Seiridium cardinale newly reported on Cupressus sempervirens in Morocco

Cypress canker, caused by Seiridium cardinale, is a serious fungal disease on Cupressus spp. that are native and widely planted in the Mediterranean region (Graniti, 1998). Although the disease is mentioned as a potential threat for cypress in Morocco (Stiki, 1994; Ghaioule et al., 1999), it has never been scientifically described in this location.

In July, 2007, in a garden a few kilometres north of Imouzzer Kandar, Morocco, 10-year-old ornamental C. sempervirens trees were observed with crown reddening, branch dieback (Fig. 1) and resin exudation from bark lesions. Fungal isolations were made from fragments of necrotic bark from two trees.

Dense, cottony colonies, 61-68 mm in diameter, with a white margin, a thicker olive green centre, and a salmon orange reverse side, developed on potato dextrose agar (PDA) after 21 days at 25° C in the dark. Colonies produced acervuli and conidia after three weeks at 18° C under a mixture of fluorescent and near ultraviolet light on water agar. Conidia were fusiform, straight or slightly curved, 22.3-28.2 x 7.9-9.7 μm, 5euseptate, with hyaline, conical end cells lacking any appendage, and the four median cells yellow-brown (Fig. 2).Based upon these characteristics, the fungus was identified as S. cardinale (Graniti, 1998).An isolate (CBS 123991) was deposited at the Centraalbureau voor Schimmelcultures, Utrecht, The Netherlands.

Stem inoculations with isolate 123991 were done in May, 2008 on three year old susceptible, tolerant and resistant clones of C. sempervirens, as described by Danti et al. (2006). Three months later, elliptical, 54-72 mm long, purple-brown cankers were clearly visible on all inoculated stems (Fig. 3). The fungus was successfully re-isolated from the inner necrotic periderm. Control trees, inoculated with sterile PDA plugs, healed normally.

This is the first report of S. cardinale in Morocco. The disease has also been observed on adult C. sempervirens trees in Rabat and Marrakesh (Fig. 4). Since both early (crown reddening) and advanced (bare branch) symptom development were observed on diseased trees, S. cardinale has probably been spreading in Morocco for some years that may give rise to epidemics, as occurred in other Mediterranean countries and recently reported in Cyprus (Tsopelas et al., 2008). A detailed survey on cypress is needed to plan proper control measures.