Seedling mortality and development of root rot in white pine seedlings in two bare-root nurseries
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Canadian Journal of Plant Pathology 18:335-341
Seedling mortality and development of root rot in white pine (Pinus strobus) were followed across locations and over time within three operational nursery fields with loamy sand soils at a provincial nursery in southwestern Ontario, Canada, and a state nursery in southern Wisconsin, USA. One Ontario field was fumigated with dazomet; the other was not fumigated. The Wisconsin field was fumigated with methyl bromide-chloropicrin. Mortality and disease severity data were collected; the latter were based on visual assessment of seedling roots. White pine root rot (10 to > 30% incidence) was observed in the fields regardless of soil fumigation treatment. Systematically placed plots in the outer two seedling beds in the Wisconsin field had higher mortality levels than those in the other beds during the second growing season, and they had higher disease severity in July and October of the same year. Plot locations in the Ontario fields were stratified according to topographic features. Cumulative seedling mortality level during the second growing season in the Ontario fumigated field was highest in the low areas (P < 0.001) and equal in the mid-slope and high areas; cumulative mortality in the nonfumigated field did not differ among location types. Higher disease severity was observed in the low areas of the nonfumigated field in July and October of the same growing season (P = 0.03) compared to pooled mid-slope and high areas. Seedling mortality was higher than expected in mid-spring and less than expected in October of the second growing season in the outermost bed of the Wisconsin field and for all topographic areas in the Ontario fields.
Juzwik, J.; Rugg, D. J. 1996. Seedling mortality and development of root rot in white pine seedlings in two bare-root nurseries. Canadian Journal of Plant Pathology 18:335-341