Fungistatic activity of essential oils of Laurus nobilis, Mentha X Piperita and Ruta graveolens against Rhizoctonia solani Kunn and Sclerotinia sclerotiorum (L.) De Bary

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Control of powdery mildew in cut roses using natural products in the greenhouse.

Roses grown under greenhouse cultivation are commonly affected by diseases and regular fungicide applications are commonly used. The aim of this research was to identify natural products that can substitute and reduce the health and environmental impacts of typical chemical treatments in the control of powdery mildew [(Podosphaera pannosa (Wallr. Fr.) de Bary] and grey mould (Botrytis cinerea Pers.). Treatments were applied in the greenhouse on the cut rose cultivars Sunluck (Gold Strike®) and Nirpbredy (New Fashion®) growing in a soilless system. Oregano and clove essential oil at 0.5 ml/l (an emulsifier was added) and sodium bicarbonate (NaHCO3) at 4 g/l were sprayed on rose plants to runoff. The controls were untreated roses and a standard chemical control (the fungicides Dinocap, Triadimenol, Dimethomorph+Sulphur, Bupirimate, Dithianon, Iprodione and Thiram) was applied in rotation. Sprays were applied every 7-10 days after the first symptoms of disease appeared. Disease incidence was checked on 100 leaflets and symptoms were evaluated using a scale from 0 (no disease) to 7 (76-100% infection). At three different times (June and November 2005 and January 2006) biometric data (stem height, stem diameter, stem flexibility, flower diameter, number of petals/flower and thorniness) and colorimetric analysis of the leaves were evaluated in order to determine the effect of treatments on cut rose quality. Treatment with essential oils and NaHCO3 was able to control the incidence and the severity of powdery mildew on roses. Ambient infection of grey mould was low and comparisons between treatments were not possible. Significant differences among the chemical and natural product treatments were found for all traits examined. Although NaHCO3 treatment controlled powdery mildew to a greater extent than essential oils, it resulted in slight phytotoxicity. These results indicate the potential use of natural products to control powdery mildew of roses and could be a good alternative to chemical fungicides. However, differences in response to powdery mildew depend on the cultivar susceptibility, period of treatments and level of control needed

Lemon post-harvest decay control by natural products

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