Damage to currants - Ask Extension
For the past few years, my currants, in particular the red and the black variety (the latter is actually a cross with a different berry), have been da...
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Damage to currants #757374
Asked June 21, 2021, 5:11 AM EDT
For the past few years, my currants, in particular the red and the black variety (the latter is actually a cross with a different berry), have been damaged by some insect(s). It’s the same type of damage year after year. Almost all of the red currants have some kind of damage by the end of the season and are rendered inedible. A lot of the damaged fruit simply falls to the ground. This damage coincides with the presence of brown marmorated stink bug (although this year, so far, I have only seen one specimen, which I crushed), two other types of stink bug, and a fly (?) with orange striped wings. Every season I collect the bugs that I can see and catch in a jar with a soap solution. A picture of my “catch” from earlier this season is attached. So far this season, I have collected over a hundred of these bugs (stink bugs are fairly easy to collect but the fly is super elusive; it is featured in the uploaded picture though). Occasionally, I also find small eggs laid on the underside of the leaves of a nearby honey berry bush. I believe they are laid by the stink bugs. Pictures of clusters of two types of such eggs are also attached, one shows small bugs emerging from a cluster of eggs. Please help me identify the bugs and the fly and let me know which one(s) cause the damage and how to manage this problem. I'd be happy to attach a picture of the fruit damage but it appears that only 3 files can be uploaded. Thank you very much for your help!
Washington County Oregon
Expert Response
Thank you for the images that accompany your inquiry.
If you have additional images, you reply multiple times to this email, each with up to 3 images. Images of the damaged fruit, plus an overview of the planting area would be helpful.
And, yes, you definitely have stink bugs, some are adults, others nymphs (youngsters), also eggs.
If you have additional images, you reply multiple times to this email, each with up to 3 images. Images of the damaged fruit, plus an overview of the planting area would be helpful.
And, yes, you definitely have stink bugs, some are adults, others nymphs (youngsters), also eggs.
Hello Jean,
Thank you for responding so promptly. I am enclosing a couple of pictures of the planting area.
1. Area 1 (along the fence in the backyard) shows from the left: the "black/cross" currant plant, 2 blueberry bushes, and 2 red currant bushes
It's the black and red currant plants that are affected by the damage. I get some damage to the blueberries from the spotted wing drosophila later in the season but it varies from year to year and is totally different from the damage to the currants. Drosophila also causes some damage to the honey berries (just about this time of the year) but I haven't seen any of it yet (no liquified berries at this point)
2. Area 2 (center of the backyard) shows 2 white currant bushes (there is also a small blueberry bush in the center front and blueberry bushes on the sides) and 2 honey berry bushes just behind them. It is all a bit of a tangled mess.
What I have observed is that sting bugs seem to tend to lay eggs in the honey berry plants, then the young move on to the white currant bushes and then they migrate to the red current bushes. This season so far I have been able to collect many youngsters on the white currant bushes before they moved on to the red currant bushes (I started the collection really early in the season, late May that is); I have not seen any youngsters on the red currants yet this season and only a few adults. In prior seasons I was a bit too late to act (typically mid June) and they managed to migrate to the red currant bushes by that time of the year. However, the damage to the red currants this year so far appears to be comparable to what I saw in past years, which kind of leads me to believe that this orange fly (?) with black striped wings may be the culprit. Do you know that it is? It is featured in the picture of my collection jar that I sent earlier. It is definitely not drosophila. It spends a lot of time poking around the currant fruit and there are quite many of them frequenting all of the currant bushes. It is very hard to capture.
I will include pictures of the damaged fruit in my next message.
Again, thank you very much for your help!
Anita Aslett
On 06/21/2021 10:42 AM Ask Extension <<personal data hidden>> wrote:
Hello Jean,
I am enclosing a couple of pictures of the damaged fruit (and it is just the beginning). White currants don't have nearly as much damage as the red ones. That is how it's been over the years since the arrival of whatever causes this problem. I typically get a pretty good crop of white currants even with the bug damage but the red currants basically turn into "garbage" over the course of the growing season. I have had these bushes for over a decade and the damage started roughly 4 to 5 years ago. Prior to that I used to get a beautiful and bountiful crop.
I have some pictures of the damaged fruit that I took last summer. I'd be happy to send them as well, if it may be helpful.
Best regards,
Anita Aslett
On 06/21/2021 10:42 AM Ask Extension <<personal data hidden>> wrote:
Thank you for the update. And, yes, please send images of last year's damage. If possible, send images as the damage progresses.
After sorting through your images, plus reading the history of the damage, it appears that the fly with banded wings -- the Currant Fruit Fly, aka the Gooseberry Maggot, Euphranta canadensis -- is the main pest you'll need to manage.
Both the currant fruit fly and the Spotted Wing Drosophila (Drosophila suzuckii, aka SWD) lay their eggs in the fruits. The result is a maggot inside the fruit which, then, spoils. In order to effectively treat these pests, it must be determined which maggot is present. Although their general appearances are similar -- small white "worms" -- differences can be seen with a dissecting microscope. Although I've never seen a gooseberry maggot, it's likely larger than a SWD maggot.
Managing the currant fruit fly relies on cultural tactics, including removing damaged fruit as soon as you see it, and more, namely the following:
Both the currant fruit fly and the Spotted Wing Drosophila (Drosophila suzuckii, aka SWD) lay their eggs in the fruits. The result is a maggot inside the fruit which, then, spoils. In order to effectively treat these pests, it must be determined which maggot is present. Although their general appearances are similar -- small white "worms" -- differences can be seen with a dissecting microscope. Although I've never seen a gooseberry maggot, it's likely larger than a SWD maggot.
Managing the currant fruit fly relies on cultural tactics, including removing damaged fruit as soon as you see it, and more, namely the following:
- "Place tarps beneath bushes by mid-June to prevent larvae from entering soil to pupate.
- Pick and destroy all infested fruit on a daily basis, when practical.
- On new or uninfested plantings, screen plants with a floating row cover or similar barrier before adult flies emerge. For best fruit production, row covers must be placed at petal fall after pollination has occurred. Row covers placed after fruit formation begins may not be completely effective at preventing infestation. This may be ineffective on previously infested plantings unless the infestation has been eradicated." (Source: Currant Fruit Fly - here.)
- Collect and discard all fallen infested fruits; bag and dispose in the trash. Do not compost infested fruits.
Limiting stink bugs will also be important. Typical damage is one or more dimples on the surface of the fruit with a dry, corky area underneath each dimple.
Crush the eggs on the leaves on your daily (if possible) search-and-destroy rounds. And spray commercially prepared insecticidal soap directly on the nymphs (youngsters).
Here's a color brochure to help sort who's who of the stink bug world: Stink Bugs of Oregon.
