Knowledgebase

Pests of currants #866330

Asked April 29, 2024, 3:01 PM EDT

Most old (dead) stems covered with tiny red bugs (or eggs). Little or no fruit since these discovered. Only solution I can think of is prune infested stems out and burn.

Jefferson County Colorado

Expert Response

Hi, Hugh:
Thanks for contacting the Jefferson County Plant Diagnostic Help Desk. 
We cannot identify the red potential insects without seeing them. You could bring in some stems with these structures or send photos to the plant diagnostic help desk: <personal data hidden>. Please note in any email that this is a reply regarding an "Ask Extension" question #0132651.

Several insects do infect currants: aphids (though, while various colors not typically red), spider mites (which are red or pink and quite small), and the larvae of sawflies and borers and fruit flies. 

It is safe to remove canes where you see these critters but optimal to know what they are so as to prevent or manage them if they occur in the future, so please let us look at what you are seeing.

Pat B
Thanks for your interest and reply.  There are hundreds of them on a stem.  They are not much bigger than pin-head size, but not so small as mites.  They might be eggs - they've been there all winter.  If you'll give me a mailing address I'll send you samples,
On Wed, May 1, 2024 at 2:06 PM Ask Extension <<personal data hidden>> wrote:
The Question Asker Replied May 01, 2024, 9:01 PM EDT
Jefferson county extension - at the fairgrounds. Address is below. Insect identification for Jefferson county residents is $10 and I believe you will be billed after submission.  You can bring them to the extension office Tues thru Friday 8 to 4:30. Or you can sSend some canes with the tissue you observe, in a rigid container, with the canes in a plastic bag in case these are eggs that hatch. If you come in person you will have a submission form asking for information. If you are mailing them, please describe the extent of this infestation, when you first noticed it, any insects you saw on the canes last season, and  any impact on the plant's vigor (including affected cane decline or death) or fruit production. Include a phone number so we can contact you if we have further questions. 

Best regards,

pat b

 

Plant Diagnostic Call Center, Horticulture

Colorado State University Extension, Jefferson County

jeffcoextension.org

<personal data hidden>

303.271.6627 - Direct

15200 West 6th Ave, Unit C

Golden, CO 80401

 

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From: ask=<personal data hidden> <ask=<personal data hidden>> on behalf of Ask Extension <<personal data hidden>>
Sent: Wednesday, May 1, 2024 7:01 PM
To: Plant Diagnostics <<personal data hidden>>
Subject: --{EXTERNAL}-- New response added to your question (#0136251)
 
This Message Is From an External Sender
This message came from outside your organization.
 

Hi Jeffco Plant Clinic,
A new response was appended to question #0136251 [ask2.extension.org]

From: Hugh Gardner
Subject: Pests of currants

Thanks for your interest and reply.  There are hundreds of them on a stem.  They are not much bigger than pin-head size, but not so small as mites.  They might be eggs - they've been there all winter.  If you'll give me a mailing address I'll send you samples,

On Wed, May 1, 2024 at 2:06 PM Ask Extension <<personal data hidden>> wrote:



To view or respond to the question, please login [ask2.extension.org] to Ask Extension.


Please join the Ask Extension Experts group in Connect Extension [connect.extension.org]. We will use that group to post updates about Ask Extension.
This message was sent by Ask Extension. If you need help, please visit https://askhelp.extension.org/ [askhelp.extension.org].

The Question Asker Replied May 02, 2024, 10:32 AM EDT
regarding an "Ask Extension" question #0132651 - sample cane mailed w/hard copy of this

describe the extent of this infestation, when you first noticed it - Infested first red currant plant during drought period 20-21, gradually spread to five other plants, including black currants.  All plants on north side of 6' fence and in considerable shade.  Altitude about 6,700' 

any insects you saw on the canes last season - Probably related to outbreak of small (.5") dark grey caterpillars which appeared to be eating foliage.  Sprayed last year and worms have not appeared on new growth (yet).

any impact on the plant's vigor (including affected cane decline or death) or fruit production -  There's been no fruit since these guys showed up - many dead canes covered with these little red things.  Fortunately new canes come up, but some plants have clearly declined.  I've read they do better in full sun - this was certainly true of the very first red I planted years ago.  Local water restrictions probably played a role too.

My telephone number is<personal data hidden>.

