Site-related influences on cone-borne inoculum and asymptomatic persistence of Diplodia shoot blight fungi on or in mature red pines

• Published in: Forest ecology and management Vol. 257; no. 3; pp. 812 - 819
• Main Authors: Munck, Isabel A., Smith, Denise R., Sickley, Theodore, Stanosz, Glen R.
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier B.V 10-02-2009; [Amsterdam]: Elsevier Science; Elsevier
• Subjects: Animal and plant ecology; Animal, plant and microbial ecology; Biological and medical sciences; carrier state; detection; Diplodia; Diplodia pinea; Diplodia scrobiculata; edaphic factors; environmental factors; forest trees; Forestry; Fundamental and applied biological sciences. Psychology; fungal diseases of plants; Phytopathology. Animal pests. Plant and forest protection; Pinus resinosa; plant pathogenic fungi; Presettlement vegetation; Red pine regeneration; seed cones; shoots; soil; Soil type; Sphaeropsis sapinea; Synecology; Terrestrial ecosystems; Wisconsin; Presettlement vegetation; Red pine regeneration; Sphaeropsis sapinea; Soil type; Site; Pinus resinosa; Plant pathogen; Asymptomatic; Diplodia; Fungi; Soil types; Softwood forest tree; Gymnospermae; Fungi Imperfecti; Vegetals; Cone; Forest ecology; Forest tree; Woody plant; Persistence; Regeneration; Forestry; Vegetation; Coniferales; Spermatophyta; Maturity; Inoculum
• ISSN: 0378-1127; 1872-7042
• DOI: 10.1016/j.foreco.2008.10.023

The shoot blight and canker pathogens
Diplodia pinea and
D. scrobiculata sporulate abundantly on cones of many pine hosts. Variation in incidence and abundance of potential inoculum from cones and frequency of asymptomatic persistence on or in shoots was examined for mature red pines in sites differing in dominant presettlement vegetation and soil type in Bayfield and Douglas counties in northern Wisconsin. Collections were made in each county from 6 plantations, 3 each in areas historically vegetated with jack pine and soils mapped as sands and three in areas historically vegetated with red pine with soils mapped as loamy sands. At each site, 5 cones were collected from each of 5 red pines and 10 shoots were collected from up to 5 red pines. Conidia from cones were quantified with a water wash and filtration technique.
Diplodia species were cultured from surface-disinfested asymptomatic shoots. A species-specific PCR assay was used to identify the
Diplodia species from cones and shoots. Although cones and asymptomatic shoots from each county yielded
D. pinea and
D. scrobiculata,
D. pinea was detected more frequently. More conidia were obtained from cones from Douglas Co., where there is a history of severe shoot blight damage, than cones from Bayfield Co. In Douglas Co., more conidia were obtained from cones from plantations in areas of more sandy soil and presettlement jack pine dominance than cones from plantations in areas of less sandy soil and presettlement red pine dominance. The numbers of conidia and frequencies of cultural detection of
Diplodia species from asymptomatic shoots at a site were positively correlated. These results provide evidence for site-related influences on abundance of pathogen inoculum and asymptomatic persistence on or in red pine crowns that may contribute to differences in frequency and severity of damage from Diplodia shoot blight.