What are the main diseases of peach, plum (284268) and plum and their control?
(1) Symptom Peach Brown Rot mainly harms fruits, flowers and new shoots. The fruit is fragile from small to large, and the closer it is to maturity, the heavier the damage. At the early stage of the disease, brown round spots appear on the fruit surface, which can spread to the whole fruit within a few days when conditions are suitable, and the pulp turns brown and rots, and then a grayish brown mold layer grows on the rotten fruit surface, often arranged in concentric circles. The diseased fruit is easy to fall off, but some of it dries up and shrinks into hard fruit, which will not fall off for a long time. Petals and stigma were damaged, brown spots began to appear, and gradually spread down to sepals and pedicels. When the weather is wet, the diseased flowers become soft and rotten, and the surface is covered with gray mold; When the weather is dry, flowers will wither and turn brown. The sick flowers stay on the branches for a long time without falling off. Pathogens on diseased flowers and fruits can spread down to branches through pedicels and form ulcers on branches. The ulcer is rectangular, with purple-brown edges, slightly concave center and grayish brown. In the early stage of ulcer, glue often flows, and in severe cases, branchlets can be strangled. When the weather is wet, botrytis cinerea will grow on the ulcer.
(2) The pathogen is Ascomycetes (see Figure 2-87), and the botrytis cinerea seen at the diseased site is the conidium of the pathogen. The conidia are colorless, single-celled, lemon-shaped or round, with the size of 10 ~ 27μ m× 7 ~ 17μ m, and arranged in beads on the conidiophore. During sexual period, pathogens produce cysts on hard fruits that fall to the ground or are buried in topsoil. The whole hard fruit is pseudosclerotia, and the inside is completely filled with hyphae, which is in the shape of an ascocyst. A hard fruit can germinate and grow 1 ~ 20 ascospores, and an ascospore contains 8 ascospores. The spore size is 6 ~ 65438 0.5 μ m× 4 ~ 8.2 μ m. The optimum temperature for conidia germination is 20 ~ 25℃.
Figure 2-87 Peach Brown Rot
1. diseased fruit 2. Conidiophore and conidia chain of pathogenic bacteria. Dead fruits and ascomycetes germinated by pathogenic bacteria.
(3) Pathogenic law: Pathogenic bacteria overwinter in dead fruit or branch ulcer with mycelium, and produce a large number of conidia in spring, which are spread by wind, rain and insects. Invasion of fruits through wounds and lenticels can also directly invade flower organs from stigma and nectaries, and then spread to new shoots. After that, under suitable conditions, a large number of conidia can grow and reinfect repeatedly. The flowering period and young fruit period are low temperature and rainy, and the diseases such as high temperature, sultry and high humidity during fruit maturity and harvest, storage and transportation are serious, and there are many diseases, insect injuries and mechanical injuries, which are conducive to the infection of germs and the disease is serious; Orchards with extensive management and weak trees are also seriously ill. After the fruit is ripe, the varieties with soft and juicy flesh, sweet taste and thin skin are more prone to disease.
(4) Prevention and control methods ① Do a good job in clearing the garden and strengthen management. Combined with pruning in winter, the residual hard fruits on branches can be thoroughly removed, diseased branches can be cut off, and the diseases on the damaged ground can be collected. At the same time, the source of overwintering bacteria can be greatly reduced. ② Strengthen pest control. Many pests in Taoyuan, such as peach moth, peach moth and peach stinkbug, not only spread germs, but also cause wounds conducive to infection. Therefore, timely pest control or bagging during the fruit expansion period can reduce the occurrence of diseases. ③ Chemical control. Spray Pomei 5 degree stone sulfur mixture for the first time before the peach tree germinates. For the second time, about 65,438+00 days after flowering, spray 500 times of 65% zineb wettable powder (or 700 times of 80% zineb wettable powder), 300-500 times of 65% Fumei zinc wettable powder, 65,438+0,000 times of 50% zineb wettable powder, or 0.3 Baume degree. In the areas with frequent flower rot, it is necessary to spray chemicals once in the early flowering period (when the flowers bloom about 20%), and it is appropriate to spray chemicals in zineb this time. The orchard without bagging should be sprayed once after the second spraying 10 ~ 15 days, and then sprayed again until the fruit ripens 1 month. According to foreign reports, spraying benglinide three times before peach harvest has a good effect on preventing and treating this disease.
