Behavior of Italian Lemon Rootstocks towards Mal Secco Leaf Infection with Tunisian Fungus Phoma tracheiphila in Controlled Environment

Abstract

Studying behaviors of four Italian lemon rootstocks towards Mal Secco leaf infection with the fungus Phoma tracheiphila, isolated in Tunisia in controlled environment, is the aim of this research work. It involves prospection of infected lemons fields in Tunisia, isolation and morphological identification of the fungus, preparation of inoculum and infection of leaves of four rootstocks. Following the artificial inoculation in three assessments after 10, 20 and 30 days post inoculation (dpi) by observing the appearance of disease symptoms, counting the percentage of positive inoculation and determining the average disease intensity according to the leaf empirical scale. All these parameters indicated about the behaviour of the rootstock towards disease in addition to allowing the classification of the four lemon rootstocks according to susceptibility to Mal Secco. Therefore Volkameriana which showed great sensitive behavior was considered as susceptible rootstock. However, Sour Orange showed an intermediate susceptibility to Mal Secco infection and was classified as tolerant rootstock. Nevertheless Flying Dragon and Citrange Troyer were considered as resistant rootstocks after showing a great resistance to the leaf infection by Phoma tracheiphila.

Scientific Opinion on the pest categorisation ofPlenodomus tracheiphilus(Petri) Gruyter, Aveskamp & Verkley [syn.Phoma tracheiphila(Petri) L.A. Kantschaveli & Gikashvili]

“…In a recent study from Turkey, it was reported that effective control of the disease would double production in lemon-producing countries (Gulsen et al, 2007). In addition, Ziadi et al (2012Ziadi et al ( , 2014 recently reported that the disease causes serious damage in Tunisia having affected up to 100 % of trees of susceptible lemon cultivars. Nigro et al, 2011).…”