Precision And Accuracy Of Pest And Pathogen Damage Assessment In Young Eucalypt Plantations |
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Authors: | A. H. Smith E. A. Pinkard C. Stone M. Battaglia C. L. Mohammed |
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Affiliation: | (1) CSIRO Forestry and Forest Products, Hobart, Tasmania, Australia;(2) CRC for Sustainable Production Forestry, Hobart, Tasmania, Australia;(3) State Forests of NSW, Beecroft, New South Wales, Australia;(4) School of Agricultural Science, University of Tasmania, Hobart, Tasmania, Australia |
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Abstract: | Fungal pathogens, browsing mammals, birds, insects, nutrient deficiencies, drought, frost and waterlogging are all damaging agents to plantation species. The subsequent loss in leaf tissue or reduced photosynthetic potential can reduce growth and potentially lead to tree death. The Crown Damage Index (CDI) was developed in Australia to quantify damage in young eucalypt plantations. The accuracy and precision of assessing damage at a tree level were determined to ensure the reliability, objectivity and repeatability of the CDI method. Nine assessors, with varying levels of experience, estimated damage on three plots of fifty trees each, to obtain an understanding of the subjectivity of assessing damage caused by insects (e.g. Chrysophtharta spp.) and fungal pathogens (e.g. Mycosphaerella spp.) on Eucalyptus globulus. Damage levels were measured by destructive sampling to enable direct comparisons between estimates and damage levels to be made. The most experienced assessors provided the most repeatable estimates and were generally the most accurate. The incidence of foliar necrosis was the least subjective measure while defoliation was the most subjective and the least accurate of the indices measured. All assessors, regardless of experience, were able to predict the Crown Damage Index (a combined index of all damage classes) to within 12% of measured damage levels. |
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Keywords: | assessment Crown Damage Index defoliation disease discoloration Eucalyptus globulus foliar necrosis forest health insect pests Mycosphaerella |
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