Spotted Wing Drosophila, left, and the damage it can cause in cherries, right.


ash, honeysuckle and asparagus, amongst others.


For us in the Okanagan- Similkameen it is most serious in cherries, where at this point there is a market zero tolerance for worms in fruit.


Okanagan Tree Fruit Company estimates that 10 to 15 percent of Lapins and later varieties were rejected due to the presence of drosophila species. Crop loss in peaches, nectarines and apricots so far only seemed to occur in tree-ripened fruit.


In B.C. there may be up to five SWD generations per year. Oviposition lasts 10 to 59 days, with seven to 16 eggs laid per day and averaging 34 eggs per female. Eggs hatch in two to 72 hours and larvae mature in three to 13 days. The accompanying picture of infested cherry fruit indicates just how damaging this pest can be. Monitoring is particularly difficult as females outnumber males until early August, and identifying females is difficult without training and impossible without a dissecting microscope. Males with the distinctive black spot on their wing makes males easier to identify, but females predominate at the time of year when monitoring is most critical. Four materials received emergency registration in 2010—Delegate, Entrust, Malathion, and Ripcord—but were not widely used until after larvae were found in the fruit. Although cherries receive coverage for cherry fruit fly, Sevin and Admire were not adequate to provide control. As well GF120 for cherry fruit fly will not control SWD. More work is certainly required on efficacy and timing of materials.


— Retired orchardist and horticulturist Peter Waterman can be reached at peter@omedia.ca


26 British Columbia FRUIT GROWER • Spring 2011


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