Tackling Control of a Cosmopolitan Phytopathogen: Sclerotinia

Abstract

Phytopathogenic members of the Sclerotinia genus cause widespread disease across a broad range of economically important crops. In particular, Sclerotinia sclerotiorum is considered one of the most destructive and cosmopolitan of plant pathogens. Here, were review the epidemiology of the pathogen, its economic impact on agricultural production, and measures employed toward control of disease. We review the broad approaches required to tackle Sclerotinia diseases and include cultural practices, crop genetic resistance, chemical fungicides, and biological controls. We highlight the benefits and drawbacks of each approach along with recent advances within these controls and future strategies.

Keywords: biocontrol; biopesticide; fungal pathogen; fungicide; horticulture; necrotroph; row crops; sclerotia.

FIGURE 1

Generalised Sclerotinia disease cycle. Image credits: Smith, 2018 CSIRO and Tian, 2020 CSIRO.

FIGURE 2

Sclerotinia disease management. Current strategies to control Sclerotinia diseases rely on integrated disease management, each with its pros and cons (blue panels) toward the desired outcome. This may involve a combination of management strategies suited to the host crop and requires consideration and monitoring of multiple factors to guide decision on best suited disease control tools (green panel).

FIGURE 3

New opportunities and tools for Sclerotinia control. New tools exist or are emerging that allow targeted manipulation of pathogen, host, or beneficial microbial populations that facilitate a reduction in Sclerotinia disease symptom development. These includes exogenous controls such as RNAi or biochemicals and biopesticides that can act directly on the pathogen (e.g., antifungal activity, fungal development) or indirectly by enhancing plant defense responses. Powerful endogenous controls such as crop genetic modification can provide durable resistance, but the process is costly, and not all crops are readily transformable or afford public acceptance. New knowledge of the pathogenicity and virulence of Sclerotinia species can be acquired through global omics studies on the pathogen infecting diverse crops of varying disease resistance, and this knowledge can be used to identify essential pathogen processes or weaknesses that can be targeted in new management tools.