2. Peach bacterial perforation (see Figure 2-88) is a common leaf disease of peach trees, which occurs in peach cultivation areas. Among them, coastal areas, lakeside areas, rainy areas and years are seriously affected, which is easy to cause a large number of fallen leaves in advance, weaken the tree potential and affect the yield. Besides peach trees, the disease also harms plum, plum, apricot, cherry and other tree species.
(1) Symptom Peach bacterial perforation mainly damages leaves, but also branches and fruits. Come on, leaves At first, waterlogging spots were produced, which gradually expanded into round or irregular spots of about 2 mm, brown or purple-brown, with yellow-green halo around the spots. When the weather is wet, slime mold pus overflows from the back of the affected part. Soon the lesion dried up and fell off to form perforation. There are two kinds of ulcer spots when branches are damaged. One is spring ulcer, which happened on the branches smoked last summer and became infected in late summer and early autumn. Because the lesion is small, it is not obvious. When new leaves appeared in the following spring, small brown herpes appeared on the branches, about 2 mm, which gradually expanded to 1 ~ 10 cm in the longitudinal direction and not more than half of the vertical expansion of the branches. In severe cases, branches will dry up and die. Before and after flowering in late spring, the epidermis of the diseased spot broke and the overflowing bacterial liquid spread. The other is summer ulcer, which occurs on the tender shoots extracted that year. At the end of summer, there are water spots, round or oval, brown, which are not easy to expand, quickly dry up and not easy to spread. The fruit is damaged and produces brown spots and cracks when it is dry.
Figure 2-88 Peach Perforation Disease
1. Pathogen and conidia of peach brown spot perforation. Infected leaves and pathogens of peach bacterial perforation.
(2) Xanthomonas Pruni (Smith) dowson, a pathogenic bacteria, is called Xanthomonas drupes. The pathogen is short rod-shaped, with round ends, the size is 0.4 ~ 1.7 μ m× 0.2 ~ 0.8 μ m, and it is single or short-chained. The optimum temperature for the development of the pathogen is 24 ~ 28℃, and it can survive at the branch ulcer for more than 1 year. The bacteria that fell into the ground disease tissue died after about 6 months.
(3) The pathogen of bacterial perforation mainly overwinters in the canker tissue in spring, and the overwintering bacteria begin to move after the temperature rises in the next spring. Before and after flowering of peach trees, pathogen pus overflowed from diseased tissues, spread by wind, rain and insects, and invaded from stomata on leaves and lenticels on branches and fruits for primary infection. The incubation period after invasion is generally 1 ~ 2 weeks, which can be extended to 20 ~ 30 days when the temperature is low. In the rainy season, after the initial infection, new bacterial pus can overflow for reinfection. Summer ulcer and spring ulcer have different effects on the overwintering and infection of bacteria. Bacteria in summer ulcers generally cannot survive winter. Because when the ulcer forms in summer, when the temperature is high, the host tissue can produce embolus layer to prevent the further invasion of bacteria; At the same time, ulcers are easy to dry in summer, and bacteria will die after 10 ~ 13 days under dry conditions. The spring ulcer was infected in late summer and early autumn last year. At that time, the temperature had gradually dropped, and the bacteria in the tissue propagated slowly. At the same time, the host can't form a cork layer, the diseased tissue won't dry, and the bacteria lurk for the winter. By the next spring, bacteria proliferated, forming ulcers and pus. At this time, new branches and leaves germinate and are easy to be infected, so spring ulcers are the initial main source of infection. The disease usually begins in the first half of May and spreads fastest in the rainy season in June. The high temperature and dry weather in summer inhibited the development of the disease, and there was another expansion process in autumn rain. A warm and rainy climate is conducive to the outbreak of diseases, and strong winds and fog can promote the outbreak of diseases. Taoyuan, with weak trees, poor drainage and ventilation, has serious diseases.
