# Plant pathology (picture) **URL:** \ **Category:** Factual Questions\ **Created:** [June 12, 2011, 7:20pm UTC](https://boards.straightdope.com/t/plant-pathology-picture/585235 "2011-06-12T19:20:08Z")\ **Posts on this page:** 18\ **Page:** 1
**Author:** ![kayaker](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/kayaker/32/441_2.png) [@kayaker](https://boards.straightdope.com/u/kayaker)\ **Post date:** [June 12, 2011, 7:20pm UTC](https://boards.straightdope.com/t/plant-pathology-picture/585235/1 "2011-06-12T19:20:08Z")
One of our rhododendrons has something going on. [It looks like someone used a saw to cut a straight line through the bark.](http://i681.photobucket.com/albums/vv174/kayaker01/rhodopath.jpg) Insect? N.B.: the branches cut off were intentional, the plant is being trained. The straight line through the bark is the concern. There are many identical lesions on the plant. Thanks! ---
**Author:** ![Ostrya](https://avatars.discourse-cdn.com/v4/letter/o/35a633/32.png) [@Ostrya](https://boards.straightdope.com/u/Ostrya)\ **Post date:** [June 12, 2011, 7:26pm UTC](https://boards.straightdope.com/t/plant-pathology-picture/585235/2 "2011-06-12T19:26:23Z")
It looks like a string or wire was left on, disappeared under the outgrowing bark and is now creating a girdle of the cambium layer. I have never seen an insect do what is shown, it looks like a classic girdle from a wire or something. Does it encompass the entire tree? Also, the stub below should be removed so the limb scar has a chance to heal over. Otherwise, eventually rot will set in. Also, the stub on the opposite side should be cut more flush, leave a little collar but it’s too much stub sticking out, you can see it’s starting to rot. ---
**Author:** ![TriPolar](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/tripolar/32/3008_2.png) [@TriPolar](https://boards.straightdope.com/u/TriPolar)\ **Post date:** [June 12, 2011, 7:27pm UTC](https://boards.straightdope.com/t/plant-pathology-picture/585235/3 "2011-06-12T19:27:06Z")
Was something tied around it right there? Maybe even years earlier. Sure looks man made. ETA:\*\* the lone cashew \*\*got there first. ---
**Author:** ![kayaker](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/kayaker/32/441_2.png) [@kayaker](https://boards.straightdope.com/u/kayaker)\ **Post date:** [June 13, 2011, 10:43am UTC](https://boards.straightdope.com/t/plant-pathology-picture/585235/4 "2011-06-13T10:43:49Z")
No string/wire/etc ever. The pic shows one lesion but there are ten or so others. Will address the branch stubs. This plant is my gf’s project. Trained kinda lolli-pop style. ---
**Author:** ![Blake](https://avatars.discourse-cdn.com/v4/letter/b/a9a28c/32.png) [@Blake](https://boards.straightdope.com/u/Blake)\ **Post date:** [June 13, 2011, 11:22am UTC](https://boards.straightdope.com/t/plant-pathology-picture/585235/5 "2011-06-13T11:22:56Z")
How thick are those stems? I’m guessing about as thick as your wrist, but without any sort of scale it’s difficult to tell. If they were thinner stems I would put it down to twig girdlers. But at that size I would suspect foul play by some bored kid with a knife of pipe cutter. ---
**Author:** ![kayaker](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/kayaker/32/441_2.png) [@kayaker](https://boards.straightdope.com/u/kayaker)\ **Post date:** [June 14, 2011, 2:33pm UTC](https://boards.straightdope.com/t/plant-pathology-picture/585235/6 "2011-06-14T14:33:42Z")
Two more pictures. Unlikely kids, as we are the last home on a long gravel private road, and our dogs are pretty scary toward trespassers. 😉 [A representative pic.](http://i681.photobucket.com/albums/vv174/kayaker01/rhod1.jpg) [A group of them, with my hand to show size.](http://i681.photobucket.com/albums/vv174/kayaker01/rhod2.jpg) ---
