Mycogone perniciosa is the fungal pathogen causing the wet bubble of white button mushrooms (Agaricus bisporus). The main symptoms of disease are undifferentiated, irregular forms of mushroom tissue, cap spotting and development of amber liquid droplets on the distorted mushrooms. The aim of the research was to assess the pathogenicity of M. perniciosa isolates that were obtained from the infected sporophores. Six isolates from Polish mushroom farms as well reference strain of Hypomyces perniciosus CBS 322.52 were used in this study. The pathogenicity of isolates was assessed on the basis of severity of disease symptoms and crop reduction in the first flush. Mushroom crop was infected with different suspensions containing of M. perniciosa aleuriospores. Significant variability was shown between tested isolates. It was stated that the pathogenicity of isolates and concentration of conidia had a significant influence on the mushroom yield. The isolate of high pathogenicity caused significant yield losses, after inoculation with 1.3 × 10 4 ·m -2, whereas the isolate with fairly pathogenicity did not produce symptoms of wet bubble disease or caused slight deformation of single sporophores, even when the casing soil was inoculated with 1.3 × 10 6 ·m -2 spores.

Fungal diseases are a persistent problem in the cultivation of white button mushrooms (Agaricus bisporus). The chemical control of pathogens is becoming less effective and less desirable, so new ways to limit these infections are urgently required. What is more, the disease is mostly controlled through cultural practices and good hygiene on mushroom farms. The aim of this study was to evaluate the fungicidal effects of ozone on fungal pathogens of common mushrooms. Experiments with the use of ozone gas for disinfection of growing rooms after the completion of the mushroom growing cycle were carried out. The fungicidal effectiveness of ozone fumigation was evaluated on the basis of the survival rate of the spores of the pathogens tested (Lecanicillium fungicola, Cladobotryum dendroides, Mycogone perniciosa, and Trichoderma aggressivum). Spore suspension was applied to aluminum plates and then was exposed to gaseous ozone. The assessment of the growth of colonies of fungal isolates obtained from infected surfaces was carried out using Rodac contact test plates. The results showed that L. fungicola, M. perniciosa, and C. dendroides isolates were sensitive to the gas ozone. In order to achieve 100% efficacy against Mycogone strains, a minimum of 6 hours of ozonation had to be applied, whereas for Cladobotryum strains, a minimum of 8 hours had to be applied. The Lecanicillium species was the most sensitive to ozonation because 30 minutes of ozonation was enough to gain 100% inhibition of its growth. No satisfactory results were obtained in the case of the pathogenic species of Trichoderma, regardless of the experimental conditions. Nevertheless, this study has demonstrated the usefulness of ozone as a disinfectant for empty growing rooms after the completion of the mushrooms’ cultivation cycle.

Efficacy assessment of selected fungicides in the control of wet bubble (Mycogone perniciosa) in white button mushroom (Agaricus bisporus)Ocena skuteczności wybranych fungicydów w ochronie pieczarki (Agaricus bisporus) przed białą zgnilizną (Mycogone perniciosa) Joanna Szumigaj-Tarnowska*, Zbigniew Uliński, Czesław Ślusarski SummaryMycogone perniciosa is the fungal pathogen causing the wet bubble of white button mushroom (Agaricus bisporus). The main symptoms of disease are undifferentiated forms of mushroom tissue, cap spotting and development of amber liquid droplets on the distorted mushrooms. There is only one fungicide based on prochloraz-Mn available for the control of fungal diseases of white button mushroom. The aim of the study was to assess the effectiveness of chemical products such as prochloraz-Mn and imazalil, and natural fungicides obtained from plants (grapefruit extract and tea tree extract) in the control of wet bubble. The inoculum of M. perniciosa at different concentrations of spores was applied to the casing and then fungicide was added. The effectiveness of examined products was assessed on the basis of mushroom yield and severity of disease symptoms in the first and the second flushes. The products based on imazalil showed a high effectiveness, comparable with prochloraz-Mn efficacy, in both flushes at conidia concentration of 1.3 × 10 4 and 13 × 10 6 per m 2 of casing. The natural fungicide based on a grapefruit extract was effective in reducing the wet bubble in the first flush, at conidia concentration of 1.3 × 10 4 per m 2 of casing soil.Key words: wet bubble; Mycogone perniciosa; Agaricus bisporus; control; natural plant protection products StreszczenieMycogone perniciosa, grzyb patogeniczny, wywołuje białą zgniliznę pieczarki dwuzarodnikowej (Agaricus bisporus). Choroba objawia się powstawaniem dużych, nieregularnych, nabrzmiałych tworów z tkanki pieczarki, a także rozwojem bursztynowej zawiesiny na porażonych grzybach. Obecnie w ochronie pieczarki przed chorobami grzybowymi dostępny jest jeden preparat zawierający prochloraz-Mn. Celem badań była ocena skuteczności środków chemicznych (prochloraz-Mn oraz imazalil) i naturalnych z ekstraktów roślinnych (ekstrakt z grejpfruta oraz drzewa herbacianego) w ochronie pieczarki przed białą zgnilizną. Badania polegały na zainfekowaniu uprawy pieczarki zawiesiną makrokonidiów izolatów grzyba M. perniciosa o różnej koncentracji, a następnie zastosowaniu fungicydów. Skuteczność preparatów oceniano na podstawie zebranego plonu owocników, a także stopnia porażenia uprawy w pierwszym i drugim rzucie. Preparat zawierający imazalil wykazał wysoką skuteczność, porównywalną do prochlorazu-Mn, w I i II rzucie przy zainfekowaniu uprawy zarodnikami w liczbie 1,3 × 10 4 i 1,3 × 10 6 na m 2 okrywy. Preparat z ekstraktu grejpfruta skutecznie ograniczył chorobę w I rzucie przy koncentracji zarodników 1,3 × 10 4 na m 2 okrywy. Wstęp / IntroductionUprawa pieczarki dwuzarodnikowej (Agaricus bisporus) jako typowa monokultura jest narażona na infekcje pochodzeni...

The aim of the research was to assess various strains of white button mushrooms (Agaricus bisporus) susceptibility to brown blotch caused by Pseudomonas tolaasii bacteria. The mushroom strains used in this study are distinguished in size of cups. The investigated mushrooms were characterized by cup size in the following categories: intermediate between large and medium size, medium size and small size. Mushroom crop was infected with suspension containing different concentrations of bacterium cells. The susceptibility to brown blotch of A. bisporus was assessed on the basis of healthy and infected mushroom yield in the first and second flush. An inoculum concentration of 2.6 × 10 6 bacterium cells per m 2 casing resulted in a significant yield reduction of healthy mushrooms. The most susceptible to bacterial blotch were the mushroom strain P23, characterized by a small size of cups, and F60 characterized by intermediate between large and medium sized of cups, what resulted in the high yield of infected mushrooms, respectively, in the first and the second flush.

The chemical stability of chlorine dioxide (ClO₂) in the presence of prochloraz manganese (prochloraz-Mn) as biologically active substances used in agrochemical treatments in the cultivation of mushrooms are presented. For model mixtures of the tested components, a relative decrease in ClO₂ content over time was measured in the proportions applied during the mushroom cultivation cycle. Within 20 min after preparing a mixture of 1 500 ppm prochloraz-Mn and 100 ppm ClO₂ in water, the relative decrease in the concentration of ClO₂ was 20%. The obtained results indicate a possibility of simultaneously introducing the working mixture of ClO₂ and prochloraz-Mn salt into the champignon peat casing, assuming its use directly after preparation.