(4) Prevention methods ① Strengthen cultivation management and clear the garden in winter. It is necessary to increase the application of organic fertilizer and phosphorus and potassium fertilizer, pay close attention to the drainage after rain, keep the orchard well ventilated, enhance the tree potential and increase the disease resistance. Combined with clearing the garden in winter, thoroughly removing dead branches, fallen leaves and fallen fruits can greatly reduce the source of overwintering bacteria and reduce the incidence in spring. ② Chemical control. Spraying 4 ~ 5 Baume lime-sulfur mixture before germination in spring. After the new leaves are exposed, they are usually sprayed every 7 ~ 10 day for 2 ~ 3 times in the early stage of the disease. Commonly used drugs are: 65% zineb wettable powder 500 times solution, zinc sulfate lime solution (zinc sulfate 0.5 kg, hydrated lime 2 kg, water 120 kg).
3. Peach leaf shrinkage disease is common in peach cultivation areas, especially in Sichuan, Chongqing, Hunan, Hubei, Anhui, Jiangsu, Zhejiang and other provinces and cities. The disease will lead to a large number of fallen leaves in the early stage of peach trees, affect the yield of the current year, weaken the tree vigor, have a bad influence on the next year, and also harm plum (288272), plum and other fruit trees.
(1) Symptomatic leaf shrinkage mainly harms leaves, and in severe cases, it also harms tender shoots, flowers and young fruits. When the leaves are infected, the young Ye Gang will wrinkle, wrinkle and curl, and the color will turn red. With the development of the leaves, the degree of wrinkling and curling will be aggravated, and the diseased parts will become fragile, uneven and reddish brown. At the end of spring and the beginning of summer, a layer of gray-white toner grows on the surface of the affected area, which is the ascus layer of the pathogen. Finally, the leaves dried up and fell off. If the new shoots themselves are not damaged and the diseased leaves wither backward, the axillary buds can still extract healthy new leaves. After the new shoots are damaged, they are gray-green, the internodes are shorter and thicker than normal, and the leaves are clustered. Petals are enlarged and lengthened, diseased fruits are deformed, often cracked and easy to fall off early.
(2) pathogenic bacteria. ] is a ascomycete (see Figure 2-89), which is called deformed fungus. Ascomycetes and ascospores are formed during the sexual period of pathogenic bacteria. Ascomycetes are mostly arranged in a grid-like seed layer, which is the gray-white toner seen on the surface of diseased leaves. Ascomycetes are cylindrical, with a size of 25 ~ 40 μ m× 8 ~12 μ m. Endophytic ascospores ≤8, oval or round, single spore, colorless. The size is 6 ~ 9 microns × 5 ~ 7 microns. Many spores can be produced by budding inside or outside ascospores. Spores are ovoid, 2.5 ~ 6 microns ×4.5 microns. The optimum temperature for pathogen germination is 20℃ and the optimum temperature for infection is 10 ~ 16℃. Spores are resistant to drying, and thick-film spores are more resistant to cold, and can survive in orchards for more than 1 year.
Figure 2-89 Peach Leaf Atrophy
1. Ascomycetes and Ascomycetes 2 of pathogens. sacrifice
(3) The pathogen overwinters as ascospores or spores on the surface of peach bud scales or in the gap between bud scales. By the next spring, when the peach buds spread out, spores germinated and invaded the young leaves or shoots. The invasion of pathogens can stimulate a large number of cells in leaves to divide, and at the same time, the cell wall thickens, causing the diseased leaves to expand and contract. After that, sporogenous cells are formed between the cuticle and the upper epidermal cells of the diseased leaves, which develop into ascospores and spores. Ascomycetes and spores, without reinfection, overwinter on the surface of bud scales or between bud scales in summer. Therefore, peach leaf shrinkage disease only infects once a year. The optimum temperature for peach leaf shrinkage is 10 ~ 16℃. If it exceeds 2 1℃, the disease will stop developing. The occurrence of peach leaf shrinkage disease is closely related to the weather during the germination and leaf expansion of peach trees in spring. Low temperature, rainy and humid weather lasts for a long time, which is not only beneficial to the germination of overwintering spores, but also prolongs the time of peach tree germination and leaf spreading, that is, prolongs the infection period and increases the number of peach trees. Peach trees in lakeside and seaside areas often suffer from serious diseases. If the weather is warm and dry in early spring, it won't be so serious. Generally, early-maturing varieties are more serious than late-maturing varieties.
