Prevention of bluestain in lodgepole pine by sour felling : compilation of reports|Prevention of bluestain in lodgepole pine by sour felling : Trial 1 - Final report
Development of bluestain in logs prevents the Canadian forest industry from producing maximum-value products from a considerable proportion of the resource every year. Bluestain-control strategies that can be implemented without disrupting woodlands or mill productivity are required and one of the most promising is sour felling. This involves felling the trees and leaving the foliage on for about a month before delimbing. Sour felling has been proposed as a method of reducing the moisture content and transportation costs of trees. However, due to continued respiration and transpiration the sapwood nutrients are also expected to be somewhat depleted during the period in which delimbing is delayed. These nutrients would then not be available for staining fungi. We therefore focused on sour felling as a possible control measure for stain in lodgepole pine and did trials to determine if sour-felling can reduce nutrient status and/or incidence of stain in lodgepole pine roundwood.
In 1999 a trial (Trial 1) of sour felling proceeded in Alberta. Trees were felled with mechanical harvesting equipment and either delimbed or left with the limbs intact. After six weeks, trees were destructively sampled for measurement of bluestained area and for chemical analyses of four classes of wood extractives. The trial was repeated twice again in 2000 (Trials 2a and 2b) but wet conditions delayed access and felling and set-up of the Trial 2a could not be done until June 2000. An additional experiment was done alongside Trial 2a, and consisted of forest storage of sour felled trees which had none of the bark damage that normally occurs during the process of forwarding the trees to the roadside. Non-destructive sampling of trees for analysis of nutrient content occurred at 0 and 7 weeks for Trials 2a and 2b and at 13 weeks for Trial 2a only. Destructive sampling of trees for assessment of stain development was done only for Trial 2a at 13 weeks; Trial 2b was abandoned at 12 weeks due to cool fall weather which was unsuitable for the development of stain.
The 1999 trial (Trial 1) gave indeterminate results because no bluestain appeared in the freshly felled (control) trees. However chemical analyses of the discs resulted in a body of information about changes in the nutrient status of the trees with storage. Starch was the extractive most depleted during the storage period. For the first time we have detailed information about the extractive content of lodgepole pine sapwood that provides the nutrients for development of bluestain.
Measurements of stained area done on the discs from the 2000 Trial 2a indicated that there was less stain in the sour-felled logs than in the delimbed trees. However both 1999 and 2000 years were less severe for bluestain than normal and the experiment must be repeated to provide industry with sufficient confidence in the benefits of changing harvesting practices. It is planned to re-test the concept by repeating a sour-felling trial in 2001-2. This requires extending the project for an additional year.
This summary covers three reports: 1) Prevention of Bluestain in Lodgepole Pine by Sour Felling: Trial 1 – Final report (report to CFS); 2) A trial of “sour”felling to prevent bluestain by depletion of sapwood nutrients (draft publication: International Research Group on Wood Preservation Paper); 3) Prevention of bluestain in lodgepole pine by sour felling: Trial 2 - Progress report (to CFS)
Stains - Fungal - Control
Pinus contorta Dougl. var. latifolia - Stains, Fungal