Possibility of preparation of EC formulation from Eucalyptus extract and its effect in controlling Alternaria leaf spot of potato (Alternaria alternata) under green house condition.

The extract derived from seeds and leaves of eucalyptus contains eucalyptol as active ingredient act as disinfectant and has a pesticide property. Its fast degradation and very less toxicity for mammals has caused attention toward its use as a safe pesticide. Eucalyptus is found in different parts of Iran and observing the effectiveness of its extract against several plant pathogens in pesticide research laboratory of plant pest and diseases research institute and some agricultural research centers led to thinking for preparing its formulation in controlling Alternaria leaf spot of potato (Alternaria alternata). Its efficacy in controlling the mycelia growth and spore germination of A. alternata under laboratory condition was approved in Shahrood agricultural research center. During the first year of this study, an emulsifiable concentration of its extract was prepared in pesticide research laboratory of plant pest and diseases research institute and in the second year, the efficacy of three concentrations of its formulation in controlling Alternaria leaf spot disease of potato was conducted in a completely randomized design with five treatments and four replications under green house condition in Shahrood agricultural research center. Although our results indicated superiority of mancozeb in controlling the disease but all eucalyptus treatments also showed significant differences in controlling the disease compared to control ( p = 0.01). Mancozeb and eucalyptus formulation (15%) were kept in same statistical group. In this study percentage of disease incidence in mancozeb, eucalyptus formulations of 15, 10 and 5% and also untreated control were 6.52, 9.29, 16.28, 24.80 and 34.77% respectively. By increasing the percentage of eucalyptus formulation its phytptoxicity increased. Percentage of phytotoxicity in 5, 10 and 15% of eucalyptus formulations were 4.02, 10.65 and 21.34% respectively. If by modifying in preparation of this formulation, its phytotoxicity could be dismissed, its formulation might be used as a safe biofungicide in controlling Alternaria leaf spot of potato.