Even if they get through winter relatively unscathed, their weaker immune systems will be more open to the heat and humidity that the spring rains and summer heat bring. In this way, the roses might contact a fungal infection that destroys them, despite all of your best efforts.

There are a number of common diseases you might encounter with your roses:

Powdery Mildew

Powdery mildew is a fungus. As explained by its name, it produces a bright white powder along the tops and bottoms of the leaves and even along the stems. If you neglect to see to the mildew, the rose will not mature fully as the leaves will drop off.

Rust

Rust on roses looks just like rust on metal will. It appears on the underside of the leaves and quickly spreads to other parts of the plant as well.

Blackspot

Hybrid teas are completely resistant to blackspot, but other roses have been known to get it. If there are circular black spots on the leaves of the plant that are 1/16 to ½ inch in diameter, you might have the disease. Treat the disease right away to avoid destroying your plant's foliage.

Rose Mosaic

Unlike most of the rose diseases that are fungi, the Rose Mosaic disease is a virus. The signs of this disease have mosaic patterns of green and yellow that are discolored.

You can only stop the spread of disease completely by removing the plant. You must also clear all clippings and leaves of the diseased plant to make sure it doesn't contaminate other plants. If the disease cannot be contained by yourself, seek professional aid and get commercial solutions that can help.

How can you avoid giving your plants these diseases? There are a few things you can do. Always water the soil around the rose and not the rose itself. Do take care not to let dead leaves pile up underneath, so clear the beds of roses often. Snip off the stricken blooms and discard them immediately. Prune regularly. Close all cuts in the plant with Elmer's glue. Giving your rose nutrients often will make them stronger and less susceptible to diseases.

And you should know that you can opt to grow disease-resistant roses if possible to prevent the problems from arising. If you grown plants that are resistant to diseases and fungus, there is less threat of promoting threats to your plants.