Field trials of the rodenticide 5-p-chlorophenyl silatrane against wild rats (Rattus norvegicus Berk.)

Rattus norvegicus infestations on six farmsteads were poisoned with 0.5% 5-p-chlorophenyl silatrane and those on another six with 2.5% zinc phosphide. Both poisons were applied in pinhead oatmeal bait containing also 5% corn oil, after pre-baiting. The result of each treatment was assessed by comparing the take of pre-bait with that of a census bait (wheat) laid after the poisoning.The zinc phosphide treatments were generally more effective than those done with 5-p-chlorophenyl silatrane, but the latter were somewhat detrimentally affected by cautious baiting on the part of one of the operators.The results are discussed and it is concluded that although they indicate that 0.5% 5-p-chlorophenyl silatrane may have approached zinc phosphide in effectiveness under the conditions of the trial, it would in most circumstances be significantly less effective and possibly less safe to use than the latter, well-tried poison.