Prevalence of Fusarium Species Associated with Peach Decline in Tunisian Nurseries

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Abstract
Aims: To survey nurseries and diagnosis of the young peach seedlings decline, to investigate the Fusarium species associated with the decline of peach in Tunisian nurseries using morphological and molecular tools and determine the pathogenicity of the most predominant species on peach seedlings. Place and Duration of Study: Tunisian peach nurseries and Department of Biological Sciences and Plant Protection, Higher Institute of Agronomy of Chott Mariem, 4042, Sousse, Tunisia, between November 2012 and July 2014. Methodology: The surveys were conducted in peach nurseries. Five root samples were taken from each vigor of each peach variety. The isolation and the morphological identification were done on PDA medium. The molecular identification was done using ITS1 and ITS4. Pathogenicity tests were made for the dominant species which are F. oxysporum (25 isolates) and F. solani (8 isolates). Results: The isolation was done on PDA medium and morphological and molecular identification (using ITS1 and ITS4) revealed the presence of 62 isolates of Fusarium oxysporum, 32 isolates of F. solani, 7 isolates of F. equiseti, 4 isolates of F. proliferatum and 2 isolates of F. chlamydosporum. F. oxysporum and F. solani were isolated from roots from all surveyed nurseries. F. equiseti were isolated from roots from nurseries in Chebika, Zaghouan and Monastir. F. proliferatum was recovered from roots from nurseries in the Chebika and Zaghouan regions. F. chlamydosporum were recovered only from roots in nurseries at Monastir region. Pathogenicity of Fusarium oxysporum and Fusarium solani was evaluated by using two varieties of peach, Carnival and Royal Glory grafted onto the Garnem rootstock (Prunus dulcis x hybrid clonal of Prunus persica) planted in inoculated soil Symptoms of peach decline namely browning of the apical vegetative part, height reduction and collar rot. These two Fusarium species were more virulent on Carnival than Royal Glory. Fusarium solani induced root and collar rot symptoms whereas F. oxysporum induced necrotic roots symptom, browning and height reduction. Conclusion: This finding showed that Fusarium oxysporum and F. solani were the most dominant species. They were virulent to peach seedlings.