Effect of Northwestern Ontario Forest Ecosystem Classification treatment units on the infection levels of Armillaria in black spruce plantations

Abstract

Eight 5- to 15-year-old black spruce (Picectmariana (Mill.) BSP) plantations from each of the Northwestern Ontario Forest Ecosystem Classification treatment units B, C, D, E, and F were sampled for Armillaria root rot. All the plantations sampled were infected by Armillaria, with an infection rate ranging from slightly less than 1% to 32%. Some differences were observed among Northwestern Ontario Forest Ecosystem Classification treatment units but these differences were not statistically significant (p < 0.05). Plantations in treatment unit F had the highest average infection level (16.93%), while those in treatment unit B had the lowest (7.24%). Plantations in treatment unit F had significantly higher cumulative mortality levels than did those in treatment unit B (p < 0.05). The average ratio of infected healthy trees to infected dead trees was 3.28:1 across all treatment units. The total number and total basal area of all stumps and of all infected stumps were similar across the treatment units. Variations did exist in the ratio of conifer to hardwood stumps and reflected the differences in the species composition of the original stands. Infection levels based on trembling aspen (Populustremuloides Michx.) trap logs were not found to be a good indicator of percent infection in the trees. The use of colour and relative shoot growth was only moderately effective in identifying trees infected by Armillaria.

Epidemiology of Armillaria root disease in Douglas‐fir plantations in the cedar‐hemlock zone of the southern interior of British Columbia

“…Surveys of plantations on one to several occasions have been used to estimate percentages of trees killed or infected or both by Armillaria root disease (Whitney 1988; Livingston 1990; Bruhn et al. 1996; Wiensczyk et al. 1996; Self et al.…”

Root diseases in forest ecosystems†

“…The machinery used for site preparation can spread infected material throughout the site. It may partially explain the high incidence of Armillaria disease in black spruce plantations studied in Ontario (Wiensczyk et al, 1996). Among several variables, bare root seedlings are more affected by Armillaria diseases than seedlings produced in containers (Wiensczyk et al, 1997).…”

Juvenile response to conifer release alternatives on aspen-white spruce boreal mixedwood sites.Part II: Quality of aspen regeneration

“…Because of logistical limitations, a sample of the most common stains and decays observed were selected for further analysis. Over 55 wood samples per treatment containing typical stain and decay were cultured on selective media (Wiensczyk et al 1996) for identification of decay fungi (only nine samples from the glyphosate treatment plots were cultured). For damaged stems, most samples were taken from the points where the new stem sprout or new leader initiated on the pre-treatment aspen sucker, as this was where treatment effects were expected to occur (Fig.…”