Stain and mould fungi

Assessment of performance is by a visual grading system although individual types of defacement may be recorded (stain, mould or decay). 

2 Blue stain in service. Bluestain in service can be evaluated either in the laboratory or as part of a field evaluation using coated timber samples such as L-joints (EN 330, 1993). In the laboratory, accelerated results can be obtained although treated samples are often pre-conditioned by external weathering or by a period of exposure to UV in the laboratory (EN 152, 1988). Performance is evaluated by determining the degree of visual defacement. 

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Benzimidazole fungicides. Of the benzimidazole fungicides, both thiabendazole [II, 15.9.] and carbendazim [II, 11.4.] have been evaluated as components of wood preservative formulations. Of these, carbendazim has been valued for its activity towards stain and mould fungi, particularly in combination with chlorothalonil as noted above. Carbendazim (a breakdown product of benomyl [II, 11.5.]) has very low solubility in most solvents and therefore is most commonly applied as a dispersion in antisapstain treatments. Carbendazim is however soluble at lower pH (as an acid salt), and has been used as a mould control agent in CCA treatment solutions. Acid salts of carbendazim (hydrochloride and phosphate) have been used in the treatment of Dutch elm disease. 

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