Chemical pesticides and fertilizers are used in agricultural production worldwide to prevent damage from plant pathogenic microorganisms, insects, and nematodes, to minimize crop losses and to preserve crop quality. However, the use of chemical pesticides and fertilizers can severely pollute soil, water, and air, posing risks to the environment and human health. Consequently, developing new, alternative, environment-friendly microbial soil treatment interventions for plant protection and crop yield increase has become indispensable. Members of the filamentous fungal genus Trichoderma (Ascomycota, Sordariomycetes, Hypocreales) have long been known as efficient antagonists of plant pathogenic microorganisms based on various beneficial traits and abilities of these fungi. This minireview aims to discuss the advances in the field of Trichoderma-containing multicomponent microbiological inoculants based on recent experimental updates. Trichoderma strains can be combined with each other, with other fungi and/or with beneficial bacteria. The development and field performance of such inoculants will be addressed, focusing on the complementarity, synergy, and compatibility of their microbial components.

White button mushroom—Agaricus bisporus (J.E.Lange) Imbach—is among the most popular cultivated mushrooms worldwide. The most serious challenge in industrial mushroom production is the green mold disease caused by Trichoderma species. Our aim was to isolate and examine bacterial strains from mushroom casing material for their potential use as biocontrol agents. Twenty-seven bacterial strains were isolated and tested against mold pathogens of white button mushroom. The Bacillus velezensis strain SZMC 25431 was selected for further examination and tested under simulated Agaricus cultivation conditions against T. aggressivum SZMC 23834 in a 1200-L Fitotron SGC120 standard plant growth chamber. Our results showed that the bacterial treatment was effective against the pathogen in all cases, but the best results were achieved at an application concentration of 10⁵ cells mL⁻¹. Industrial-scale experiments were also carried out in Agaricus growing houses with a bearing surface of 480 m²: the bacterial suspension was mixed in water tanks applied for daily irrigation. The results suggest that the bacterial treatment may even increase the crop yield of A. bisporus. Based on our results, we concluded that the selected B. velezensis strain may potentially be used for biological and integrated treatment in Agaricus cultivation.

Pathogenic moulds (e.g., Trichoderma, Hypomyces, and Lecanicillium) cause huge problems in industrial scale production of Agaricus bisporus. It is important to choose the right control strategy, either chemical or biocontrol-based, to prevent substantial economic losses. The present study was carried out to reveal the in vitro efficacy of some fungicides and disinfectants against causative agents of wet bubble (Hypomyces perniciosus), dry bubble (Lecanicillium fungicola var. fungicola), cobweb disease (Hypomyces odoratus), and green mould (e.g., Trichoderma aggressivum f. aggressivum, T. aggressivum f. europaeum, T. harzianum), the four most devastating fungal infections in mushroom production. Prochloraz was efficient against Trichoderma and H. perniciosus isolates. Metrafenone did not cause complete inhibition for any of the isolates even at the highest concentration (5%) tested. In both cases Lecanicillium isolates displayed the lowest growth rate inhibition. Concerning the tested disinfectants, treatment with Sekusept Aktiv resulted in complete growth inhibition for all isolates in the concentration range of 1.25-5%. Terralin Protect, Disinflex and Formalin were also effective, except against the tested isolates of T. agressivum f. agressivum which proved to be the most resistant.

Plant growth-promoting microorganisms (PGPM), including plant growth-promoting bacteria (PGPB) and plant growth-promoting fungi (PGPF), can improve plant performance while simultaneously suppressing plant pathogens. Most PGPM colonize the rhizosphere, and some are also able to establish endophytic populations within plant tissues, where they contribute to plant health through direct antagonism, induced systemic resistance, improved nutrient acquisition, and phytohormone-related effects. These properties make PGPM attractive alternatives or complements to conventional pesticides in sustainable plant protection. This mini-review summarizes the principal mechanisms by which PGPM suppress pathogens, with particular emphasis on antimicrobial secondary metabolites, siderophore production, extracellular hydrolytic enzymes, mycoparasitism, mycophagy, and induced systemic resistance. In addition, nutrient mobilization and microbial phytohormone production are discussed as indirect but important contributors to disease reduction and plant vigor. Overall, PGPM-based approaches provide a multifunctional framework for sustainable plant protection by integrating direct pathogen suppression with improved plant performance and defense.