Field Performance of Mini-Plug Transplants

A new stock type, mini-plug TM transplant (MPT), has been developed at Weyerhaeuser Company. MPT's are started in the greenhouse and transplanted into the nursery where they are grown for one season. Advantages of using MPT's are (1) short production time to improve flexibility of regeneration planning, (2) ease of planting due to compact mop-like root system and (3) relatively low production costs. A total of 68 trials to evaluate Douglas-fir MPT's were installed at six regions in Washington and Oregon in 1985, 1986 and 1987. Survival, vigor, damage and height growth were measured annually. The results showed that probably owing to favorable root to shoot ratio and fibrous roots, MPT's performed as well as or better than other bareroot stock types including 2+0's, low density 2+0's, 1+1's, plug+l's and 2+1's at a majority of sites. MPT's put on the same amount of height growth or greater than the other stock types. Furthermore, MPT's appreciably exceeded the other stock types on a relative growth rate based on the original height. However, MPT's had less total height than other stock types due to its smaller initial height. There appeared to be no preference of MPT's over other stock types in terms of frequency of big-game browsing and rabbit clipping. But, because of their smaller size, MPT's were unable to withstand heavy animal damage as well as larger stock types.

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Author(s): Yasuomi Tanaka, Byron Carrier, Alex Dobkowski, P. Figueroa, Rod Meade

Publication: National Nursery Proceedings - 1988

Event: Combined Meeting of the Western Forest Nursery Associations
1988 - Vernon, CAN