Cyttaria galls on silver beech

Transcription

1 Forest Pathology in New Zealand No. 9 (Second Edition 2009) Cyttaria galls on silver beech P.D. Gadgil (Revised by P.D. Gadgil) Causal organisms Cyttaria gunnii Berkeley Cyttaria nigra Rawlings Cyttaria pallida Rawlings Fig. 1 - Fruiting bodies of Cyttaria gunnii, covering and obscuring the small gall on which they are borne. The immature fruiting bodies are lighter in colour than the honeycombed, mature fruiting bodies.

2 Type of injury Development of perennial galls on branches and stems leading to malformation and occasionally to death of branches. Diagnostic features The fungi produce galls on branches and stems of silver beech (Nothofagus menziesii); these galls are perennial and produce crops of fruiting bodies each spring (September -November). The distinguishing features of the three species are as follows: Cyttaria gunnii (Fig. 1, 2) Branch galls roughly spherical, rarely more than twice the diameter of the host branch, and usually occupying about two-thirds of its circumference. Stem galls usually in the form of encircling bands. Gall surface under the bark contorted and projected into sharp spines. Fawn to bright yellow fruiting bodies, pear-shaped, up to 2 cm in diameter. Cyttaria nigra (Fig. 2) Galls roughly spherical, usually considerably more than twice the diameter of the host branch or stem. On larger trees, galls 1 m or more in diameter are common. Gall surface under the bark has bluntly rounded projections and a few, very short spines. Slack or black and gold fruiting bodies, pear-shaped with black incrustations, up to 2 cm in diameter. Cyttaria pallida (Fig. 2) Branch and stern galls long and spindle-shaped, sometimes several feet long. Dirty white fruiting bodies, spherical, somewhat flattened, up to 1.5 cm in diameter.

3 Host Nothofagus menziesii Distribution The fungi are present throughout New Zealand, wherever the host tree is found. Disease development Germinated spores invade the tissues of new shoots and produce chemical substances which cause proliferation of the host tissue and lead to gall formation. With C. gunnii and C. nigra the fungus travels only a short distance in the host, producing localised galls. With C. pallida, however, the fungus grows down the branch or stem and the gall increases steadily in length for many years. Fruiting bodies arise from the spines produced in the wood of the host by the action of the fungus. These spines, consisting of fungal hyphae and woody tissue, project through the bark nearly to the exterior. Spores are discharged in visible clouds from ripe fruiting bodies. The galls are perennial and keep growing as long as the host branch or stem is alive.

4 Fig. 2 - Left: Fruiting bodies of Cyttaria nigra. Note the large size of the gall in relation to the diameter of the branch. Centre: Fruiting bodies of Cyttaria pallida produced on long, spindle- shaped galls. Right: Fruiting bodies of Cyttaria gunnii. Economic importance Cyttaria galls are most often found on heavily branched trees growing either on the borders of clearings or in open stands. Girdling galls may lead to the death of upper parts of the branch or stem. Galls of C. pallida cause twisting of the branches, which often break in high winds. The effect of Cyttaria spp. on timber production in managed N. menziesii stands has not been studied. Control No control measures are known. Note: Species of Cyttaria grow only on Nothofagus spp. and are also found in South America (6 species) and Australia (2 species). In South America, the galls are used for making ornaments and the fruiting bodies are eaten.

5 BIBLIOGRAPHY Gadgil, P.D. 2005: Fungi on trees and shrubs in New Zealand. Fungi of New Zealand Volume 4. Fungal Diversity Research Series 16: Rawlings, G. B. 1956: Australasian Cyttariaceae. Transactions of the Royal Society of New Zealand 84: