Perforation mainly damages leaves.Initially near the leafveinThere are light brown water stain like small spots at the spot, and water stain like yellow halo around the spot.Finally, cracks appear at the junction of disease and health, and perforation is formed. The edge of the hole is irregular.
Xanthomonacampestris (Smith) Dovosen, saidXanthomonasBlack rot of cabbageXanthomonas, belonging to bacteria.The mycelium is short rod-shaped, 0.3-0.8 × 0.8-1.1 μ m in size, round at both ends, and polarSingle flagellum, NoneSpore, YesCapsule，Gram staining negative。The optimum temperature for pathogen development is 24-28 ℃, the maximum temperature is 38 ℃, the minimum temperature is 7 ℃, and the lethal temperature is 51 ℃.The pathogen can survive for 10-13 days under dry conditions and more than 1 year in the ulcer tissue of branches.
Perforation disease
Transmission route and incidence conditions: the bacteria overwinter in the tissues of the injured branches, and the bacteria in the diseased tissues begin to move in the next spring. Before and after the plum blossom, the bacteria overflow from the diseased tissues, spread by wind, rain or insects, and invade from the stomata of the leaves and the bud marks of the branches. The incubation period is 7-14 days.The ulcer spot is easy to dry in spring, and the surrounding healthy tissue is easy to heal. Therefore, the bacteria in the ulcer spot will die in 10-13 days under dry conditions.The temperature is 19-28 ℃, and the relative humidity is 70-90 ℃.The disease usually occurs in May and is serious in July and August.
The occurrence of the disease and climateTree vigor, management level and variety.The temperature is suitable, and the frequent rain or foggy and heavy fog season is conducive to the propagation and infection of bacteria, causing serious disease.During heavy rain, bacteria are easy to be washed to the ground, which is not conducive to their reproduction and infection.In general, the disease expands rapidly in the spring and autumn rainy season, and slowly in the summer dry months.The incubation period of the disease is related to temperature: temperature 25-26 ℃ incubation period 4-5 days, 20 ℃ 9 days, 19 ℃ 16 days.The disease of strong trees is light and late, and the disease of weak trees is early and serious.
Occurrence of perforation disease
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Harmful symptoms
BacterianaturePerforation disease: The leaves damaged by bacterial perforation disease are initially translucent watery light brown spots, and then turn purple brown to black brown. The disease spots are round or irregular, with a diameter of about 2 mm.There are watery yellowish green halos (circles) around the lesion, cracks on the edge, and finally fall off or perforation, with irregular hole edges.When the air is humid, there are yellow bacteria on the back of the disease spot, and the leaves fall off early in serious cases.There are two kinds of disease spots, spring ulcer and summer ulcer.The spring ulcer occurred on the branches in the summer of the previous year, and the dark brown herpes formed on the branches in the spring of the next year, with a diameter of about 2 mm, and then expanded to a length of 1-10 cm, but the width was not more than half of the diameter of the branches.When the diseased spot rings around the branch, the branch will wither.Summer ulcers mostly occur on the green branches of the same year in late summer. Centered on lenticels and bud eyes, they form watery dark purplish red spots, which are round or oval, and then expand into brown or purplish black patches, slightly concave. The outer edge of the spot is watery, and there is glue overflow. After drying, it cracks. In severe cases, the branches are dead.After the fruit is injured, the disease spot initially appears as a watery brown spot, and gradually expands to dark purple (dark brown), round, slightly concave in the center, and watery in the edge;When wet, yellowish white mucilage overflows from the disease spot, which can also produce large and small cracks, and is infected by other saprophytic fungi, leading to fruit decay.
Mildew perforation disease: it damages the leaves. At first, it is yellowish green, round or irregular, with purple edges, then brown, 2-6mm in size, and finally perforated.When it is wet, a dirty white mold like substance grows on the back of the spot.The young leaves become withered and charred after being injured, without perforation.After the branches were injured, round disease spots were formed with the buds as the center, with purple brown edges, cracks and glue flow.After the fruit is damaged, the disease spot turns purple at first, then brown, with red edges and sunken center.
