How to treat roses to prevent cane borers?

13 years ago

I've searched the web and have found a mix of opinion. Some say use paint, wax, colored glue on the ends of freshly cut canes. Others say that nothing works. I did just lose a Double Delight to cane borers. What are your opinions out there. Thx, cj

Featured Answer

michaelg

8 years ago

last modified: 8 years ago

The insects that drill in cut cane ends are the Small Carpenter Bee (an important pollinator) and a tiny wasp (preys on aphids). They are just making a nesting chamber where they feed the young. They do not eat the rose tissue, and IMO do not need to be controlled. The kinds of borers that do serious damage do not drill in cut cane ends. One of those that is common in the West is the Raspberry Horntail, a sawfly. Here we have a very similar one, Raspberry Stem Sawfly. If I see just a couple of rose growth tips wilting when they should not be wilting, I examine the stem and may find a white larva boring down the cane through the pith. This happens occasionally in midsummer. The egg-layer has made neat cuts in the bark a few inches below the tip.

Everyrose has a good post above. "Rose cane borers" is a gardeners' expression for the little wasps and bees. It is good to know the official common name (like Small Carpenter Bee) if you want to get more information from science-based sources.

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Comments (12)

zack_lau z6 CT ARS Consulting Rosarian
13 years ago
I use molding and trim wood glue--it doesn't drip.
jim1961 / Central Pennsylvania / Zone 6
13 years ago
Elmers carpenters wood glue
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Zyperiris
13 years ago
ditto on elmers
ronda_in_carolina
13 years ago
Ditto on Elmers as well.
kentstar
13 years ago
Elmer's glue either wood or regular white work well yup.
everyrose
13 years ago
Here in the PNW we have two types of cane borers--rose cane borers and raspberry cane borers. Rose cane borers are mostly annoying. They kill the top inch or two of the rose cane but new growth will emerge further down the cane and the rose will be fine. Some people will seal the cane but those of us who have lots of roses don't bother--it takes too much time!

Raspberry cane borers are a differant matter. They will burrrow all the way down the cane and even into the crown of the plant and maybe kill the rose. Since you say your rose was killed I'm guessing that this is what you have. The good news is that roses are not the prefered food of raspberry cane borers--they prefer raspberries and if they can't get them they go for blackberries. If you have them on your roses it is usually a sign that somewhere in your neighborhood someone has taken out their raspberries or taken out blackberries and the hungry critters ate your roses. After a few years the cane borers will either die out or the raspberries or blackberries will come back and they will go eat those.

In the meantime, you can control the borers by keeping an eye on your roses and if you see dieback on the canes below two inches, cut back the cane to below the dieback. You will see a catapillar-ish looking thing at the bottom of the tunnel. Dispose of it. The good news is that since these critters have a one year life cycle, once you have disposed of them, they will not come back for a year. I don't know if a systemic insecticide will work. Systemics cannot be used on edibles and since this is mainly a pest of raspberries, the insecticides will not be labeled for use on raspberry cane borers. But they might work for raspberry cane borers on roses. But it is probably less work to just cut them out when you see them rather than spraying.
reg_pnw7
13 years ago
What everyrose said. Cane borers are not a big problem here and I don't generally recommend sealing pruning ends. Raspberry borers are a rare menace. Sealing pruning ends won't stop them.
cjrosaphile
Original Author
8 years ago
last modified: 8 years ago
What I find in the canes is a wasp and not a catapillar.
countrygirlsc, Upstate SC
8 years ago
That is the rose cane borer. I don't seal mine anymore either.
rugose
8 years ago
Rugosas are as delicious to borers as raspberries. I have at least three types of borers. I find primacanes wilting from just inches above the ground (with no other visible damage) and find a grub, having gained entrance to the cane via puncture in the side of the primacane, burrowing a few inches below. I also find new growth tips ragged and blackened with a grub gaining entrance into the cane by chewing through the center of the new growth. Lastly, I find cigar-like swellings mid-cane (with no sign of wilting), that sometimes contain a stem-girdling grub. I've found the literature confusing when I've tried to ID these pests. The good news is the treatment is the same: cut the damaged canes progressively lower until there is no visible damage to the interior. The bad news is that even though there is one generation of each type per year, the fact that the pests emerge at different times makes mine an all-summer battle.
michaelg
8 years ago
The bug that makes the "cigar-like swellings" on rugosas has the official common name of Rose Stem Girdler.