Applying updated bioclimatic information to validate models and refine Integrated Pest Management program recommendations for carrot rust fly and carrot weevil management

Project Code PRR17-020

Project Lead

 Suzanne E. Blatt   Agriculture and Agri-Food Canada

Objective

To improve carrot rust fly and carrot weevil control in carrot production in Ontario and the Maritimes by refining emergence prediction models and evaluating efficacy of entomopathogenic nematode products

Carrot rust fly (CRF) (Psila rosae Fabricius) and carrot weevil (CW) (Listronotus oregonensis Leconte) are two major pests of carrots causing serious economic damage in Eastern Canada. The CW causes damage in Ontario (ON) and Nova Scotia (NS), while CRF causes damage in ON and Prince Edward Island (PEI). Larvae of both pests create tunnels in the roots of carrots, making them unmarketable. Furthermore, bacteria and fungi may invade the roots through these tunnels and cause important post-harvest damage to carrots prior to and during storage. Damage is highly variable based on location and year, but carrot losses have been reported to be as high as 70% due to CW and 100% due to CRF.

The CRF is a pest with multiple generations, two in ON and NS and up to 3 in PEI. In ON, most of the damage is caused by the second generation. For CW, typically only one generation occurs in the Eastern provinces, but two generations have been previously reported in ON and Quebec (QC).

The primary method of control is the use of insecticide sprays containing organophosphate or pyrethroids. However, insecticides often miss reaching their target as eggs, larvae and pupae are protected in the carrot or soil. Also, some insecticides are being de-registered due to regulatory review and there is evidence for insecticide resistance developing in CW and CRF adult populations.

This work was identified as a priority for action under Agriculture and Agri-Food Canada’s Pesticide Risk Reduction Strategy for Root Insect Pests of Carrot, Parsnip and Onion. A previously funded project, PRR07-090 - Development of bioclimatic models to forecast the dynamics of two insect pests: carrot weevil and carrot fly updated the old predictive models developed in the mid-1980s, however, the accuracy of these models in provinces outside of QC was unknown. More recently, the Pesticide Risk Reduction Program funded project PRR14-020 - Develop spatial modelling and forecasting tools for carrot rust fly and carrot weevil in Eastern Canada carrot producing regions and showed that the degree day (DD) models used in QC did not predict emergence of either study species in NS, PEI and ON.

This two year project will add several field-years data to the previously collected data obtained during the PRR14-020 project, in order to refine and validate DD models for NS, PEI and ON. This is anticipated to improve prediction of CRF and CW emergence in carrots and provide growers with information to better synchronize current insecticide controls. Concurrently, several commercial entomopathogenic nematode products will be evaluated for their efficacy against CW and CRF in the field and in the greenhouse. This biocontrol option has previously shown some success against pest weevils and may provide a useful tool as part of an integrated management program.

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