DOWNEY MILDEW

[rosy]

The last few years I've had losses, most certainly to "Downey Mildew".....
(not powdery mildew) with red blotches on the canes, and general malaise of
the plant...... spraying with Daconil....... it appears to spread.

Is there anything I can do besides start over? I have over 100 roses.

[Cass]

In article >, rosy > wrote:

> The last few years I've had losses, most certainly to "Downey Mildew".....
> (not powdery mildew) with red blotches on the canes, and general malaise of
> the plant...... spraying with Daconil....... it appears to spread.
>
> Is there anything I can do besides start over? I have over 100 roses.

Don't have any sure experience with DM, but there is information
available several good websites. I do know that you should make
absolutely sure you are dealing with downy mildew because the cane
symptoms can look a lot like botrytis and canker. And the cost of the
fungicide is out of this world.

http://www.rosecare.com/diseases.html

http://hortipm.tamu.edu/publications/Pathup1.html

http://www.primaryproducts.com/files/specials.htm

http://www.ces.ncsu.edu/depts/pp/notes/Ornamental/odin002/rosebbs.htm

[Daniel Hanna]

In > rosy wrote:
>
> Is there anything I can do besides start over? I have over 100 roses.

I haven't had downy mildew as such, but the remedy I've tried this
season (which definitely works on all other fungi) is a milk spray. 1
part milk, 6 parts water.

Apparently it's supposed to work because one of the proteins or fats in
the milk smothers existing spores and stops new ones from settling.
However it works, the results have been spectacular for me.

[Julia]

rosy wrote:
> The last few years I've had losses, most certainly to "Downey Mildew".....
> (not powdery mildew) with red blotches on the canes, and general malaise of
> the plant...... spraying with Daconil....... it appears to spread.
>
> Is there anything I can do besides start over? I have over 100 roses.


Been there. Done that. The only fungicide that will touch downy (no
'e') mildew is Aliette. You're wasting your time and money using
anything else. When temps climb to over 80, the disease will go
dormant. It's really a pretty vicious ailment and I know that some
growers spray bare-roots for it before shipping. But Cass is right when
she says you should confirm it's downy before you cough up $140 for more
chemicals, because it very much resembles other scourges.

http://rosemania.com/shopsite_sc/store/html/page5.html

[Cass]

rosy > wrote:

> T;hanks for your reply.....the photos are pretty good on Baldo's site
> http://members.tripod.com/buggyrose/ipm/83downymildew.html
>
> but lacking in the one dead giveaway (IMHO) the bright red blotches on one
> healthy cane, later turning purple, then black---the blotches growing
> finally together. Then spreading to other healthy canes. I wish I'd
> destroyed the first one when I discovered it, instead of trying to treat
> it.... Once you've seen the blotches on the canes, I don't think you'd
> mistake it for anything else......the markings on the leaves can be easily
> mistaken for blackspot--only difference is dark purple edges.
> The costs of those fungicides is incredible. Wish I knew where I got
> it....but it looks like it is airborne anyway.

The reason I mention botrytis is that here in Marin County, botrytis is
everywhere and it's airborne. I know it's everywhere because all the
pavement roses in boulevard strips have massive cases, all up and down
Highway 101. One slightly eccentric rose nurseryman swears that when
he sprayed his greenhouse for botrytis, the stuff everyone thought was
downy mildew disappeared too. Just food for thought. It's a no-win
situation when DM is difficult to diagnose because the spores aren't
easily detected.

I have a bourbon that probably has downy mildew, complete with
inexplicable sudden twig death and maroon blothes on new leaves. I'm
about to destroy it. But it hasn't spread. I grow mostly disease
resistant roses, so that may be why. Do you grow a bunch of fragile
roses?

> "Cass" > wrote in message
> > rosy > wrote:
> >
> > > The last few years I've had losses, most certainly to "Downey
> > > Mildew"..... (not powdery mildew) with red blotches on the
> > > canes, and general malaise of the plant...... spraying with
> > > Daconil....... it appears to spread.
> > >
> > > Is there anything I can do besides start over? I have over 100
> > > roses.
> >
> > Don't have any sure experience with DM, but there is information
> > available several good websites. I do know that you should make
> > absolutely sure you are dealing with downy mildew because the cane
> > symptoms can look a lot like botrytis and canker. And the cost of the
> > fungicide is out of this world.
> >
> > http://www.rosecare.com/diseases.html
> >
> > http://hortipm.tamu.edu/publications/Pathup1.html
> >
> > http://www.primaryproducts.com/files/specials.htm
> >
> > http://www.ces.ncsu.edu/depts/pp/notes/Ornamental/odin002/rosebbs.htm
>
>