Red pine harvest debris as a potential source of inoculum of Diplodia shoot blight pathogens

• Published in: Forest ecology and management Vol. 262; no. 4; pp. 663 - 670
• Main Authors: Oblinger, Brent W., Smith, Denise R., Stanosz, Glen R.
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier B.V 15-08-2011; Elsevier
• Subjects: Animal and plant ecology; Animal, plant and microbial ecology; bark; Biological and medical sciences; blight; clearcutting; conidia; Debris; Diplodia; Diplodia pinea; Diplodia scrobiculata; forest health; Forestry; Fundamental and applied biological sciences. Psychology; germination; hosts; Inoculum; Inoculum persistence; Intervals; managers; Needles; Pathogens; Phytopathology. Animal pests. Plant and forest protection; Pine; Pinus resinosa; polymerase chain reaction; researchers; risk; seedlings; shoots; Slash; soil; Soil (material); Stems; Synecology; Terrestrial ecosystems; Woody debris; Slash; Pinus resinosa; Diplodia pinea; Woody debris; Diplodia scrobiculata; Inoculum persistence; Organic matter; Plant pathogen; Forest ecology; Potential; Diplodia; Source; Fungi; Persistence; Dead wood; Pathogenic; Softwood forest tree; Gymnospermae; Forestry; Coniferales; Spermatophyta; Fungi Imperfecti; Debris; Inoculum
• ISSN: 0378-1127; 1872-7042
• DOI: 10.1016/j.foreco.2011.04.038

► Diplodia shoot blight was found on planted red pine seedlings growing near debris. ► Conidia of
Diplodia pathogens were extracted from logging debris after harvest. ► Germinable conidia were recovered from debris 6
months to 5
years after harvest. ► Less germinable and fewer conidia were obtained from debris with soil contact.
A high incidence of Diplodia shoot blight (site means ranging 85–100%) was observed on recently planted red pine (
Pinus resinosa) seedlings where mature red pine stands previously had been clearcut. An investigation of the potential of harvest debris as a source of inoculum of
Diplodia pathogens then was conducted. Cones, bark, needles, stems from shoots bearing needles, and stems from shoots not bearing needles (both suspended above the soil and in soil contact) were collected from harvest debris left at sites where clearcutting occurred. Conidia were quantified, and their germination rate was assessed, and
Diplodia species were identified using PCR. Conidia of
Diplodia species were found at all study sites and conidia counts increased from samples collected from 6 to 18
months after harvest. Germinable conidia were obtained from debris collected 6
months to 5
years after harvest. Fewer conidia were obtained from debris collected at intervals of up to 4–5
years after harvest and the percentage of germinable conidia was lower after longer intervals following harvest. More conidia were obtained and a greater percentage germinated from debris collected above the soil than from debris in soil contact. The host substrate also influenced the number of conidia and the percentage that germinated. Planting red pine seedlings next to debris infested with
Diplodia pathogens could provide a persistent source of inoculum. Results should prompt further consideration by land managers and researchers of the potential forest health risks, in addition to benefits, that may be associated with harvest debris.