Postharvest diseases of lemon fruits represent one of the most severe sources of loss production. They are controlled by imazalil (IMZ), thiabendazole (TBZ) and sodium ortho-phenil-phenate (SOPP) registered fungicides for postharvest treatments. Nowadays, the chemical use is becoming more restricted for environmental concerns and development of fungicide-tolerance strains of fungal pathogens. In the last few years a renewed interest in alternative methods of postharvest decay control has been increasing and the research for natural products has provided encouraging results. The aim of this research has been the in vitro and in vivo effectiveness evaluation of six essences (garlic, cloves, oregano, mint, geranium and eugenol) and three mineral products (sodium bicarbonate, metabisulphite and kaoline) against Penicillium digitatum Sacc. and Phytophthora citrophthora (R. e E. Sm.) Leonian, the main responsible agents of postharvest decay in lemon fruit. In the in vitro assay, the essences and mineral substances were tested, in 2006-2008, at different concentrations using the Grover and Moore method. In the in vivo trial the products were tested on mature lemons both on intact (or unwounded) and wounded fruits, the latter previously infected with Penicillium spores and a Phytophthora colony fragments. In both experiments fruits were sprayed with products at different concentrations, air dried and stored at 5°C for 5 weeks. In vitro results, oregano, geranium and cloves essential oils showed a better inhibition against P. citrophthora at all concentrations in comparison to garlic and mint oils, that were effective only at the highest concentration. Only mint essential oil showed a good inhibition against P. digitatum at all concentrations. Geranium, oregano, eugenol, sodium bicarbonate and metabisulphite in vivo treatments, on intact (or unwounded) fruits showed a higher control against both fungi as well as IMZ treatment. On artificially infected lemons, the results showed the higher efficacy of IMZ compared to a light inhibent activity of natural products. Among the natural products, a better inhibition was obtained by mint essential oil against Penicillium while geranium, cloves, oregano and eugenol oils were more effective against Phytophthora.
|Number of pages||1|
|Publication status||Published - 2008|