Screening trials on raspberries to identify reduced risk solutions for insect contamination in mechanically harvested fruit

Project Code SCR07-010

Project Lead

Victoria Brookes - Agriculture and Agri-Food Canada

Objective

To assess the efficacy of a number of reduced-risk pest control products for their potential use in control of harvest insect contaminants of raspberries, focusing on Lepidoptera and weevil species

Summary of Results

Raspberries are a significant crop in B.C. At least 1,600 ha are grown annually, representing 70% of Canada's production and a value of over $20 million at the farm gate. The majority of raspberry fruit grown in British Columbia and most other processing caneberry producing areas of North America is mechanically harvested. The shaking action of the harvester causes the fruit to fall from the plants into collection trays, however, at the same time insects are dislodged from the plant canopy contaminating the harvested fruit. These insect contaminants are often Lepidopteran (caterpillar pests such as leafrollers and cutworms) but there can be other insects as well including weevils, stink bugs and earwigs. When the fruit is received at the processing plants this insect contamination causes the fruit to be downgraded or even rejected. Leafrollers, cutworms and weevils cannot be completely removed from fruit on the harvester grading belt or at the processing plant because they are hidden under or within the individual berries.

This screening project was planned to collect data on all insects that were in the raspberry plots. This study took place in 2007 at two field sites in Langley and Abbotsford near the AAFC Pacific Agri-food Research Centre located at Agassiz in BC. The effectiveness of four different insecticides for control of contaminants was tested on clay coloured weevil, black vine weevil, obscure weevil and earwig. Similar testing of insecticides for caterpillar pests was planned; however data could not be collected due to the absence of pressure from these pests while the trials were being conducted.

Collections of live and dead insects were used to determine the effectives of the different insecticides. Three of the products demonstrated effective control of insect contamination. Thiamethoxam provided good control of black vine weevil and obscure root weevil contaminants. Bifenthrin was effective against clay coloured weevils, black vine weevil and obscure root weevil contaminants. Metaflumizone was effective for all three species of weevil and also had the least impact on beneficial insects such as ladybird beetles.

The results of this study provide support for the submission of metaflumizone for weevil control in caneberries through AAFC's Minor Use Pestides Program and will ultimately improve growers' access to a new reduced risk product for management of these harvest insect pests. Further work is still required to determine the best control options for caterpillar pests in harvested raspberries.

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