Lecanicillium fungicola: causal agent of dry dubble disease in white-button mushroom

Lecanicillium fungicola causes dry bubble disease in commercially cultivated mushroom. This review summarizes current knowledge on the biology of the pathogen and the interaction between the pathogen and its most important host, the white-button mushroom, Agaricus bisporus. The ecology of the pathogen is discussed with emphasis on host range, dispersal and primary source of infection. In addition, current knowledge on mushroom defence mechanisms is reviewed. Taxonomy:Lecanicillium fungicola (Preuss) Zare and Gams: Kingdom Fungi; Phylum Ascomycota; Subphylum Pezizomycotina; Class Sordariomycetes; Subclass Hypocreales; Order Hypocreomycetidae; Family Cordycipitaceae; genus Lecanicillium. Host range:Agaricus bisporus, Agaricus bitorquis and Pleurotus ostreatus. Although its pathogenicity for other species has not been established, it has been isolated from numerous other basidiomycetes. Disease symptoms: Disease symptoms vary from small necrotic lesions on the caps of the fruiting bodies to partially deformed fruiting bodies, called stipe blow-out, or totally deformed and undifferentiated masses of mushroom tissue, called dry bubble. The disease symptoms and severity depend on the time point of infection. Small necrotic lesions result from late infections on the fruiting bodies, whereas stipe blow-out and dry bubble are the result of interactions between the pathogen and the host in the casing layer. Economic importance:Lecanicillium fungicola is a devastating pathogen in the mushroom industry and causes significant losses in the commercial production of its main host, Agaricus bisporus. Annual costs for mushroom growers are estimated at 2–4% of total revenue. Reports on the disease originate mainly from North America and Europe. Although China is the main producer of white-button mushrooms in the world, little is known in the international literature about the impact of dry bubble disease in this region. Control: The control of L. fungicola relies on strict hygiene and the use of fungicides. Few chemicals can be used for the control of dry bubble because the host is also sensitive to fungicides. Notably, the development of resistance of L. fungicola has been reported against the fungicides that are used to control dry bubble disease. In addition, some of these fungicides may be banned in the near future

Effects of fluorescent Pseudomonas spp. isolated from mushroom cultures on Lecanicillium fungicola

Dry bubble disease, caused by Lecanicillium fungicola, is a serious economic problem in the cultivation of the white button mushroom. Biological control of the disease would meet the mushroom industry’s efforts to minimize the use of chemicals. A total of 160 bacterial strains were isolated from colonized casing and screened for in vitro antagonism of L. fungicola. Fifty-three isolates inhibited L. fungicola in vitro. Using BOX-PCR, the 53 antagonistic isolates were grouped in 18 unique genotypes. Further characterization based on the 16S rDNA identified all isolates as Pseudomonas spp. Using previously characterized Pseudomonas isolates and their mutants it was determined that L. fungicola is sensitive to both siderophore-mediated competition for iron and production of antibiotics. However, when tested for disease suppression, none of the Pseudomonas spp. strains isolated from colonized casing effectively controlled dry bubble disease. The insensitivity of dry bubble disease to direct biological antagonism and the implications for biological control of mushroom diseases are discussed

Effects of fluorescent Pseudomonas spp. isolated from mushroom cultures on Lecanicillium fungicola

Dry bubble disease, caused by Lecanicillium fungicola, is a serious economic problem in the cultivation of the white button mushroom. Biological control of the disease would meet the mushroom industry’s efforts to minimize the use of chemicals. A total of 160 bacterial strains were isolated from colonized casing and screened for in vitro antagonism of L. fungicola. Fifty-three isolates inhibited L. fungicola in vitro. Using BOX-PCR, the 53 antagonistic isolates were grouped in 18 unique genotypes. Further characterization based on the 16S rDNA identified all isolates as Pseudomonas spp. Using previously characterized Pseudomonas isolates and their mutants it was determined that L. fungicola is sensitive to both siderophore-mediated competition for iron and production of antibiotics. However, when tested for disease suppression, none of the Pseudomonas spp. strains isolated from colonized casing effectively controlled dry bubble disease. The insensitivity of dry bubble disease to direct biological antagonism and the implications for biological control of mushroom diseases are discussed

On the Use of Backward Difference Formulae to Improve the Prediction of Direction in Market Related Data

The use of a BDF method as a tool to correct the direction of predictions made using curve fitting techniques is investigated. Random data is generated in such a fashion that it has the same properties as the data we are modelling. The data is assumed to have “memory” such that certain information imbedded in the data will remain within a certain range of points. Data within this period where “memory” exists—say at time steps t1,t2,…,tn—is curve-fitted to produce a prediction at the next discrete time step, tn+1. In this manner a vector of predictions is generated and converted into a discrete ordinary differential representing the gradient of the data. The BDF method implemented with this lower order approximation is used as a means of improving upon the direction of the generated predictions. The use of the BDF method in this manner improves the prediction of the direction of the time series by approximately 30%

Absence of induced resistance in Agaricus bisporus against Lecanicillium fungicola

Lecanicillium fungicola causes dry bubble disease and is an important problem in the cultivation of Agaricus bisporus. Little is known about the defense of mushrooms against pathogens in general and L. fungicola in particular. In plants and animals, a first attack by a pathogen often induces a systemic response that results in an acquired resistance to subsequent attacks by the same pathogen. The development of functionally similar responses in these two eukaryotic kingdoms indicates that they are important to all multi-cellular organisms. We investigated if such responses also occur in the interaction between the white button mushroom and L. fungicola. A first infection of mushrooms of the commercial A. bisporus strain Sylvan A15 by L. fungicola did not induce systemic resistance against a subsequent infection. Similar results were obtained with the A. bisporus strain MES01497, which was demonstrated to be more resistant to dry bubble disease. Apparently, fruiting bodies of A. bisporus do not express induced resistance against L. fungicola