New-Ground Syndrome: An Ectomycorrhizal Deficiency in Pine Nurseries
Abstract In July 1986, stunted loblolly pine (Pinus taeda L.) seedlings were studied at a nursery in Union Springs, Alabama. Stunted seedlings were found only in seedbeds formed on new ground (soil having no history of producing a nursery crop of ectomycorrhizal tree seedlings). The stunted seedlings were either nonmycorrhizal or had extremely low levels of ectomycorrhizae, whereas nonstunted seedlings had a greater degree of ectomycorrhizal development. Stunted seedlings were deficient in phosphorus (0.07%), whereas nonstunted seedlings had sufficient phosphorus (0.15%). An application of phosphoric acid (H3PO4) to stunted seedlings increased shoot phosphorus and resulted in substantial growth improvement. The phosphorus application reduced the percentage of cull seedlings (root-collar diameter <3.2 mm) from 62% to 8%. This study also demonstrates that when a seedbed is formed on new ground, ectomycorrhizal deficiencies can occur even when ectomycorrhizal tree hosts are present in the immediate vicinity. The ectomycorrhizal deficiency in the seedlings observed in this study may have been related to restricted spore dispersal caused by insufficient rainfall that had occurred after spring fumigation. South J. App. For. 12(4):234-239.