Scion deterioration in storage and inappropriate time of scion collection appear to be the principal reasons for graft failure in spruces.
A total of 1051 grafts were made during May and June, 1977 at the Vernon Research Station. Scions originated from Wisconsin (96), Ontario (352), and a clone bank located at the Red Rock Research Station near Prince George (603). All grafts were made on white spruce root stock potted in 1975 and 1976.
The Wisconsin scions consisting of Picea glauca, P. bicolor, P. abies, P. montigena, and P. glehnii were cut in February, packed in plastic bags, and stored in a freezer. Grafting was completed in May, 1977 and survival at the end of July was 31.25%.
The Ontario scions were from several white spruce trees. They were cut in February, the cut ends were dipped into bees' wax and were packed in pIastic bags with lightly moistened peat moss. They were also stored in a freezer until grafted in May and June. Survival at the end of July was 98.3%.
Scions from the Red Rock, clone banks were collected in May. Most scions had buds in an advanced state of development and many were partially flushed. The scions were wrapped in lightly moistened paper towels, packaged in plastic bags, and stored in a cooler. Grafting was completed within a week of collection. Survival of these grafts was 69.65% at the end of July.
Obviously, the, time of collection and the method of packaging and storing played an important role in graft survival. leader growth on the new grafts was also much greater on the grafts from Ontario than from the other sources. Some of the Ontario grafts grew over 30 centimeters, which was more than double the maximum growth of those from other sources.
It appears that scions collected in mid winter were completely dormant at the time of grafting. The wax and the moist peat prevented them from desiccation. Following grafting, bud break was delayed long enough for the development of a proper graft union allowing an adequate supply of moisture to the developing scion. The Wisconsin scions desiccated during the long storage hence the low survival. The clone bank scions continued to flush following grafting and the Incomplete union was unable to supply adequate moisture to the developing graft.
In conclusion, spruce scions should be collected in late winter, the cut surface should be sealed with bees' wax, and the scion thus prepared should be packed in lightly moistened peat moss in a plastic bag and stored in a freezer.
For further information write to Mr. G.K. Kiss, Vernon Research Station, B.C. Forest Service, 4604 Pleasant Valley Road, Vernon, B.C. VIT 4M6
[Abstract contains full text of memo.]
BC Forest Service - Research Division. 1977. Effects of scion storage on grafts survival of various spruces. British Columbia Ministry of Forests, Lands, Natural Resource Operations and Rural Development. Research Memo (FLNRORD). RM20
Topic: FLNRORD Research Program
Keywords: FLNRORD, Research Memo, British Columbia
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