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Old 02-06-2003, 08:08 PM
Radika Kesavan
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Default Blackspot on roses near tree

Henry wrote:
lms wrote:

R. foetida, full sun 24 hours a day;

Where are you that you get 24 hours of sun?

May be it is a perk from his employers, since he works at a
radioastronomy laboratory ;-).

USDA 9 / Sunset 15

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Old 03-06-2003, 04:08 AM
Scopata Fuori
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Default Blackspot on roses near tree

"Shiva" wrote in message
So that is what Messenger is for. I'll have to look into it.

Take a look at my pictures on the Imagestation site. The difference is
unmistakable. I am a skeptic, and it takes a whole lot of convincing, with
hard, reproducible facts, and unquestionably obvious results, to persuade me
of anything, especially something intangible.

See for yourself. Group 1, is the treated group of seven minis. The picture
of three from the top down, are the smallest three from each group.

The other photos, are of some of the others in my gardens. They were all
sprayed with Messenger once, and just the seven minis int he control group
didn't get it. I sprayed it again last weekend, but it rained yet again
unexpectedly, so I may have to reapply it. The relative absence of blackspot
is nothing short of a miracle, as much rain as I have had. I did get a round
of botrytis, but a spray of Banner Maxx took care of that, and they
rebounded beautifully.

I am still counting buds and basal breaks on the seven controls vs. seven
treated minis, to ensure this was not just a fluke. But they are so
obviously healthier that it doesn't take a close look to see the difference.

Scopata Fuori

"Bad cat!"

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Old 04-06-2003, 05:56 AM
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Default Blackspot on roses near tree

In article [email protected], lid says...

lms wrote:
In article ,


Note that the scientific name of most of the fungal diseases include the
word 'rosa' in some form. These diseases are specific to roses and are not
transmitted from non-rose plants or trees.

amen. an apple tree with blackspot is a scary thing to contemplate.

Apple black spot (a.k.a. Apple Scab) is the most important disease of
apples and is caused by the fungus Venturia inaequalis. It is a
different but similar fungus (Diplocarpon rosae) than the one that
causes black spot in roses. The conditions for spread and outbreaks of
the two types of black spot are similar, however so if you have both
apples and roses, a bad season for black spot on one will probably be a
bad season for the other, as well.

good info Henry but the fact is I've seen the willing roses defoliate quite
the number of times, though certainly not every year, but I've never had
any similar problems with apples. With apples, I either get 10,000 or I get
the big zero, plus or minus a few hundred, this year it's the latter.
I've never seen any of them do anything but blot out the sun entirely, I've
lost an Olds mobile out there.

In both cases, primary infection (when your plants get the disease) is
caused by mainly by ascospores. Ascospores are one of two types of
spores produced by the fungus during their life cycle. In the spring,
ascospores are released from infected leaves or canes, often those that
have fallen to the ground the previous season. For the spores to infect
healthy leaves, the leaves must be continually wet for several hours,
the relative humidity high, and the temperature around 68F to 75F. Here
is the east, that's a common enough situation and pretty much describes
standard spring weather. In New Mexico, I expect black spot is all but

That's one to remember and is fairly accurate, although there are two times
of the year it happens--one's an exception (El Nino[a]) and the other's the
rule (fall) maybe a little less than half the time. By this time it's way
too late to even worry about, the freezes come. A few years back with El
Nino, the monsoon started and never stopped. For a couple years after that
things were weird, I began to question what was normal. The last couple/three
have been dry dry, even Tropicana keeps its leaves.
One thing is for certain, even if you live in Saudi Arabia--Soleil d'Or, the
mother of all yellow Hybrid Teas, will blackspot in the fall.

Once infected, it's pretty much impossible to "cure" black spot so
preventing infection is your only real alternative (well, I suppose
living with it is another available option).

Most roses just get ugly when they blackspot--and face it, a hybrid tea rose's
mid-summer foliage in the best of cases usually ain't nothin to write home
about--but Soleil d'Or's behavior is a real study in how much roses really
care whether they spot or not. As soon as the leaves are gone--basically
all at once--it erupts in this spring-green color all over, just literally
busts out in new growth. hahahaha, then it freezes, bye bye.
Worrying about blackspot is strictly a human thing, I don't think it plays
much lead in the list of life cycle determinants. And if all the leaves are
gone, it's just 'damn roses' and ThankGod for buddleia and pecan crops and
naked ladies.

The susceptibility of
different roses varies quite a bit. There are also different races of
this pathogen and a rose that seems to be resistant in one region may be
damaged in another. Applications (often repeated) of fungicide will
certainly help. It's also important to get rid of infected tissue
(leaves and canes). Don't just throw them on the compost or you'll be
storing up spores for next year. It's actually best to burn them but of
course that's not allowed for many of us in the suburbs. A large supply
of last year's infected leaves can lead to infection even when the
conditions are less then ideal (from the fungus' perspective).

hey man, I've made an incoherent career outa pounding two-headed frog makers,
and it's all just ****ing in the wind, one way or the other. Might as well be
talking about abortion. I think all the sprayers live in Scarborough Country.

In any case I think all this should be 'don't ask, don't tell', but that would
never work, this is a rose group for godsake. Right after we learn the word
rose we learn the word spray and as long as there are high centered roses and
new austin introductions there will be people chained to this rut. Save the
spray for the hordes of locusts. And my avocados for godsake.

I burn dead canes cause I'm too lazy and don't want needle holes in all my
fingers after a few hours. But for me mulch is mulch, you definitely know I've
never worried about dormant little spores.



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