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Edwin
Rose plants infected by black dots

I had planted Hedge Rose and some Vine Rose plants. This year the leaves on all the plants were infected by black dots. I tried spraying the leaves Bayer Advanced All in One Rose & Flower Care and Ortho Flower Care Elementals with no success.

Can you advise what is the best treatment to permanently get rid of this disease?

dj1
Re: Rose plants infected by black dots

You probably have aphids. You can treat the roses chemically or introduce insects that will devour them. Search for the best answer on line.

ordjen
Re: Rose plants infected by black dots

Blackspot is a fungal disorder. You have to start spraying as soon as the condition is seen, and continue all summer long a about 2 week intervals.

One of my favorite spots here in Portland is the International Rose Test Garden. I once asked one of the workers how they keep the roses looking so healthy and spot free. Her answer was as above. They do not spray for insect diseases, prefering natural measures against them, but they spray every two weeks for fungus. Portland is a mild and moist climate most of the year, accept for the high summer months. Fungus loves this moist climate.

Start spraying at the first sign of fungus. It is not hard to control early on, but difficult when it has gotten established.

ed21
Re: Rose plants infected by black dots

In addition to the fungicide, it helps to clean up any dead leaves over the winter and replace any mulch so the spores don't get splashed back up on the plants. The removed mulch can be used elsewhaeer, just not near the roses. Spraying the mulch may help too. I've heard spraying horticultural oil on the plant in the spring before it leafs out may help act as a barrier to the fungus.
Look for rose varieties that are labeled as disease resistant. Knock Out roses tend not to get black spot where I am in Maryland

Cotopaxi
Re: Rose plants infected by black dots

Bonide Rose RX Systemic!
works like a charm

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