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Rose Cane Borer

15 years ago

I've had trouble with Rose Cane Borer for years. This particular pest is a small wasp which tunnels down the center of pruned canes to lay eggs. I've found them at the tunnel base by dissecting the cane. Some forums have suggested they are harmless and beneficial, as they eat aphids. That's not the case. They open the rose up to fungus infection, and no cane I've seen bored into survived. I've been able to almost eliminate cane loss by glueing every cut end with Elmers waterproof outdoor / indoor glue (Regular Elmers won't last). Doing things this way, my roses no longer fade away over the years. ......Dave

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Comments (6)

Zyperiris
15 years ago
Dave, I do this as well. Works like a charm
karl_bapst_rosenut
15 years ago
Really thick canes with a borer hole will not die. Enough woody pith survives to allow the cane to continue to grow and leaf out. I stopped using sealer of any kind and have experienced some but not severe damage since.
The wasp drills down into the cane to deposit it's egg along with an aphid to feed the newly hatched larva. The waps themselves are predatory insects.
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Alisande, The phrase "cane borers" isn't very useful. In sealing the cane ends, you are protecting against twig-nesting predatory wasps and small carpenter bees, which are beneficial pollinators. The damage these do is actually minimal, because they don't eat the rose tissue. See the Baldo Villegas IPM page. Everyone has these, but many gardeners, including me, don't bother with sealing. Then there are two or three insects that lay eggs near the growth tips. The larvae then tunnel down the cane and destroy it. IPM for these is to watch for tips that are wilted in the AM and kill the worms before they travel far. Sounds like what you may be seeing. On northern rugosas especially, there is a common stem borer (Agrilus) that lays eggs on middle or lower canes. The larvae tunnel under the bark in a spiral pattern, producing a swelling, with the cane dying above. Again the IPM is to destroy them as soon as you notice.
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I have a large potted rose garden in Marin co.Ca. above San Francisco.I am a renter and have moved many times.Each time my garden travels w/ me to the new home.Call me CRAZY and some have, but I love flowers and plants and esp. beautiful,fragrent ROSES.Anyway in my last move I noticed an unusual amount of cane dieback in the spring.To make a long story short,after months of cutting back, seeking answers from local nursery men and women,trying various things and products to NO AVAIL,COTINUALLY CUTTING THE DEAD OFF SEEING ONCE HEALTHY,FULL VIGOROUS PLANTS DWINDLE TO NOTHING,DESPERATE I FOUND THE MARIN ROSE SOCIETY AND GOT ONE OF THEIR NICE ROSARIANS TO COME BY.She knew instantanty what it was....CANE BORERS! UGH! She said to cut the canes back and seal the ends and clean off the union buds smooth and that Icould scratch the surface of the union bud with a wire brush to encorage NEW CANE GROWTH and my plants would be as good as new.Finally I had hope.Yesterday I finished a gruelling 2 full days of cutting and sealing 75 rose bushes and trees.MY HANDS WERE A MESS CUT AND PUNCTURED,BUT IT WAS A LABOR OF LOVE! I was losing my plants at the fast rate of cane borers appetite.The infestation was so bad that I did find a very strong product from Bauer called tree and shrub insect control.Its so strong and toxic that you can only use it once a year,but I was desperate.I used it 1 month ago AND TO REALLY KICK SOME BORER-ASS,Im going to spray as soon as the winds die down with a Bondi product made with pyrithrenes,supposedly not too toxic made from chrysanthamums.I hate using chemicals but nothing was working.Well see how it goes...My beautiful Ballerina rose,which lost all but 3 spindally canes and was the 1st rose I treated is full of healthy new leaves and growth.Iam so happy.I also upped their feeding routine and plan on adding alot of rich new soil and nutrients later this year and I will take the kind rosarians advice and try to encouragr lots of new cane growth.Oh p.s. I used clear silicone glue to seal the ends.It doesnt look great,but its waterproof and permenant.Hope my experience helped you.
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So that's what it looks like! I never knew. Thanks for the picture.
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Zyperiris
15 years ago
Karl, that probably explains why I have seen so many older roses that look great with obvious cane borers. I don't have too many roses yet, so I still seal mine
michaelg
15 years ago
Baldo Villegas, a distinguished rosarian and professional entomologist, says not to worry about it. You probably get a slight benefit from sealing, if you want to take the trouble, but it greatly increases the time required for deadheading. I don't seal, and across 30 years I can recall only a few cases of substantial damage, losing a good-sized cane. These were caused not by the tiny wasps, but by the Small Carpenter Bee that nests in similar fashion. They look like 1/4" flying black ants.
mashamcl
15 years ago
I have had some loss of laterals because of cane borers, not major losses but annoying. I have been trying to deadhead lightly all year, and prune back harder in winter.
Masha
anntn6b
15 years ago
There are multiple borers and the damage they do varies. Baldo has written that his borers only go a short way into the canes. In my garden, I've found larvae four or five inches down. (Those HAVE to be two different critters.)
Yesterday I found a really disgusting nest of ants in a rose cane; carpenter ants tending their young. (Gone now).

Something I've tried to get numbers on, and have had zero success with, is timing when my borers get active. When I've done a HT pruning in early January, the cut surfaces ahve hardened off and the borers haven't been a problem. But when I pruned when the local rose society recommended (to get HT blooms for a scheduled show), I found most canes were bored. That implied an early to mid April borer activity here.
Sealers worked, BTW.
That late Easter freeze two years ago knocked my plannings for a loop and the critters haven't had many good canes to go into for the past two years.

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