Outplant Evaluation of Container Red Alder Grown with Bonzi® Plant Growth Regulator

Red alder (Alnus rubra Bong.) seedlings are challenging to grow due to their tendency to reach excessive heights in nursery culture. We evaluated several Bonzi® (paclobutrazol) plant growth regulator frequency by rate applications on large plug seedlings (15 in3 [250 ml]) then compared the best treatment (three applications of 25 ppm Bonzi®) with our standard Plug+1/2 stocktype at two outplant sites. We also evaluated all nursery treatments, including non-treated plugs, at a garden plot. Large plugs, even without treatment, broke bud several days earlier than P+1/2s and this effect increased with increasing Bonzi® intensity. The P+1/2s had greater height and stem diameter growth at one location and greater height growth at the other. Survival did not differ between stocktypes. The nursery grower can use Bonzi® to produce a balanced plug that is easier to frost protect in the nursery and less susceptible to mechanical damage, with overall higher average nursery packout (yield). This study shows, however, that reducing treatment intensity may lead to better outplant success. This paper was presented at the Joint Annual Meeting of the Western Forest and Conservation Nursery Association and the Intermountain Container Seedling Growers Association (Coeur d’Alene, ID, October 25-26, 2018).

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Author(s): Nabil Khadduri, Brian C. Morris

Publication: Tree Planters' Notes - Volume 62, Numbers 1, 2 (2019)

Event: Joint Annual Meeting of the Western Forest and Conservation Nursery Association and the Intermountain Container Seedling Growers Association
2018 - Coeur d’Alene, ID

Volume: 62

Numbers: 1, 2