Perspectives of disease threat in large-scale Pinus radiata monoculture―the New Zealand experience

Large scale P. radiata monoculture has been in existence in New Zealand for over 60 years. During this time a number of damaging diseases (e. g. Sirex-Amylostereum, Dotbistroma, Armillaria, Cyclaneusma needle cast. Spbaeropsis die-back etc.) have occurred but the impact was by no means devastating as these diseases are either controllable or in some the losses were deemed acceptable. As a large proportion of the biomass produced before age 10-12 is waste-thinned, the acceptable level of disease loss is thereby very high. The practice of clear felling and short rotation reduces some of the disease risks common in other forest systems. Outlook for future disease threat is discussed with respect to current trends toward clonal forestry and the possible arrival of additional exotic pathogens.