Which oil are you using? Dormant or a Superior?
What fungus are you trying to control?
Why do you need to spray 3 times a year to control that fungus?

Copper and horticultural oils cannot be sprayed on evergreen (broad leaf or needleleaf) plant together. That combination is ONLY for dormant season deciduous plants. Period.

I'd wait before you decide that the evergreens are dead. The foliage will be dead, of course, but perhaps new buds will come forth in the spring.

If you are going to spray the deciduous plants again, be sure to read and follow the directions for both chemicals carefully. Improper applications can be deadly for your plants. This is a very common combination, but don't take it for granted.

Did the "experts" at the Grange know what kinds of plants you were going to treat? If so, I'd pick a bone with them. Be sure to let them know what happened to the evergreens.

Kimmsr I used a dormant oil ,as for the fungus I don't know it's name and as for 3x/year that was the recommendation from Master Gardeners at the Grange.

Thanks Rhizo, I'll definately do some more research before spraying again and when I do it will ONLY be for the deciduous. Yes, the Grange knew what I was spraying and I will definately let them know.

I'm not dissing Master Gardeners, but they are not professionals, and their training programs can vary from extensive to not much more than a few weeks of very basic information. Mostly they are trained to steer you to professionally written advice published as university bulletins. Oil burnt plant material can recover.........or not. Rhizo is correct, and warnings are on the lablels of plants you should NOT use oils for.

I'm curious as to where you live in Oregon.

And please don't spray again until you tell us which plant has what sort of problem.

This post was edited by jean001a on Wed, Jan 22, 14 at 2:08

Danell, thanks for letting us know that Master Gardeners were the source of your very faulty information. Please be their educator so that others don't become victims of their lack of knowledge.

Thanks, I'll try to borrow a camera and post pics this weekend so you guys and gals can see what I'm dealing with - I do so appreciate the help.

I live in White City, Oregon.

in the mean time.. talk with your county extension office ...

OR is one of the horticultural hubs of the US ... and i find it hard to believe.. that it has such endemic problems ...

ken

Well WiFi here is glitchy so can't post pics of the Portugese Laurels but the ones I sprayed are dead - all leaves are brown and no green in the stem. The ones I did not spray have frost damage but thats all. The Arbuto is the same but there is some green in the stem about 5 inches up from ground. As for the Juniper, it looks okay although I expect it may not be as blue this year as a result.

The recommendation here is to spray with Copper Sep/Oct, Dec/Feb and again before bud break usually around March/April to avoid fungus during our rainy season. I combined "All Seasons Horticultural & Dormant Oil" with "Liqui-Cop." Nothing to do now but replace lost plants. (The label on oil states it can be used on evergreens and again Master Gardeners at the Grange recommended.)

The question I have for this forum is should I still spray the deciduous (Venus Dogwood, Birch, Heptacodium, Acer, Redbud) with this combination or just use the "Liqui-Cop"?

Oh, and Ken I've heard OR is a horticultural hub but does that hold true for Medford? It's my understanding we have more of a Mediterranian climate not true Oregonian.

I would wait until well into spring. Roots may still be okay.

For evergreen plants, use oil OR copper. Don't combine and don't apply one within several weeks of the other. The combination is safe for woody deciduous plants WHEN THEY ARE DORMANT only.

Yes, oils can be used on the evergreens safely as long as you stay within the temperature restrictions stated on the label. Always read and follow those directions carefully.

I've used horticultural oils for many years on a wide assortment of broad leaf and coniferous plants in the winter.

Does that make sense? The Master Gardeners (or their instructors) need some re-training.