(4) Control methods ① Chemical control. Because peach leaf shrinkage disease only infects once in spring, the effect of spraying medicine at the critical period is obvious. According to local experience, when the peach buds are exposed to red but not spread, spraying a mixture of lime and sulfur with a Baume degree of 5 degrees or a Bordeaux solution with a ratio of1:1:10,000 can control the occurrence of initial infection, and the effect is very good. Continuous spraying for 2-3 years can completely prevent and eliminate peach leaf shrinkage. Spraying requirements are comprehensive and thoughtful, leaving no dead ends. (2) Strengthen orchard management, remove diseased leaves in time and burn them before the first appearance of gray-white pigment, which can reduce the source of overwintering bacteria, strengthen fertilizer and water management for seriously ill trees and promote the recovery of tree vigor.
4. Anthracnose is one of the important diseases that harm fruits. Colletotrichum gloeosporioides is distributed in Hubei, Jiangsu, Zhejiang, Sichuan, Chongqing, Guizhou and other provinces (municipalities directly under the central government) in southern China and some producing areas in northern China, which poses a great threat to production. When the disease is serious, the fruit damage rate can reach more than 80%, causing huge losses.
(1) Symptom Anthracnose mainly harms fruits, as well as new shoots and leaves. When young fruits are damaged, waterlogged brown spots first appear, which gradually expand into round, oval and reddish brown, and the spots are obviously depressed. When the climate is humid, pink dots will grow. The most obvious feature of fruit ripening symptoms is concentric annular shrinkage of diseased spots, except for similar young fruits. Most of the diseased fruits rot and fall off, and a few become stiff fruits and stay on the branches. After the branches are damaged, they produce long oval lesions with brown depressions and pink spots on the surface. Because of the uneven growth on both sides, the branches bend to one side, the leaves droop and roll vertically into a tube. Leaf diseases produce round or irregular spots. Finally, the lesion dries up and falls off to form perforation.
(2) The pathogen [Gloeosporium Laeticolor Berk] (as shown in Figure 2-90) is a kind of semi-knowledge bacteria, which is called brown sporoderm laoting. The pink spots seen in the affected area are colorless. Conidia is oval and contains two oil balls, the size of which is16 ~ 23 μ m× 6.9 ~ 9 μ m. The optimum temperature for the development of the pathogen is about 25℃.
Fig. 2-90 Aspores and conidia of Colletotrichum gloeosporioides.
(3) Pathogenic bacteria mainly overwinter in diseased branches or hard fruits with hyphae, and start to grow conidia in the following spring, which spread with wind, rain or insects to invade young fruits and twigs, causing initial infection, and continue to produce conidia for reinfection when conditions are suitable. If the temperature is low and rainy in the young fruit period and the weather is warm, stuffy and humid in the mature fruit period, it will be beneficial to the occurrence and development of diseases. Orchard management is extensive, drainage is not smooth, pruning is too dense, trees are weak, and diseases are more serious. Among different peach varieties, the diseases of early-maturing varieties are more serious, while those of late-maturing varieties are less serious.
(4) Control methods ① Strengthen cultivation management, rationally prune and fertilize, increase the application of organic fertilizer and phosphorus and potassium fertilizer, improve soil conditions and ventilation and light transmission conditions, enhance tree vigor and improve disease resistance; Clean the garden thoroughly in winter, reduce the source of overwintering bacteria, control pests and reduce insect-borne diseases. ② Chemical control. Spraying 3 ~ 4 Baume sulfur mixture and 0.3% sodium pentachlorophenol mixture or 1: 1: 1000 bordeaux mixture before spring germination to eliminate the overwintering bacteria source. Spraying medicine to protect young fruits after flower falling is the key to control, spraying medicine once every 10 ~ 15 days, * * * 3 ~ 4 times. Commonly used drugs are 50% Tejun wettable powder 1000 times solution, 5% Tianan wettable powder 500 times solution, or 70% thiophanate-methyl wettable powder 1000 times solution, 65% zineb wettable powder 500 times solution, 80% anthrax thiram wettable powder 500-600 times solution, and more than 50% solution. ③ The fruit bagging time should be advanced appropriately. Before bagging, the diseased fruits should be removed and sprayed with fungicides.
