Impact of root rot and other diseases in young Douglas-fir plantations

Abstract

Buckland et al. (1954) and Buckland (1953) on Poria and Armillaria root rot, Porter (unpublished) on dieback pre-conditioned by low temperatures, Molnar (1959) on drought injury and Weir (unpublished) on sunscald. Although these papers provide a better understanding of the diseases described, most lack an appraisal of occurrence and data required for developing sampling plans.An analysis of disease in three 15-to 17-year-old Douglas-fir plantations on Vancouver Island, British Columbia, was initiated in 1957. The specific objectives were to describe the more frequently occurring diseases, ascertain patterns of diseased and healthy trees, examine frequency distributions encountered in quadrat sampling and evaluate field sampling procedures appropriate to disease assessment. Foster and Johnson (1963) presented an assessment of the patterns, frequency distributions and sampling of diseases occurring in the plots at the initiation of the studv.During later examinations, the following points of interest to those concerned with the impact of diseases in Douglas-fir plantations emerged and, we feel, warrant a new look at Foster and Johnson's assessment. Armillaria mlellea. Poria weirii and Fomes annosus root rots were the only diseases developing in a manner of concern to forest managers. Armillaria root rot, even though present at a high incidence in young stands, will probably be a little concern after age 25-30 years, provided the trees are not undergoing continuous stress. If Poria weirii and Fomes annosus root rots are present in a significant number of centers in young stands, losses by rotation age will undoubtedly be high. Location and method of studyThe plantations studied were located at Robertson River, Campbell River and Tsable River (Table 1 ). Each consisted of one age class of Douglas-fir, was uniform in site and topography, and was of sufficient size to permit establishment of the required number of contiguous recording units (Foster and Johnson 1963). Following establishment of the plots, coordinated measurements were obtained to establish the relative position of every tree 4.5 f t and higher within 10.43 foot-square recording units. Diseases at various levels of intensity were present in each area.Trees 4.5 f t and higher were examined in late August and in September following plot establishment, and 3, 6 and 11 years thereafter. When small trees, including ingrowth, reached the 4.5-foot minimum height limit, they were included for detailed examination. lngrowth during the 11 years was primarily Douglas-fir, western hemlock (Tsuga heterophylla (Raf.) Sarg.) and western red cedar (Thuja plicata Donn) but, except for sunscald and frost injury on hemlock, diseases of the latter two species are not considered here.When examining the plantations for root rot, w e turned our attention first to the above-ground symptoms: crown deterioration, basal stem lesions. and standing and down mortality. Having located infection centers in this manner, we then examined

Predicting Present and Future Suitable Climate Spaces (Potential Distributions) for an Armillaria Root Disease Pathogen (Armillaria solidipes) and Its Host, Douglas-fir (Pseudotsuga menziesii), Under Changing Climates

“…Thus, predictions of P. menziesii maladaptation under future climate scenarios likely underestimate the extent of maladaptation and associated increased susceptibility to Armillaria root disease. However, east of the Cascade Range, P. menziesii is one of the most susceptible tree species to Armillaria root disease (Morrison, 1981;Robinson and Morrison, 2001), but the faster growing coastal variety of P. menziesii succumbs less often to A. solidipes infection (Johnson et al, 1972;Robinson and Morrison, 2001).…”

Lesion formation and host response to infection by Armillaria ostoyae in the roots of western larch and Douglas‐fir

“…The new cambium differentiates in the callus, and resulting woundwood grows over the exposed wound (O VEN and T ORELLI 1999). Callus has been associated with the recovery of coastal Douglas‐fir from A. mellea sensu lato (= A. ostoyae ) infection (J OHNSON et al. 1972).…”

“…In the roots of conifers, host response in the form of periderm formation (D AY 1927; T HOMAS 1934; R YKOWSKI 1975), resinosis (B UCKLAND 1953, R ISHBETH 1972; R EDFERN 1978; S HAW 1980), compartmentalization (S HIGO and T IPPETT 1981), and callus formation (J OHNSON et al. 1972) has been associated with infection by various species of Armillaria .…”

Tree vigour and the susceptibility of Douglas fir to Armillaria root disease

“…Mortality in westside plantations is usually scattered atid elosely assoeiated with large stumps from the previous stand (Fiup 1979). In addition, mortality declines after about age 15 years on most westside sites, and trees are seldom killed after age 25-30 years (HADFIHLD et al 1986;MORRISON et al 1985;JOHNSON et al 1972;FOSTER and BARANYAY 1971). Eocally, however, as in the present study area, the disease is more severe, and mortality may contitiue as the stand ages.…”