Re: fungi

**"Mary C. Weaver" mcweaver@bellsouth.net>**

Linda wrote:

>I hate to be disagreeable but here in south Texas rainfall has nothing
>to do with getting black spot on the roses here.  We had no rain for 104
>days straight from mid June to September.  Many days the humidity would
>knock you down, I still had black spot.

You're not disagreeable. I take no offense--I'm merely passing along 
what plant pathologist Ken Horst of Cornell U writes in his 
"Compendium of Rose Diseases."

>
>I get mildew on some of my roses, much less of a problem actually than
>Black Spot.  The mildew comes when the days are warm and the nights
>cool.

Both mildew and blackspot are encouraged (and discouraged) by 
specific temperatures. In other words, specific environmental 
conditions must be present for the spores to germinate.

>Once summer gets here and our nights are in the 80-90's, the mildew
>disappears.  I learned to 'bathe' my roses when I water them, hitting
>them with a hard jet to knock off the bad leaves.  This has been the
>best solution I have found and had much less problems after I started
>bathing than I did before.

Were you watering this way during the dry summer you mentioned? That 
would be enough to germinate blackspot spores, rainfall or no 
rainfall. All it takes is water--but it has to be water in liquid 
form (e.g., rain, dew, water from a hose), not water vapor.

>
>
>I think a lot has to do with the disease resistance of the plants to
>begin with since some of mine planted in deep shade under a tree or on
>the west side of something don't get fungi no matter what happens.

Absolutely. Some classes and individuals are just plain extremely 
disease-resistant. I bring up the health concerns because every rose, 
even the disease magnets, will be *more* disease-resistant if in 
robust health.

>Actually I think the under planting has
>helped the roses by keeping the fungi spores from being blown around as
>much and the leaves compost faster.

Right. The spores are in the soil as well as fallen leaves, so 
anything (mulch, companion plants, etc.) that prevents wet soil from 
splashing up onto foliage will help the roses.

>
>>  I recently wrote an article for hgtv.com on a dozen easy-care roses.
>>  If people are interested, I'll post the link when the article goes up.
>
>Yes, please do!

Will do. I think it's scheduled to go up February 14.

>
>This year will be the year of the shovel!!  I need roses who can take
>the extremes of weather and fend for themselves.  Unfortunately it's to
>hot here for Rugosa's, all I have tried have croaked in the heat.  The
>China's do very well here thank goodness.

Chinas are great. I live in Zone 6 and wish I could grow more of them.

Have you read Liz Druitt's book The Organic Rose Garden (Taylor 
Publishing, 1996)? She's a Texan too and recommends a whole slew of 
desirable, tough roses. Another good book--now out of print but 
perhaps available at your library--is Landscaping With Antique Roses 
(Taunton Press, 1992) by Liz Druitt and G. Michael Shoup. Mike Shoup 
has a new book out, and although I haven't read it, I'll bet it's 
good: Roses in the Southern Garden (Antique Rose Emporium, 2000).

As you probably know, the Antique Rose Emporium is Shoup's nursery in 
Brenham, Texas. His rose catalogs are fabulous.

All the best,
Mary W.

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Mary C. Weaver
Author, Roses: A Growing Guide for Easy, Colorful Gardens (Macmillan, 1998)
mcweaver@bellsouth.net or maryweaver@mac.com

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