How to Treat Rose Diseases? A Detailed Guide to Practical Prevention and Control Methods
Roses have a very long cultivation history, and the myths and legends of various countries all contain stories about roses. In China, because its stems and branches bear thorns, the rose is regarded as a symbol of assassins and knights-errant. In the West, however, the rose is regarded as a symbol of keeping secrets. In addition, roses of different colors also have their own meanings or languages of love. So when growing roses, which diseases deserve attention? And how are they treated?
I. Prevention and control of rose diseases
Common rose diseases include powdery mildew, downy mildew, branch blight, black spot, and rust. When disease occurs, the specific disease should be determined according to its symptoms. In general, spraying with Aolike-Liangguoan plus Wofengsu plus garlic oil can be used, but specific conditions still require specific analysis.
Rose powdery mildew mostly occurs from late autumn to early spring, and is prone to occur when the temperature difference between day and night is large and humidity is high. It usually infects young leaves, but other old leaves, flower stems, and even branches are also commonly infected. When infected, the leaves appear raised, the raised areas become lighter in color and covered with a white powdery substance, and the leaves become uneven and gradually curl. As the pathogen spreads, the entire underside of the leaf is covered with a layer of grayish-white mold. The control method is to spray regularly, using 600 times diluted myclobutanil solution or 800 times diluted chlorothalonil and other agents for control, spraying once every 7-10d. In addition, promptly prune away diseased branches and leaves to reduce the chance of further spread.
Downy mildew mainly harms leaves, new shoots, stems, flower stalks, and petals. Symptoms show that it first infects the growing points, the leaves turn purple to brown-black, and infected leaves initially show irregular small spots, then gradually wither or fall off, and diseased shoots dry up. Flowers, flower stalks, and petals develop similar spots when infected. When humidity is high, a grayish-white mold layer readily appears on all diseased parts. The control method is to spray 72% Kelu or similar promptly at the first onset of disease. In addition, when planting roses, it is best to choose disease-resistant varieties.
In the early stage of branch blight, small red or purple spots appear on the leaves, which later gradually expand into lesions and extend to the stems, with a grayish-brown center and reddish-brown edges. In severe cases, it can cause the plant to die. For treatment, the diseased branches need to be cut from the plant, and 600 times diluted carbendazim wettable powder or Tuijunling Te wettable powder should be sprayed.
Black spot is the most common disease in rose cultivation, and it is most severe during periods of high temperature and high humidity. It occurs on leaves, petioles, and stems. When the plant is infected, black round lesions appear on the leaves, especially on mature leaves close to the ground. Diseased leaves gradually yellow and fall off. When the disease is severe, most of the leaves on the whole plant fall off, photosynthesis cannot be carried out, and growth is poor. After discovery, spray with Aolike-Liangguoan plus Wofengsu plus garlic oil.
Rose rust is one of the important diseases of roses and occurs commonly. This disease causes early leaf fall, weakens growth vigor, affects ornamental effect, and reduces fresh flower yield. The main symptoms are yellow lesions appearing on the upper surfaces of new buds, stems, and petioles, or chlorosis appearing on the upper side of leaves, orange-red blister-like protrusions forming on the upper side of leaves, and orange-red appearing on the underside of leaves, soon becoming dark brown-red, and finally turning into small black powdery masses. The main treatment method is to spray 20% triadimefon emulsifiable concentrate 1500 times solution, or 40% DuPont Xinxing emulsifiable concentrate 9000 times solution, or 2% 120 antimycin 100-200 times solution, etc., at the early stage of disease. About once every 10 days.
The above are the main diseases of roses. When caring for roses, pay attention to observation, promptly determine the disease, and take targeted measures for treatment.