AND HELPFUL ANSWERS TO THREE CHALLENGES
It is the end of June as I write. The weather is getting warmer. Strawberries are ripe, raspberries
are coming along fast, and early cherries are ready.
1. It is still early in the season. So far I have had no reports of Spotted Wing Drosophila sighted,
nor have I picked up any in my vinegar traps – although I am starting to see suspicious small
flies hanging around raspberries. We will be able to identify male SWD by the spots on wings,
but females do not have spots and it takes a microscope to identify them. The SWD start to get
active and begin to deposit eggs as soon as fruit has ripened enough for the skin to be soft
enough for them to pierce the skin with their ovidepositors. We expect their numbers to steadily
increase through July and August.
fully ripe. Once picked, store it cool. Then keep picking regularly through the harvest period,
and at the end pick the tree/bush clean of all fruit. Also clean up all fruit that has fallen to the
ground. Do not throw it into your compost. (Hints below on getting all the fruit picked.)
3. If you have not yet
set out vinegar traps for SWD, this is a good time to do it. Place them low
and on the shady side of your fruit bush. (See Bulletin # 6) I have discovered that the clear
plastic cups from smoothies and slushies make very good vinegar traps!
4. Last week we set out some specialized traps with lures in Wildwood to see if we get
specimens of Cherry Fruit Fly (CFF). If anyone else suspects they had CFF last summer, contact
me asap. Remember that CFF hosts only on cherries and the tell-tale sign of CFF is the exit
holes in the cherries. (See Bulletin #7) We want to identify if CFF is here – or not - so that we
can use appropriate control methods.
5. I got a report of grubs found in gooseberries south of town, and now of grubs in currants on
Manson near Gouthro Park. This looks like the work of the Currant Fruit Fly which attacks only
gooseberries and currants. It has been in the Powell River area for many years. With it being
one of the rhagoletis family, which pupates in the ground under the host tree or bush, it helps to
cover the ground under the bushes (see Bulletin #7). If you have this problem, pick the plant
clean and also rake up all the fallen fruit – and bake, boil, nuke, freeze or solarize it.
6. If you find grubs in your fruit, from either SWD or CFF, they will not make you sick. If you
pick it before it is spoiled, the fruit can still be used for jams, jellies and juice.
IT’S A CHALLENGE. BUT HELP IS AVAILABLE. . .YOU MAY BE WONDERING:
1. HOW CAN I GET ALL THE FRUIT OFF MY TREES?
Sometimes this can be a challenge. No doubt some of us already invite friends and neighbours to
come over and help us out by picking fruit for themselves.
. . . or now we can call “THE SKOOKUM GLEANERS”!
• David Parkinson has just revived The Gleaners!
• They will come in and pick a crop clean and share the fruit between the owner, the
pickers and a needy group in town.
• They do not want to see valuable fruit going to waste. They also want to remove
temptation for bears - and as we know this will also remove breeding sites for fruit flies.
• This can be a great help if the crop is too much for you, or the trees are too big, or if you
are going to be away at the time your fruit will come ripe.
• I’d say this is a win-win-win.
To contact them: David Parkinson - firstname.lastname@example.org or 604-485-7940
Give them adequate warning and don’t call at the last minute.
Make sure there is a good supply of fruit to be fair and make the job worthwhile for them.
You can suggest them to neighbours too, or let The Gleaners know about abandoned or neglected
2. HOW CAN I GET SUITABLE NET TO COVER BUSHES?
• Eternal Seeds has the information and is ready to order fine mesh suitable to cover bushes
such as blueberry, against the SWD.
• They will bring it in as soon as they get orders.
• Contact Gary and Ellen at 487-1304 or email@example.com
3. HOW CAN I CHECK IF THERE REALLY ARE GRUBS IN MY FRUIT?
There are two simple methods to test if there are grubs in the fruit.
CHECKING FOR GRUBS IN FRUIT
a. Salt-water flotation test
• Make a solution of 4 cups water to 1/4 cup of salt.
• If fruit are suspected of being infested, either collect a standard sample of fruit, or only
suspicious (oviposition scars and soft spots) fruits.
• If you are sampling in fields, place fruit in a plastic “ziploc” bag and crush lightly to
break the skin. Perhaps label the bags for the sites where you are testing.
• Add the salt-water mixture. Leave the fruit in the mixture for an hour, then check it.
• Drosophila larvae will float in the liquid making them easier to see. Detection of small
larvae may require the use of a hand lens, and this works well with a light behind the bag
to shine through onto the larvae.
• If this is being done indoors, place suspect berries on a tray and pour the salt solution
over the lightly crushed fruit. Observe the fruit after an hour to see if larvae are present.
Note that this method doesn’t allow for differentiating between SWD larvae and other similar
species. The only way to be sure larvae in the fruit are SWD is to rear them until they are adult
flies. It takes two to three weeks for adult flies to develop from larvae.
(I also found that it drives grubs out in a hurry if you put the fruit in rubbing alcohol!)
b. Boil test
• To do this, cover a sample of fruit/berries with water and boil for one minute.
• Sometimes larvae will soon start to just float to the surface .
• Or then pour the fruit and liquid onto a sieve or a mesh-covered frame over a tray and
mash the fruit with the back of a spoon. Lightly wash through with water and look in the
tray for larvae.
NOTE: Although the boil test is used as a standard sampling method for checking fruit by
processors, it is better to detect any potential infestation in the field and control it before any
infestation reaches the processor.
I will write again when there is anything new to report or advise.
Please let me know how things are going.