Evaluating the Effectiveness of GF-120 against Apple Maggot in
Apple Orchards

The apple maggot (Rhagoletis pomonella) is indigenous to North America and has been found in all Canadian provinces with the exception of Newfoundland. It is a quarantine pest in Canada, especially widespread throughout eastern Canada, causing fruit damage and significant economic losses. Organic apple growers have a very limited control material list to select from; premature drop and fruit injuries caused by apple maggots can reduce saleable crop by as much as 75 %. To date, the only apple maggot control product registered is Surround WP. Surround WP is a particle film kaolin clay product, very dusty to work with and creating an unpleasant work environment.

Our research on apple maggot control first received funding from the Pest Management Centre in 2007. Six research trials, two in Ontario and four in Nova Scotia, were conducted in 2007 to test the efficacy of an organic product, GF-120 Naturalyte Fruit Fly Bait (active ingredient: spinosad). This project has shown positive results. The Ontario Ministry of Agriculture, Food and Rural Affairs and Agriculture and Agri-Food Canada in Nova Scotia have prepared a rationale leading to an emergency use registration of GF-120 in 2008 for the suppression of apple maggot in organic apples in Nova Scotia, New Brunswick, Prince Edward Island, Ontario and Saskatchewan. In addition, a complete minor use label expansion has been submitted to the Pest Management Regulatory Agency to seek eventual, full registration of GF-120 for apple maggot control on apples in Canada.

Funding obtained in 2008 from the Pest Management Centre has allowed research to continue; the objective was to optimize the delivery of this control product to suppress apple maggots in organic orchards.

In Ontario, a trial was carried out in a commercial ‘McIntosh’ orchard to refine application methods for the maximum distribution of GF-120 within tree canopies and to prune large-sized trees for better penetration of GF-120 into inner tree canopies. In Nova Scotia, three trials were carried out in research orchards. The effectiveness of applying GF-120 at two different application intervals(7-day and 14-day), was evaluated in a seedling orchard; The potential for using perimeter sprays or alternate row spraying with GF-120 was tested in ‘Cortland’ and ‘McIntosh’ orchards.

The goal of this research is to reduce apple maggot pest populations yet at the same time minimize the amount of control product used. Apple maggot pest pressure was between 31 -42 % in all the orchards in this study with the exception of the seedling orchard, where infestation reached 69 %.

Results suggested that in orchards of very large trees with dense canopies, uniform distribution and good penetration of GF-120 into tree canopies are extremely important to attain effective apple maggot control. In orchards with severe pest pressure and resident infestations throughout the orchard, GF-120 should be applied every 7-10 days following label recommendations for adequate apple maggot control. If the apple maggot is not a resident pest, it may be possible to apply spray to alternate tree rows or only to the perimeter of the orchard to control a fly-in pest situation.