Phenological and monitoring considerations for carrot weevil (Listronotus oregonensis) in Nova Scotia

Carrot weevil is a pest of carrot in Nova Scotia. A model to predict emergence of adults in the spring was developed in Quebec in the 1980s. This model is based upon the accumulated heat units, starting at the beginning of April. As conditions in Nova Scotia in the spring can be variable with warmer periods occurring in March, it is possible the model would not be accurate under such conditions. Carrot weevil emergence was monitored in several fields throughout Nova Scotia in 2014-2016 and the emergence dates in Nova Scotia were compared with those predicted by the model. The temperature when 50% of the population was found in the field was roughly the same for both Nova Scotia and Quebec, but the initial captures of adults were different. Carrot weevil in Nova Scotia would emerge from overwintering earlier in Nova Scotia and the population would continue to emerge for a longer period than in Quebec. These differences mean that a different model is needed to accurately predict carrot weevil emergence in Nova Scotia.