Brown spot perforation disease: after the leaves are damaged, round or nearly round disease spots can be produced on both sides, with purple or purplish red edges and slight whorls, and grayish brown mold like substances can grow on both sides of the disease spots in the later stage.The middle part is dry, falling off or perforated, and the edge of perforation is neat.The disease spots on new shoots and fruits are similar to those on leaves, and can also produce brown mold layers.
Bacteria of bacterial perforation overwinter on canker spots or leaves in spring.Therefore, the spring branch ulcers were the main source of primary infection.After flowering, pathogens overflow from ulcers, spread by wind, rain and insects, and invade from leaf pores, branch bud scars and fruit lenticels.The optimum temperature for bacterial development is 24-28 ℃, and leaves often get sick between April and May.The disease develops slowly in dry summer and again in autumn.In warm, rainy or foggy seasons, the disease is serious, poor drainage and partial application of nitrogen fertilizer are also conducive to the disease.Mold perforation and brown spot perforation, both with hyphae orConidiaOverwintering in diseased leaves, branches, etc.In the spring of the next year, when the temperature rises and becomes warmer, and appropriate rainfall occurs, conidia will form, which will infect young leaves first, then branches and fruits after being spread by wind and rain.Low temperature and rainy weather are conducive to disease.
prevention and cure
Prevention and treatment of bacterial perforation disease: I. Strengthen cultivation management.Attention should be paid to drainage, ventilation and light transmission of the garden, increase the application of organic fertilizer, avoid biased application of nitrogen fertilizer, enhance tree vigor and improve disease resistance.2. The diseased branches shall be cut off and burned in winter.For the diseased branches that cannot be cut off, the mixed solution of 800 ml of 0.2% mercuric chloride water, 200 ml of 95% alcohol and 200 ml of glycerin shall be applied for disinfection.Timely prune during the growing period to make the tree ventilated and transparent.3. Timely spray for protection.Spray 1-2 Baume degrees before germinationStone sulfur mixtureAfter leaf spreading, spray 0.3-0.4 Baumedol sulfur mixture, or spray 65% Daisenzi 500 times solution at the beginning of disease, once every 10-15 days, 2-3 times in total, with good control effect.Spray zinc sulfate lime solution (1 part of zinc sulfate, 4 parts of hydrated lime, 240 parts of water - it has special effect on this disease, but it is prone to drug damage, so it must be sprayed after the test.)
Prevention and treatment of two kinds of fungal perforation diseases: to prevent and treat mold perforation disease or brown spot perforation disease, spray 5 Baumedol sulfur mixture, or spray O.5:1:100 zinc sulfate lime solution, or use 65% mancozeb 600 times solution before germination.Spray 75% chlorothalonil 600-800 times, or 70%Thiophanate methyl1000-1500 times liquid;Or 100 to 500 parts per millionAgricultural streptomycin。
Pathogenesis
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The pathogenic bacteria of bacterial perforation mainly overwinter in the tissue of ulcer spot in spring.The next year, before and after the flowering of peach trees, bacterial pus overflowed and infected through wind, rain and insects.Under the condition of weak tree vigor, the incubation period only takes 4-5 days, and if the tree vigor is strong, it can take up to 30-40 days.Warm, rainy, foggy and dewy are conducive to disease occurrence.
The pathogen overwinters in the diseased shoot or bud scale with mycelium and conidia.In the warm and humid spring of the next spring, conidia grow and infect through wind and rain.Low temperature (average temperature is about 20 ℃), rainy and humid weather is suitable for this disease.
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Bacterial perforation of peach
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along withpeachWith the large increase of planting area, bacterial perforation disease of peach trees is becoming increasingly serious, and some orchards even have a big outbreak. Many fruit growers do not know much about the disease or choose improper chemicals, so that some even use pesticides, but because the drug effect is not ideal, a large number of peach trees fall off, bringing great economic losses.
1、 Causes of Difficulty in Controlling Peach Bacterial Perforation
1. Improper fertilizer and water management and pruning, especially many fruit growers are accustomed to applying nitrogen fertilizer, resulting in overgrowth of trees, poor ventilation and light transmission, and poor stress resistance, creating conditions for pathogen infection.
2. Most fruit growers are accustomed to using streptomycin to control bacterial perforation disease, while some agricultural streptomycin or penicillin in the market are poor in quality, low in content, or even zero in content. Fruit growers mistakenly believe that the control effect of streptomycin is poor.
