Common Rose Diseases
Roses are fairly easy to grow if you have the right conditions for the right care of roses, but rose diseases always seem to come out every now and then. Indeed, members of the rose family, including roses, apple trees, strawberry bushes, and almond trees (You didn’t know they were members of the same family until now, did you?), are the most affected when it comes to plant diseases.
It helps for you to know the different kinds of fungal, bacterial, and viral diseases that infect rose plants so that you can deal with them properly. Here is a run-through of the most common diseases of roses, their symptoms, and how they can best be treated.
Black Spot.
In the southern regions of the United States, where the climate is warmer and the air is more humid, black spot is considered to be one of the most difficult “thorns in the flesh”. This disease is caused by the Diplocarpon rosae, a fungus that can cause all the leaves of the plant to fall and eventually kill the entire plant if left to its own devices.
It is easy to distinguish black spot from other diseases obviously because of the tiny black spots that grow on the upper sides of the leaves. These spots generally range from 1/16 to ½ inch in size and are usually surrounded by a yellowish ring that separate it from neighboring spots. Left untreated, the black spots will grow to combine with other black spots and consume the entire leaf, killing it in the process and letting it fall out.
Black spot can also infect the stems in more severe cases, producing reddish-purple spots that will also grow over the entire stem if left untreated. Black spots proliferate when the leaves are exposed to moisture for extended periods of time.
To treat roses with black spot, prune away all infected leaves and stems. The ground should also be cleared of everything infected with the diseases. A proper fungicide spray program should be followed religiously over the next few months to ensure that the fungus
Powdery Mildew.
Ever seen a white, fuzzy substance that’s been growing on your rose plants? They may have powdery mildew, a fungal infection caused by Sphaerotheca pannosa. Like all other rose diseases, powdery mildew is best treated early on by regularly spraying the leaves with a lime-sulfur combination to prevent fungi from taking over. If you live in an area where rain and fluctuations in temperature are frequent, fungicide application should be done more often. You should also cut away all the leaves, buds, and stems that are infected and avoid including them in your compost, as these will only come back to haunt next year’s growth. In worse cases, powdery mildew can even climb down to the canes and prevent young buds from opening up.
Rust.
As the name implies, rust on roses is characterized by orange-brown spots that first grow on the underside of the leaves followed by yellowish spots on the upper side. Over time, rust can also develop into narrow streaks on the stems. Rust is a contagious disease that can be transferred to neighboring rose plants via the wind. If not treated early, rust will cause the defoliation of the entire plant and will eventually kill your roses.
Much like black spot and powdery mildew, the best way to prevent rust is to prevent the leaves and stems from being sprayed with water. Though this cannot be totally avoided, especially in areas of heavy rainfall, rust can be prevented by using a fungicide spray of lime-sulfur and triforine. All infected areas should also be cut away to prevent the rust spores from infecting other leaves and other plants. You should also make sure that there are no dead leaves and stems carelessly left strewn across the ground.
Brown Canker.
Unlike the rose diseases mentioned above, there is no chemical solution to treat brown canker in roses. This disease occurs as an infection caused by the Cryptosporella umbrina, a fungus that manifests its symptoms in small steps, making it hard to notice the disease until it has taken over almost the entire plant.
Brown canker first appears as small gray-white lesions on the stems. Eventually, they move up the leaves in bigger white patches as a result of the small lesions combining then turn into large brown cankers that can climb down to the stems. The cankers appear elongated and sunken, and when left to stay they will consume the entire stem and kill it off.
The only way to treat brown canker is to prune away the infected stems and leaves before everything else gets infected.
In all the common rose diseases mentioned above, proper care or roses is required for you to successfully prevent microorganisms from growing and causing diseases in your plants. Remember the three requisites of growing healthy roses: sun, soil, and water. You should be able to provide these three elements in their proper amounts to keep happy and healthy rose plants all throughout the year.
