Core Tip: Osmanthus fragrans has many advantages, such as strong adaptability, drought resistance and heat resistance, straight trunk, complete crown, thick leaves, dense flowers, rich colors, rich fragrance and different flowering periods. It integrates greening, beautification and fragrance, which can be described as "shape, color, rhyme and taste".
Osmanthus fragrans has strong adaptability, drought resistance and heat resistance, tall and straight trunk, complete crown, thick leaves and dense flowers, rich colors, strong fragrance and different flowering periods. It is a combination of greening, beautification and fragrance, which can be described as "excellent in shape, color, rhyme and taste", and people have endowed it with lofty, chaste, noble, friendly and auspicious meanings.
It is not only suitable for garden planting, flower bed solitary planting, community planting, road planting, landscape planting and potted plant display, but also can be used as a special flower-picking cultivation, which has extremely high ornamental and edible production and processing value and huge promotion and development space.
1987 was selected as one of the top ten traditional famous flowers in China. Among many traditional famous flowers in China, it is a wonderful flower with both ornamental and processing. It has become one of the key and large-scale economic tree species in China, and has formed the main planting areas centered on Yangshuo in Guilin, Guangxi, Manjuelong in Hangzhou, Zhejiang, Gui Hu in Xindu, Sichuan, Bai Dun in Xianning, Hubei and Guangfu in Suzhou, Jiangsu. By the end of 2005, nearly 20 cities in China, including Suzhou, Hangzhou, Xianning, Enshi, Laohekou, Hefei, Lu 'an, Maanshan, Hanzhong, Nanyang, Luzhou and Xindu, have designated Osmanthus fragrans as city flowers, and Guangxi Zhuang Autonomous Region has also designated Osmanthus fragrans as district flowers. At present, there are 154 osmanthus fragrans varieties in China, which belong to Jingui, Yin Gui, Dangui and Sijigui. Since 2003, the annual "China Hefei Osmanthus Exhibition" was held in Hefei Botanical Garden, Anhui Province, and the annual "Miss China Osmanthus" was selected, which greatly improved the popularity of Osmanthus fragrans.
Pests and diseases of osmanthus fragrans planted sporadically in natural environment rarely occur. However, in recent years, the pests and diseases of osmanthus fragrans have been fierce and rampant, which not only have a wide range of pests and diseases, but also cause heavy losses, such as brown spot disease of Jingui variety group, which almost makes the leaves of plants fall off; The widely distributed red spider (mainly tetranychus cinnabarinus) in China causes the leaves to turn green and yellow; It not only affects the appreciation of trees and the normal growth of plants, but also can not germinate and bloom normally in severe cases.
Investigate its reason:
First, the continuous warm winter in recent years has prevented a large number of overwintering bacteria and pests from freezing to death, laying a hidden danger for next year's outbreak;
Second, organochlorine and organophosphorus pesticides used to control leaf-eating pests over the years have certain control effects, but the control effects on many sucking pests are not ideal, especially after the natural enemies of pests are killed by extensive pesticides, mites, whiteflies, scale insects and so on will occur in a large area;
Third, in recent ten years, seedlings have been widely circulated, and it is difficult to completely quarantine pests and diseases, which has led to the rapid spread and cross-spread of some seedlings with pests and diseases;
Fourthly, large-scale single seedling raising and planting osmanthus forest have also highlighted the pests and diseases of osmanthus;
Fifth, the long-term use of single pesticides such as dichlorvos, dimethoate, carbendazim and chlorothalonil has caused strong drug resistance of pests and bacteria. According to preliminary statistics, there are more than 50 kinds of common pests and diseases in osmanthus fragrans, including more than 30 kinds of pests and more than 20 kinds of diseases.
This paper briefly introduces the occurrence characteristics, identification methods and control measures of common and serious pests and diseases in osmanthus cultivation.
1. Identification and control of main diseases of osmanthus fragrans
The diseases of Osmanthus fragrans mainly include coral anthracnose, fuso anthracnose, orchid anthracnose, Osmanthus fragrans anthracnose (Hefei, Chuzhou and Huangshan), Daphne odora sooty blotch in Phnom Penh, Gardenia sooty blotch, camellia algae spot (Hefei), Osmanthus fragrans leaf blight (Hefei, Chuzhou, Wuhu and Huangshan) and Osmanthus fragrans red spot (Hefei and Huangshan). Osmanthus fragrans polychaete gray leaf spot (Huangshan city), Osmanthus fragrans monospora brown spot, Osmanthus fragrans stem spot (Huangshan city), Osmanthus fragrans brown spot, Osmanthus fragrans Alternaria leaf spot (Huangshan city), sunburn, root-knot nematode disease, carcinomatosis, etc. Brown spot and leaf blight are the most serious and common diseases.
