Analysis of several common diseases and insect pests of Chinese rose with the approach of midsummer early detection and early treatment

Flower friends who like to cultivate rose flowers all know that rose flowers are famous medicine jars in the flower family, especially in the muggy summer environment, all kinds of diseases and insect pests will be infected accidentally in the process of breeding, once they are disturbed by diseases and insect pests, they should be sprayed in time to prevent the spread of the disease.

1. Powdery mildew. It is one of the fungal diseases most easily infected by rose. Easy to infect rose for the first time in the middle and late May of each year, and gradually spread with the increase of temperature in June and July. The main manifestation is that there is a layer of white powder on the leaf surface and tender shoots, which is a typical feature of powdery mildew. It can cause the leaves to curl and scorch, and when the infection is serious, the young shoots die, the leaves turn yellow and fall off, which seriously affects the plant growth and flowering. The main cause of powdery mildew is that the growing environment of Chinese rose is warm, dry or humid, the branches and leaves of the plant are too dense, and the disease is serious when the ventilation and light transmission is poor. Long-term application of too much nitrogen fertilizer, lack of calcium or potassium fertilizer in the soil is easy to cause powdery mildew.

Control methods: put the plant in a better light and ventilation position, timely pruning and shaping, thinning too dense branches and overlapping branches to increase the permeability of the plant. At the same time, spraying 1000 times of methyl topiramate or Guoguang triadimefon has a good control effect. Note when spraying: it is generally recommended that 8: 10 a.m. and 4: 7 p.m., when there is no wind in sunny days, the spraying effect is the best.

two。 Black spot. Black spot of rose is a worldwide disease, which is common in China. The main damage was leaf, followed by petiole, leaf tip, young shoot and pedicel. At the beginning of the disease, there are purple-brown to brown dots on the leaves, and then spread into round spots, which are often surrounded by yellow halos. The leaves around the disease were yellowed in a large area, and in severe cases, all the lower and middle leaves of the plant fell off, leaving only a few new leaves at the top.

Black spot of rose is a fungal disease, which is serious in rainy season. Black spots can be spread with the help of Rain Water or sprinkler water splash, and insects can also spread. In the rainy season, the disease can be easily induced by damaged roots and weak growth of newly transplanted plants. The outbreak period of the disease is from July to September. Prevention and cure method: remove the diseased leaves in time, avoid the basin soil too wet at ordinary times, choose sunny morning as far as possible when watering, and avoid spraying. Can also cooperate with drug prevention and treatment: spray diazepam or Bordeaux solution every 7 days for three times, which has obvious prevention and control effect.

3. Red spider. It is one of the most easily infected insect pests of Chinese rose. The results are as follows: starting from the lower leaves, adult or young mites concentrate on the back of the leaves, suck juice, form gray-white spots on the leaves, and then the leaves are yellow and weak, as if dried by fire, so that the leaves can not carry out normal photosynthesis. when the harm is serious, it can cause early defoliation.

Red spiders often occur in May to October when the weather is dry and the temperature is high. It is a common pest of the rose that gives flower friends a headache. If red spiders are found, the leaves with gray spots can be removed and burned in combination with pruning at the early stage, and the plant leaves can be washed, and it can also be controlled with medicament: 1000 times of Fenitol EC can be used, or 73% of acarate EC is 2000 times. Aika mite, dacarine, etc., it is recommended that the two drugs should be used alternately, spraying once every 7 days, and spraying 3 times successively to achieve better results.

4. Aphids. It is one of the most harmful pests in the world, green or gray. It is usually distributed in the tender shoots and buds of rose flowers. To do harm by sucking plant branch sap. It not only hinders the normal growth of rose, but also causes the deformity of rose flowers, leaves and buds.

If a small number of aphids are found, they can be caught manually or sprayed with imidacloprid once a week, usually 2 or 3 times.

In addition to the above diseases, yellow leaf disease and rust are also common diseases of rose. Yellow leaf disease is usually due to excessive watering, soil partial alkali caused by yellow leaves, you can choose loose and breathable slightly acidic soil, appropriately reduce the number of watering, and wait for the soil to dry and re-irrigate. Rust is also a disease easily infected by rose, characterized by brown spots on the branches and leaves, and then the whole leaves turn yellow. The main cause of the disease is that the culture environment of rose is dark and humid, and the ventilation is not good. When rust is found, the diseased leaves should be removed in time and can be prevented by spraying fungicides such as chlorothalonil or methyl topiramate solution.