On Thu, May 2, 2024 at 8:32 AM Ask Extension <<personal data hidden>> wrote:
The Question Asker Replied May 16, 2024, 5:58 PM EDT
Hi Hugh,
I'm following up to make sure your question was answered.  The Jeffco Sample Log doesn't have an entry for your currant, so looks like you haven't submitted a sample yet.  In place of a physical sample, can you send a photo close-up of the affected branches?  You can send here, or directly to the Jeffco Diagnostic Desk:  <personal data hidden>.

Best,
Mari H
Yes, I sent a sample by 1st class mail, should be there this week.  Appreciate your help.

On Wed, May 22, 2024 at 2:41 PM Ask Extension <<personal data hidden>> wrote:
The Question Asker Replied May 23, 2024, 10:32 AM EDT
Thank you. We will watch for it.
Mari
Hugh,
We received your sample in the mail - thank you.  For reference, we have assigned it as Sample #240028.

Three requests/questions for you:

First,  Attached is a copy of a form we require for samples that we receive.  Please provide us with the missing information - we have completed as much as we can based on information you have provided so far.
  • your billing address, and the address where the currants are growing if they are not the same.
  • Please verify that you are a Jefferson County resident.
  • Also please see the statement below the address portion of the form, which states: "If we are not able to complete diagnosis/identification, we will send the sample to the CSU Statewide Plan Diagnostic Clinic for evaluation (CSU SPUR).  Client will be charged CSU SPUR rates in addition to the Jeffco fee.  I give the Jeffco Clinic permission to do this"
    • This means: if we are unable to diagnose the problem, we can forward your sample to the state plant lab. We need your permission to do this.  It is not required, and the Jeffco Diagnostic Team will evaluate and attempt to diagnose the problem regardless.
    • Please respond and let us know if you want the sample to go on to SPUR or to stop with Jeffco.
Secondly, please send us the following photos of the plant(s):
  • A wide shot of the row of bushes, so we can see the area where they are growing.
  • A closeup of an individual bush, but trying to get one entire affected bush in the photo.
  • Zoomed in photos of the red bumps.
Finally, a few additional questions:
  • The sample we received was very dry, and the red bumps were crunchy when we removed one to look at it under the microscope.  Are the bumps soft on the plant, or were they dried out when you cut the sample?
  • How old are the plants?  Have they produced many berries in past years before this problem?
  • You mention that the bumps persisted all winter.  What month last year did you first notice them?  At any point did you notice insects in the vicinity? At any point were the bumps soft on the cane, or sticky? (There appears to be sugary crystals on the cane.)
  • Have all canes with the bumps died?  What percentage of the plant(s) are affected?  How long did it take canes to die once you discovered the bumps?
  • Are the leaves healthy, with good color?
  • How much/how often are the plants irrigated?  Roughly how many hours of sun do they get per day?
We may have additional question for you, but this will get us started.

Thank you.
Jeffco Volunteer Diagnostician Annette
Attn:  Charlotte

Thanks for the call the other day.  The odd plant I told you about is a native (though apparently rare) - blitum capitatum, also known as "Indian Ink," "Strawberry Spinach," and many other names.  The berries are edible though bland, and were used by indians to make paint.  The leaves are edible raw (when young) or as a potherb. Bradford Angier's Field Guide to Edible Wild Plants has a page about it.  Fascinating!  No one I know has seen it here before.

On Thu, Jun 6, 2024 at 12:01 AM Ask Extension <<personal data hidden>> wrote:
The Question Asker Replied June 26, 2024, 1:49 PM EDT
Hello Hugh,
I'm following up on 'open' questions.  I see that your sample to Jeffco Extension was diagnosed as likely White Pine Rust.  If you need confirmation, you'll need to submit a sample to the CSU Spur Plant Diagnostic Lab  https://agsci.colostate.edu/agbio/plantclinic/

The main management strategy is to prune off and discard (not compost) affected plant parts.  See https://extension.umn.edu/plant-diseases/white-pine-blister-rust

Best regards,
Mari Hackbarth
Thank you for the clarification. 

On Sun, Jun 30, 2024 at 8:18 PM Ask Extension <<personal data hidden>> wrote:
The Question Asker Replied June 30, 2024, 10:33 PM EDT
You are most welcome!  Pester us if you need more info.
Best,
Mari
You are welcome!  If you have additional questions, send them to <personal data hidden>, so that whoever is staffing the Diagnostic Desk knows to look in the sample log for the background information on the sample.

Thanks for using the Jeffco Diagnostic service!

Mari Hackbarth

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