Types of Diseases

• The rose is the most popular garden plant. Its many varieties from delicate hybrid tea roses to hearty shrub roses give gardeners a good selection to choose from according to their desires and the area they live in. Unfortunately, the beautiful rose is also susceptible to a number of diseases such as Black Spot, Powdery Mildew, Downy Mildew, Stem Canker, Rust, and Botrytis Blight as well as many other diseases. A fungus called Diplocarpon Rosae causes Black Spot. It occurs after a long, wet spring where weather conditions are warm. A fungus called Sphaerotheca pannosa causes Powdery Mildew. It occurs when the humidity is high at night but low during the day. Peronospora sparsa fungus causes Downy Mildew when the humidity is over 85 percent and the temperature is less than 80 degrees F. Cankers are a variety of different fungi that enter plants injured by winterkill or by Black Spot. Phragmidium fungi cause Rose Rust. It occurs when plants are crowded and do not get enough air circulation. Botrytis Blight is a gray mold fungus that occurs when conditions are cool and moist.
  
  

How to Protect Roses

• Sanitation methods, disease resistant plants, fungicides, and cultivation techniques are all important elements when fighting rose disease. Black Spot is one of the most common diseases that you can control by choosing roses that are resistant to the disease. Keep the area clear of dried leaves and debris, prune any infected areas of the plant, and plant your roses in full sun. Like Black Spot, Powdery Mildew is common. It causes a grayish film on the plants. Keep the area clear of debris and prune away any infected areas. If Black Spot or Powdery Mildew are severe, consider a fungicide spray. Downy Mildew causes reddish black colored spots on leaves. The leaves will drop quickly; whereas, with Black Spot, they will drop slowly. You need to spray fungicides to the underneath of the leaves as well as the top. Prune the rose bush back severely. To avoid Stem Canker take care of any winterkill or damaged plants, and avoid fungi such as Black Spot or Powdery Mildew. To avoid Rose Rust, don't crowd the plants and allow plenty of air circulation. Keep the area clean of debris. The same prevention is true for Botrytis Blight. Keep the area clear of debris and trim off any damaged leaves or stems.
  
  

Disease Resistant Roses

• Some roses that are resistant to Black Spot are the grandiflora rose called Prima Donna, the floribunda rose called Sexy Rexy, and the hybrid tea rose called Pride N Joy. The shrub roses called All That Jazz and Carefree Wonder are moderately resistant to Black Spot and Powdery Mildew. Because each part of the country has different weather conditions, always consult your garden center for the best roses to grow in your area.