any reason plain old baking soda is not better [and its probably cheaper than milk]

besides your plants smelling like rotting milk

every new thing is not better.. rote memory exercises are better than anything taught in grade school today

ken

50-50 milk (even skim milk) and water works to prevent powdery mildew but it won't cure it once you've got it. It works on my zinnias when I remember to use it in time. Here that's generally around mid July. Have not used it on roses. Hitting the plants with a spray of plain water also works (I know, counterintuitive) as long as the plants dry out quickly.

tj

the real key.. is avoiding it in the first place ...

i used to come home from work.. and after dinner.. spend hours wetting everything down.. an early evening shower ... it looked so shiny and pretty ....

then i found out that if a plant go into warm darkness .. wet... bingo bango ... they mildew... whats that all about.. lol ..

sooo never water at night.. insure all plants are dry before dark ... and space your plants for the most air movement as possible.. and i bet you can reduce PM significantly ... [no english cottage garden look here]

as to lilac.. thin out the interior.. and practice rejuvenation pruning so that it is lighter and airier ...

frankly ... i gave up worrying about it ... on lilac ... if it bothers you that much.. get rid of the lilac.. because you will never prevent it in toto..

realistically.. just consider the PM a glaucous coating on the leaf.. and come to appreciate it for what it is.. rather than wishing it were a dark green plant.. there.. the zen approach .. lol ...

it really has no impact on the plant itself.. other than aesthetics.. so your wish for an antiseptic plant.. is really the base issue ...

good luck

ken

ps: i mean really.. so you are going to start spraying this thing in late spring [just before the hot nights start].. as the temps rise .. and spray it every couple days [since milk or baking soda wont stick to the plant very long] .. and after every rain.. FOREVER!!!! .... whats the use ... accept it for what it is.. or get rid of it ... i opted for acceptance .... i've got other things to worry about ...

Some plant species are simply highly susceptible to certain problems....like your lilac and powdery mildew. I'm on board with ken on this and try to avoid bringing problem plants into my keeping from the very beginning.

Follow all of the important housekeeping practices that 'may' reduce PM pressure (you can find that list with a little bit of research). Then, it might be worth your while to begin spraying your lilac with plain water every day. Horticultural oil or Neem oil can work wonders at preventing PM, as long as you begin treatment early. Neem can prevent AND cure. I've used it for PM and black spot.

Can't say anything about the milk treatment, but I've read (in numerous places) it is effective. I believe you have to use whole milk though - no skim or 2%.

I did try the baking soda thing on cucumbers last summer and was impressed. For as long as I can remember, my cukes would always get mildew early in the season and be completely covered by mid to late summer. That happened year after year. Last summer I was diligent at spraying them with the soda every week before the mildew set in and continuing through the summer.

(Just for the record, last summer was one of the worst we've ever had as far as humidity goes)

Without a doubt, the cukes lasted weeks longer. Eventually they succumbed to mildew, but it took much, much longer than normal. I'll be doing it again this year.

Kevin

When I saw the claim about milk being an effective fungicide on roses I thought "This sounds like another of those goofy homemade remedies Howard Garrett (a.k.a. The Dirt Doctor) promotes." ("Vanquish Fire Ants with Apple Cider Vinegar!" "Rub Muenster Cheese on Pesky Woodchucks!"*).

And what do you know, it is.

"(In 1999), researchers in South America discovered a new alternative to controlling powdery mildew. Wagner Bettiol, a scientist from Brazil, found that weekly sprays of milk controlled powdery mildew in zucchini just as effectively as synthetic fungicides such as fenarimol or benomyl. Not only was milk found to be effective at controlling the disease, it also acted as a foliar fertilizer, boosting the plant's immune system."

Boosting the plant's immune system? Hmm...

What I'm not seeing is any large controlled study on roses and milk spray.

I suppose it wouldn't do any harm to try this in your garden as an experiment (unless it was overly attractive to neighborhood cats), spraying some typically hard-hit roses and leaving others untouched to see what happens.
I don't have this particular problem, but if I did I'd look first to getting rid of susceptible varieties and/or spacing them more widely for optimal air circulation.

*O.K., I made that last one up.

More good reading. Looks like it can prevent the spread of viruses too.

Kevin

Here is a link that might be useful: Milk

Some interesting take-home points from that article, including the following:

"Recently, milk has made an appearance as an antifungal agent, specifically in powdery mildew prevention...[Note that there have been no published scientific studies investigating roses or any other ornamental plant species.]...The results of (other) studies suggest that milk treatment under controlled (greenhouse) conditions is more successful than in the field."

They also point out that the fungi that colonize leaves coated with milk and break it down, can result in an undesirable appearance - and that some pathogens apparently are encouraged by milk, at least in certain species.

the problem with it all is.. both the baking soda and presumably the milk .. will leave a chalky looking residue.. that when you get down to it.. is the same or no better than the PM .. lol ...

the best remedy, as per above ... track down a resistant variety.. and be done with the problem one ...

ken

Baking soda doesn't leave any visible residue in my limited experience. If I remember correctly, the amount used is only 1 tsp per gallon of water.

Generally I don't take most of the home remedies seriously. Lord knows there are a billion of 'em out there. In this case (milk), it's nice to find some actual research data limited as it may be.

As far as disease resistant varieties go, I don't put much weight in those claims either. I would be interesting to learn how the developers of these supposed "disease resistant plants" can make these claims? Is there an industry standard for instance?

Kevin

I doubt that there is universally rigorous testing (over at least a few years, in various climates) in order for roses to be categorized as disease-resistant. What's most critical for me is whether they've stood the test of time, especially in my garden.

Rugosas, Griffith Buck hybrids and some of the modern shrub roses (i.e. "Home Run") are dependable for me, not suffering from any noticeable leaf diseases. Hybrid teas and other fussy varieties can apply elsewhere.

Re: rugosa roses: The more rugose the leaves, the more resistant to blackspot it is. There are many rugosa hybrids out there which are crossed with non-rugoasas with non-rugose leaves that are easily susceptible to blackspot.

The worst case I ever had of powdery mildew was on my "Schneekoppe" rugosas a few years ago. What a mess.

I'm to lazy to be spraying all this stuff. That's why I gave up on roses, save the rugosas, years ago - too much fussing and mussing required to keep them looking good. Plant a good rugosa and leave it alone, they're usually completely trouble-free, my kind of plant (what happened with the PM attack that year is beyond me, but only affected that grouping, none of the others, and hasn't shown up since - ?).

So I'm with Ken on this one. If it requires too much input to keep it looking good, plant something else.

I guess I was talking about plants in general that are listed as disease resistant. You see that a lot in veggies. Tomatoes come to mind. Cukes too.

How do they get the "official" stamp of approval as being resistant to whatever?

Kevin

Don't they splice in genes from plants that have natural immunity/resistance when they hybridize? Not sure how/where they get the "stamp", or if there even is such a thing, but new varieties of annuals and veggies have trial gardens, so is the designation of "resistant" a comparitive and not a definitive issue - ?. I'm guessing it is, since I've never seen a plant/seed variety designated as "immune".