Blue Stain on Broadleaf Trees

Aspen Populus tremuloides) is the most widely distributed tree species in North America. In Canada aspen represents more than 50% of the merchantable hardwood timber. Its previously neglected utilization has increased substantially in recent years. A serious limitation to its use in the pulping process, however, is the pronounced susceptibility to blue stain caused by fungi (77). 

The two most important aspen blue stain fungi are Ophiostoma crassivaginatum and O. piliferum. The secondary metabolites of the blue stain fungus O, crassivaginatum were studied in an attempt to obtain insight into the nature of the staining material. Several simple phenolic compounds were identified which, at least in part, can be responsible for the discoloration of aspen wood infected with this fungus (72). 

Chart 2. Some antifungal homologs and analogs of isobutyric acid 

Stachybotris cylindrospora often has been isolated from clean xylem tissue of P. tremuloides. The metabolites produced by S. cylindrospora cultured in liquid medium were subjected to bioassay guided separation on XAD-16 non-ionic resin, followed by Sephadex LH-20 and silica gel chromatography to afford two known antifungal sesquiterpenes, trichodermin (20) and trichodermol (21) (Chart 4). Both compounds 

Chart 3. Antifungal derivatives and analogs of senecioic and tiglic acid 

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