United States 

 Department of 

 Agriculture 



Forest Service 



Intermountain 

 Forest and Range 

 Experiment Station 

 Ogden, UT 84401 



Research Paper 

 INT-300 



January 1983 



Lifting, Storage, 

 Planting Practices 

 Influence Growth of 

 Conifer Seedlings in 

 the Northern 

 Rockies 



Stephen E. McDonald 

 Raymond J. Boyd 

 Donald E. Sears 



INTRODUCTION 



Until 1976, the Coeur d'Alene Nursery, like most northern 

 temperate zone nurseries, lifted all of its coniferous bare root 

 stock in the early spring for later spring planting. Typically 

 stock has been lifted in March, placed in cold storage (34° to 

 38° F [1° to 3° C]), and planted when conditions were favor- 

 able at the planting site. With the large geographical and ele- 

 vational range served by the nursery, the planting season can 

 extend into early July. Although every effort has been made to 

 lift stock while it was still dormant and to plant as early as 

 possible, weather conditions and the magnitude of the lifting, 

 sorting, and packing job often resulted in undesirable delays. 



Investigations in Canada, the northeastern United States, 

 and Europe have shown that trees can be lifted in the fall and 

 stored overwinter (Hocking and Nyland 1971). This is feasible 

 when storage temperatures are lowered to below freezing to re- 

 duce physiological activity and pathogen growth (Nyland 

 1974a), and if the trees are protected from desiccation by a 

 suitable vapor barrier (Nyland 1974b). The potential advant- 

 ages of fall lifting and frozen storage of nursery stock 

 prompted study of the technique at the Coeur d'Alene Nurs- 

 ery in 1972. 



This paper reports the results of nursery trials in 1972 and a 

 limited field trial in 1973. 



The study was conducted to obtain comparative information 

 on the effects of storage conditions, in combination with 

 various spring planting dates, on the survival of outplanted 

 stock. The primary objective was the testing of overwinter 

 storage at subfreezing temperatures. Other temperature 

 regimes were used as controls or as additional alternatives to 

 conventional storage methods. Because planting normally ex- 

 tends over a period of 2Vi to 3 months in the Northern Rocky 

 Mountain area, planting date was also studied as an interactive 

 variable. 



PHASE I. NURSERY-BASED SURVIVAL 

 COMPARISONS, 1972 



Methods 



Three coniferous species, Engelmann spruce {Picea engel- 

 mannii Parry), lodgepole pine (Pinus contorta Dougl. var mur- 

 rayana [Grev. and Balf.] Engelm.) and western larch (Larix 

 occidentals Nutt.) were selected for trial. Lodgepole pine and 

 spruce were used because of the long storage periods usually 

 involved; larch because of past storage difficulties. 



The objective of this initial study was to obtain comparative 

 information on the effects of storage conditions, in combination 

 with various spring planting dates, on the survival of outplanted 

 stock. Storage regimes were as follows: 



1. Frozen. — On November 17, 1971, 1,125 trees of each spe- 

 cies were lifted and sealed in plastic (4-mil polyethylene) bags, 

 put into preconditioning refrigerated storage at 34° F ( 1 ° C) to 

 38° F (3° C) for 2 days, at 32° F ± 1° (0° C) for 1 week, and 

 finally at 28° F ± 2.5° (-2° C ± 1°) for the remainder of the 

 storage period. Trees were tied into 25-tree bundles, then stored 

 with three bundles (75 trees) per bag. At each planting date the 

 following spring the requisite number of seedlings of each species 

 were removed from the freezer 5 days before planting and placed 

 in refrigerated storage at 34° to 36° F (1° to 2° C) to thaw. By 

 calling this treatment "frozen" we mean that the ambient stor- 

 age temperature was subfreezing. Tree tissue temperature was 

 not determined. 



2. Refrigerated.— On March 18, 1972, 1,125 trees of each spe- 

 cies were lifted and placed in refrigerated storage (34° to 36° F 

 [1° to 2° C]) in the tree storage rooms at the nursery. These trees 

 were packaged in polyethylene-lined Kraft bags. This was the 

 standard procedure then in use at the Nursery. Wet sphagnum 

 moss was placed around the seedlings' roots. 



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