Rose Twig Dieback Disease: Symptoms, Hazards, and Control Measures
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Rose Twig Dieback Disease: Symptoms, Hazards, and Control Measures
Distribution and Hazards of Rose Twig Dieback Disease: Also known as rose common stem canker or shoot dieback, rose twig dieback disease is widespread in rose cultivation areas around the world, causing significant damage and losses. Besides roses, it also harms flowers in the genus Rosa, such as roses.
Symptoms of Rose Twig Dieback Disease: The disease mainly affects rose branches, including grafted and cuttings. Initially, the branches develop light yellow or light red spots, which later expand into irregular brown spots. In the later stage, the edges of the lesions bulge out from the surrounding tissue, the center becomes grayish-white and sunken, the epidermis cracks, and needle-like black dots appear on the ulcerated spots, which are the fruiting bodies of the pathogen. If the ulcerated spots encircle the stem, they cause the branches and leaves above the affected area to wither, severely impacting the plant's growth and flowering. The pathogen can sometimes also infect leaves affected by black spot disease.
Etiology of Rose Twig Dieback Disease: The pathogen is called Coniothyrium Fuckelii, also known as Diplocarpon Rosae, belonging to the Fungi imperfecti, Diaporthales family.
Incidence Pattern of Rose Twig Dieback Disease: The pathogen overwinters in the infected tissue of the stems and branches, with the sexual stage forming on the diseased branches in early spring of the following year. It is then spread as ascospores or conidia by wind, rain, and water splash to become the primary source of infection. It usually infects through dormant buds or wounds rather than through the intact epidermis. Throughout the growing season, the disease is mainly spread and caused by conidia, with secondary infections occurring. Since the disease primarily enters through wounds, the optimal temperature for conidial germination and growth is relatively high, between 28-30°C, hence the higher incidence in summer. Drought stress can exacerbate the disease, which is likely mainly due to the reduced resistance of the host under drought conditions.
Control Methods for Rose Twig Dieback Disease
1. Prune and burn the diseased and withered branches promptly. Branches damaged by typhoons should also be pruned, with the cuts as close to the axillary buds as possible, and some healthy branches should be cut along with them. Pruning on sunny days allows the wounds to dry and heal more easily. The cut surfaces can be涂抹red with a Bordeaux mixture of copper sulfate, lime, and water (1:1:15) for better results.
2. Protective sprays should be applied immediately after pruning. Fungicides such as 50% carbendazim 800-1000 times liquid, and a mixture of 0.2% zineb and 0.1% benomyl can be used.
Now that the detailed introduction to the symptoms, hazards, and control measures of rose twig dieback disease has been shared, do you understand it?