Resistance of Xanthium occidentale to Colletotrichum orbiculare, a Pathogen of X. spinosum

Abstract

Colletotrichum orbiculare (syn. C. lagenarium), a common pathogen of the weed Xanthium spinosum in eastern Australia, is a potential mycoherbicide for that weed. Related Xanthium spp. are resistant to the fungus, A comparison of experimental infections of X. spinosum and X. occidentale indicated that resistance in leaves of the latter included surface morphology, hypersensitive cell death and formation of lignin-like substances around leaf infections indicated by staining. Infection of stems and fruits occurred in X. occidentale through wounds but lesions continued to grow only on fruits.