Spring greenhouse cultivation of roses: beware of one disease and one pest

March and April are an important stage when roses in the greenhouse move from recovery into rapid growth, and also a period when various pests and diseases are relatively active. During this time, special attention should be paid to the prevention and control of downy mildew and red spider mites.

Downy mildew is a greenhouse disease, prone to occur after the roses leaf out, and occasionally seen in open fields, mainly because moisture in the tillage layer or potting soil in the greenhouse cannot evaporate effectively for a long time. During the onset of the disease, the leaves wilt and shrivel and are accompanied by white powder, the whole plant loses apical dominance, and then the leaves drop and growth stops. This disease is characterized by rapid onset and fast spread. Under normal circumstances, it can infect half or an entire greenhouse of roses within half a day or a few days, and the consequences are very serious.

To prevent this disease, ventilate as much as possible every day after the leaves emerge, and open the vents as wide as possible. On nights without strong wind and when the temperature is above 5°C, the vents do not need to be closed. If leaves are found to be wilting and accompanied by white powder, promptly use chlorothalonil powder diluted at 500 times and spray the entire greenhouse of roses, including other unaffected plants, cleanly, comprehensively and thoroughly. During the recovery period, watering should also be halved until new leaves grow.

Red spider mites harm almost all crops and occur in most areas of our country. They are prone to occur in closed greenhouse environments and open fields. Damage to roses by red spider mites is prone to occur in the greenhouse environment after leafing out and in open fields from mid-to-late April to late June. Dry air in the greenhouse very easily triggers a major outbreak of red spider mites. The early symptoms of damage are extremely dense and fine yellow spots on the leaf surface of the lower half of the plant, and red spider mites can be seen on the underside of the leaves piercing and sucking sap. In the later stage, the leaf surface, leaf underside and branches of the whole plant are covered with red spider mites and spin silk webs, and their population increases sharply, causing flowers to shrink, lose their vivid color, and the whole plant to wither and lose vitality. The degree of damage is very serious. This pest is mainly prevented, and prevention and control need to be combined.

1. During routine maintenance, pay attention to ventilation and cooling. In the greenhouse, whether ground-planted or potted, sufficient space should be kept between plants and between pots to facilitate ventilation.

2. Around the planting area, it is not advisable to pile up weeds, dry firewood and other miscellaneous items unrelated to roses.

3. Technical personnel should observe every day. Once signs of red spider mite damage are found, immediately use dicofol and other acaricides specifically for mite control to spray the affected plants and other unaffected roses comprehensively and thoroughly, and follow this method to spray once every 4 to 7 days. Production enterprises should strengthen preventive awareness, stop problems before they grow, and reduce losses to a minimum.

Spring greenhouse roses: beware of one disease and one pest

March and April are an important stage when roses in the greenhouse move from recovery into rapid growth, and also a period when various pests and diseases are relatively active. During this time, special attention should be paid to the prevention and control of downy mildew and red spider mites.

Downy mildew is a greenhouse disease, prone to occur after the roses leaf out, and occasionally seen in open fields, mainly because moisture in the tillage layer or potting soil in the greenhouse cannot evaporate effectively for a long time. During the onset of the disease, the leaves wilt and shrivel and are accompanied by white powder, the whole plant loses apical dominance, and then the leaves drop and growth stops. This disease is characterized by rapid onset and fast spread. Under normal circumstances, it can infect half or an entire greenhouse of roses within half a day or a few days, and the consequences are very serious.

To prevent this disease, ventilate as much as possible every day after the leaves emerge, and open the vents as wide as possible. On nights without strong wind and when the temperature is above 5°C, the vents do not need to be closed. If leaves are found to be wilting and accompanied by white powder, promptly use chlorothalonil powder diluted at 500 times and spray the entire greenhouse of roses, including other unaffected plants, cleanly, comprehensively and thoroughly. During the recovery period, watering should also be halved until new leaves grow.

Red spider mites harm almost all crops and occur in most areas of our country. They are prone to occur in closed greenhouse environments and open fields. Damage to roses by red spider mites is prone to occur in the greenhouse environment after leafing out and in open fields from mid-to-late April to late June. Dry air in the greenhouse very easily triggers a major outbreak of red spider mites. The early symptoms of damage are extremely dense and fine yellow spots on the leaf surface of the lower half of the plant, and red spider mites can be seen on the underside of the leaves piercing and sucking sap. In the later stage, the leaf surface, leaf underside and branches of the whole plant are covered with red spider mites and spin silk webs, and their population increases sharply, causing flowers to shrink, lose their vivid color, and the whole plant to wither and lose vitality. The degree of damage is very serious. This pest is mainly prevented, and prevention and control need to be combined.

1. During routine maintenance, pay attention to ventilation and cooling. In the greenhouse, whether ground-planted or potted, sufficient space should be kept between plants and between pots to facilitate ventilation.

2. Around the planting area, it is not advisable to pile up weeds, dry firewood and other miscellaneous items unrelated to roses.

3. Technical personnel should observe every day. Once signs of red spider mite damage are found, immediately use dicofol and other acaricides specifically for mite control to spray the affected plants and other unaffected roses comprehensively and thoroughly, and follow this method to spray once every 4 to 7 days. Production enterprises should strengthen preventive awareness, stop problems before they grow, and reduce losses to a minimum.