1. Leaf spot occurs on both sides of leaves. At the beginning of the disease, only a few scattered brown spots appeared on the leaves. In the late stage, the center of the leaf spot is grayish white to light brown, and its shape is approximately round or irregular. In severe cases, several spots are combined. The edge of the lesion is reddish brown to dark brown, with a light brown halo outside, and a large number of gray-black mildew spots are scattered on the front of the leaf, which are conidia and conidia of pathogenic bacteria; Leaf back disease is brown; Because the diseased spots gradually expand and converge into large areas, leaves often die and fall off in large numbers, which seriously affects the normal growth and flowering of plants.
The pathogen overwinters in mycelium on diseased plants and fallen leaves. In April-June of the following year, when the temperature rises, new conidia will be produced, which will be spread by airflow and rain, and then new conidia will be produced, which will infect the disease again. The disease can occur in April-10; In plants, the diseases of old leaves are more serious than those of young leaves. Jingui variety is the most susceptible, followed by Yin Gui variety, and Dangui variety is not easy to get sick. Plants with weak growth or transplanted in the same year are prone to disease; The disease is easy to occur when the soil is hard and sticky and the fertility is insufficient. In the hot and humid season from July to August, the disease can spread rapidly.
Prevention and control methods: strengthen water and fertilizer management, loosen soil frequently, avoid soil water accumulation, promote plant growth and improve plant disease resistance; Thorough removal of diseased leaves in winter and centralized incineration to reduce overwintering bacteria can obviously inhibit the occurrence of this disease in the coming year; In spring, before the leaves of osmanthus fragrans plants germinate and harden, spraying Bordeaux solution with 1: 2: 100 lime every half month can prevent the occurrence of this disease. At the early stage of onset, spray with 50% polysulfide suspension 800 solution, or spray with 50% carbendazim and 75% chlorothalonil wettable powder 500 solution, or spray with 50% zineb wettable powder 800 solution; It can also be sprayed with 5000 times of 25% propiconazole EC at intervals of 48 days. When the seedlings in the hardest hit areas leave the nursery, they can be disinfected by spraying 0. 1% potassium permanganate solution.
2. Leaf blight, also known as leaf spot, is an important disease of osmanthus fragrans. It mainly harms leaves. The disease often begins at the tip or edge of leaves with small yellow-green or light brown spots, and then gradually expands to reddish brown to grayish brown, with a nearly round or irregular shape. The back of the lesion is light in color and the edge is dark brown. Lesions are sometimes curly and fragile, and several lesions can fuse with each other to reach 1/2- 1/3 of leaves, or irregular large patches; There are many small black spots scattered on the lesion in the later stage, which are conidia of pathogenic bacteria. The disease can occur all year round, causing large areas of leaves to dry up, leading to early shedding; The damage of middle and lower leaves of crown is more serious than that of top, and the disease of old leaves is more serious than that of new leaves.
The pathogen overwinters on the diseased leaves with mycelium and conidia, and infects conidia when the temperature and humidity are suitable in spring, especially in July-165438+1October. When the temperature is 20-27℃, there is much rain or humidity, poor ventilation, insufficient fertilizer, weak trees or freezing and mechanical damage, which is easy to get sick; The climate is hot and dry, and the illness is aggravated if you don't water it in time.
Prevention and control methods: thoroughly remove diseased leaves in late autumn and early winter, burn or bury them centrally, and reduce overwintering bacteria, which can effectively inhibit the occurrence of diseases in the coming year; Transplanted or introduced seedlings should be removed from diseased leaves and burned centrally. When necessary, the seedlings can be disinfected by spraying 500 times of 50% carbendazim wettable powder or 0. 1% potassium permanganate solution before leaving the nursery. Strengthen management, increase the application of phosphorus and potassium fertilizer, often loosen the soil and weed, prevent soil hardening or water accumulation, water and spray water in time in case of high temperature and dry weather, and increase the disease resistance of osmanthus plants; In areas with serious diseases, 70% mancozeb wettable powder 500 times solution, 75% chlorothalonil wettable powder 800 times solution or 1: 2: 100 lime bordeaux solution are sprayed once every two months for 3-4 times continuously, and the control effect is good. It can also be sprayed with 5000 times of 25% propiconazole EC at intervals of 48 days.
