Invasive Species Compendium

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Abstract

Loss of merchantable wood in Radiata Pine associated with infection by Diplodia pinea.

Abstract

Inoculations with D. pinea on the cortical tissue of healthy 4-year-old Pinus radiata growing on three soil types in Victoria, on 3-year-old grafted ramets from scions of 15-year old trees, and on 2-year-old seedlings in the greenhouse gave rise to cankers, stem kinking and, in some cases, death of the leader, similar to the defects observed in naturally infected trees. Histological examination confirmed the presence of D. pinea. The studies suggest that cortical tissues of trees may be infected after damage by e.g. hail, wind or insects. The effect of the dead-topped condition on tree mortality and growth was studied over a two-year period in a 15-year-old P. radiata plantation. Dead-top occurred among trees of all ages, but was more frequent in the smaller size classes. The defect appeared to have occurred intermittently throughout the life of the stand; the incidence of dead-top is thus likely to increase with stand age. A comparison of the regressions of tree growth on tree b.a. for dead-topped and unaffected trees of comparable size indicated that dead-topped trees grew ca. 40% less in b.a. than did unaffected trees. Total b.a. increment was estimated to be reduced by ca. 6%. The effect of dead-top and canker on the amount of degrade of standing merchantable wood in 10- and 17-year-old stands and its relation to topography is reported [cf. F.A. 29 No. 4335]. The influence of moisture stress on the susceptibility of P. radiata to D. pinea attack is briefly discussed. [Cf. F.A. 31 No. 898. KEYWORDS: Die back \ fungal diseases \ fungal diseases \ effects \ increment \ yield \ Macrophoma pinea \ Pinus radiata diseases \ disorders dieback, wilt \ Pinus radiata diseases \ disorders foliage