The biological control of Russell lupin in riverbeds with endemic plant pathogens

Abstract

The control of Russell lupin (Lupinus polyphyllus) in wildlife habitats in braided riverbeds in the central South Island is discussed. A survey of plant pathogens as prospective biological control agents for the plant was carried out. Four pathogens, all of them new records for this host in New Zealand, were identified; Pleiochaeta setosa, Colletotrichum gloeosporioides, Verticillium albo-atrum andFusarium heterosporum. Symptoms of a disease very similar to bacterial wilt of lucerne were also found but the suspected causal organism, Clavibacter michiganensis subsp. insidiosus, has yet to be verified. In the light of experimental infection results, these pathogens were assessed as potential bioherbicides together with Ascochyta pisi, Sclerotinia sclerotiorum and S. minor, already recorded on lupin species in New Zealand.