Investigation of GF-120 Fruit Fly Bait to suppress carrot rust fly populations in Eastern Canada and British Columbia
Project Code: PRR15-030
Suzanne Blatt - Agriculture and Agri-Food Canada
Evaluate the potential of GF-120™ Fruit Fly Bait to suppress or control carrot rust fly populations
Summary of Results
Carrot rust fly, Psila rosea is an important pest of carrot with limited pest management strategies available. Currently, organic growers have no registered products for the control or suppression of carrot rust fly and can lose up to 25% of their crop to this pest. Conventional producers in some regions are concerned that currently registered insecticides may be ineffective due to the development of resistance. The identification of alternative approaches to managing this pest was identified as a priority under Agriculture and AgriFood Canada’s Pesticide Risk Reduction Strategy for Root Insect Pests of Carrot, Parsnip and Onion.
GF-120™, a formulated bait containing spinosad, is a registered insecticide in Canada and in the United States, where it is also certified by the Organic Materials Review Institute (OMRI) for use in organic production. Spinosad has low mammalian toxicity, low environmental impacts, and is compatible with integrated pest management programs. The low volume and concentration of material used (1.5 Litres of product per hectare (L/ha)) could provide a reduced risk option that may fit the needs of both organic and conventional growers. This one-year project assessed the potential of this product to suppress or control carrot rust fly populations on grower collaborator sites in British Columbia and Prince Edward Island.
The product was tested using two methods: spray application of the product directly on plant foliage and the use of bait stations containing the product on the perimeter of the field. Yellow sticky traps were placed in each plot or near each bait station and monitored twice per week to assess carrot rust fly emergence and population development over the growing season. Treatments occurred when pest threshold numbers were reached according to yellow sticky traps. At harvest, researchers took carrot samples from near each sticky trap and evaluated them for damage.
The spray application trial took place on Prince Edward Island and included three treatments: control (no spray); Matador® 120EC (lambda-cyhalothrin, the registered industry standard) at a rate of 83 millilitres per litre; and GF-120™ at a rate of 1.5 L/ha. A Latin-square design was used with three replicates of each treatment. Buffer zones were created between treatments to ensure no contamination between plots. GF-120™ was applied using a backpack sprayer. Preliminary investigations of the potential for bait stations to suppress carrot rust fly pest were conducted on organic farms in British Columbia and at one conventional site on Prince Edward Island.
Carrot rust fly populations in the spray trial on Prince Edward Island reached and exceeded the economic threshold during the field season. GF-120™ was applied 8 times over the season, largely due to rain events, compared with 3 applications of Matador® 120EC. Damage observed in the GF-120™ plots (5.5%) was not significantly different from damage observed in the control plots (7.5%) but both were significantly greater than damage observed in the Matador® 120EC plots (3.5%). When used as a spray, the GF-120™ product did not present an economically viable alternative to the conventional standard in the current study.
Carrot rust fly populations in British Columbia were very low due to drought conditions, and the product could not be evaluated on Vancouver Island. In the Lower Mainland, one field reached threshold (based on yellow sticky trap counts) late in the season but damage was below 1% for all treatment areas. The two bait station field sites on Prince Edward Island also did not reach threshold and no comparison was possible. Results from the bait station efforts either did not have enough pest pressure to evaluate the effectiveness, or the results were not statistically significant. While the outcome of the bait station work was inconclusive, this tactic could be explored further as part of an overall integrated pest management approach for carrot rust fly.
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