How to prevent and control common rose pests and diseases? A full analysis of the latest methods

Rose flowers are beautiful in appearance, endlessly varied in form, richly fragrant, and bloom in all four seasons. In particular, they have a great many varieties and are easy to propagate and cultivate. They are praised by people as the “Queen of Flowers” and are one of China's top ten famous flowers. However, rose pests and diseases often cause poor growth and even death, seriously affecting their ornamental value. Now let us take a look together at the prevention and control methods for common rose pests and diseases!

Rose powdery mildew

[Symptoms] On diseased leaves, chlorotic yellow spots first appear, then expand and become covered with white powder, with rolling, wrinkling, and thickening. After the petioles and tender shoots are infected, they become slightly swollen and bend backward. After flower buds are infected, the flower form becomes deformed. In severe cases, the leaves wither and yellow, and the plant becomes weak.

[Occurrence pattern] The pathogen overwinters on buds, leaves, and branches and spreads by wind. The optimal temperature for disease onset is 17-25°C, and May-June and September-October are the peak periods of onset. It is prone to occur when there is too much nitrogen fertilizer or too little potassium fertilizer in the soil.

[Prevention methods] 1. Select disease-resistant varieties. 2. Fertilize reasonably and avoid nitrogen fertilizer. 3. Remove and burn diseased leaves in early spring. 4. Prune moderately to keep the plant well ventilated and exposed to light. 5. Spray fungicides such as triadimefon and chlorothalonil before and after disease onset for control.

Rose black spot

[Symptoms] Rose leaves, pedicels, and tender branches can all be damaged. In the early stage, the lesions are seed-brown to brown small spots, then expand and become black or dark brown, often surrounded by a yellow halo. In severe cases, all the leaves on the middle and lower parts of the whole plant fall off, and branches die.

[Occurrence pattern] The pathogen overwinters in diseased branches, leaves, or fallen leaves and spreads by wind and rain. It is most severe after late summer. Under high temperature and drought, disease expansion is slow. Weak plants are prone to disease.

[Prevention and control methods] 1. Remove diseased leaves in time, and heavily prune diseased plants in winter. 2. Prune often during the growing season to maintain good ventilation. 3. Fungicides such as chlorothalonil, carbendazim, zineb, and thiophanate-methyl can be used for control.

Rose leaf blight

[Symptoms] It occurs on rose leaves. In the early stage, yellow-green needle-point spots appear on the leaf surface. Later, the lesions expand into round or irregular shapes with purple edges. After expansion, they merge into patches, and the boundary between diseased and healthy tissue is obvious. In the later stage, small black spots appear on the diseased parts, and the edges of diseased leaves look scorched.

[Occurrence pattern] The pathogen overwinters in diseased leaves or soil and spreads by wind and rain. Old leaves, weak branches, rainy seasons, and extensive management lead to severe disease.

[Prevention and control methods] 1. Remove and destroy diseased leaves in time. 2. Select disease-resistant varieties, plant at reasonable density, and strengthen maintenance. 3. Spray 3-degree lime sulfur mixture during the dormant season. 4. Spray fungicides such as chlorothalonil before disease onset for prevention. 5. Spray fungicides such as carbendazim in the early stage of disease for control.

Rose crown gall

[Symptoms] Tumors of varying sizes and shapes appear on the roots and stems of roses. The plant grows poorly, with short branches and leaves, yellowing and early falling leaves, and small flowers or no flowers.

[Occurrence pattern] The pathogen survives in the soil and spreads through water and tools. In the early stage, the galls are small, soft, and white; later they gradually enlarge, turn dark brown, have rough and cracked surfaces, and become hard and lignified.

[Prevention and control methods] For open-field planting, try as much as possible not to grow on the same land repeatedly, improve grafting standards, change grafting methods, reduce wounds, and avoid transmission.

Rose mosaic disease

[Symptoms] It mainly manifests as mosaic, with some showing ring spots or oak-leaf patterns, and some showing chlorotic spots, yellow veins, or stunting.

[Occurrence pattern] A viral disease. Diseased plants used as propagation material, sap contact, and piercing-sucking pests can all transmit it. Strong summer light and drought are conducive to symptom expression and spread.

[Prevention and control methods] 1. Avoid using diseased plants as propagation material. 2. If diseased plants are found, pull them out and destroy them in time. 3. Select disease-resistant varieties or tissue-cultured seedlings. 4. During the growing season, pay attention to controlling aphids and other transmission vectors. 5. Spray amino-oligosaccharin aqueous solution in the early stage of disease to inhibit virus spread.