Diplodia pinea . [Descriptions of Fungi and Bacteria

Abstract

Abstract A description is provided for Diplodia pinea . Information is included on the disease caused by the organism, its transmission, geographical distribution, and hosts. HOSTS: On Pinus species. Also on Abies excelsa, Araucaria cunninghamii, Chamaecyparis lawsoniana, Cupressus macrocarpa, Cupressus lusitanica, Cupressus sempervirens, Picea abies, Pseudotusga menziesii, P. taxifolia and Thuja orientalis [Platycladus orientalis] . DISEASES: Tip and twig blight, stag-head, red top, bud-wilt and seedling collar rot of conifers. Causes stunting of new growth, browning of needles, bending or curling of young shoots and discoloration and death of parts of the crown. Also affecting germination of Pinus seed and causing blight and dieback of coniferous seedlings in the nursery. Frequently found as a wound parasite of injured or weak trees causing bark cankers and dieback of branches and as a saprophyte causing blue-stain of sap-wood of fallen or freshly cut timbers (17: 150; 36: 436; 41: 339). GEOGRAPHICAL DISTRIBUTION: Africa (Kenya, Malawi, Mauritius, Mozambique, Rhodesia, S. Africa, Tanzania, Uganda); Asia (Japan, Malaysia, Thailand); Australasia & Oceania (Australia, New Zealand); Europe (Austria, Belgium, France, Germany, Italy, Portugal, Rumania, Spain, Sweden, U.K.); North America (Canada, U.S.A.); Central America & West Indies (Jamaica), South America (Argentina, Brazil, Chile, Paraguay). (CMI Map 459, 1969). TRANSMISSION: The pathogen is disseminated as spores by wind, rain and in fluid secreted by the pine spittle-bug, Aphrophora parallela and as mycelium on seed of Pinus (16: 219; 21: 398). Infection may take place through natural infection courts such as leaf traces or cones and cone-stalks (5: 708; 48, 3187) as well as through living tissues following wounding (31: 1; 44, 889; 48, 3187) or damage from hail (8: 535; 16: 219; 20: 150), frost (21: 398; 40: 388) or insects (pine spittle-bug, 21: 398; bark beetles, Myelophilus piniperda [Tomicus piniperda] , 14: 727) or attack by rust, Cronartiurn ribicola , causing progressive wilt in Pinus halepensis (25: 493) or by drought (14: 65) or other unfavourable growing conditions (13: 426, 553; 16: 148). Gilmour found that the amount of infection in P. radiata appeared to be correlated with trunk wounding and varied with the type of pruning tool used: secateurs, 12%; axe, 48%, slasher, 68% (44, 889). The pathogen may persist in infected tissues up to 400 days (48, 3187) and is commonly saprophytic on forest debris which provides a source of abundant spores during periods of rain (41: 339).