Control methods of harmful symptoms of plant brown spot and the difference between plant brown spot and anthracnose

Brown spot is a fungal disease caused by Rhizoctonia solani, which is widely distributed all over the world, and can infect all turfgrasses, especially cold-season lawn grasses, causing lawn plant death, causing lawn to form a large area of bald spots, and greatly destroying the lawn landscape. let's take a look at what drugs are used to control brown spot.

Brown spot of lawn

[symptoms] when the disease begins on the lawn, near-round withered grass spots of different sizes often appear. When the conditions are suitable, the disease develops rapidly, and the diameter of subtilis spot can be extended from a few centimeters to one or two meters. As the diseased plant in the center of the disease spot can be recovered, as a result, the subtilis spot is mostly in the shape of "frog eye", that is, the center is green, and the edge is withered yellow band.

[prevention and control] it is necessary to apply little or no nitrogen fertilizer before or during the high temperature and humidity weather, maintain a certain amount of phosphorus and potassium fertilizer, avoid series irrigation and flood irrigation, especially in the evening. When there are withered spots on the lawn, spit (or dew) should be removed as early as possible in the morning to help alleviate the disease. Do not cut grass too low in summer (usually 5-6 cm), over-dense lawn should be properly punched, combed, withered grass and mowed residual grass should be removed in time, disease-resistant varieties should be planted, and timely and effective chemical control should be carried out.

Red and brown spot

[symptoms] the damaged leaves are small yellow-brown spots at first, and sometimes there are dozens of disease spots on one leaf. The small spot gradually enlarged into a disease spot with a diameter of 1 cm to 2 cm, with a light brown inside and a slightly angular and slightly different thickness of the concentric wheel spot. When the disease is serious, the diameter of the lesion can reach 2cm to 3cm. Grayish white woolly mildew occurred in the dark gray part of the transfer between the sick and healthy.

[prevention and treatment] thoroughly remove the diseased and residual bodies and reduce the source of primary infection. Do a good job in the management of temperature and humidity in the greenhouse, pay attention to ventilation and dehumidification, and improve ventilation and permeability.

Tulip brown spot

[symptoms] the infected leaf buds are malformed and curled, and the leaves that grow up after the tender buds are damaged become curly. If the environment is humid, a large number of gray mold conidia will be produced on the diseased tissue, which will affect the nearby healthy plants and make the leaves susceptible, so the growth of the bulb will be greatly affected. After the flowers are injured, white or light yellowish brown spots begin to appear, then expand rapidly and wither, or turn brown and dry. Banding also appears on the pedicel, and the conidium sometimes occurs above it.

[control] remove the diseased bulbs before planting, and carry out rotation planting. Once a bud or bud showing symptoms of the disease is found, it should be removed immediately to control the development of the disease. Before planting, soak the bulb in 2% formalin solution for 30 minutes, dry and plant, in order to reduce residual bacteria. During the growth period, 50% prohydantoin can be sprayed 1000 times or 50% promethrin 2000 times or 50% carbendazim 1000 times.

Sweet-scented osmanthus brown spot

[symptoms] occurred from April to October, and the disease was serious in rainy season and year, and the disease spread most rapidly from July to August. The disease of the old leaves is more serious than the tender leaves, and the plants with weak growth and transplanting in the same year are easy to suffer from the disease. Different varieties of sweet-scented osmanthus had different resistance to brown spot, and the disease resistance of osmanthus was stronger than that of Jingui and Yingui.

[prevention and treatment] when the seedlings came out of the nursery, remove the diseased leaves and spray 1000 times potassium permanganate solution for disinfection. The disease-free plant was selected as the breeding mother plant. Strengthen cultivation management, combined with crown shaping, cut off weak and diseased branches, adjust the density of branches and leaves, and enhance the tree potential. The whole tree is protected by spraying at the early stage of the growing season, such as 70% can kill 300 × 500 times, amiceta 1000 × 1500 times, or 50% carbendazim 500 times.

Brown spot of impatiens

[symptoms] Impatiens Brown spot, also known as Impatiens Leaf spot, occurs in the north and south of China. The disease mainly occurs in leaves. The foliar spot is a light yellowish brown spot at first, then expands into a circle or oval, and then the center becomes light brown, the edge is brown, with inconspicuous rims. On the seriously susceptible leaves, there are a series of disease spots, which causes the leaves to turn brown and yellow until the plant dies.

Impatiens prefers fertile sandy loam and is not resistant to waterlogging. Therefore, it is appropriate to plant sandy loam to facilitate drainage, potted impatiens, and should be poured out in time after rain. Diseased leaves and plants should be destroyed at the end of autumn to reduce the source of infection in the coming year. The initial stage of the disease with 25% carbendazim wettable powder 300 times 600 times liquid, or 50% methyl topiramate 1000 times solution, or 75% chlorothalonil 1000 times solution for prevention and treatment.

Morning glory brown spot

[symptoms] the disease spot on the leaf is scattered between the leaf veins and the leaf margin, nearly round to polygonal, 2mm in diameter, brown, or dark gray in the center, dark brown on the edge, light black mildew layer on the surface of the disease spot, in severe cases, the disease spot is covered with the whole leaf, and the leaf withered early.

[prevention and control] properly close planting, avoid excessive watering, spray 7500-fold solution of phytotin to promote early growth and rapid development of plants. Spray 75% chlorothalonil wettable powder 1000 times and 70% methyl thiobacillus wettable powder 1000 times, or more than 40%. Suspension emulsion 600 times liquid, 50% Sukeling wettable powder 2000 times liquid, once every 7-10 days, continuous prevention and treatment for 2 times.

