First Report of Curvularia spicifera, As New Causal Agent of Root Rot in Citrus Rootstock (Citrus aurantium) in Morocco

Abstract

An isolate of Curvularia spicifera obtained from citrus auruntium, was capable of inducing different symptoms in plants of Citrus aurantium, the most widely used citrus rootstock in Morocco. The pathogenicity test was confirmed through dipping inoculation method of roots of Citrus aurantium plants into spore suspension (106 spores/mL) of Curvularia spicifera isolate which has led to diverse disease symptoms expression. Among these, root necrosis is accompanied by moderate to general stunting of root system and aerial plant parts. In terms of plant growth parameters, the length of the root and aerial parts were reduced to 6.1 and 6.8 cm in inoculated plants relative to 9 and 12.1 in control plants. The infection was established through the roots which failed to branch normally displaying less density of secondary and tertiary roots with 8/23 compared to 18/42 in the controls. Furthermore, Koch’s postulate was verified by re-isolating the original B. spicifera isolate from roots of diseased citrus plants. Based on macroscopic, microscopic and pathogenicity characteristics, Curvularia spicifera was recognized as a new pathogen of Citrus aurantium rootstock in Morocco.