3. sooty blotch is characterized by a layer of gray-black powder with different shades on its leaves and branches, sometimes even forming a black film. The reason is that when aphids, scale insects, whiteflies and other insects harm osmanthus fragrans, the excreta secreted by them cause parasitism of many fungi, thus inducing a dark gray sooty blotch.
It usually occurs in hot and humid seasons and in hot and humid, hidden and poorly ventilated environments. The gray-black coal pollution layer not only affects the ornamental of osmanthus fragrans plants, but also affects the photosynthesis of leaves, resulting in poor plant growth and early shedding of susceptible leaves after yellowing and wilting.
Prevention and control methods: strengthen the shaping and pruning of osmanthus plants, ensure the ventilation and light transmission in the plant cavity, and promote the good growth of plants; When aphids, scale insects, whiteflies and other pests are found to harm osmanthus fragrans, effective prevention and control should be carried out in time to kill them; Potted plants, often spraying water to wash leaves; At the initial stage of the disease, spraying branches and leaves with 500 times of 50% methyl sulfide suspension, 800 times of 50% carbendazim wettable powder or 500 times of 75% chlorothalonil wettable powder has a good control effect.
4, chlorosis is iron deficiency chlorosis. If it is mild iron deficiency, it means that the veins of young leaves turn green and yellow, and the vein tissue is still green; If the iron deficiency is serious, the new and old leaves will turn yellow, the young leaves will slowly stop growing, some old leaves will appear yellow-brown spots, and the plants will not grow and bloom normally, which will seriously affect the ornamental effect and the harvest of flowers. The reasons are as follows: first, the soil quality of plants planted on the ground is alkaline; Second, when preparing potted soil, the pH value of potted plants is unbalanced due to improper formula ratio; Third, osmanthus planted after urban and rural demolition is not completely cleaned up due to building residues; Fourth, management mistakes, such as high pH value of irrigation water; In this way, the iron in the soil exists in the form of insoluble iron hydroxide and cannot be absorbed by the root system of osmanthus fragrans.
Prevention and treatment methods: mild iron deficiency can be treated by pouring 0.5% ferrous sulfate solution on roots and spraying 0.2% ferrous sulfate solution on leaves; When the iron deficiency is serious, 20-40g chelating iron [F-EDTA] can be applied to the soil around the rhizosphere of each osmanthus fragrans (including potted osmanthus fragrans), and 0. 1% chelating iron solution can be sprayed on the leaves at the same time. Spraying leaves with 0.2% ferrous sulfate solution every half month during the growth season of new shoots in spring; When preparing potted soil, the pH value can be adjusted to below 6.5 with 0.5% ferrous sulfate solution.
5. Dry rot mainly occurs on newly transplanted osmanthus plants with large specifications.
When landscaping or transplanting osmanthus fragrans, the trunk or branch bark of osmanthus fragrans plants is seriously damaged or large pieces of dry bark are not properly protected in time due to reasons such as bumps during digging, scratches during long-distance transportation and strangulation during hanging planting. When rain and sewage infect wounds, fungi (such as wood rot fungi, etc. ) and bacteria (such as soil wild Bacillus, etc. ) is induced to invade and parasitize, causing the wound to rot.
Prevention and treatment methods: for small wounds on tree trunks or branches, wound healing agents should be applied in time; For small wounds that have been partially decomposed or slightly decomposed, the wound can be partially cleaned until the fresh xylem and phloem are exposed, and then the wound healing agent can be applied to the fresh wound to promote the wound healing as soon as possible; For the old big wounds with the phloem damaged for a long time and the xylem exposed for many years, the rotten exposed xylem can be cleaned up, and the stone sulfur mixture can be applied regularly every year to prevent corrosion or the two-component "marble glue" can be quickly applied to the fresh wounds, which will have better protection effect; For the thick osmanthus plants with cavities in the trunk, the rotten parts can be thoroughly removed first, and the isolation layer between rotten xylem and non-rotten xylem should not be destroyed, and the cavities should be filled with polyurethane foaming agent.