Biological control of plant diseases – what has been achieved and what is the direction?

The global sustainability agenda is increasing the demand for reduction in inputs into agricultural production whilst maintaining profitable yield of quality products. Plant diseases are a major constraint for both yield and product quality, but often tools for their control are ineffective or lacking. Biological control using antagonistic microorganisms has long been a subject of research which has resulted in a wide range of products that are now available and marketed in specific territories around the world. These preparations are often niche products with narrow uses. The research effort is intense both to develop new biological control products (BCAs) and to obtain knowledge of the mechanisms underlying biological disease control. The prospects for biological control are promising. As a minimum, BCAs supplement other sustainable disease management practices such as disease resistance and presents opportunities for controlling diseases for which other approaches are ineffective or unavailable. We can realistically expect an increasing usage of BCAs to control crop diseases in ways, which will benefit the environment. This review paper arose from a Webinar held by BSPP as part of the International Year of Plant Heath (IYPH2020). Many of the 300 participants posed or discussed interesting questions. This review is based on that input and the panel members at the webinar are all included as co-authors in this review.