3. Didn't distinguish betweenBacterialPerforation disease or fungal perforation disease, there is blindness in selecting pesticides, and no pesticides to prevent bacterial diseases are used.
4. No reasonable prevention and control period is selected, and the disease spots are often found before prevention and control, and the best prevention and control period is missed.
2、 Control of bacterial perforation disease of peach trees
1. Strengthen the management of fertilizer and water in peach garden, increase the application of organic fertilizer, nitrogen, phosphorus and potassium, and pay attention to the application of trace elements.Prune properly to make the peach garden ventilated and transparent.Combine pruning, cut off diseased branches, remove fallen leaves and burn them collectively.
2. Select streptomycin or penicillin produced by regular manufacturers.From the perspective of pesticide market, the quality of agricultural streptomycin or penicillin is uneven, and even some products have no content. With such products, the control effect is very poor or no control effect. Therefore, reliable products should be selected for control.
3. Understand bacterial perforation andfungusDifferentiation of sexual perforation disease, rational drug selection and medication.Peach perforation disease can be divided into bacterial perforation disease and fungal perforation disease.At the initial stage of bacterial perforation, the back of the leaf was watery and polygonal;The disease spots on the front of the leaves are polygonal or irregular, and further develop. The disease spots on the leaves fall off, forming perforations. In serious cases, the perforations are continuous, forming large notches or holes.At the initial stage of fungal perforation, the disease spots on the leaves are nearly round and brown, and the disease spots lag behind to form near round perforation.The lesion of fungal perforation is larger than that of bacterial perforation.Therefore, only by distinguishing between them can we have a clear aim in medicine, such as choosing the foliconazoleSodium dichloroisocyanurates, chlorobromoisocyanuric acid, mesobiotics, etc. to prevent bacterial perforation.
4. Seize the critical period, select special pesticides and spray them for protection.Before germination, spray 5 Baume degrees of sulfur or 45% of sulfur to crystallize 30 times solution for thorough garden cleaning.After germination, since canker spots in spring are the main primary source of infection of the disease, pesticides should be reasonably selected during this period, such as 20% bacteria killingWettable powder1000 times liquid, 20% Segal wettable powder 1000 times liquid, or 50% ultra copper water soluble powder 1500 times liquid+3% Kejunkang wettable powder 1000 times liquid.The above pesticides can prevent and control fungi and bacteria with good effect.After bagging, you can choose 33.5% Haizhengbilu No. 2 suspension solution 2000 times, or 20% bactericidal wettable powder 1000 times, or 50% ultra copper water-soluble powder 1500 times,+3% Kejunkang wettable powder 1000 times,Inhalable bactericideAndProtective bactericideUsed in combination.
5. In winter, the diseased branches shall be removed by pruning, and the dead branches, fallen leaves, fallen fruits, and withered grass shall be thoroughly cleaned up and burned to eliminate the overwintering disease source.Pay attention to the drainage of the orchard and trim it reasonably to make the orchard well ventilated and light transparent and reduce the humidity of the orchard.Increase applicationOrganic fertilizerTo avoid partial application of nitrogen fertilizer, so as to make fruit trees grow healthily and improve disease resistance.
6. When building a new peach garden, do not build the garden in a place with high or low groundwater level.Vigorously promote the new technology of "ridging and covering, furrow irrigation".
Prevention and control methods
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(1) Strengthen management and enhance tree vigor.Pay attention to drainage, apply more organic fertilizer, avoid biased nitrogen fertilizer, and prune reasonably to make the peach garden ventilated and transparent, so as to enhance the tree vigor and improve the disease resistance of the tree.
(2) Remove the overwintering bacteria source.Combined with winter pruning, cut off diseased branches, remove fallen leaves and burn them collectively.
(3) Spray protection.Spray Baume 5 degree stone sulfur agent or 45% crystal stone sulfur agent 30 times solution or 1:1:100 times formula before germinationBordeaux liquid72% agricultural streptomycin after germinationSoluble powder3000 times liquid orStreptomycin sulfate4000 times liquid or oil emulsion:Mancozeb: water=10:1:500, which is effective for bacterial perforation disease and can also be preventedaphid、scale、Tetranychus mitesEtc.
