The Spotted Winged Drosophila (Drosophila suzukii) has arrived in New York state. First spotted in California in 2008 this exotic from Asia, a close relative of the common household fruit fly, has been working its way across the continent making life difficult for small fruit growers on the way.
Our Raspberry crop has been devastated. The Spotted winged drosophila lay their eggs in the just under ripe fruit – and as the fruit ripens the eggs hatch and the little fruits are filled with maggots! The maggots are tiny and it took us a while to figure out what was going on with our otherwise amazing looking crop of berries. Finally, after talking with a conventional fruit grower colleague who was having the same problem we figured it out.
We also sell at the Ithaca Farmers’ Market on the weekend and normally by this time of year most every produce vendor has their fall raspberries – I’ve seen none this year at all, even the conventional growers gave up. We’re beside ourselves – there’s really no effective organic control, and we have thousands of dollars invested in our raspberries. This week we decided to mow the crop and till it in, because we don’t want the fruit-flies attacking our strawberries in the spring, and if we don’t eliminate the host plants, the drosophila will overwinter in the leaf litter.
This raises the question of the future of organic raspberries in the North East. Controlling with pesticides an insect pest that attacks a fruit just days before it ripens usually means spraying right up to the day of harvest. This is going to be tricky for even conventional growers since there aren’t many pesticides labeled for use up till day of harvest. There is some evidence that the SWD is more active in the fall, so maybe switching to early producing varieties will help. High Tunnel production in carefully screened houses could be effective if the screens keep out All of the SWDs. One of the issues with fruit flies is that they reproduce very quickly, a female can deposit 300 eggs at a time and the lifecycle takes as short as 14 days to complete – it doesn’t take long for just a couple of adults to turn into millions.
At this point our strategy is to wait for some organic management strategies for growing raspberries to emerge before replanting our crop. This problem is sure to be a hot topic at all the winter farming conferences!