5. Peach blight, also known as rot, is an important disease that harms peach branches. Peach cultivation areas in northern and southern China mainly occur in Jiangsu, Zhejiang, Yunnan and other provinces in the south. If it is not stopped in time, the whole tree will die. In addition to peach trees, the disease will also harm plum (292276), apricot, cherry and other fruit trees.
(1) Symptom peach blight mainly damages trunk and first and second branches, and the lesion mostly occurs in the southwest of the tree. Its symptoms are hidden, and the incidence rate in orchards is often high, which is not easy to find in the early stage or when the illness is mild. There are several types of symptoms of this disease: ① Glue bleeding. At the initial stage, the diseased part was slightly depressed, and there were glue spots the size of rice grains outside. With the development of the disease, gum spots increase and the amount of gum flows out. When the victim was serious, the trunk was covered with glue. The lesion is light yellow at first and gradually becomes brown, tan or black. ② Ulcer. It's a symptom in the middle and late stages. The lesion was rectangular or irregular, with yellowish brown cortex, rot and distiller's grains. After that, the rot reached the xylem, and the internal lesions expanded in a long spindle shape. If the rotten cortex is cut off, a long black line can be seen on the white xylem, and it becomes sharper at the top. In summer, when the temperature is high, the affected part loses water and cracks, and the surrounding healthy parts produce cork-like tissues with slight uplift. Black spots grow in the later stage of the disease, which is the daughter seat of bacteria. ③ concave points. This is a special symptom of old branch weakness. There are long concave spots on the branches that are obviously sunken than the surrounding healthy parts, and the tissues turn brown and rot. The rotten part extends up and down, up to more than 3 meters long, but rarely extends around, and there are black spots on it in the later stage. The diseased branches gradually died, causing the branches to wither.
(2) Pathogen [Bacterial Blight (Pers). ) Fr] is an ascomycete (see figure 2-9 1), and the small black spots seen by the diseased part are conidia and the daughter seat of the ascomycete. A subsessile has 1 ~ 6 conidia. Conidia are sausage-shaped, single-celled and colorless, 5.5 ~ 7 μ m× 0.8 ~ 1. 1 μ m, and are born in conidiophore. Ascomycetes are also embedded in the stroma. Ascomycetes are rod-shaped or spindle-shaped, and each ascomycete has 8 ascospores. Ascomycetes are sausage-shaped and colorless, 7.5 ~ 8.8 μ m×1.9 μ m. The optimum temperature for pathogen development is 28 ~ 32℃, and the optimum temperature for spore germination is 18 ~ 23℃.
Fig. 2-9 1 Fusarium oxysporum
1 .spore 2. Conidiophore and conidia 3. Spore 4. Ascomycetes 5. Ascomycetes 6. Ascomycetes.
(3) Pathogenic law Pathogens overwinter in the diseased parts of branches with hyphae, ascomycetes and conidia. In the spring of the following year, conidia spread through wind, rain and insects, invaded the trunk and main branches from the wounds or lenticels of the host, and then developed between the bark and xylem, invading not only the cortex but also the xylem. When the bark is stimulated, it will produce gum. Spring and autumn are the most suitable periods for onset, especially in spring. This tree is most likely to get sick when it is weak. Pathogen is a kind of weak parasite, which can only invade from wounds or natural orifices. Various factors that cause wounds will aggravate the occurrence of diseases, and wounds caused by frostbite are an important way for germs to invade.
