Return to the Trees Forum | Post a Follow-Up

 o
Powdery mildew on lilac

Posted by kimcoco Zone 5, Wisconsin (My Page) on
Sun, Mar 14, 10 at 12:20

I know this is technically a shrub, but I thought I'd ask here anyway since it's tree size.

The lilac shrub is original to our home. It's planting location is not the best, right next to the house and windows, but I've trimmed it up to tree form to allow for better air circulation, and have been on a three year pruning schedule to remove all the older, crossing branches. It's on a west facing wall, full sun noon on.

Given the location, with windows in close proximity, an air conditioning unit within three feet, it's not the easiest to treat with any type sprayer that attaches to the garden hose. I was perusing my options yesterday, not sure what to get.

I have the 3 in 1 Bayer systemic for roses, but not sure if this would be adequate for a shrub this size (reaches my second floor airing porch).

What is the best product to treat powdery mildew on large shrubs like this, that won't harm the birds?


Follow-Up Postings:

 o
RE: Powdery mildew on lilac

Well, you might just consider doing nothing. Mildew on lilacs is unsightly, and some years can be pretty intense, and then other years it's not much of a problem - but it won't kill the shrub.

In other words, imo, this is a garden aesthetic problem, not a horticultural problem.

I suppose another option you might try is to use the "vibrant media" product that is embedded in your post - Arm and Hammer baking soda. There is apparently some indication from rose growers that it may be effective in controlling mildew. Certainly would be safe to use! Altho the inclusion of that very product as vibrant media in my post is by no means meant as an endorsement! LOL!

brian


 o
RE: Powdery mildew on lilac

  • Posted by bboy USDA 8 Sunset 5 WA (My Page) on
    Mon, Mar 15, 10 at 0:16

Susceptible type of plant + suitable environment for mildew = infestation. Remove the plant or change the site conditions and the infestation goes away.

For a PDF on results of testing baking soda for control of plant diseases...

Here is a link that might be useful: Will fungi fail and roses rejoice?


 o
RE: Powdery mildew on lilac

sounds like a monster ....

any chance at a picture????

my gut tells me to tell you to just get rid of it.. perhaps replace it with a mildew resistant lilac .. if there is such ....

sometimes it is just time to stop banging your head against the wall ....

bayer can be used on any sized plant [if labeled for said plant].. JUST READ THE DIRECTIONS .. or easier.. call the 800 number for specific info .... but it will not be cheap on such a large tree

Here is a link that might be useful: 800 number is right there


 o
RE: Powdery mildew on lilac

I'm with Brian on this - PM on lilacs is pretty much just a cosmetic issue. On an established shrub, it really doesn't do any serious harm. If you feel you must treat, you can try a dilute milk spray (or the baking soda approach) before the problem becomes noticeable. Both the lactic acid in the milk and the baking soda alter the surface pH of the foliage, making it inhospitable to the fungal spores. Repeat applications may be necessary, especially after heavy rainfalls.


 o
RE: Powdery mildew on lilac

  • Posted by bboy USDA 8 Sunset 5 WA (My Page) on
    Mon, Mar 15, 10 at 11:05

From PDF I linked to above:

There are a handful of articles testing the value of SBC
on ornamental plants other than roses in field situations.
Unfortunately, the results are not encouraging. SBC did not
reduce powdery mildew on lilacs, marigolds, or rosemary and
in the latter case caused severe foliar damage. Neither was it
effective in treating white rust in field-grown chrysanthemums.
Only when combined with horticultural oil was SBC useful
in treating powdery mildew in Euonymus. Baking soda itself is
not likely to control fungal disease in your garden or landscape,
but very easily could cause leaf damage if used at a higher
concentration. Low concentrations of SBC, combined with a
horticultural oil, may have some effectiveness on mild cases of
powdery mildew.
The most promising strategy Ive seen for controlling fungal
diseasesthe use of microbial antagonists in combination with
SBChas only been developed for post harvest disease control.
So far, there are no similar, published efforts for addressing foliar
diseases


 o
RE: Powdery mildew on lilac

For additional research on the use of bicarbonates to control powdery mildew......

On lilacs specifically: Journal of Aboriculture research

Note that a combination of sodium bicarbonate together with all-season horticultural oil effected almost 100% control.

Here is a link that might be useful: additional bicarbonate research


 o
RE: Powdery mildew on lilac

I can testify to the success of the baking soda + horticultural oil on roses and crapemyrtles. No lilacs where I'm from. I've also used plain horticultural oil.

You can also simply spray the lilac with plain water every day until the threat passes. I did that successfully for three years with a very susceptible crapemyrtle that came with the house I bought. As I recall (I've gotten rid of that tree by now), I only had to spray it for a couple of weeks when the leaves first came out.

Neem oil is also effective against PM.


 o
RE: Powdery mildew on lilac

A little late here, but PM on Syringa may decrease vigor sliiightly, but that is it. If the spouse doesn't like the white, then I would use Neem as rhizo sez, in a tank sprayer - works well for me when I see it here. Of course no surprise that I can't view the ISA doc on their server, and our sub doesn't go back that far, so can't lend my valuable 2 there... ;o)

Dan


 o
RE: Powdery mildew on lilac

I'm also with Brian on this one. Plenty of lilacs in the D.C. area with hot, humid summers. PM is pretty much ubiquitous as a result, but doesn't faze/harm lilacs. I believe Father Fiala (breeder/authority on lilacs who authored the monotype "Lilacs" on the genus) also said to disregard powdery mildew. If it really is unsightly to you, my own experience is that tree lilacs (S. reticulata) and some of the S. patula varieties do not seem to get PM although they don't smell like a S. vulgaris. Of the S. vulgaris varieties, President Poincare, Nadezhda, Krassavitsa Moskvy, Congo and Agincourt Beauty have done very well here (we have about 30 varieties in the yard) and seem more resistant to PM than common lilac and some of our other varieties.


 o
RE: Powdery mildew on lilac

  • Posted by bboy USDA 8 Sunset 5 WA (My Page) on
    Wed, Mar 17, 10 at 14:14

Again, when attempting reduction with hosing down be sure to do it so that it washes the plants instead of merely dampening them.

And do it in the morning, during a dry day. Causing them to remain damp for an extended period (all day or over night) could even encourage mildew growth.

The optimum with mildew-susceptible garden plants is probably consistently moist root zones combined with tops that are completely dry at all times.

Although some mildew spores travel with their own moisture droplet attached, so they can germinate on dry leaf surfaces.


 o Post a Follow-Up

Please Note: Only registered members are able to post messages to this forum.

    If you are a member, please log in.

    If you aren't yet a member, join now!


Return to the Trees Forum

Information about Posting

  • You must be logged in to post a message. Once you are logged in, a posting window will appear at the bottom of the messages. If you are not a member, please register for an account.
  • Posting is a two-step process. Once you have composed your message, you will be taken to the preview page. You will then have a chance to review your post, make changes and upload photos.
  • After posting your message, you may need to refresh the forum page in order to see it.
  • Before posting copyrighted material, please read about Copyright and Fair Use.
  • We have a strict no-advertising policy!
  • If you would like to practice posting or uploading photos, please visit our Test forum.
  • If you need assistance, please Contact Us and we will be happy to help.


Learn more about in-text links on this page here