**Author:** ![TriPolar](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/tripolar/32/3008_2.png) [@TriPolar](https://boards.straightdope.com/u/TriPolar)\ **Post date:** [June 14, 2011, 3:30pm UTC](https://boards.straightdope.com/t/plant-pathology-picture/585235/7 "2011-06-14T15:30:23Z")
I’m not going to put myself out as a botanist, but those still look like the marks left from the pressure of something tied to the plant in the past. Was anyone ever trying to change support that trunk or force it into a different direction? I know those scars can show up long after the pressure was applied. Otherwise, it looks like they were made with a sharpened instrument. If the plant were larger I might guess a dog was tied up to it at some point. BTW: Slight highjack, how big are those plants? We have several behind our house now about 10 feet tall, and showing no signs of slowing down. What kind of training are you doing? ---
**Author:** ![kayaker](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/kayaker/32/441_2.png) [@kayaker](https://boards.straightdope.com/u/kayaker)\ **Post date:** [June 14, 2011, 3:49pm UTC](https://boards.straightdope.com/t/plant-pathology-picture/585235/8 "2011-06-14T15:49:39Z")
This rhododendron is a lone survivor from long ago when my gf planted a row of them along the driveway. Deer destroyed all except this one, which barely survived. Then, a few winters ago a massive snowstorm messed this one up some more. Nothing has ever been tied to it. Never any string/wire/etc. “Training” has been done by my gf who has done some topiary stuff with other shrubs and trees. She has just been removing lower branches and trimming the top into a globe shape. She noticed the “lines” this weekend and pointed them out to me. ---
**Author:** ![Troppus](https://avatars.discourse-cdn.com/v4/letter/t/a587f6/32.png) [@Troppus](https://boards.straightdope.com/u/Troppus)\ **Post date:** [June 14, 2011, 5:22pm UTC](https://boards.straightdope.com/t/plant-pathology-picture/585235/9 "2011-06-14T17:22:30Z")
> [@kayaker](#): > > This rhododendron is a lone survivor from long ago when my gf planted a row of them along the driveway. Deer destroyed all except this one, which barely survived. Then, a few winters ago a massive snowstorm messed this one up some more. Nothing has ever been tied to it. Never any string/wire/etc. > > “Training” has been done by my gf who has done some topiary stuff with other shrubs and trees. She has just been removing lower branches and trimming the top into a globe shape. She noticed the “lines” this weekend and pointed them out to me. Maybe the original plant sales tag/label was overlooked for a couple years, then the rhodo limb grew big enough to snap it. Old scar? ---
**Author:** ![kayaker](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/kayaker/32/441_2.png) [@kayaker](https://boards.straightdope.com/u/kayaker)\ **Post date:** [June 14, 2011, 5:29pm UTC](https://boards.straightdope.com/t/plant-pathology-picture/585235/10 "2011-06-14T17:29:38Z")
> [@Troppus](#): > > Maybe the original plant sales tag/label was overlooked for a couple years, then the rhodo limb grew big enough to snap it. Old scar? But there are many such lesions… ---
**Author:** ![TriPolar](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/tripolar/32/3008_2.png) [@TriPolar](https://boards.straightdope.com/u/TriPolar)\ **Post date:** [June 14, 2011, 5:38pm UTC](https://boards.straightdope.com/t/plant-pathology-picture/585235/11 "2011-06-14T17:38:10Z")
I’m sorry to say there is only one remaining possibility, another case of _Alien Rhododendron Mutilation_. ---
**Author:** ![Troppus](https://avatars.discourse-cdn.com/v4/letter/t/a587f6/32.png) [@Troppus](https://boards.straightdope.com/u/Troppus)\ **Post date:** [June 14, 2011, 5:46pm UTC](https://boards.straightdope.com/t/plant-pathology-picture/585235/12 "2011-06-14T17:46:53Z")
> [@kayaker](#): > > But there are many such lesions… No chance those are weed-eater bites? ---
