Most rose diseases are caused by attacks on your plants by different kinds of fungi. The good news is that no matter what type of fungi is damaging your roses, the treatment options are virtually the same.
To start, there are several things to do to prevent your roses from attracting fungus. One way to avoid attracting fungi is to water the soil, not the actual pant. Fungi will be attracted to any moisture on leaves, blooms and stems. Check on a regular basis for exposed canes because fungi can find its way into the plants this way.
Try to keep the plant clean and remove any plant litter, particularly any fallen leaves and petals that gather at the base. Any canes, leaves or blooms that are suspect should be removed right away. You should always throw these away or burn them. You should not use suspect plant litter in your compost pile – in all likelihood this will only add to your problems.
How to Spot Rose Fungus
There are different ways to spot fungi. The fungus Diplocarpon rosae causes the fungal disease known as Black spot. Aptly named, this disease starts with small black spots surrounded by a yellow halo on the leaves and can eventually case a complete defoliation if you do nothing to treat it. This fungus spread through splashing water and infection can occur if the leaves are wet for a few hours.
Powdery Mildew is another kind of fungus that attacks rose plants. Young leaves can curl and die and young canes may not grow as fully as they should. You can spot Powdery Mildew from the white coating on buds, stems and leaves. This mildew spreads rapidly during humid weather.
The fungus Botrytis Blight affects the flower buds. Buds can decay and even die. The fungus is grayish-black in color and the lesion will develop below the bloom’s head. You need to cut off and remove any decaying or dead blossoms to prevent the spread of the fungus.
Rust – which looks just like the rust that develops on your car – can first appear on the underside of leaves. If not treated, orange and brown spots can also develop on the top surface of leaves.
The Brown Canker fungus can attack any portion of the plant that is above the ground. In a worst case scenario, brown canker can kill an entire stem. If you spot red or purple spots on the new canes or gray-white lesions on more mature stems then you might be dealing with Brown Canker.
If you discover that your roses are already infected with fungi you should try to remove any infected leaves, blooms and canes. You could spray with a fungicide.
You can purchase this at your garden center or make up your own homemade version. A mixture of water, baking soda and dishwashing liquid is very effective in curing fungus problems.
Most fungus spreads through splashing water so it is important that you are vigilant in removing decayed leaves and infected canes and blooms. Not removing these makes it very easy for the fungus to spread from part of the plant to another or even from one plant to another one.
It is also important that you plant your roses in an area with good drainage and air circulation. Shady spots will only encourage moisture and fungus attacks.
Fungicide should really be your last option. Roses do not take to pesticides well, so it is important to try other options first. Remove plant litter, prune properly and ensure the drainage is good before resorting to a chemical cure. In extreme cases, though, fungicide use may be necessary.
If fungus is a concern, then you should try to plant disease-resistant species of roses. Though there is no guarantee, with the proper care you should be able to avoid most major fungi infections.
Some locations are more prone to fungus than others, so if you live in a damp, humid climate you will need to be alert about fungus issue and you should take the time to research disease-resistant varieties.
To prevent major fungus issues, you need to be observant. Dealing with fungus problems as soon as you spot them will make all the difference.
Top Photo by Ryan Durham