Occurrence and control methods of main diseases and insect pests of sweet-scented osmanthus

Osmanthus fragrans, also known as osmanthus, is a precious aromatic plant native to our country. Xianning is located in the south of Hubei Province, known as the "hometown of osmanthus flowers" reputation, in recent years, osmanthus pests damage increased, resulting in a decline in ornamental value, common are: anthracnose, leaf spot disease, rot disease, Jiding insect, psyllid, whitefly, scale insect, thorn moth, leaf roller moth, Pteroi moth and ruler diameter, etc., combined with the control practice in recent years, the occurrence characteristics and control experience are described as follows.

(1)Hair rot disease: easy to occur in high temperature and humid environmental conditions, produce nearly round purple-brown spots on the leaves and stems, and have black dots on them. When the damage is serious, the dead leaves.

From June to July, spray 500-600 times of zinc to prevent; pay attention to ventilation and light transmission, reasonable watering and fertilization. Discovered diseased leaves shall be removed and destroyed in time, and 50% mefenamine 800-1000 times solution shall be sprayed for prevention and control. or thoroughly remove litter and weeds from fields in winter.

(2)Leaf spot disease: It is easy to occur under high temperature and humid environmental conditions. Irregular black spots occur on the leaves, and there are black molds on them, causing the leaves to fall early. From June to July, spray 140 times equivalent Bordeaux mixture for prevention, spray 70% topojin 800-1000 times solution after onset; water and fertilize reasonably; pay attention to ventilation and light transmission; remove litter and burn intensively to reduce contamination sources.

(3)Rot disease: mostly occurs in the root neck, the injured part is water-soaked, the disease spots gradually expand, causing plant growth weakness and even death. Summer rainy season occurs severely. Sprinkle a small amount of sulfur powder around the plants in early spring; apply thiram kerosene to seriously affected areas.

(4)Jiding insect: adults bite young leaves into a gap, but mainly larvae in the cortex of branches eat, damaged cortex has prominent cracks, outflow of oily brown colloid, serious damage, bark burst, main branches or whole plant dead.

Artificial killing: adult eclosion period, the use of its pseudo-death, in the early morning dew before the vibration of branches, landing after killing.

Brush stem: brush 20-30 times of dichlorvos emulsion, omethoate emulsion or monocrotophos emulsion on stem from adult emergence to larva damage stage, repeat 3-4 times (interval 7-10 days); mix 80% dichlorvos emulsion and 10-20 times of clay, add appropriate amount of water into paste, brush on damaged part of branch, so that adult will bite bark after emergence and die of poisoning when coming out of hole.

Adult control: 90% trichlorfon 1000 times solution can be used for tree crown spraying 2-3 times (about 7 days interval); poisoning larvae: scraping bark at the peak of larva hatching, coating 80% dichlorvos emulsion 20 times solution.

(5)Psyllid: adults and nymph suck bud, leaf and tender shoot juice, brown withered spots occur on the affected leaves, and the whole leaves turn brown in severe cases, causing early defoliation. The nymph secretes a large amount of honey on the leaves, inducing soot disease. At the peak of nymph development, spray 25% carbaryl WP 200-300 times or 50% monocrotophos 2000-3000 times.

(6)Whitefly: Adults and larvae swarm on the back of leaves to suck sap, causing yellowing, wilting, and even death. The insect secretes large amounts of excrement, which pollutes leaves and can cause soot disease. To catch the young larvae, 40% speed kill 1500 times solution or 2.5% dichlorothion 40ml or 40% iminothion 150ml per mu can be selected for spraying.

Occurrence and control of common diseases and insect pests in osmanthus fragrans

1. leaf spot disease. It mainly damages leaves, brown spots at the beginning, round or irregular spots, gray to gray in the center at the later stage, reddish-brown at the edge, black-gray mold on the spots. High temperature and humidity are often the inducement of the disease, which is transmitted by wind and rain and infected, and the disease subsides after October. Prevention and control: ① pruning in winter to remove diseased leaves and clearing diseased leaves, and burning them intensively;② spraying 1∶2∶100-200 Bordeaux mixture in early May, and spraying 50% benzolide 1000 - 1500 times solution or 500 times solution of azinamine or 70% thiophanate-methyl 1000 times solution later.

2. blight. The damage of leaves starts from leaf tip and leaf edge, small spots are light brown, then expand to round or irregular shape, the spots can be connected to each other up to 1/3 to 1/2 of the leaves, gray brown, green edge, and small black spots appear on the late spots. High temperature and humidity, poor ventilation, weak plant growth, the disease is more serious, usually from July to November, spread by wind and rain. Control: ① At the initial stage of disease, spray 65% zinc 500 times solution or 1∶2∶200 Bordeaux mixture;② After that, spray 50% carbendazim WP 800 to 1000 times solution or 50% benlaite WP 1000 to 1500 times solution.

