Special Therapy for Rose Powdery Mildew
Let's talk about the content of rose cultivation at home, the special therapy for rose powdery mildew. Next, the editor will introduce it.
Symptom Identification of Rose Powdery Mildew: The disease mainly affects the leaves, leaf stalks, young shoots, and flower buds of roses and roses. Initially, the disease causes white powdery spots on both sides of the young leaves, which then spread to cover the entire leaf, turning it into a light gray color, sometimes turning the leaf color to purplish red. It causes the new leaves to shrink and deform. On mature leaves, the disease first causes irregular powdery mold spots, and then the leaves turn brown from the tip or edge, causing the whole leaf to dry up and fall off. When the leaf stalks and young shoots are infected, the internodes shorten and the stem becomes thinner, some diseased shoots show reverse drying, and the surface of the diseased part is also covered with white powder. The flower buds infected with the disease shrink and die, and the sepals, petals, and peduncles become deformed. It loses its medicinal value.
Rose Powdery Mildew
Incidence Regularity: The pathogen overwinters as mycelium in diseased buds. In the following spring, when the diseased buds germinate, the pathogen infects the leaves and young shoots. Roses and roses are cultivated in the open air, greenhouses, and plastic greenhouses. The conidia can reproduce throughout the year and have strong cold resistance. Even at 0°C, they do not lose their vitality. Therefore, conidia are also an important primary infection source, capable of causing primary and secondary infections.
Ascospores generally do not play a role in infection. The optimal growth temperature for the fungus is 21°C, the highest is 33°C, and the lowest is 3-5°C. Conidia have a high germination rate at relative humidity of 97-99%, and a few can still germinate at 23% relative humidity. The germination rate is very low in water droplets. Under favorable conditions, it can complete its asexual cycle in 72 hours, and it takes 7-10 days in the field. Roses are more likely to get the disease in May and June and September and October in the open air, and it can occur all year round in greenhouses.
Planting too densely or applying excessive nitrogenous fertilizer, poor ventilation, or insufficient sunlight can easily cause the disease. The tender leaves of young plants, which contain beta-alanine, are favorable for the germination of spores and the onset of the disease. Red-flowered roses are not resistant to the disease, while thorny climbing roses are often more resistant.
Prevention and Control Measures:
(1) When pruning in winter, pay attention to cut off the diseased branches and buds, and remove the diseased leaves in time when found.
(2) Strengthen management, apply less nitrogen fertilizer during the onset of the disease, increase the application of phosphorus and potassium fertilizers to enhance disease resistance. Attention should be paid to ventilation and lighting, and排水 after rain to prevent moisture retention, which can reduce the incidence of the disease.
(3) Spray 70% methyl thiophanate-methyl wettable powder 800-1000 times liquid or 20% triadimefon emulsion 2000 times liquid, 25%敌力脱 emulsion 4000 times liquid, 40% Fuxing emulsion 8000-9000 times liquid, or 0.2°-0.3° Bordeaux mixture.
Some netizens have summarized that using the rust preventive liquid is very effective, while the powdery effect is not good!
The above is the detailed content of the special therapy for rose powdery mildew, hoping it can be helpful to you!