(4) Prevention and control methods ① Strengthening cultivation management, cultivating strong trees, doing a good job of anti-freezing and reducing the trauma caused by freezing injury are the fundamental measures to prevent and control peach blight. It is necessary to increase the application amount of organic fertilizer and prevent partial application of nitrogen fertilizer. Pay attention to ditch drainage after rain. Timely control pests that damage branches, such as longicorn beetles. (2) scraping the diseased spots. Early spring comprehensive examination, found that the disease spots, timely scraping clean, coated with drug protection. Commonly used chemicals are: 50 times solution of 40% thiram wettable powder, 50 times solution of 50% triamcinolone acetonide wettable powder, 10 baumeishi sulfur mixture, etc. Because it is not easy to completely scrape off the diseased spots, it does great harm to trees, so we can also refer to the common method of "stripe application" to prevent and control apple rot, just like pear rot (peach rot and pear rot, the pathogen of apple rot is different kinds of fungi belonging to Ascomycetes, the infection period is basically the same, and the control methods are basically the same). Please refer to the pear rot section for details. ③ Spray protection. Immediately after pruning in winter, spray 5 waves of meishi sulfur mixture to protect the cut. Before the peach trees germinate in early spring, the lime-sulfur mixture of 5 Baume degrees was sprayed once in early and middle March. Spraying 500 times of 65% zineb wettable powder solution or 0.3 Baume lime-sulfur mixture every half month from April to June, focusing on spraying lower branches of peach trees to protect trees from germs.
6. Li Hong spot disease occurs in all plum tree producing areas in China, especially in Sichuan, Chongqing, Yunnan, Guizhou and other provinces (cities) in the south, which is an important disease of plum trees in the south, seriously causing a large number of early leaves to fall off, affecting yield and tree vigor.
(1) The symptoms of red plum spot disease only harm leaves and fruits. After leaf infection, the initial lesion is orange-yellow, nearly round, slightly convex and with clear edges. After that, the lesion enlarged, the color deepened, the mesophyll thickened, and many crimson particles grew, that is, conidia of the pathogen. In the later stage, the lesion becomes reddish brown, with concave front, convex back and black spots, which is a cyst of pathogen. Curly diseased leaves often lead to early defoliation. After the fruit was damaged, orange-red round spots appeared, slightly protruding, and later the spots turned reddish brown, and many black spots also grew. The diseased fruit is deformed, inedible and easy to fall off.
Figure 2-92 Plum Erythema
1. Ascomycetes and Ascomycetes 2. Pathogenic conidia. Sick fruit 4. Sick leaves.
(2) Pathogen [Polyacanthosis rubrum (Pers)DC. ] belongs to Ascomycetes (see Figure 2-92). Conidiophore is oval or round and embedded in the substrate, and Ascomycetes are embedded in the substrate on the back of leaves. Ascomycetes are rod-shaped with 8 ascospores. Ascomycetes are single, colorless and rectangular, with the size of10 ~14 μ m× 3 ~ 4 μ m.
(3) Pathogenic law: Pathogenic bacteria overwinter on diseased leaves in the form of ascomycetes, and the overwintering ascomycetes release ascospores at the late flowering stage in the following spring, which can occur in Ye Sheng through wind and rain. Its conidia generation, no infection. It is cold and rainy in spring, warm and rainy and humid in summer and autumn, with too many branches and leaves, poor ventilation and light transmission, and serious diseases.
(4) Prevention and control methods ① Strengthen cultivation management, pay attention to drainage after rain, reduce humidity and improve ventilation and light transmission conditions of fruit trees. (2) Thoroughly cleaning the garden in winter can effectively reduce overwintering germs and alleviate the illness in the coming year. Because the disease can no longer be infected, its bacterial source only comes from the diseased leaves and fruits that overwinter. ③ chemical control: spray 1∶2∶200 bordeaux solution at the late flowering stage and bud opening stage, and spray 65% zineb wettable powder 1 ~ 2 times 500 times solution from late May to early June.
7. Peach gummosis is a common serious disease. In the south, it is very common because it is warm, rainy and humid. Diseases seriously weaken the tree vigor, affect the yield, and even the whole tree dies. In addition to peach trees, stone fruit trees such as plum (296280), apricot and plum often suffer from gummosis, which is very serious.
