An Integrated Research Approach to the Development of Fungal Isolates as Bioherbicides for the Control of Woody Weeds

Prickly acacia (Acacia nilotica) is an invasive weed tree in Australia, ranked seventh on the list of Weeds of National Significance because of its aggressiveness and its economic and environmental impacts. The significant downsides to manual and chemical control of this species drove the search for a biological control mechanism. Surveying and sampling stands of A. nilotica naturally exhibiting disease symptoms yielded several native Australian fungi capable of pathogenesis in this species, which are currently under assessment as potential bioherbicides for this weed. Three field trials were established at the same site in order to further advance current understanding of this disease system, examining the ability of different fungal strains and different application techniques to produce a viable infection. All three experiments were established successfully, and previous work suggests that they will yield data valuable to the development of the bioherbicide technology. The fungal material used in the experiments was tested both before and after the trials for pathogenicity on seedlings of both A. nilotica and Parkinsonia aculeata, another woody weed species. All material was found to be active and capable of pathogenesis in seedlings of both species, indicating the likelihood of effective pathogenesis during the trial. Immediately following the establishment of the field trials, a presentation was given at a weed workshop organized to spread information about integrated weed management techniques and the bioherbicide research in particular. Interviews conducted at this workshop indicated a high degree of public, industrial, and governmental interest and optimism about the bioherbicide technology. The success of this technology in previous trials suggests that in time, it is likely to become a commercially viable control tool for the management of A. nilotica, with significant economic benefits for both the government and the grazing industry. The technology also holds great potential for environmental benefit, both for land resources and for the marine environments receiving freshwater inputs from infested areas. Commercialization of the research is currently under way and, barring unforeseen difficulties, the technology is likely to reach the market within the next few years