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In Puerto Rico, the agricultural production of pineapple (

Among the biotic constraints of common mushroom (Agaricus bisporus) production, bacterial blotch is considered the most important mushroom disease in terms of global prevalence and economic impact. Etiology and management of bacterial blotch has been a major concern since its original description in 1915. Although Pseudomonas tolaasii is thought to be the main causal agent, various Pseudomonas species, as well as organisms from other genera have been reported to cause blotch symptoms on mushroom caps. In this review, we provide an updated overview on the etiology, epidemiology, and management strategies of bacterial blotch disease. First, diversity of the causal agent(s) and utility of high throughput sequencing-based approaches in the precise characterization and identification of blotch pathogen(s) is explained. Further, due to the limited options for use of conventional pesticides in mushroom farms against blotch pathogen(s), we highlight the role of balanced threshold of relative humidity and temperature in mushroom farms to combat the disease in organic and conventional production. Additionally, we discuss the possibility of the use of biological control agents (either antagonistic mushroom-associated bacterial strains or bacteriophages) for blotch management as one of the sustainable approaches for 21stcentury agriculture. Finally, we aim to elucidate the association of mushroom microbiome in cap development and productivity on one hand, and blotch incidence/outbreaks on the other hand.

Among the biotic constraints of common mushroom (

In 2012, stem gall samples on Loropetalum chinense were sent to Florida diagnostic labs from Alabama and Florida nurseries. A fluorescent pseudomonad was consistently isolated from the galls. The organism was originally identified in Alabama based on 16S rRNA sequencing as Pseudomonas savastanoi, which causes a production-limiting disease of olive. The loropetalum strains and reference strains were compared using LOPAT, Biolog, fatty acid analysis, multilocus sequence analysis (MLSA), and pathogenicity tests. The LOPAT tests placed the loropetalum strains within Pseudomonas syringae. Biolog and fatty acid analysis placed the strains in various pathovars of P. syringae and P. savastanoi, respectively. MLSA of a set of housekeeping genes separated the loropetalum strains from the olive knot-inducing strains. Our work indicates there is a need to use more tests than 16S rRNA to accurately diagnose new bacterial diseases. In pathogenicity tests, the loropetalum strains produced galls only on loropetalum, but not on olive, mandevilla, or almond, indicating this strain is not a threat to the olive industry. Based on the pathogenicity assays and molecular tests, loropetalum strains represent a distinct and new pathovar, P. amygdali pv. loropetali pv. nov., for which the strain PDC13-208 (= DSMZ 105780PT) has been designated as the pathotype strain.