Saturday, February 1, 2014

Fruit Fly 2

FRUIT FLY BULLETIN #2  (Nov. 12, 2013)

Fruits susceptible to Spotted Wing Drosophila (SWD)

While you are finishing up your garden's autumn clean up, don't forget to give special attention to your fruit canes and trees. If you are not sure, here is the list of fruits susceptible to SWD.

According to the BC Ministry of Agriculture:

In British Columbia, spotted wing drosophila has been confirmed infesting:
- strawberry (Fragaria)
- crabapple (Mallus)
- plum (Prunus) – including Italian prune plum
- cherry (Prunus)
- Raspberry (Rubus) -- the first choice, and most susceptible to attack
- Himalayan blackberry (Rubus)
- loganberry, tayberry, boysenberry
- blueberry (Vaccinium)
- peach, nectarine, apricot (Prunus) -- though not a first choice
SWD is suspected in:
- hardy kiwifruit (Actinidia)
- grapes (Vitis) -- especially soft-skinned varieties or if skin is broken
- fig (Ficus) -- can be infested when conditions are right, or like grapes, if the skin is broken.
Berries in the Ribes genus are also susceptible:
- currant
- jostaberry

Wild hosts confirmed as infested in Coastal B.C. include, or susceptible here because they have been infested in other areas with similar growing conditions:
- saskatoon (Amelanchier)
- dogwood (Cornus kousa)
- salal (Gaultheria shallon)
- wild honeysuckle (Lonicera)
- Oregon grape (Mahonia)
- mulberry (Morus)
- Indian plum (Oemleria)
- wild Prunus species (Indian plum, wild cherry, etc.),
- black cap raspberry (Ribes)
- currant (Ribes)
- wild rose hips (Rosa)
- trailing blackberry / dewberry (Rubus)
- salmonberry (Rubus)
- thimbleberry (Rubus)
- elderberry (Sambucus)
- wild cranberry (Vaccinium)
- red huckleberry (Vaccinium)
- wild blueberry (Vaccinium)

SWD does not attack:
- apples
- pears
- tomatoes
However, they will lay their eggs in these fruits if the skin is broken. Do a thorough autumn cleanup of these fruits because they can offer breeding sites.


Himalayan blackberry are the bridge crop that will re-infect both domestic fruits and carry it into our wild berries. Here are some control strategies:


-Remove all fruiting canes and old fruit and burn them in a hot bonfire this autumn.
-If you are renting, ask your landlord to manage the stands. Blackberries fruit on the second year’s wood.
- If you are not harvesting your HB stand, but still want them as a hedge or barrier, here is an ongoing strategy:

1. Minimize possible SWD infestation by cutting down and burning the whole stand this
autumn / winter.

2. HB fruit on second-year wood. Next year, before they fruit, CUT THEM DOWN IN
EARLY SUMMER. Within a month or so you will have more than half the stand back
again. If you keep cutting each year, the canes will always be first year growth – nice
hedge but no fruit.

If you have a susceptible tree that is too big to pick or cover, please consider the following:

- Hire someone to pick it clean, and offer to share the harvest, or

- Budget to have it removed this winter or next spring before fruit sets.

Wild and neglected fruit trees can sabotage the efforts of getting SWD under control.

If you wish to keep the tree:

-Reduce the height of the fruit trees to a manageable height so fruit can be picked. If the tree is quite large, it will take a few pruning cycles (ie years) to get down to the desired height.

-Talk to a certified arborist, like John Meilleur of Ferns to Firs, to help to you with information and schedules. This type of pruning is done in the dormant season. John is making the SWD challenge a business priority. Email him at or telephone 604-483-7774 or website

Margaret and Jo

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