancozeb have been approved under permit conditions to be used for rust control in Australia. Phomopsis blight caused by Phomopsis asparagi appeared on a group of properties and resulted in fern death and subsequent debilitation of affected stands. All cultivars have become diseased but fungicide screening has indicated benomyl, chlorothalonil and difenoconazole have significantly (P<0.05) restricted disease development (3-16 lesions/stem). Other fungicides including, mancozeb, copper-oxychloride and azoxystrobin were not as effective against Phomopsis blight (19-26 lesions/stem). Colletotrichum gloeosporioides is the causal pathogen of the third disease, anthracnose. Anthracnose has previously been reported as a serious stem disease of asparagus in the Northern Territory of Australia but little is known of its distribution elsewhere. This disease is so far restricted to Queensland’s tropical production areas. Fungicides such as mancozeb, chlorothalonil, benomyl and azoxystrobin are used successfully to control Colletotrichum spp. on other hosts and may also prove useful in controlling epidemics in asparagus. Presently these diseases are unknown in the major asparagus production areas in other Australian states but it is probably inevitable pathogen dissemination will eventually occur within the country. New disease management strategies involving fungicides, trash destruction, production hygiene, balanced nutrition and host resistance are discussed in relation to current asparagus production methods in Australia.