Predicting field diseases caused by Sclerotinia sclerotiorum: A review

Abstract

Predicting diseases caused by Sclerotinia sclerotiorum in field crops remains difficult, and published literature is largely inconsistent in finding significant relationships with environmental and agronomic factors for various life stages of the fungus. A scoping review was performed to synthesize the current quantitative insights into the role of the environment on the life cycle of S. sclerotiorum and the relationships between various life stages of the fungus and final disease expression under field conditions. For most variables, relationships with stages of the life cycle showed a wide range of responses ranging from closely related (high correlations or r2 values) to not related at all. The effects were often moderated by year, location and/or the presence of another variable such as irrigation, soil type, row spacing or cultivar. Studies that based analysis on a more nuanced understanding of pathogen biology rather than looking only at linear relationships tended to find stronger associations between variables. Yield was consistently negatively associated with disease levels, but cultivar, year, location and planting density were all important determinants of yield. Suggestions for improvement to future research in predictive model development of S. sclerotiorum diseases are discussed.

A Bacillus velezensis strain shows antimicrobial activity against soilborne and foliar fungi and oomycetes

“…S. sclerotiorum is a broad-range, soilborne pathogen known to infect 425 plant species, but likely infects many more (Derbyshire et al, 2022). It has been difficult to manage for many reasons: infection with S. sclerotiorum is unrelated to crop loss in the field, and the environmental variables that impact life stage of S. sclerotiorum in the lab are not relevant in the field (reviewed in (Reich and Chatterton, 2022)).…”

Strategy to identify common beans with resistance to white mould for dry‐irrigated areas: Additional evidence

“…Architectural traits are fully expressed in the field (Schwartz & Singh, 2013). Among the most important architectural traits that could help reduce bean WM‐intensity in the field are tall upright plants, porous canopy, and reduced lodging (Kolkman & Kelly, 2002; Miklas et al., 2013; Reich & Chatterton, 2022; Schwartz & Singh, 2013). In dry‐irrigated areas, Mesoamerican genotypes selected for partial resistance, especially those of type II, seem to rely mostly on avoidance traits (Ender & Kelly, 2005; Lima et al., 2020; Miklas et al., 2013).…”

“…Alternating wet and dry conditions were detrimental to germination but did not suppress it (Shahoveisi & Del Río Mendoza, 2020). Thus, the same number of ascospores released may result in much greater disease in wetter years than in drier years (Reich & Chatterton, 2022). Hence, it seems that the rainfall events during the pre‐flowering period of the Andean genotypes (G3) in 2016 in Viçosa were the primary cause of the higher WM intensity observed in bean plants compared with those in the WM‐resistance groups, which are late‐maturing genotypes.…”

“…In previous studies conducted in dry-irrigated areas of Brazil (Lima et al, 2020;Paula Júnior et al, 2009;Vieira et al, 2022), with final WM levels (Reich & Chatterton, 2022). According to these authors, 30 or 40 days of soil moisture may be useful for predicting the presence of apothecia in the field, but not necessarily ascospore levels.…”

“…Similarly, in Nebraska, USA, WM severity (percentage of the aboveground portion of bean plants infected by S. sclerotiorum) lower than 40% did not affect bean yield (Kerr et al, 1978). Due to the considerable year-to-year variation in WM intensity (Lima et al, 2019(Lima et al, , 2020Reich & Chatterton, 2022;Teixeira et al, 2019;Vieira et al, 2022), trials for this type of study must be repeated for two or more years. In trials with WM pressures between zero and moderate levels, selection for partial resistance to WM may be ineffective.…”