They start arriving in July here in NJ, and it's usually pretty hot by then.

I have used some of the Bayer sprays for blackspot with great success in other years, and was hoping to switch to an organic solution for this and JB.

Unfortunately my experience with Neem Oil has been that it has scorched my plants so I abandoned its use in favor of the Bayer fungicide.

For pests I usually use ladybugs with great results, but this, obviously, does nothing for JBs.

JBs in my yard are OUT OF CONTROL and I was hoping to find something to at least suppress them some. My guess is they breed and are attracted by the ornamentals in the golf course behind me, and University across the street. My little yard alone cannot be their only source, given their numbers.

I'm hoping to not have to switch to chemical sprays.

I say "no" to oil-based products, unless you are doing a dormant spray. I don't think I have heard of using cedar oil on roses. I use cedar mulch in the beds, and that hasn't slowed down the population. I have garlic in one of my smaller beds, I haven't seen any difference in the beetle population.

Even though you are next to a golf course, I would still try the milky spore. It would eradicate the grubs in your immediate area. Also, a few folks have had success with the Japanese beetle traps, but you would have to place them in a strategic area.

The other "trick" is to cut off all of the blooms when the JBs appear in late June/early July, and wait them out.

Same as above here Jb's don't emerge until weather is too hot too spray. I have burned my leaves with neem oil even in milder weather so no longer use it. I did closely follow directions but have not experimented with using less than directed.

I have purchased Mycotrol O but have not used it. I read that it can affect caterpillars and since I'm growing plants to attract monarchs this would not be good. Mycotrol O is Beauveris bassiana strain GHA that I picked up during bad outbreak of Tarnished Plant Bugs. I decided not to use it still have the true bug and nice caterpillars.

Nicholas.... I forgot to address the cedar oil products. I got mine from Ashdown Roses back when they had them and they caused extreme leaf burn even when used as directed. Worse damage than neem oil. Could not use those in cool weather either. Your most likely talking about the same product as I have still seen it is sold at some places. As a side note it is toxic too pets.

I tried cedar oil as a JB repellant per info from Paul Zimmerman's site. Small amount of oil did not repel, increased oil amount until it started burning rose foliage & still did not repel JB's so my experience is that it doesn't do anything for JB control. The only thing that I have found to repel & have a residual control of JB's is a pesticide called Demand CS, which won't meet your organic control criteria.

Demand CS drastic ingredient is λ-cyhalothrin which is 'just' another WIDE range pyrethroid insecticide.

I am not necessarily opposed to using a pesticide during JB season. I just favor an organic solution when there is one available that is at least moderately effective.

Like I said, I switched to a "chemical" fungicide over organics because I found it completely effective, while I found more organic solutions to damage my roses and to have been useless against a blight of rust that broke out one year and defoliated my rose garden.

Over the years I have found that "organic" gardening methods (and by organic I mean non-chemical) really do do better over the long term in regards to soil health and structure and subsequent plant health.

But so far I have yet to find the same to be true in terms of fungus and JB control. I was hoping this year would change my mind on this and that cedar oil would be a silver bullet for me. But if the experience of it is anything like Neem oil, I will pass.

See: http://jee.oxfordjournals.org/content/96/1/81

The following recent Ph.D. thesis may provide interesting reading about using oils.

https://etd.ohiolink.edu/!etd.send_file?accession=osu1343666756&disposition=inline

I have the general idea that spraying is useless against beetles of any sort,for two reasons: 1) they are hard-bodied, relatively speaking BIG insects. Any poison that would be in any way truly effective against them would have to be extremely strong; i.e., strong enough to cause harm to animals and humans. At first I tried spraying, but got the impression that all I was doing was giving the frigging beetles an augmented resistance. 2) They can and do fly. Even if you did spray this "strong insecticide" (and it would have to be very very strong, since beetles are not soft and squishy and easily permeated on contact, as are aphids - at bottom,harmless critters; why are aphids seen as such pests, I wonder?- and caterpillars and their ilk) , other beetles will soon fly in and replace the dead ones. Beetles do nothing other than eat and...ahem, "reproduce". I seem to be having success with an IPM approach with the Oxythyrea funesta beetles that are native to my area.. I put out pherormone traps, to figure out exactly from whence they were flying in,and also to mass-trap them. This is only do-able perhaps if you have a very large piece of land, but I wonder if the golf-course people would object to you hanging out some traps on their land???That would also help "pull " the beetles out of your garden. You would of course have to be vigilant about monitoring and emptying the traps...) By now I've sort of mapped out the flyways of the Oxys (I HOPE) and am working on putting up barriers ;: planting fast-growing trees and vines that will eventually "block " the flyway,supported for the present by netting. In the garden itself I dig and dig, destroying grubs ,and try to hand-pick them off as much as possible. Good luck; beetles are a sticky, icky problem!

Talk to the golf course. A severe JB infestation is also bad for them because the grubs eat grass roots. There is the possibility that their tolerance is greater than yours because it is spread out over a larger area, but it is also possible that they are already applying milky spore.

Do you have bird houses dispersed around your garden?

https://www.google.com/webhp?hl=en&authuser=0&gws_rd=ssl#newwindow=1&hl=en&authuser=0&q=%22japanese+beetle%22+bird

I agree with most comments. I was ecstatic to find that cedar oil would repel the Japanese beetles. When I sprayed my roses woke up the next day song that roses were burnt to a crisp. Huge the cedar oil it was one year roses along with other beautiful plants to my dads. I'm desperate and still inserts and how to repel those annoying Japanese beetles

henry- thanks for the link. Great article.

Sharon

Ha, the solution to my original posted problem -- get rid of the golf course!

This year they are re-designing it, and the architects have come in and stripped away anywhere from a few inches to a few feet of earth. They have also (alas) gotten rid of a large number of very old, pretty ornamental trees. (Miss them already).

However, I've had maybe a dozen JB's this year compared to hundreds in summers past!