3. Thorn moth. Green or yellow-green, dorsal line white, most likely to occur on the back of the leaf, feeding on mesophyll, leaving cortex. Before the larvae cocoon under the tree, loosen the soil around the trunk to lure the larvae to concentrate on cocooning, and then collect and destroy them. or spray Bt emulsion 500 - 800 times solution containing more than 10 billion spores/ml, or spray 2.5% cypermethrin emulsifiable solution or 20% fenvalerate emulsifiable solution 3000 times solution.

4. Scale insects. It can occur 2 to 3 generations in the Yangtze River Basin, and the serious damage is from May to June and August to September. It likes to gather on the shady surface of the main shoot and branches, or on the leaves of branches. Both adults and nymph secrete nectar, resulting in the occurrence of coal pollution disease of flowers and trees. High temperature and high humidity are conducive to occurrence, when a small amount occurs, it can be gently brushed with a soft brush, with good results. In summer, it is most beneficial to spray 0.3 to 0.5 Baume sulfur mixture, or 50% monocrotophos EC 1500 times solution, single use or mixed use, spray once every 7 to 10 days, continuous spray 2 to 3 times.

5. Starscream. High temperature and drought conditions often occur. Control methods: in dry weather should pay attention to irrigation and fertilization, promote plant health, enhance insect resistance. When applying chemical pesticides, pay attention to frequent rotation, because it will produce resistance after applying certain highly toxic pesticides. 40% Jusha EC 2000 - 3000 times or 40% dimethoate EC 1500 times can be sprayed with good control effect.

Occurrence and Control of Diseases and Pests of Osmanthus fragrans 1. leaf spot disease. It mainly damages leaves, brown spots at the beginning, round or irregular spots, gray to gray in the center at the later stage, reddish-brown at the edge, black-gray mold on the spots. High temperature and humidity are often the inducement of the disease, which is transmitted by wind and rain and infected, and the disease subsides after October. Prevention and control: ① pruning in winter to remove diseased leaves and clearing diseased leaves, and burning them intensively;② spraying 1∶2∶100-200 Bordeaux mixture in early May, and spraying 50% benzolide 1000 - 1500 times solution or 500 times solution of azinamine or 70% thiophanate-methyl 1000 times solution later.

2. blight. The damage of leaves starts from leaf tip and leaf edge, small spots are light brown, then expand to round or irregular shape, the spots can be connected to each other up to 1/3 to 1/2 of the leaves, gray brown, green edge, and small black spots appear on the late spots. High temperature and humidity, poor ventilation, weak plant growth, the disease is more serious, generally from July to November, spread by wind and rain. Control: ① At the initial stage of disease, spray 65% zinc 500 times solution or 1∶2∶200 Bordeaux mixture;② After that, spray 50% carbendazim WP 800 to 1000 times solution or 50% benlaite WP 1000 to 1500 times solution.

3. Thorn moth. Green or yellow-green, dorsal line white, most likely to occur on the back of the leaf, feeding on mesophyll, leaving cortex. Before the larvae cocoon under the tree, loosen the soil around the trunk to lure the larvae to concentrate on cocooning, and then collect and destroy them. or spray Bt emulsion 500 - 800 times solution containing more than 10 billion spores/ml, or spray 2.5% cypermethrin emulsifiable solution or 20% fenvalerate emulsifiable solution 3000 times solution.

4. Scale insects. It can occur 2 to 3 generations in the Yangtze River Basin, and the serious damage is from May to June and August to September. It likes to gather on the shady surface of the main shoot and branches, or on the leaves of branches. Both adults and nymph secrete nectar, resulting in the occurrence of coal pollution disease of flowers and trees. High temperature and high humidity are conducive to occurrence, when a small amount occurs, it can be gently brushed with a soft brush, with good results. In summer, it is most beneficial to spray 0.3 to 0.5 Baume sulfur mixture, or 50% monocrotophos EC 1500 times solution, single use or mixed use, spray once every 7 to 10 days, continuous spray 2 to 3 times.

5. Starscream. High temperature and drought conditions often occur. Control methods: in dry weather should pay attention to irrigation and fertilization, promote plant health, enhance insect resistance. When applying chemical pesticides, pay attention to frequent rotation, because it will produce resistance after applying certain highly toxic pesticides. 40% Jusha EC 2000 - 3000 times or 40% dimethoate EC 1500 times can be sprayed with good control effect.