(1) Symptom Peach Gummosis mainly harms the trunk and branches. At the beginning of the disease, the affected part swells, gradually secretes transparent and soft brown colloid, gradually accumulates and finally becomes hard brown colloid. The bark of the trunk with serious gum flow is cracked and covered with granular, massive or massive gum, which makes the tree decline day by day, the leaves become thinner and yellow, and the branches even die.
(2) Pathogen and Pathogenesis The pathogen of peach gummosis is complex, and there are different opinions in academic circles. One view is that gummosis is a non-infectious physiological disease, which is caused by diseases and insect pests, freezing injury and mechanical damage, or by physiological dysfunction caused by excessive pruning, heavy soil viscosity and high acidity, resulting in boron deficiency in soil. Therefore, all kinds of factors that can affect the normal growth and development of fruit trees will cause gummosis. Another view is that gummosis is a fungal disease. According to the research reports of Jiangsu Academy of Agricultural Sciences and Shanghai, Zhejiang and Guangdong, peach gummosis is caused by the fungus [grape ring rot pathogen gross. et dugg。 ] (Ascomycetes), whose asexual generation is Dothiorella gregaria sace (Hemiptera). Studies have shown that the fruiting bodies of some ascomycetes and fungi with little knowledge can be seen in the affected areas, and they can cause diseases alone or in combination through artificial inoculation. Germ spores spread by wind and rain and invade from wounds and lateral buds, with two peaks in a year. Therefore, it can be considered that gummosis is a compound disease caused by some wounds infected with fungi with low parasitic degree on the basis of inducing factors such as tree weakness and wounds.
(3) Control methods ① Apply more organic fertilizer, strengthen orchard drainage and improve soil physical and chemical properties. Proper application of lime in acidic soil can reduce soil acidity. At the same time, paying special attention to soil application or spraying boron outside the roots during the growing season can also achieve good results in preventing gummosis. (2) timely prevention and control of branch pests, pay attention to antifreeze and sunscreen injury. ③ Chemical control: Spraying 5 Baume lime-sulfur mixture or 40% thiram wettable powder for 400-500 times before spring bud germination. Spraying 40% thiram wettable powder 800 ~ 1000 times and 0.3 Baume lime-sulfur mixture 1 time every 15 ~ 20 days during the growth period, three times in a row. To prevent gummosis of plum trees, 500 times of 40% carbendazim solution can be sprayed once every half a month for 5-6 times, and once every half a month after fruit picking for 2-3 times, with good results. ④ Blocking therapy. According to the experiment and demonstration in southern fruit area, the disease spot was scraped into a square wound of 6 cm 2, coated with medicine and wrapped with film, and the control effect was good. Specific methods: Apply 0. 1% borax solution and a layer of tung oil (or paint) with cotton wool, or use potassium permanganate, 70% thiophanate-methyl, Baja powder, yellow mud and water in a ratio of 0.001:0.1:5: 65438+.
8. Bacterial root cancer of fruit trees is widely distributed, mainly in Hubei, Anhui, Jiangsu, Zhejiang and other provinces in the south. There are many harmful tree species, which not only harm peach and plum (29728 1) and plum, but also harm pear, apple, grape, apricot, jujube, persimmon, papaya and other fruit trees. This is an important root disease of fruit trees.
(1) Symptomatic root cancer mainly damages the root neck, but also occurs in lateral roots and branched roots, forming nodules at the injured site. Nodules vary in size, ranging from beans to walnuts and fists, ranging from 65,438+0 ~ 2 to 65,438+00, and are spherical, oblate or amorphous in shape. Nodules are milky white or reddish at first, soft and smooth, then gradually turn brown and dark brown, and the surface is rough and hard. After the seedlings are damaged, the growth is slow, the plants are short, premature aging, loss of economic value, adult trees get sick, the tree is weak, the tree age is shortened, and in severe cases, it dies.
(2) pathogen [Agrobacterium tumefaciens (Smith et towns. (Bacillus tumefaciens Smith et conn. )] is a kind of bacteria, short rod-shaped, with the size of 1.2 ~ 5 μ m× 0.6 ~1μ m. The optimum temperature of development is 22℃, the pH range of development is 5.7 ~ 9.2, and the optimum pH is 7.3.
