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Aims: This study investigated the efficiency of six fungicides against Fusarium spp. associated to peach seedling decline in Tunisian nurseries.
Place and Duration of Study: Department of Biological Sciences and Plant Protection, Higher Institute of Agronomy of Chott Mariem, 4042, Sousse, Tunisia, between March 2016 and June 2016.
Methodology: The activity of six fungicides against Fusarium oxysporum and F. solani associated with peach seedling decline in Tunisian nurseries was evaluated in vitro and in vivo.
Results: The in vitro test showed that Carbendazim was the most effective at a low dose (10 ppm) against F. solani with 84.39% of hyphal growth inhibition, while it gives 60.55% of growth inhibition against F. oxysporum at 100 ppm. The percent of growth inhibition generated by Mancozeb was between 59.02 and 90.21% at 50 and 100 ppm, respectively. The efficacy of fosetyl-Al was not important in vitro at 10, 25, 50 and 100 ppm against the two tested pathogens. Hymexazol revealed to be effective against F. oxysporumbut without effect on F. solani for all used doses. The Chinosol was effective at different doses against F. oxysporum, with 88% of growth inhibition at 50 ppm for the two tested species. Thus, the fosetyl-Al, hymexazol and chinosol are the most effective on F. oxysporum and F. solani. Carbendazim was moderately effective against F. oxysporum (40. 15%), whereas it was the most effective against F. solani (98.02%). The mancozeb and metalaxyl-M+mancozeb were the lowest effective against the two pathogens tested with percents of inhibition of 27.41% and 28.96% for F. oxysporum respectively, and 48.02% and 42.46% for F. solani, respectively.
Results of in vivo test indicated that disease severity parameters of peach seedlings recorded after three months of inoculation by Fusarium spp. showed that the fosetyl-Al and metalaxyl-M + mancozeb reduced significantly root browning induced by Fusarium oxysporum by 62.55%. The mancozeb and carbendazim reduced also the root browning without significant effect. Whereas, all products didn’t reduce the severity of root browning or the vegetative sanitary states index of peach seedlings inoculated by F. solani. For the growth parameters, plants inoculated by F. oxysporum and treated by fosetyl-Al and metalaxyl-M+mancozeb increased the root weight by 34% and 24.89%, respectively. The metalaxyl-M+mancozeb improved also the plant height by 8.05% compared to the control inoculated by F. oxysporum. However, chinosol was the only product that improved plant height by 10.31% and root weight by 9.78% of plants inoculated by F. solani.
Conclusion: The fungicides Alliette express (fosetyl-Al), Ridomil Gold (mancozeb+ metalaxyl-M),Dithane-M45 (mancozeb) and Prodazim (carbendazim) were the most effective in vivo against F. oxysporum associated with a peach seedling decline in Tunisian nurseries, whereas Beltanol (chinosol) is the only product that improved the seedling growth inoculated by F. solani. Thus, it will be important to test them in the future against the other genera associated with this disease like Pythium and Phytophthora species. Then, it is necessary to test them against the combination of these pathogens because the causal agent of this disease is a complex.