Microbial biocontrol agents: Opportunities and barriers

Abstract

Armillaria species are a fungal plant pathogen found worldwide affecting a range of woody trees and shrubs in gardens, horticulture, and forestry. The root disease is primarily spread through an underground network of rhizomorphs and by root-to-root contact. Chemical controls have been banned or are ineffective, making the only available control options expensive and labour intensive. A study was conducted to determine the potential of native Trichoderma spp. endophytes to antagonise Armillaria mellea and offer protection to host plants. Dual culture assays showed significant reductions in A. mellea colony size. Host-associated isolates of Trichoderma spp. were endophytically inoculated into strawberry and privet roots. Much variation in Armillaria root rot infection was noted, but several isolates reduced disease severity.

The growing number of pesticide withdrawals raises concerns over effective plant disease control. Biocontrol plays a major role in IPM in mitigating these effects. A workshop was held in the UK with stakeholders representing major plant health sectors. The opportunities for increasing use of biocontrol and barriers to uptake were discussed. Although commercial products are available, uptake is low. Significant barriers exist and key recommendations for improved uptake include better knowledge exchange and guidance. Many of the opportunities and barriers are applicable to a New Zealand situation.