Studies on the Persistence and leaching in Soil of Nematidides Having Use in Flower Bulb Production in Humboldt and Del Norte Counties, California. 1. Phorate and Ethoprop

摘要

Small plots were established in commercial daffodil flower production fields in Del Norte and Humboldt Counties to study the persistence and leaching of phorate, an insecticide-nematicide currently used in flower bulb production, and ethoprop, a nematicide that has potential for future use. Phorate residues in the zone of application decreased dramatically during the 8 month study period. Residues of phorate were found at a maximum depth of 45 inches in Humboldt County. Ethoprop residues were found at maximum sampling depths of 48 inches (Del Norte County) and 54 inches (Humboldt County) in the plots. Heavy rainfall, 37 inches at the Humboldt County plot and 50 inches at the Del Norte County plot, that fell during the study period was probably responsible for leaching of the two nematicides.