The top 4 roses diseases

Despite the best efforts to keep plants disease free, there will inevitably be problem periods to deal with. If you keep an eye on your rose bushes you can remedy the situation before it gets out of hand. Be sure your identification of the problem is accurate before reaching for a spray and start with the least toxic solution.

The Top 4 Rose Diseases

1. 1.Black Spot: Black spot is a fungus that is very common during humid weather because it is a water disease. As its name implies, small black spots form on leaves and stems, eventually causing the leaves to drop and weakening the plant.


Treatment: To treat black spot you should prune off infected leaves. You should be very careful about clean up as well. Always water from the roots and water in the morning so the leaves have time to dry.If Black Spot is an annual problem, try a dormant spray of lime sulfur at the end of the season and again in early summer. Once Black Spot appears, it is hard to stop. Neem oil and Sprays containing Potassium bicarbonate are somewhat effective.

2.Downy Mildew: Downy mildew is a very serious disease that spreads rapidly and can defoliate a rose plant in days. It is not as common as Black Spot and favors cool, wet weather. Purple spots with yellow edges form ,at the veins on the top side of the leaves and along the stems. Gray fuzz can form on the under side of the leaves. The leaves will eventually fall.

Treatment: The good news is that Downy Mildew often clears up with the weather. To reduce the chance of Downy Mildew, practice good garden sanitation and keep the rose plants well pruned for air circulation. As with other diseases, a dormant spray may help.

3.Rust: A Rust infection is easy to spot. Small orange pustules spots form on the undersides of the leaves. This fungus can also cause defoliation. Rust is most prevalent when nights are cool.

Treatment: Treatment of Rust is similar to treatment of Black Spot, above: Good sanitation and a preventative dormant spray after pruning. Once infected, remove all infected leaves and try Neem oil for control.

4.Mosaic Virus: Once a rose is infected with Rose Mosaic Virus, there’s not much to be done except check with the nursery for a replacement. Rose Mosaic Virus shows up as yellow mottling on leaves and deformed new growth. It can stunt growth or it can be a mild infection. If there are only a few affected leaves, the plant may continue growing and blooming fine. The really good news is that it won’t spread to your other roses.