keskat
Full Member
Posts: 58
Joined: Sun Nov 28, 2010 5:50 am
Location: Pine Grove, CA

Newly Unhealthy Roses

I know nothing about roses. I think they smell bad and they tend to attack me when I get too close. :lol: But these little guys were healthy before the snow and now they are decidedly not. To my very untrained eye... It looks like powdery fungus and black spot. Am I right? And if so, how should I go about fixing it? The black spots are on both of the parent roses, and the powdery stuff on just one.

[img]https://i31.photobucket.com/albums/c378/santashh/Garden%20Mystery/rose01.jpg[/img]

[img]https://i31.photobucket.com/albums/c378/santashh/Garden%20Mystery/rose02.jpg[/img]

[img]https://i31.photobucket.com/albums/c378/santashh/Garden%20Mystery/rose03.jpg[/img]

The trouble is, I am in the process of... Doing a thing to make more rosebushes. :P I've got canes from the larger of my roses bent over, partially buried, and am attempting to root them. (I figured since they're there, I may as well try and multiply them). Is a fix going to require me to start the process all over again? Because if that's the case, I'd rather just dig them out and replace them with something I like.

Thanks for any and all advice. I'm out of my depth here.
Bloom where you're planted!

luis_pr
Greener Thumb
Posts: 815
Joined: Sun Jul 05, 2009 12:31 pm
Location: Hurst, TX USA Zone 7b/8a

Your diagnosis of powdery mildew and black spot agrees with mine, keskat. You can use fungicides but the first thing that I recommend is to determine what is causing all the problem. I suggest you apply good sanitation practices to minimize fungal problems.

Here are some things that you can do... water the shrubs early in the morning and try to water the soil around the base of the plant instead of watering the leaves. Keep the area under the shrubs clean of plant debris (leaves, etc). Do not grow the plants close to others in order to improve air flow. Discard plant debris in the trash, not in the compost pile. Do not overwater the plant as too much water may help these fungal infections grow. Replace the mulch of the infection is severe; consider transplanting to another place where the shrub gets more sun and air.

Never forget that you can always try to get rose varieties that are resistant to these diseases! This is a must in places where your weather is normally humid.

As far as what to do to treat the diseases, you can choose.

* Neem Oil,
* a mix of water and milk (10/20 milk; 80% water) or a mix of water and
* baking soda (1 tablespoon of baking soda + I gallon of water + 1/2 teaspoon of any liquid soap + 1 tablespoon of ultra-light horticultural oil)

All of the above can help with powdery mildew. Neem Oil comes in a sprayer bottle here but for the other two, you will need to get a sprayer at a plant nursery or Lowes/HD. Spray with milk once a week; dispose of the solution when done (do not save it). Spray with baking soda weekly to prevent a case of powdery mildew & spray every three days to get rid of a case of powdery mildew.

You can also use chemical fungicides that will treat these infections (read the labels and see if they can treat powdery mildew and black spot). Examples: Bayer Advanced Disease Control , Mancozeb, Banner Max, Daconil, Funginex (renamed to something else like OrthoPride maybe). Always spray very early in the morning or at night (less wind... less chance of burning the leaves). When using chemical solutions, it is a good idea to apply two types of different active ingredients so the fungus does not become resistant to the fungicides. Use fungicide "A" the first time; then use fungicide "B"; then use "A" again; and so forth.

Does that help you, keskat?
Luis

keskat
Full Member
Posts: 58
Joined: Sun Nov 28, 2010 5:50 am
Location: Pine Grove, CA

Oh, thanks! I had almost given up on a response on this one. :) These roses actually belong to my landlord, and they seem to have been taken care of - at one time. The whole yard has gone to seed the past few years, though, and since I moved in last fall, I've been trying to learn about and take care of the existing plants, as well as add my own.

It doesn't sound like the roses are a total loss, which is a relief - I'd hate to have to chop them down and dig up what I'm pretty sure is an extensive root system.

The methods you suggest don't seem like they would hinder the bent-n-buried canes from setting roots and growing, which was a concern for me. I'd already been peeling the black-spotted leaves off the canes (hopefully this was a good call) which seems to have worked for the black spot - no new black spots showing up, anyway. The powdery mildew had me stumped, though. Its been an unseasonably wet couple months, and I guess it just took its toll on the bushes.

Thanks so much for all the info! Its very helpful. :D
Bloom where you're planted!

luis_pr
Greener Thumb
Posts: 815
Joined: Sun Jul 05, 2009 12:31 pm
Location: Hurst, TX USA Zone 7b/8a

Periods of long humid weather can cause powdery mildew. In my case, I get a little because the house on one side has a pool and I have a small creek on the other end.

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