**Author:** ![Harmonious\_Discord](https://avatars.discourse-cdn.com/v4/letter/h/74df32/32.png) [@Harmonious\_Discord](https://boards.straightdope.com/u/Harmonious_Discord)\ **Post date:** [June 14, 2011, 5:49pm UTC](https://boards.straightdope.com/t/plant-pathology-picture/585235/13 "2011-06-14T17:49:51Z")
Somebody in the past slightly damaged the bark. It doesn’t look like it was beyond the plants capabilities to heal. It’s a shallow wound regardless that didn’t cause much damage. The cuts facing one side reminds me of what a sloppy branch trimming does to the neighboring branches, when the saw slips and hits the neighboring branch. The completely around the branch wound looks like when a string holding the tag does damage. ---
**Author:** ![sitchensis](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/sitchensis/32/4892_2.png) [@sitchensis](https://boards.straightdope.com/u/sitchensis)\ **Post date:** [June 14, 2011, 5:59pm UTC](https://boards.straightdope.com/t/plant-pathology-picture/585235/14 "2011-06-14T17:59:28Z")
Do you guys have [European Giant Hornets?](http://www.hort.uconn.edu/Ipm/homegrnd/htms/43rhodo.htm) If you do “Alien Rhododendron Mutilation” was probably the closest answer. ---
**Author:** ![kayaker](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/kayaker/32/441_2.png) [@kayaker](https://boards.straightdope.com/u/kayaker)\ **Post date:** [June 14, 2011, 6:15pm UTC](https://boards.straightdope.com/t/plant-pathology-picture/585235/15 "2011-06-14T18:15:54Z")
> [@Troppus](#): > > No chance those are weed-eater bites? Well, I am the one that operates the weedeater, so I strongly doubt it. My gf would kill me. > [@Harmonious\_Discord](#): > > The cuts facing one side reminds me of what a sloppy branch trimming does to the neighboring branches, when the saw slips and hits the neighboring branch. The completely around the branch wound looks like when a string holding the tag does damage. :D:D:D I’ll relate this info to my gf. However, she rarely uses a tree saw, and is pretty handy with pruners. ---
**Author:** ![Harmonious\_Discord](https://avatars.discourse-cdn.com/v4/letter/h/74df32/32.png) [@Harmonious\_Discord](https://boards.straightdope.com/u/Harmonious_Discord)\ **Post date:** [June 14, 2011, 6:18pm UTC](https://boards.straightdope.com/t/plant-pathology-picture/585235/16 "2011-06-14T18:18:35Z")
> [@kayaker](#): > > Well, I am the one that operates the weedeater, so I strongly doubt it. My gf would kill me. > > :D:D:D I’ll relate this info to my gf. However, she rarely uses a tree saw, and is pretty handy with pruners. It looks like old damage, not new. ---
**Author:** ![sitchensis](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/sitchensis/32/4892_2.png) [@sitchensis](https://boards.straightdope.com/u/sitchensis)\ **Post date:** [June 14, 2011, 7:00pm UTC](https://boards.straightdope.com/t/plant-pathology-picture/585235/17 "2011-06-14T19:00:49Z")
From the link I provided University of Connecticut, \*\*Common Insect Pests of Rhododendron \*\* > [@](#): > > European Giant Hornet, Vespa crabro germana > Recognition and Life Cycle > > The adults are the largest hornets in North America. They vary in length from 3/4 to 1 1/4 inches and are dark reddish-brown with yellowish-orange markings on the face and abdomen. Nests are located in building partitions, tree holes or holes in the ground. The adults are unusual in that they are active at dusk and are often attracted to porch lights at night. > > \*\*Damage > > The adults strip bark from the plant resulting in girdled twigs and branches. Researchers believe they do this to obtain nest-building material or to feed on the sap. The larvae live in the nests and do not cause plant damage.\*\* > > Monitoring > > Examine plants in late August into September for early signs of girdled branches and for adults. > > Control > > Spray twigs and branches with carbaryl as soon as damage is noted. Repeat treatments seven to 10 days later, if necessary. Bolding mine ---
**Author:** ![kayaker](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/kayaker/32/441_2.png) [@kayaker](https://boards.straightdope.com/u/kayaker)\ **Post date:** [June 14, 2011, 8:20pm UTC](https://boards.straightdope.com/t/plant-pathology-picture/585235/18 "2011-06-14T20:20:58Z")
**sitchensis** ; looks likely. I initially read the link and did a GIS for the hornet, but looked at the wrong pic. Thanks!