The Author 



John P. Sioan is a Research Forester in the Ecology 

 and Regeneration of Rocky Mountain Conifers Research 

 Work Unit at Boise, ID. He received a B.A. degree in 

 biology from Wartburg College and an M.S. degree in 

 forest ecology from the University of Minnesota. He 

 joined the Intermountain Research Station in 1984. 



Research Summary 



Several root dips (vermiculite, light vermiculite slurry, 

 medium vermiculite slurry, thick vermiculite slurry. Terra 

 Sorb®, and Aquagel®) were compared on seedlings of 

 four conifer species: lodgepole pine (four experiments), 

 ponderosa pine (three experiments), Douglas-fir (two 

 experiments), and Engelmann spnjce (one experiment). 

 The studies took place in the growth chamber, in the 

 greenhouse, and in the field. Potted seedling studies 



included forest soils with three different textures: basal- 

 tic loamy clay, granitic loamy sand, and limestone clay 

 loam. We made a fourth soil from peat, vermiculite, 

 and sandy loam. 



The effects of root dipping varied with species, soil 

 type, and the type of root dip. Under dry conditions, 

 root dipping did not improve shoot growth, root growth, 

 or survival. The thickest root dip treatments inhibited 

 root growth. Lodgepole pine produced the best root 

 growth. The peat-vermiculite-sandy loam soil was the 

 most conducive to root growth. Seedlings on the basal- 

 tic soil showed the lowest plant water potential. More 

 mycorrhizal activity took place on the granitic soil. 



If conifer planting stock is handled properly in the 

 Northern Rocky Mountains,. avoiding exposure of roots 

 to drying elements, root dipping is not necessary. 



The cover photo shows ponderosa pine seedlings 

 that were root dipped or were not root dipped before 

 being planted in peat-vermiculite soil. 



The use of trade or firm names in this publication is for reader information and does not 

 imply endorsement by the U.S. Department of Agriculture of any product or service. 



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