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Re: [SHADEGARDENS] Horticultural oil

Thanks Janet for the note about horticultural oil. It sounds like great
stuff and its just the sort of thing I'm looking for.
        To add to the thread, copper and oils can have a synergistic effect
when used with sulfur that causes the sulfur to be more potent against
plant pathogens. This can also increase the likelihood of the sulfur
burning plant tissue. So don't apply sulphur within a month of an oil
spray. Confusing because most of us use lime sulphur and oil as a
dormant oil. Key word here is "dormant".
        My book (olkowski, W."Common Sence Pest Control")says that "the new
superior oils can be sprayed as a 2% solution against insects and mites
on plants in full leaf if environmental conditions are right". "Right
conditions" seem to be only that the plants are not water stressed.
Apparently, the superior oil can also be used with dormant evergreens,
including conifers, except for those such as blue spruces which lose
their bluish frost.
        So what is a good preventive spray (preferably organic) for evergreen
non dormant plants. I have some oregon grape (mahonia nervosa;
aquifolia) and salal (gaultheria shallon) which have some kind of
leafspot problem - red circles that turn dark.

Barb

Janet Schulz wrote:
>
> Hi all,
> Just a quick note on horticultural oil. The new oils have been refined to the
> point that they are now called growing season oil or just horticultural oil
> instead of dorment oil.
> I apply this oil on all newly leafed out plants in spring to protect the
> plants from powdery mildew and black spot. The oil is highly refined and
> allows the plant to breathe while putting a protective coating to stop the
> pathogen that starts powderymildew. I do this twice in a season , once just
> after the leaves emerge on most plants and later toward mid summer. I spray
> this on my lilacs as well as my perennial bed and it keeps mildew off
> phlox,lilac and even monarda . I do not use this on my evergreens but I use
> the oil to kill any scale that may be on my euonymus.
> This works for me so you all might give it a try as long as the temp. is under
> 80 degrees.
> Happy Gardening from Janet, 20 mi. west of NYC in zone 6

--
Barbara and Richard Porter, Streamside Native Plants,
3300 Fraser Road, RR#6, Site 695, C 6,
Courtenay, B.C., Canada  V9N 8H9
Tel/FAX: 250-338-7509
http://mars.ark.com/~barport/streamside.htm
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