Fusarium circinatum, the causal agent of pitch canker of mature pines and root/collar rot of pine seedlings/cuttings, has resulted in large-scale losses to pine forestry in various parts of the world. The disease caused by this fungus is now regarded as one of the most important threats to pine plantations by a pathogen. Fusarium circinatum was first discovered in South Africa in 1990 where it infected Pinus patula seedlings in a nursery. Subsequently, the pathogen spread to pine nurseries in all other parts of the country, where it affects several Pinus species. Fusarium circinatum then appeared in the field where it has resulted in large-scale mortality of mostly young P. patula seedlings after planting. Pitch canker first appeared on mature P. radiata in 2006 and sporadic outbreaks of the disease have occurred subsequently on this species and on P. greggii in the western, southern and north-eastern Cape. Pinus patula is the most important softwood species grown in South Africa, comprising 50% of all softwoods planted, and is highly susceptible to F. circinatum. The pathogen, therefore, poses a potentially devastating threat to the future sustainability of the South African softwood industry. Strategic measures to minimise further spread are urgently needed. This review presents an overview of the impact that F. circinatum has had on South African forestry, and it considers the long-term prospects for pine forestry in the country as this relates to the presence of the pitch canker fungus.

The fall rate of nearly 600 lodgepole pines(Pinus contorta)killed by the mountain pine beetle (Dendroctonus ponderosae) in central Oregon was investigated in thinned and unthinned stands. Estimates were obtained by fitting a complementary log-log model to the conditional probabilities of trees falling within a given year. Snags began falling 3 yr after death in thinned stands and 5 yr in unthinned stands. Small trees fell slightly faster than large trees in thinned stands, but tree size was not a factor in the fall rate in unthinned stands. In thinned stands, 50% were down in 8 yr and 90% were down in 12 yr. In unthinned stands, 50% were down in 9 yr and 90% were down in 14 yr. No particular calendar year had tree fall that was significantly greater than average. All beetle-killed trees broke off at the ground when they fell. The rate that trees fall in different environments may be related to the speed of bole decay at the ground level. West. J. Appl. For. 13(1):23-26.

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SYNOPSISThe maturation and ageing effects of parent or donor plants have been reported to have both positive and negative influences on the performance of rooted cuttings. A general decline in rooting ability, root quality and speed of rooting in the nursery, and a reduction in tree survival, growth and form in the field, have been associated with donor plants that have reached a state of reproductive or ontogenetic maturity. Increased maturation has also been shown to affect wood quality negatively. Provided that donor plants are still relatively young, positive effects from increased donor age have been observed through an improvement in tree form and branching habit, as well as a reduction in bark thickness and stem taper. These improvements have resulted in increased timber yields over seedlings of the same genetic origin. This report summarises current understanding of the effects of donor maturation.

Literature Cited found the aphid killing Pacific silver fir stands around Mount St. Helens in Washington (Johnson and Wright 1957). Further searching the same year revealed the aphid also present in subalpine fir, in both Oregon and Washington. By 1957, an estimated 600, 000 acres of forest in the two States were infested by the balsam woolly aphid (Whiteside 1958). Since then, aphid infestations have also been found on Pacific silver fir near Vancouver, British Columbia, and on grand fir on Vancouver Island (Silver 1959).