Mosaic Stunting in Jack Pine Seedlings in a Northern Michigan Bareroot Nursery

Potvin, L., Dumroese, R. K., Jurgensen, M. F., and Richter, D. IN: National Proceeding: Forest and Conservation Nurs­ery Associations - 2009. USDA Forest Service, Rocky Mountain Research Station, Proceedings RMRS-P-62, p. 82-85. 2010.

Mosaic, or patchy, stunting of bareroot conifer seedlings is thought to be caused by deficiencies of mycorrhizal fungi following fumigation, resulting in reduced nutrient uptake, particularly phosphorus. Mosaic stunting of jack pine (Pinus banksiana) seedlings was observed in 2005 at the USDA Forest Service JW Toumey Nursery in Watersmeet, MI. We initiated a study to determine if either the species of mycorrhizal fungi or the quantity of mycorrhizae were different on stunted and healthy seedlings. In 2006 and 2007, we tested the soil, sampled root tips, and analyzed seedling growth and foliar nutrient concentrations. In 2006, we used DNA sequencing to identify mycorrhizal fungi. Our results showed four main fungal taxa (Sistotrema brinkmannii, Thelephora terrestris, Suillus luteus, and Laccaria spp.) were associated with mycorrhizal root tips on stunted and healthy seedlings, and that the number of mycorrhizal root tips was high on both types of seedlings, although we observed variation among stocktypes and years. Despite soils having similar nutrient concentrations, we observed differences in foliar concentrations between stunted and healthy seedlings. Only 1+0 seedlings in 2007, however, showed significant differences. This suggests that reduced root nutrient uptake was a factor in stunting of 1+0 seedlings in 2007, but does not appear to be related to ectomycorrhizal fungi.

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Author(s): Dana Richter, Lynette Potvin, Martin F. Jurgensen, R. Kasten Dumroese

Publication: National Nursery Proceedings - 2009

Event: Northeastern Forest and Conservation Nursery Association Meeting
2009 - Grand Rapids, Michigan