Carbaryl degradation on tree bark as influenced by temperature and humidity

We examined the rate of carbaryl degradation on the bark of two tree species under laboratory conditions with three temperatures and two relative humidities. Tree species and relative humidity were the main factors affecting the degradation process. We recovered 98-100% of the carbaryl residues from loblolly pine, Pinus taeda L., within all temperature and relative humidity groups after 60 d of incubation. In contrast, we recovered approximately 67% (97% RH) and 97% (33% RH) of the residues from the bark of white spruce, Picea glauca (Moench) Voss, at 25 degrees C after 60 d of incubation. Several metabolites of carbaryl were found on the bark of white spruce, whereas no detectable amount of carbaryl metabolites was found from loblolly pine in all treatment groups. Two major metabolites were identified based on cochromatography with standard 4-hydroxycarbaryl and 5-hydroxycarbaryl; maximum amounts of these metabolites reached approximately 28 and 24%, respectively