Roses with black spot disease

Monday, June 02, 2008

My rose bushes are exploding with their brilliant red blooms. Deep, satiny, sumptuous flowers they are. I enjoy going out in the mornings and taking a deep breath of their deliciously sweet scent. How lucky I am to have moved into a house with a row of established roses. They're a real treat. I only did a little bit of pruning earlier this year and -- bam! -- we have a flood of roses.

How easy it was, or so I thought.

When I went out a few days ago to get my daily fill of rosy goodness, I noticed that some of the leaves on the undersides of the plants had dark spots and were turning yellow. Those sickly looking leaves would fall from the plant at the slightest touch.

"Is my rose honeymoon over already?" I thought.

Black Spot Disease on Roses


A few clicks around the Internet would introduce me to something called Black Spot Disease, an apparently fairly common problem with roses. According to this source, it's a fungal disease that can take hold of roses in "warm, damp conditions, especially when leaves have been wet." During the month of May we had, oh, about 9 inches of rain -- ideal conditions for Black Spot. Left unchecked, the disease can weaken an entire rose plant.

With my once-effortless roses suddenly calling for attention, I cut back all of the infected leaves and canes and put all the debris in the trash. I read that one organic method for controlling the spread of Black Spot is to mix a teaspoon of baking soda with a quart of water and spray it on the plants in the morning. If things get worse, I might try that.

On another note, while I was trimming away the sickly leaves, I noticed only 2 bees buzzing along the entire row of roses. ONLY 2 BEES! Where are all the bees?! I know I am not the first gardener to question this. Many garden bloggers, in fact, have been commenting on the bee situation for a while now. But this is the first time I've really noticed so few bees in my own garden.

16 Comments:

Blogger Aunt Debbi/kurts mom said...

The bee situation around here last year was really scary. Hardly any to be seen. This year they seem to be back. Good luck in your area.

Debbi

8:39 PM  
Anonymous Mme. Meow said...

What lovely roses! Black spot is pretty annoying but you can also spray neem oil and it does a good job. (also takes care of those annoying aphids)

Best of luck with your roses and continue to enjoy them!

9:10 PM  
Blogger Stacy said...

If you have access to roses on Fortuniana rootstock they are naturally blackspot resistant.

8:56 AM  
Blogger lawremc said...

I'm replacing as I can some of my most problematic roses related to black spot as I can with Knockouts and others that are more resistant to the disease.

I have several old-fashioned varieties (developed in 1800s) that black spot will work on, but they grow so vigourously that they tend to outgrow the disease. Mutabilis is one.

Check out this link to a publication on on disease resistance in shrub roses from Auburn University. While it does talk about spray regimens with fungicides, it does include a list of roses that are more disease resistant naturally.

http://www.ag.auburn.edu/aaes/communications/bulletins/bull656.pdf

Bees are buzzing at my house and that's a good thing.

9:22 AM  
Blogger lawremc said...

This comment has been removed by the author.

9:23 AM  
Anonymous Anonymous said...

They're all in Pasedena, CA...
http://urbanhomestead.org/journal/2008/03/13/another-swarm/

10:34 AM  
Blogger rowena said...

Those are quite a ROW of roses! We've had wet/damp weather as well, but so far, so good. Also, I think because our roses sit in a corner that is the first to receive sunlight might have something to do with it.

I've never heard of the problem of the lack of bees. They seem to be enjoying the mediterranean weather here! ;-)

3:28 PM  
Anonymous Soilman said...

I know there's a problem in the States with sudden hive collapse syndrome. Mercifully hasn't spread to the UK - yet - but I expect it's just a matter of time. Bees are under serious threat from this and varroa mite; and the outlook is a bit worrying, given that we depend upon them for pollinating EVERYTHING we eat!
Blackspot is tricky to control organically, I'm afraid. Bordeaux mixture works, if you're OK with using it; it has organical approval in the UK, but perhaps not elsewhere.

4:06 PM  
Blogger i zimbra said...

There is a documentary being produced about the bee problem called Vanishing of the Bees: http://www.vanishingbees.com

10:32 AM  
Blogger Robin (Bumblebee) said...

What I have noticed about the bees this year is that there are a LOT fewer bumblebees (so far) and a LOT more carpenter bees. I would rather it be the other way around.

Robin at Bumblebee

5:50 PM  
Blogger notsocrafty.com said...

I found that neem oil if applied diligently works pretty well.

I like the new layout too by the way.

10:18 PM  
Blogger Ewa said...

lovely roses. using baking soda works well also against aphids. For black spot and aphids use only 1/4 of teaspoon for one liter and be metally prepared to see some youngest leaves to get brown. Use it twice in 2 weeks. using it more can make soils too much on alcalic side, which roses do not like, right?

3:50 PM  
Blogger Crafty Gardener said...

Your roses look lovely. Hope you can control that black spot.
The daylilies and roses are beginning to bloom at
The Gardener Side

4:39 PM  
Blogger Ed Bruske said...

Many roses are prone to various fungi. The hybrid varieties are especially vulnerable, much more so than the heirloom roses--that's our experience. I like the recommendation for mutabilis. It's a gorgeous, hardy plant.

11:17 AM  
Blogger The Nag said...

I love roses and have a lot of them but I battle constantly against blackspot. It's been so wet this year that I've finally started using a commercial fungicide.

12:29 PM  
Anonymous Anonymous said...

It will become too much of a chore. In the south here the resistant roses developed the disease but, do not die. Instead they defoliate and become nothing but a saw briar patch. It comes either wet or dry. When we had a drought last year we didn't even water the roses and they looked horrible and full of BS. After years of the battle we held up the white flag and pulled all the roses up and planted different color Rose of Sharon bushes. Nothing kills them.
I salute you in your battle though.

10:21 AM  

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