Newspaper article The Florida Times Union

Protect Roses from Leaf Spot Diseases

Newspaper article The Florida Times Union

Protect Roses from Leaf Spot Diseases

Article excerpt

Byline: Becky Wern

Can you tell me something about the leaf spot rose diseases?

There are two primary rose diseases, and both weaken the plants by defoliating them. Since plant leaves make all their food from the sun's light, fewer leaves mean less food for growing new leaves and flowers.

Black spot, the most common, starts as a small black spot on the leaves. It may have feathery borders. Cercospora has a black spot too, but it has a small purplish spot inside the spot. The purple area can change to tan or gray as the disease progresses.

Our summer weather is just about ideal for these fungi to thrive, so it's important to stack the deck in your favor.

The first step is to make sure you plant resistant rose varieties. Then, your goal is to keep water off the leaves. That means avoiding overhead irrigation which will not only wet the leaves, but will also splash the fungal spores from one place to another. Remove any leaves that fall, and prune the canes in winter.

When you have taken all these positive preemptive steps, plan to spray the new leaves with a fungicide to create a protective layer.

Chemicals such as Captan, copper sulfate, mancozeb and neem oil should be sprayed on the roses every two weeks.

Do not rely on one type of fungicide to treat the problem or you will find the fungi become resistant to the chemicals. Instead, rotate between Captan, copper and mancozeb to ensure your efforts are effective.

Getting on top of this is very important. The leaf canopy your plants carry through the summer determines the number and size of the blooms you have when temperatures slack off in the fall.

Spring and fall are peak times for rose bloom, and it would be frustrating to miss the fall bloom.

I don't understand why I can't buy St. Augustine seed. Is this some kind of a racket? …

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