Curling top leaves #542700 - Ask Extension

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Curling top leaves #542700

Asked February 03, 2019, 1:26 PM EST

I am a professional gardener, a past member of Master Gardeners, a past employee of a retail plant nursery where I was in charge of diagnosing plant diseases for the public, and I have a major problem that is stumping me. I noticed it first of Euphorbia martinii 'Ascot Rainbow' and 'Blackbird'. Their top leaves are rolling around each other and forming what look like cartoons. The leaves eventually die and then the whole plant dies. I noticed it on tree leaves ( this year only) in my own yard. I started some trash trees from seed, Paulownia tomentosa, that have huge velvety leaves. Now their margins are rolling (in growing season) and becoming distorted- but not dying. This effect lasted all season last year, starting in cold spring weather, continuing in the heat of summer, and right i to Fall. Some are doing this in Winter! I've examined the inside of the roll of leaves for insects, but found nothing, not even silk or feces. I've worked with Euphorbia for decades and never seen this, and of course they are not listed as having any known diseases at all. I was too busy working, and maybe a bit forgetful to bring a sample toy extension office for examination. I need help though, and any given is much appreciated. I fear we are dealing with a new insect or disease I have not ever seen before. Scary. I will also say; it is occurring randomly on plants in the same cultural conditions, some in each bed, and some not at all. One plant by an electrical panel looks fabulous with no damage at all. Unfortunately I have no pictures of the stunted Euphorbia at this time, but can go to my commercial planting and take a picture, which I will provide at future correspondence with your office. Thank you in advance. Monica Felt Perryman

Wasco County Oregon

Expert Response

Hi, Monica. I wonder if you have considered a virus transmitted by a white fly vector? Whiteflies have been detected in Oregon ornamentals carrying (if I understand the science) viruses causing tomato leaf curl, among other diseases.  https://swfrec.ifas.ufl.edu/docs/pdf/veg-hort/tomato-institute/presentations/ti2016/ti2016_Polston.p...

See, too, this synopsis:  https://www.ncbi.nlm.nih.gov/pubmed/21136128

This article (although primarily about the virus in cassava) indicates a known euphorbia leaf curl virus (Table 1).  https://evans.uw.edu/sites/default/files/EPAR_UW_Request_233_Whitefly%20Cassava%20Control%20Strategi...

Other than abiotic causes, I haven't been able to find any pathology linked to Paulownia leaf curl (although there is plenty of research on leaf spot.)  

If you have any further insights, I'm happy to do more research or, if you'd prefer, pass it along to the plant pathology clinic (although they might need samples.)

Fascinating!

Kris LaMar
Kristena LaMar Replied February 03, 2019, 3:38 PM EST

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