Ask a Question forum: What causing this?

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Hampshire, UK
sarahsawyers
Jun 29, 2017 5:58 AM CST
Please can someone help. What's causing this and how do I deal with it?
Thumb of 2017-06-29/sarahsawyers/1e8ac4

Name: Yardenman
Maryland (Zone 7a)
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Yardenman
Jun 29, 2017 6:11 AM CST
sarahsawyers said:Please can someone help. What's causing this and how do I deal with it?
Thumb of 2017-06-29/sarahsawyers/1e8ac4

What plant are we seeing there and what is the problem? Give us a little more information. ;)

Hampshire, UK
sarahsawyers
Jun 29, 2017 6:27 AM CST
Hi Yardenman,
It's a cordyline red star. I have 3 planted close to each other. It's a brown elongated line that progresses to a patch then a hole. All leaves will eventually be affected and destroyed. I've already had to replace one. I've tried spray pest killers which stop it for a short time then new patches appear. They are very unsightly and being ruined!! I also have a phormium that ha been affected!
Any help would be greatly appreciated.
Name: Yardenman
Maryland (Zone 7a)
Image
Yardenman
Jun 29, 2017 6:44 AM CST
Check this site: http://extension.psu.edu/pests...

I don't know this plant, but the site seems pretty detailed about the cordyline-ti diseases.
[Last edited by Yardenman - Jun 29, 2017 7:10 AM (+)]
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Name: Sue
Ontario, Canada (Zone 4a)
Daylilies Birds Enjoys or suffers cold winters Native Plants and Wildflowers Butterflies Annuals
Region: Canadian Keeps Horses Dog Lover Plant Identifier Garden Sages
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sooby
Jun 29, 2017 6:58 AM CST
Welcome!

Have you looked inside the lines or patches for an insect larva? If not maybe you could do that. Just to rule out leafminer but so far I'm not finding information about leafminers affecting Cordyline or Phormium in the UK. I did find this pic from New Zealand:

https://www.google.ca/search?q...:

If by chance you belong to the RHS they will diagnose plant problems free for members if you send them a picture.
Hampshire, UK
sarahsawyers
Jul 1, 2017 9:14 AM CST
Hi Sooby,

Thanks for your reply.
I've looked and cannot see any larva at all around the damaged parts.
Having looked at the information about cabbage tree moths, then brown elongated damage is the same but no evidence of the moths, eggs or larger chunks eaten from the leaf!

I'm not an RHS member either, but think I'll take an affected leaf to my nearest garden centre and ask them to diagnose.
Thank you for your help so far :)
Name: Sue
Ontario, Canada (Zone 4a)
Daylilies Birds Enjoys or suffers cold winters Native Plants and Wildflowers Butterflies Annuals
Region: Canadian Keeps Horses Dog Lover Plant Identifier Garden Sages
Image
sooby
Jul 1, 2017 9:23 AM CST
Since there are holes it's possible the larvae have left, if that's what it was - they could be exit holes. If the damage continues you may want to open up one of the patches without a hole, or check at the end of a line inside the leaf. If it's a leafminer you won't see them on the outside, you need to open the mine by breaking the leaf's outer skin.

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