Black spot mainly harms leaves, shoots and pedicels. Lesions usually appear in front of leaves. At first, it was a small purple-black spot with inconspicuous edge, and then it gradually developed into a black or purple-black circular spot with a diameter of 1.3 ~ 1.5 mm, with a radial edge and yellow halo around it. In the later stage, the diseased spots can be connected together, and the diseased branches are easy to fall off. When shoots or flowers are killed, black stripes appear. The pathogen is a kind of pathogen, which harms rose, rose and other Rosaceae plants. Pathogens are spread by wind and rain as conidia of mycelium. When there is water on the leaves, spores can germinate and invade the leaves in about 6 hours, and the infection can be repeated many times. It can occur in the whole growth period, and it is serious in moderate temperature, high temperature and rainy days. The annual incidence peak appears in the rainy season and June 5438+065438+ 10.
Prevention and control methods: ① Cut off diseased branches and leaves in time, and burn them centrally to eliminate the source of the disease; ② 800 times of 20% thiophanate or 50% carbendazim can be sprayed during the growth period, once a week/kloc-0; ③ Or use 1: 1:200 times Bordeaux mixture, which has good control effect on the disease.
Powdery mildew is a common disease of roses. Powdery mildew spreads fastest in the environment with much rain, high humidity, little light and poor ventilation. Once infected, a layer of white powder will grow on the tender leaves, buds, shoots and branches of plants, which is the spore of pathogenic bacteria. Since then, the disease has gradually developed, making the young branches twisted. In severe cases, buds wither, flowers are few and small, and even plants die.
In Huangmei season, the autumn rain is continuous and the disease is serious, but the disease resistance of leaves is weak when there is too much nitrogen fertilizer, or powdery mildew is prone to occur in cloudy days.
Prevention and treatment methods: ① timely excision of the diseased part, centralized incineration to prevent diffusion; ② Spraying 500-fold solution of 0.3%-0.5% sulfur mixture or 500-fold solution of 50% thiophanate powder/kloc-0 every April-May or from late August to early September can control powdery mildew; (3) Washing the leaves of the injured plants with cotton balls dipped in alcohol for 2-3 times can make powdery mildew disappear.
Branch blight occurs on branches, starting with small spots of red and purple, and then gradually expanding into large spots. The center of the lesion is dark brown, and the edge is reddish-brown or purple-brown, slightly protruding upward. In the later stage, the lesion is dark brown and the surface is longitudinally cracked. This kind of crack is an important feature of rose branch blight, and the whole plant dies when it is serious.
Prevention and control methods: ① Cut off rotten branches, dead branches and rotten leaves in time and burn them centrally; ② 75% chlorothalonil powder can be sprayed with 600 ~ 700 times solution; ③ When the condition is serious, spray 50% bacitracin 800 times or carbendazim 800 ~ 1000 times.
Root cancer is a bacterial disease, which mainly occurs in the root neck of plants, and sometimes in lateral roots and branches. Tumors of different sizes appeared in the affected area, which were gray or slightly flesh-colored. At the beginning, the surface was smooth and soft, and finally brown, with rough and cracked surface and hard texture. The ground leaves of diseased plants turn green and yellow, and the leaves are small and fall off early, which slows down the growth and affects flowering. In severe cases, plants will die.
Prevention and treatment methods: ① root cancer patients are resolutely burned to prevent spread; ② For suspicious plants, soak them in 1% copper sulfate solution for 5 minutes before replanting; (3) When transplanted or put into a pot, if a diseased plant is found, the cancerous tumor is removed with a knife, and then coated with ice iodine solution (made up of 50 parts of methanol, 25 parts of glacial acetic acid and 12 parts of iodine tablets) for disinfection for 30 minutes. If you don't have this medicine, you can also apply it with lime milk (2 kg of quicklime to 500 ml of water) or Bordeaux liquid, and spray the soil around the diseased plant with sulfur powder for disinfection at a dose of 50 ~ 100 g per square meter.
insect pest
Aphids generally occur in spring and autumn when the weather gets warmer, and most of them cluster on tender branches and buds. They use needle-like mouthparts to pierce the pulp of stems and leaves and suck the juice. After the damaged parts of plants are damaged, they grow slowly, their leaves curl, their buds decline, their florescence is reduced and their ornamental value is lost.
Prevention and treatment methods: ① a few can be brushed off with a brush, and be careful when brushing to avoid damaging young leaves; ② If it is serious, spray it with dimethoate or dichlorvos emulsion 1500 ~ 2000 times.
Starscream usually occurs in dry and hot places with no ventilation, and it is the most harmful in summer and autumn. Cluster on the leaves, endlessly sucking juice, causing the leaves to turn from green to yellow until they fall off, causing the pre-bud to shrink, which seriously leads to the death of the whole rose.
Control methods: ① DDVP or dimethoate emulsion 1500 ~ 2000 times can be sprayed; (2) light a plate of mosquito-repellent incense, put it in a pot of rotten plants, and then tie it tightly with plastic film. Smoking for about an hour can kill eggs or adults, but it is harmless to potted plants.
There are many kinds of scale insects with strong reproductive ability. Groups gather on the branches, buds, leaf backs and flower stalks of plants and suck the juice of leaves endlessly. The damaged plants not only grow poorly, but also cause the leaves to turn yellow and fall off early, and even the whole plant dies in severe cases.
Control methods: ① Spraying 40% dimethoate emulsion 1300 times solution or 30% dichlorvos emulsion 2000 times solution; (2) Use 5 ~ 10g washing powder, dilute it with 5kg water and spray it 1 ~ 2 times (once a week 1 time) to kill it all; ③ Soak the cotton ball in 50 ml vinegar, and then gently wipe it on the leaves and other places with the cotton ball stained with vinegar to wipe off the scale insects and kill them. This method is simple and safe, which can not only control pests, but also make damaged plants green and shiny.
The thorn moth is commonly known as spicy fruit, including yellow thorn moth, green thorn moth, brown thorn moth, brown edge green thorn moth and so on. Larvae has stings and poisonous hairs, and it will feel itchy and painful when touching human skin. Larvae eat the roots, causing plants to wither and die. Adults eat tender buds, leaves and flowers with chewing mouthparts, and eat up the leaves and flowers in severe cases.
Control methods: ① artificial capture, cocoon removal in winter; ② During the pest period, 90% trichlorfon 1000 ~ 1500 times solution and dichlorvos emulsion 1000 ~ 1500 times solution can be sprayed.
Sawflies are also called yellow-bellied worms. It mainly harms Chinese rose, Chinese rose and Chinese rose. Larvae gather on the roses to devour the leaves, and in severe cases, they will eat up the leaves, leaving only the main veins and branches of the leaves, losing their ornamental value.
Adult sawflies are green, with wings longer than the abdomen, red abdomen and orange abdomen, so they are called yellow-bellied worms. There are 2 ~ 5 generations a year in the south and 2 ~ 3 generations in the north. The larvae overwinter in the soil as cocoons, pupate in April of the following year and hatch in May ~ June, which is the most harmful, spawning in February ~ August, and the peak of the second generation is from late August to165438+1October.
Prevention and control methods: ① Kill larvae by digging holes in winter, cut off damaged branches and burn them; (2) When preparing soil before planting, apply carbofuran 3-5 kg per mu for prevention and control; (3) In severe cases, spray 25% chlorpyrifos 1 0,500 times or 80% dimethoate emulsion 1 0,000 times. If you spray/kloc-0.000 times of 25% triazolam, the effect will be better.