The Incidence and Control Measures of Rose Black Spot
July 22 11:20:06, 2025
Rose black spot is a widespread fungal disease that affects roses across the globe, particularly in regions where roses are cultivated. In recent years, this disease has become increasingly prevalent in various provinces across China, causing significant damage to rose crops. The occurrence of black spot can lead to premature leaf drop, which hinders the growth of the plant and reduces the survival rate of cuttings. This, in turn, lowers both the ornamental and economic value of the roses. Additionally, the disease can affect not only roses but also other species within the rose family.
Symptoms of black spot primarily appear on the leaves, although they can also occur on the petioles and stems. On the leaves, the lesions are usually round or nearly round, dark brown in color, and often have distinct radial edges. On the petioles and stems, the lesions tend to be elongated with less defined borders.
The disease typically begins in mid-May in Beijing, with severe outbreaks occurring during the rainy season in July and August. By October, the disease activity decreases, and it stops completely by early November. In southern China, the disease usually starts in April, intensifies during the rainy season from June to July, and gradually declines in August. It may reappear in September and October before ceasing in November. Wet and rainy conditions are highly favorable for the development and spread of the disease. Early and frequent rainfall can cause the disease to appear earlier, spread more quickly, and cause greater damage. Poor ventilation in greenhouses, high humidity, and dense planting of cuttings all contribute to an environment that favors the disease's progression.
To manage black spot effectively, several control methods can be applied. First, reducing the source of infection is crucial. In autumn, all fallen leaves should be removed, and infected shoots should be pruned during winter. During dormancy, a 1% copper sulfate solution can be sprayed to kill overwintering spores. Second, improving cultivation practices is essential. Planting resistant varieties instead of susceptible ones helps prevent the spread of the disease. Proper spacing between plants, avoiding overhead watering, and using root watering techniques can reduce the risk of spore dissemination. Greenhouses should maintain good ventilation and controlled humidity levels. These measures help improve plant health and resistance to disease.
Fungicides can also be used as part of an integrated approach. Spraying with 80% dexamethasone wettable powder at 500 times dilution, 70% thiophanate-methyl at 1000 times, or 50% carbendazim at 500–1000 times dilution can be effective. A diluted Bordeaux mixture (with caution due to rose sensitivity to lime) may also be used. Other options include benzene-based fungicides, captan, and mancozeb. These should be alternated to prevent resistance. Lastly, selecting disease-resistant varieties and rootstocks is a long-term strategy to reduce the impact of black spot in rose production.
Best Hydrogen Water Generator,Molecular Hydrogen Machine,Hydrogen Water Bottle Generator,Hydrogen Water Generator Bottle,Hydrogen Generator Water Bottle