(3) Occurrence regularity: The pathogen of root cancer is soil sojourners, which can overwinter in tumor tissue cortex or soil (survival 1 year or more). Underground pests and nematodes are mainly transmitted through rainwater and groundwater, and also play a certain role in transmission. Seedlings with germs are the main way of long-distance transmission. Bacteria invade from wounds (marriage joints, insect wounds and mechanical wounds), parasitize and develop in the cortex, secrete a carcinogen, stimulate abnormal division of parenchymal cells and form tumors. The time from invasion to cancer formation varies greatly, from a few weeks to more than a year. Alkaline soil, continuous cropping seedlings, continuous cropping fruit seedlings and forest seedlings are all beneficial to the disease, and those with sticky soil, high soil humidity and poor drainage are more prone to the disease. Cuttage wound is bigger than bud grafting wound, and after grafting, there are more chances and higher incidence.
(4) Prevention methods ① Check and disinfect the seedlings. Don't buy seedlings from the sick garden, and don't let the sick seedlings leave the garden. Once found, it should be cleared and burned. The seedlings were soaked in 1% copper sulfate solution for 5 minutes, and then soaked in 2% lime water for 1 minute to be disinfected. ② Strengthen orchard management. Soils without root cancer should be selected to establish nurseries and orchards; Fertilizer is added to improve the physical and chemical properties of soil; Improve the grafting method, change the cutting grafting into bud grafting to avoid wound contact. Knives used for grafting must be disinfected with 75% alcohol or 0.4% potassium permanganate before and after each use to reduce the chance of getting sick. Prevent and control underground pests and nematodes in time. (3) Resection of diseased tumor, disinfection and protection with 5 bomesite sulfur mixture or 50 times antibacterial agent 402, or application of 400 IU streptomycin to the incision, and protection with vaseline. ④ Biological control. Using K84 biological agent to soak roots before sowing can effectively prevent the occurrence of root cancer, and the validity period can reach 2 years. When in use, it is diluted with water to make the bacterial concentration per milliliter 106. ⑤ Proper application of acidic fertilizers, such as ammonium sulfate, can change the acidity of soil, which is not conducive to the occurrence of root cancer.
9. Peach root-knot nematode disease, also known as peach root-knot nematode disease, belongs to root parasitic soil-borne disease and is distributed in both northern and southern peach producing areas of China. Both seedlings and trees can occur, and seedlings are seriously damaged, which is the main disease affecting seedling production.
Symptomatic root-knot nematodiasis (1) is characterized by the formation of nodules in the roots of parasitic plants. Nodules are small at first, white to yellowish white, and then continue to expand, showing knots or chicken feet, yellow-brown, rough surface and perishable. The roots of diseased plants are shorter than those of healthy plants, and there are fewer lateral roots and fibrous roots, which are stunted. Generally speaking, the symptoms of the aboveground part of mild infection are not obvious. The heavier leaves are yellow and thin, lacking vitality, seemingly lacking in fat, and growing poorly or extremely poorly.
(2) The pathogen of peach root-knot nematodes is southern root-knot nematodes ... female and male aliens. The larva is not segmented and worm-shaped, with a body length of about 0.36 ~ 0.393 mm. Adult females are pear-shaped or bag-shaped, colorless, with a size of 0.44 ~1.30mm× 0.325 ~ 0.70mm. They can lay eggs continuously for 2 ~ 3 months and survive for a period of time after stopping laying eggs. Male worms are thick and long, unsegmented, slow-moving, and have a short life span of only a few weeks. The optimum temperature for growth and development is 25 ~ 30℃, with a minimum of 5℃ and a maximum of 40℃. Mainly distributed in the south of-1 1℃ and the north of 1 month south latitude 33. Most of them are concentrated in the soil layer 5 ~ 30 cm from the surface, and few in the soil layer below1m.
(3) The regularity of the disease is that eggs or 2nd instar larvae are at the root of the host.