CARBARYL DEGRADATION ON TREE BARK AS INFLUENCED BY TEMPERATURE AND HUMIDITY

We examined the rate of carbaryl degradation on the bark of two tree s pecies under laboratory conditions with three temperatures and two rel ative humidities. Tree species and relative humidity were the main fac tors affecting the degradation process. We recovered 98-100% of the ca rbanyl residues from loblolly pine, Pinus taeda L., within all tempera ture and relative humidity groups after 60 d of incubation. In contras t, we recovered approximate to 67% (97% RH) and 97% (33% RH) of the re sidues from the bark of white spruce, Pic ea 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 bused on cochromatograph y with standard 4-hydroxycarbaryl and 5-hydroxycarbaryl; maximum amoun ts of these metabolites reached approximate to 28 and 24%, respectivel y.