conchobor99
Newly Registered
Posts: 3
Joined: Tue Jul 04, 2006 11:28 am

Yellow leaves, black spots

Help, my roses all seem to get black spot! The leaves start to discolor, turn yellow with black spots, then fall off. The new leaves appear and in a few days, the same. I have treated with sprays and granular fungicides. I cannot stop or hault the problem.
I live in Southern Indiana. It is HOT and HUMID! 90 degrees and upper 90's% humidity. If I need to post more info, tell me what I need to post and I will.
Thanks,
Chris

JPIXI
Senior Member
Posts: 213
Joined: Mon Jul 04, 2005 11:54 am
Location: France, Paris

Hello Chris,

Under such hot weather, it is very important to provide your roses with enough water, loosen the top soil the top soil, give them deep watering at least twice per week. It is useful to cover the top soil to protect the roses to be stressed by the heat and it can reduce the watering needed as well.

I do not know what spray you have used, but chemical content spray do stress the roses more than helping them. I wonder are you keen in using organic formulas or have access to stinking nettles? If you do so, take a look at the rose care forum for more details.

Your roses are certainly weaken by the heat and caught diseases due to the high humidity. It is good to cut all affected feuillages off (throw away or burn them). Spray with organic spray after sunset.

Hope it helps.

Cheers,
Pixi

Newt
Greener Thumb
Posts: 1868
Joined: Wed May 26, 2004 2:44 am
Location: Maryland zone 7

Hi Chris,

You don't say which roses you are growing, but many of the modern and hybrid teas are prone to fungal problems. Spraying the foilage with compost tea will help. Here's some home made fungicides you can make.
https://www.ghorganics.com/page15.html

Newt

garden_mom
Senior Member
Posts: 105
Joined: Tue Mar 14, 2006 12:12 am
Location: Detroit, MI

You can also spray your roses with skim milkwhen the leaves start to come, and every time after it rains. That, in combination with picking off the leaves when you see a spot coming helps stave it off. Also, at the end ot the season, clean up the ground around the roses and burn or throw away the debris (do not compost) including any mulch. Cut your roses back, start spraying in spring.

Newt
Greener Thumb
Posts: 1868
Joined: Wed May 26, 2004 2:44 am
Location: Maryland zone 7

Garden Mom, I know that milk works on powdery mildew. If the solution is too strong it can cause more fungal problems. Using whole milk works better too.

Newt

garden_mom
Senior Member
Posts: 105
Joined: Tue Mar 14, 2006 12:12 am
Location: Detroit, MI

Yes, but it does also help control blackspot. This year is the first that I've only had it on one of my roses and a light case at that. I use 1/2% milk, as that is what we drink. Taken from the second link you listed, "The research work in New Zealand actually found that using skim milk was just as effective". Just think what we could do for ourselves if we kept ourselves as organic as we keep our plants! :lol:

Newt
Greener Thumb
Posts: 1868
Joined: Wed May 26, 2004 2:44 am
Location: Maryland zone 7

Garden Mom,

I know the info about whole milk and skim milk is conflicting, so that's wonderful to hear! Thanks for sharing that with us. :)

Newt

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