Symptoms and Control Methods of Rose Little Leaf Disease
Symptoms Rose little leaf disease is a common physiological disease of roses in northern China. Little leaf disease occurs on young shoots and young leaves, and is more obvious when roses sprout in spring. Diseased branches sprout later, and after the leaves emerge, the leaves are narrow, small and slender, with leaf margins turning upward, hard and brittle texture, and a relatively pale yellow-green leaf color, with uneven color intensity...
Symptoms
Rose little leaf disease is a common physiological disease of roses in northern China. Little leaf disease occurs on young shoots and young leaves, and is more obvious when roses sprout in spring. Diseased branches sprout later, and after the leaves emerge, the leaves are narrow, small and slender, with leaf margins turning upward, hard and brittle texture, and a relatively pale yellow-green leaf color, with uneven color intensity. The tips of new shoots are slender, the internodes of branches are short, and the small leaves cluster in a rosette shape, and the diseased branches grow weakly. This disease mostly affects the entire plant.
Occurrence Pattern
Rose little leaf disease is a physiological disease caused by zinc deficiency, and zinc is an essential element for the synthesis of auxin. When zinc is deficient, free and bound auxin are significantly reduced, causing growth to stall. When the soil contains very little zinc or other trace elements are imbalanced, zinc deficiency is likely to occur. When the zinc content in leaves is lower than 10 to 15 ppm, zinc deficiency symptoms appear.
Control Methods
① According to the local soil fertility, appropriately increase the application of organic fertilizer and trace elements to improve the soil. This is the foundation for controlling rose little leaf disease.
② In combination with applying base fertilizer in spring and autumn, mix in zinc sulfate for control. In rose gardens where zinc deficiency is induced by magnesium deficiency or copper deficiency, compound fertilizer containing magnesium and copper should also be applied at the same time to achieve obvious control results.
③ In early spring, when rose buds begin to swell, spray the branches with 0.3 to 0.5% zinc sulfate, once or twice a year is sufficient; before flowering, spray 300 mg/kg zinc naphthenate, and after flowering spray 0.2% zinc sulfate plus 0.3% urea or 300 mg/kg zinc naphthenate or 300 times amino acid zinc solution, which has an obvious effect on reducing the disease.