Mass Production of Conidia of Penicillium frequentans,a Biocontrol Agent Against Brown Rot of Stone Fruits

Conidial production of Penicillium frequentans , a biocontrol agent of the fungal pathogen Monilinia laxa , was tested in liquid and solid-state fermentation. Conidial production of P. frequentans in solid-state fermentation was higher than in liquid-state fermentation. Solidstate fermentation was made in specially designed plastic bags (VALMIC ® ) containing peat:vermiculite (1:1 w/w). Addition of nutrients to the peat:vermiculite increased conidial production of P. frequentans , especially when lentil meal was added. The number of conidia obtained in this solid-state fermentation was maintained in the range of 10 8 -10 9 conidia g -1 from 5 to 120 days after inoculation. Germinability of these conidia was > 90% until 90 days of incubation and declined at 120 days. Optimal initial moisture content in the substrate was 30-40% (v/w). At lower moisture contents, significant reductions in conidial production and germinability were observed, particularly at 10% (v/w). Conidial production was similar when the substrate was inoculated with 10 5 , 10 6 or 10 7 conidia g -1 dry substrate. Fresh conidia produced by solid-state fermentation reduced the incidence of brown rot on plums by 75%.     

Improving Biocontrol Activity of Pichia guillermondii Against Post-harvest Decay of Oranges in Commercial Packing-houses by Reduced Concentrations of Fungicides

Three commercial tests were conducted in 2000-2001 in two commercial packing-houses (Muravera and Villacidro) located in Sardinia, Italy, to evaluate the efficacy of biological, chemical and integrated treatments against Penicillium digitatum and P. italicum on naturally inoculated orange fruit. Damage caused by the packing-house processing line was also assessed. Treating orange fruits with the yeast Pichia guilliermondii (strain 5A) in the processing line generally led to a significant reduction of post-harvest decay compared to the processed control, while the commercial product Aspire®, based on Candida oleophila , was ineffective in inhibiting the pathogen when applied alone. The integrated application of thiabendazole or imazalil with the biocontrol agents significantly improved the control of fruit decay. Using thiabendazole at concentrations of 0.1 and 1.2 g L -1 , led to similar inhibition of fruit decay in two trials. Both yeasts were equally able to colonize the fruit actively during storage. Passing fruits through the packing line caused a significant increase in fruit decay.