Pruning for Japanese beetles

22 years ago

For most of the Eastern and Central areas, Japanese beetles start in early to late June. Although there are stragglers, most of them arrive in a 6-8 week period with the worst in the middle four weeks. I don't know of any repellent tactic that does any good. Basically we gather beetles every evening (shake them into a pot of soapy water) and cut opening buds every morning to preserve the ones that haven't been bitten yet. The fewer beetles and the fewer flowers left in the garden, the fewer the beetles that will be attracted to the garden the following day.

One thing that can be done to reduce the hassle is to prune so there are few if any roses during the height of the invasion. The idea is to have a good flush come on after there are few beetles left. You might then finish the season with more unspoiled roses than if you let the second flush correspond with the peak of the JB problem. Even if not, you are spared six weeks of elevated blood pressure.

To do this, you would wait until the beetles have become numerous and you figure there are about six weeks to go. (Some years in some places they will not ever become numerous.) If there are some large buds of good cutting roses, maybe you leave those and hope to cut them early. If there are some varieties that seem not to attract beetles, maybe you leave those alone until they prove otherwise. But the basic approach would be--

--Take off all the flowers.

-- Cut back or pinch back all growing shoots.

-- Use the occasion to prune thoughtfully. Shorten spindly bush roses. Pinch the tips from young basal shoots to promote branching. Shape and direct the growth of shrubs. Remove strong lateral shoots from climbers and arching shrubs if they don't look good.

-- Enjoy the respite and look forward to your mid-August (or whenever) flush.

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Comments (8)

Bruce7
22 years ago
MichaelG: Have you used this method? Does it work well? The idea occurred to me last summer. It seemed like a good idea, but I had never heard of anyone that had tried it.

Thanks in advance!
michaelg
Original Author
22 years ago
Yes, I did it three years ago and found it kind of a relief. The past two years, strange to say, we have not had enough beetles to worry about. Our area had severe droughts in late summer and fall which prevented the hatchling grubs from surviving in the dry clay soils. And most people around me do not irrigate their lawns. Ann in East Tennessee has had the same experience. But in suburbs where everyone irrigates, I don't suppose this happens.

One other point, if you leave some buds at the time you apply the scorched-earth treatment, disbud them as for exhibition, because you should cut every stem promptly on sepal-drop and bring them in the house. Leaving some buds gives you an extra two weeks of having a few flowers, which makes it easier to bite the bullet.

I think the appeal of this approach would be greater for those who get four or more flushes normally.
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klimkm
22 years ago
I did this for years. Works well in keeping them away from your yard. I just couldn't stand to see the roses decimated and did not like to pick off all those beetles. One bite and the buds are destroyed anyway.
Also, I grow Austins which tend to "sleep" during the hottest parts of our summer when the beetles come (in NW IL). Others curse their lack of rebloom, not a problem for me, it works well into my schedule.
Also I am experimenting with OGRs this year. Hopefully the blooms will be gone by the time the beetles come.
barb_roselover_in
22 years ago
I really was delighted to find that others think as I do about the Japanese beetles. I remember one year, I covered some of the roses with nylon netting. What a job! - and to get it off, you can't believe. Anyway, if there is nothing available that delights them, maybe that is the best way of handling it. The roses can take a little rest. They are usually around here for about six weeks, so we would still get the fall burst. - Barb
Bellport
22 years ago
This is very interesting, I may try this out one year. (maybe next year). Thank you for sharing this technique.

Angie
tamarava
22 years ago
MichaelG,
I was wondering about the foliage.Are JB's interested in eating the foliage? Will they go for the foliage if the blooms are absent?This is my first season dealing with these critters and I noticed they love the blooms but have been keeping away from eating the leaves.Thanks,Tamara
michaelg
Original Author
22 years ago
JBs prefer flowers, but they will eat young foliage and sometimes shed it. The thing is, open flowers are what attract JBs from outside the yard and to the rose bed. I think if there were no open flowers, you probably wouldn't have significant damage to the foliage. There might be exceptions.
merj
22 years ago
I'm glad to see this experiment has been successful. I was pondering this same idea just this morning, and wondered if I'd be considered a heretic for even mentioning such a notion on a rose forum;0) Last year (my first with roses) I put out milky spore, but failed to repeat it this year. JB's are winning the war in a big way. Next year, I think I'll try milky spore AND selective pruning.