Twenty Trichoderma isolates were collected on 13 Serbian Agaricus bisporus farms and one in Bosnia and Herzegovina during 2006-2010. Twelve isolates were classified into five species by standard mycological studies and ITS1/ITS4 sequence analyses, namely Trichoderma atroviride, Trichoderma koningii, Trichoderma virens, Trichoderma aggressivum f. europaeum and Trichoderma harzianum. Eight isolates were not identified to the species level but were shown to be related to T. harzianum. The isolates of T. harzianum exhibited the highest virulence to the harvested A. bisporus pilei and T. virens and T. aggressivum f. europaeum the lowest. Antifungal activity of two biofungicides based on Bacillus subtilis and tea tree oil and the fungicide prochloraz manganese were tested in vitro to all Trichoderma isolates. Prochloraz manganese and B. subtilis were highly toxic to all tested Trichoderma isolates, their ED 50 values were below 0.3 and 1.3 mg L −1 , respectively. Tea tree oil did not exhibit a significant antifungal activity (ED 50 = 11.9-370.8 mg L −1 ). The effectiveness of biofungicides was evaluated against T. harzianum in a mushroom growing room, and they were applied alone or in combination with the fungicide at a respective proportion of 20:80%. Prochloraz manganese showed higher effectiveness than both tested biofungicides or their respective mixtures. The biofungicide based on B. subtilis demonstrated greater effectiveness in preventing disease symptoms than tea tree oil. B. subtilis combined with the fungicide revealed less antagonism in effectiveness against pathogen than tea tree oil.

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The impact of a biofungicide based on Bacillus subtilis Ch-13 on mushroom yield and efficacy in suppression of Trichoderma aggressivum f. europaeum T77 from Serbia was estimated in comparision with a similar microbial fungicide, Bacillus velezensis QST713, and the chemical fungicide prochloraz manganese. The biofungicide B. velezensis QST713 is registered for treatments of mushrooms and other crops in many countries but it is not currently available on the Serbian market. The tested B. subtilis Ch-13 fungicide enhanced mushroom yield 12%, compared with an uninoculated control, and notably more than B. velezensis QST713 applied at its higher test concentrations. Regarding the efficacy of the biofungicides in control of the compost pathogen T. aggressivum f. europaeum, B. subtilis Ch-13 applied in concentration of 3 × 10 8 CFU per m 2 showed higher efficacy than the higher concentrations (5 × 10 9 and 1 × 10 10 CFU per m 2) of B. velezensis QST713. The biofungicide based on B. subtilis Ch-13 should be further investigated regarding its different modes of application to ensure better efficacy in disease control as it showed beneficial features in both promoting A. bisporus production and suppressing the growth of the aggressive compost pathogen T. aggressivum, the causal agent of devastating green mould disease.

A study of the in vitro sensitivity of 12 isolates of Phytophthora infestans to metalaxyl, azoxystrobin, dimethomorph, cymoxanil, zoxamide and mancozeb, was conducted. The isolates derived from infected potato leaves collected at eight different localities in Serbia during 2005-2007. The widest range of EC(50) values for mycelial growth of the isolates was recorded for metalaxyl. They varied from 0.3 to 3.9 μg mL(-1) and were higher than those expected in a susceptible population of P. infestans. The EC(50) values of the isolates were 0.16-0.30 μg mL(-1) for dimethomorph, 0.27-0.57 μg mL(-1) for cymoxanil, 0.0026-0.0049 μg mL(-1) for zoxamide and 2.9-5.0 μg mL(-1) for mancozeb. The results indicated that according to effective concentration (EC(50)) the 12 isolates of P. infestans were sensitive to azoxystrobin (0.019-0.074 μg mL(-1)), and intermediate resistant to metalaxyl, dimethomorph and cymoxanil. According to resistance factor, all P. infestans isolates were sensitive to dimethomorph, cymoxanil, mancozeb and zoxamide, 58.3% of isolates were sensitive to azoxystrobin and 50% to metalaxyl. Gout's scale indicated that 41.7% isolates were moderately sensitive to azoxystrobin and 50% to metalaxyl.