Rose bushes are commonly grown in both commercial nurseries and residential landscapes for their ornamental value. This popular plant, which displays showy flowers, is susceptible to a variety of diseases that can result in leaf wilt, including powdery mildew, rose leaf curl, and rose spring dwarf.
Powdery mildew is a fungal disease caused by Sphaerotheca pannosa. This fungus grows on the leaves of the rose bush and coats the leaves, buds and stems with thousands of spores that create a white coating. As this disease infects the bush, it can cause the leaves to turn purple, curl and eventually die completely. Buds that are infected with this mildew never open.
The best method of prevention is to apply a fungicide to the rose bush during the growing season. All fungicides should be applied according to manufacturer instruction. If leaves or branches are already showing signs of mildew, the infected areas should be pruned from the tree and disposed of. After each cut, the cutting tools should be sanitised to prevent the spread of the fungal spores.
Rose Leaf Curl
Rose leaf curl results in symptoms that closely resemble those of rose wilt or rose dieback and is most prevalent in antique roses. When this disease infects rose bushes, it results in the downward curling of the leaves of the plant. As the disease progresses, the leaves turn brittle and eventually die. In severe cases, the canes of the rose bushes can die back, stunting the growth of the plant. When purchasing plants from a nursery, ensure that the plant does not show any signs of rose leaf curl disease. The best method of prevention is to make sure that the rose bush is not propagated from an infected plant. There is not currently a treatment for this disease in rose bushes.
Rose Spring Dwarf
Rose spring dwarf is a disease that is common throughout both commercial nurseries and landscape rose bushes. Infected plants display leaves which have curled or twisted in a downward position. In severe cases, shoot tips can curl or twist and growth can be stunted or delayed. This disease causes severe damage to new growth, and symptoms become less noticeable as the shoots grow. The best method of control is to purchase nursery rose bushes that do not show any signs of infection. Infected plants in nurseries should be disposed of. Unfortunately, there is not currently a cure for this disease.