Green chrysanthemum brown spot

[symptom] Chrysanthemum brown spot is a common leaf disease of green chrysanthemum. In severe cases, the leaves are withered and yellow, causing the whole plant to wither. At the initial stage, purple-brown spots of different sizes appear in the leaves, and then become black or dark brown. In the later stage, the center of the lesion turned light gray, reproducing small black spots. When there are more disease spots on the leaves, the whole leaves turn yellow and dry. It usually starts from the lower leaves and dies upward in sequence.

[prevention and control] choose areas with good drainage for planting. The planting density should be appropriate. Select disease-resistant varieties. Remove the diseased leaves immediately. At the end of autumn, the fallen leaves and disabled bodies were collected and destroyed. Spray 50% carbendazim wettable powder 1000 times solution, or 80% Dysen zinc wettable powder 500 times solution, or 1% Bordeaux solution, or 755 chlorothalonil 500 times solution. Spray once every 7 to 10 days.

Symptoms and control methods of perforation of cherry blossom brown spot in landscape plant

[pathogen] the pathogen of cherry blossom brown spot perforation overwintered in the diseased leaves or tips, and the spores were transmitted by wind and rain in the following year, invading from the stomata. It starts in June every year and is seriously ill from August to September. The disease is serious in the year with strong wind and rain, and it is easy to suffer from drought and weak trees in summer. Bacterial perforation overwinters in branch ulcers and diseased buds, and the temperature rises in the following year. Bacteria invade from stomata or lenticels with the help of wind, rain and insects.

[symptoms] harms the leaves of cherry blossoms, causing them to dry up and fall off, forming perforations. In addition to cherry blossoms, the disease also infects cherry, plum, peach, plum, apricot and other drupe ornamental plants. Perforation can be classified as perforation caused by fungi and bacteria. Fungal perforation such as cherry blossom brown spot perforation is mainly harmful to leaves, but also infects new shoots, mostly starting from the lower part of the crown and gradually expanding upward. In the early stage of the disease, there were needle-like purple-brown spots on the front of the leaves, and then expanded into round or nearly round spots with a diameter of 3-5 mm. The brown spots appeared on the edges of the brown spots, and gray-brown mildew spots appeared on the later spots. The edge of the spot produces a separation layer, and the lesion dries up and falls off, forming a perforation. On the other hand, the disease spot caused by bacteria begins to show a watery round spot, there is a yellowish halo around it, and there is no mildew spot in the disease. when it is wet, the spot overflows with yellow secretions, and when it is dry, the spot falls off and forms a perforation.

[prevention and control methods]

① collects and burns susceptible branches and leaves in autumn to reduce the source of infection.

② should strengthen the management measures, increase the application of organic fertilizer, phosphorus and potassium fertilizer, and prevent drought and stagnant water in time, so as to enhance the tree potential and improve the resistance.

Before and after ③ leaf spreading (especially for seedlings), 65% Dyson zinc 500x solution or Baume 3-5 degree stone sulfur mixture or 1 1100-200 times Baume 3-5 degree stone sulfur mixture were sprayed.

④ can spray zinc sulfate lime solution (500g of zinc sulfate, 2000 g of hydrated lime, 120kg of water) after leaf spreading.

Symptoms and control of brown spot of oleander

Oleander is a woody plant of Oleaceae, which is poisonous with leaves and flowers, and has the effect of cardiotonic diuresis, expectorant and insecticidal. It is distributed in most provinces and regions of the country. Brown spot is an important disease on oleander, which occurs widely and does serious harm.

Symptoms of brown spot mainly harm the leaves, at the beginning of the leaf tip or leaf edge appeared purplish red spots, after expansion to form round, semicircular to irregular brown spots. There are wheel marks on the disease spot. In the later stage, the center retreated to white, and the edge was wider in reddish brown. When the humidity is high, the grayish brown mildew layer can grow on both sides of the disease spot, that is, the conidiophores and conidia of the pathogen.

Pathogen Cercospora neriella Sacc. Cercospora of oleander is called Cercospora, which belongs to the subphylum of semiknowns. The constellation is dark brown, 25-125 μ m in size. Conidium peduncle light color, uneven thickness, gathered into bundles, with 0-3 septum, unbranched, tip with small spore scars, size 5-35 × 3-5 (μ m). Conidia cylindrical, with 1-5 septum, size 15-50 × 3-5 (μ m). In addition, C.nerii-indici Yaman called Cercospora oleander, which is also the pathogen of the disease.

The pathogen of brown spot overwintered with mycelia on the diseased leaves or on the soil surface with fallen leaves. Conidia are produced in the next spring and spread to oleander through wind and rain, and the germinated spores invade from stomata or wounds, causing the disease. It occurs from March to July, and the seedling growth is too dense or the disease is weak and serious.

Prevention and cure method

(1) Agricultural prevention and control

Reasonable close planting, not too close planting; scientific fertilizer and water management, cultivate strong seedlings; remove diseased leaves and burn centrally, reduce the source of bacteria.

(2) Pesticide control

At the initial stage of the disease, 50% carbendazim wettable powder was sprayed with 1000 times or 25% carbendazim wettable powder and 36% thiophanate methyl suspension.

The difference between plant brown spot and anthracnose

Withered leaf disease is caused by the yellowing of plants, from green to yellow, and external infection. Anthrax is from the inside out and looks like it's rotten. It is an acute infectious disease of herbivores caused by anthrax. Brown spot is a fungal disease mainly caused by Rhizoctonia solani. New high-fat membrane and tree protection generals can be used for prevention and control.