First record of leaf spots and stem lesions on Pistacia lentiscus caused by Cylindrocladium pauciramosum and C. scoparium in Italy

A. Vitale and G. Polizzi^*

Dipartimento di Scienze e Tecnologie Fitosanitarie – sezione Patologia vegetale, Università di Catania, Via S. Sofia,100 I-95123, Italy

^*gpolizzi@unict.it

Accepted for publication 28/02/07

In November 2005, a foliage disease of mastic tree (Pistacia lentiscus, Anacardiaceae) was noticed in one nursery located in Giarre (Catania) in eastern Sicily (southern Italy). Symptoms including leaf spots, stem lesions, and severe defoliation were observed on about 25 % of the young (10-12 months old) and pot-growing seedlings (Fig. 1). In high moisture conditions, leaf tissues were covered with a fluffy white mass of fungal mycelium and abundant conidia referable to the genus Cylindrocladium. Hyphal tips were transferred on to potato dextrose agar (PDA) and typical microsclerotia had formed after two weeks.

Figure 1: Severe defoliation caused by coexisting infections of Cylindrocladium pauciramosum
and C. scoparium on pot-growing mastic tree seedlings

The identification of the pathogens was performed on eight fungal colonies grown on carnation leaf agar (CLA) on the basis of their respectively obpyriform or pyriform to broadly ellipsoidal terminal vesicles, conidiophore branching pattern, and conidium morphology. Five of these colonies were identified as C. pauciramosum C.L. Schoch & Crous, the remaining three as C. scoparium Morgan (Polizzi & Crous, 1999; Crous 2002). In addition, their ability to mate with Italian and South African tester strains of selected C. pauciramosum and C. scoparium isolates, as well as perithecial morphology, confirmed the identification of fungal colonies. Pathogenicity tests were done by inoculating 1-year-old mastic tree seedlings with the conidial suspensions (1 ×10⁵ CFU per ml) obtained from 14-day-old single-spore colonies of C. pauciramosum grown on CLA at 25°C. Control plants were sprayed with sterile distilled water. All plants were maintained in polyethylene bags in which the temperature was 25 ± 1°C and relative humidity was 95 to 100%. After a week, all inoculated plants developed severe symptoms similar to those observed originally in the nurseries. C. pauciramosum was always re-isolated from the respectively infected tissues fulfilling Koch’s postulates. No symptoms were detected on the control plants.  

C. scoparium was recently reported affecting mastic tree seedlings in the same area where it was responsible for leaf spots, stem lesions, blight, and crown rot (Polizzi et al., 2006). To authors’ knowledge this is the first record of leaf spots, stem lesions, and defoliation of P. lentiscus caused by C. pauciramosum and it also represents the first report of coexisting infections due to both C. pauciramosum and C. scoparium.

References

Crous PW, 2002. Key to the species of Cylindrocladium having teleomorph in Calonectria. In: Crous PW, ed. Taxonomy and pathology of Cylindrocladium (Calonectria) and allied genera. St. Paul, MN, USA: American Phytopathological Society, 133-38.

Polizzi G, Crous PW, 1999. Root and collar rot of milkwort caused by Cylindrocladium pauciramosum,  a new record for Europe. European Journal of Plant Pathology 105, 407-11.

Polizzi G, Vitale A, Castello I, Groenewald JZ, Crous PW, 2006. Cylindrocladium Leaf Spot, Blight, and Crown Rot, New Diseases of Mastic Tree Seedlings Caused by Cylindrocladium scoparium. Plant Disease 90, 1110.

The British Society for Plant Pathology