Monday, July 21, 2014

FRUIT FLY BULLETIN #11 Signs of SWD in Raspberries

Just a quick bulletin. New development.

Up until now, we had been keeping up with the raspberries nicely by picking each day.
But yesterday several of us found the first signs of the Spotted Wing Drosophila (SWD)
damaging our raspberries. There is some suspicious soft fruit on our canes now - we notice an
unusual softening at the bottom of the fruit - it just loses its normal texture, gets mushy. Then
upon examination, we find the tiny white larvae in the fruit. Last year I observed that this
softened fruit would then just hang there and shrivel up. I saw the same thing happen when the
SWD started into the blackberries.

courtesy University of Wisconsin

So what do we do now with our berry crops?

• Keep up with picking the ripening fruit daily right to the end of the crop.

• And then we try our best to clean up all the last of the fruit and what has dropped to the
ground, to remove breeding sites.

• You know this, of course, by now - with any infested or fallen fruit, don’t throw it in the
compost or over the fence; destroy it by baking, freezing, nuking or solarizing in a black
plastic bag in the sun.

• I also started to think recently, if it was only a few berries, they could even be flushed
down the toilet.

• I checked on 'When to cut down raspberry stalks'.
Advice is “after harvest to cut down the canes that have produced fruit to ground level”.
So what I am going to do after the last of the fruit is picked is cut off the old canes with
the last of the shrivelled fruit, put them into black plastic bags and tie them up and leave
them in the sun. Then, come November, when we can burn garden waste, I am going to
burn them in a hot fire.

• I am also thinking of adding a layer of soil and compost under my bushes to try to bury
any fallen fruit I miss. This will be nowhere near as deep as is required to bury infested
fruit, but I hope that every little bit helps. And I can make it a chance to fertilize the
raspberry patch.

Best wishes,


  1. Good Luck. I'm a small commercial grower and SWD drove me out of business.

    1. Sad thing to hear. I hope things are going better for you now.


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