CN114902903A - Green prevention and control method for lemon round spot - Google Patents

Abstract

The invention discloses a green prevention and control method for lemon round spot disease, which belongs to the technical field of prevention and control of lemon round spot disease and comprises the following steps: s1, reasonably applying fertilizer, and cultivating strong trees; s2, reasonably trimming and protecting young shoots; s3, reasonably loading, and harvesting in time; s4, clearing the garden comprehensively and thoroughly; s5, precise chemical prevention and treatment. According to the method, through reasonable fertilization, the soil fertility is improved, the tree vigor is cultivated and strengthened, the cold resistance and the disease and insect damage resistance of the tree body are enhanced, the young shoots are reasonably trimmed and well preserved, the planting density is proper, the tree crowns are good in ventilation and light transmission, the occurrence of diseases is reduced, through reasonable loading, timely harvesting is realized, the burden on the tree body is reduced, favorable conditions are prevented from being provided for germ infection, through comprehensive and thorough garden cleaning in winter, spring and each time of shoot extraction, the germ base number in the next year is reduced, the severity of the disease in the next year is reduced, and accurate chemical control is combined, so that the lemon wheel spot disease can be effectively prevented and controlled.

Description

Green prevention and control method for lemon round spot

Technical Field

The invention relates to the technical field of prevention and control of lemon round spot disease, in particular to a green prevention and control method of lemon round spot disease.

Background

The lemon wheel spot is a new fungal disease appearing in a lemon producing area, is a low-temperature infection disease, and usually initially explodes and infects in late winter and spring to damage lemon leaves, branches and tips and fruits. Symptoms begin to appear and gradually worsen in the middle 12 th month, the peak of onset is from the late 2 th month to the middle 3 rd month, and the diseased leaves basically fall off in the late 3 rd month. The disease is the most serious in the late winter and the early spring, and the disease is not usually caused in high-temperature seasons. The disease is also called a destructive disease because the disease has the advantages of quick transmission, serious harm, more harm to lemon varieties, difficult control and easy huge economic loss to lemon growers.

In recent years, the round spot of the lemon is more and more frequent in China, the lemon is generally damaged by the round spot in Chongqing Wanzhou in the ventral city of the three gorges reservoir area, and the disease area is from 8000 mu in 2019 to nearly 10 ten thousand mu in 2022. Once the alternaria leaf spot of the lemon is generated, the withered branches and fallen leaves, the leaf surface and the leaf surface of the fruit, a large amount of fallen fruits and even the dead fruit are caused, and the yield and the quality of the lemon are threatened. According to earlier researches, the propagation of the alternaria leaf spot is mainly influenced by wind and rain, wounds, insect pests and the like, so that the prevention and treatment of the alternaria leaf spot mainly comprises two parts of cutting off a propagation chain for reducing adverse factors of wind and rain propagation, preventing infection and preventing and treating in time after infection. The lemon trees all year round have flowers or fruits, the most serious lemon trees are not flowers or fruits in 12-3 months all year round, and the other time shows that the flowers and the fruits are the same as the trees, so the lemon trees have extremely high requirements on the wheel spot disease prevention and control technology. The occurrence severity of the alternaria leaf spot is different from the occurrence time of other fungi, and the alternaria leaf spot belongs to new diseases, and related prevention and control experience is lacked. At present, a complete and feasible prevention and control technology system is not provided for resistance identification of the lemon wheel spot disease, which causes the disease of the lemon wheel spot disease to be devastating, has little prevention and control effect and slow breeding process of disease-resistant varieties.

Therefore, through investigation, tracking and experimental research in 2019, a green prevention and control method for lemon wheel spot is developed according to the occurrence situation of the lemon wheel spot in the Wanzhou district in Chongqing, and the lemon wheel spot can be effectively prevented and controlled.

Disclosure of Invention

The invention aims to provide a green prevention and control method for lemon round spot disease, so as to realize effective prevention and control of the lemon round spot disease.

In order to achieve the purpose, the invention provides the following technical scheme:

the green prevention and control method for the alternaria leaf spot comprises the following steps:

s1, reasonably applying fertilizer, and strengthening tree vigor: 2 jin/plant of high-nitrogen germination fertilizer is applied in 2-3 months, and foliar fertilizer and brassin are supplemented and sprayed for 1 time; applying 2 jin/plant of strong fruit fertilizer in the last ten days of 6 months, and spraying foliar fertilizer for 1 time; 1.0-1.5 jin of sun fertilizer is applied to the first batch of fruits in 8 months and each subsequent batch of fruits; applying 5 jin/plant of organic fertilizer in 9-10 months, and spraying foliar fertilizer for 1 time; pruning for 11-12 months, then applying 1 time of 1.5 jin/plant of fruit picking fertilizer, and spraying brassin and foliar fertilizer for 1-2 times;

s2, reasonably trimming, and preserving young shoots: adopting a natural open-heart tree shape, and performing short-cut, thinning, retracting and big branch sawing on fruit trees after picking fruits in winter and before sprouting in spring of the next year; in spring, the ratio of spring shoots to flower buds and young fruits is adjusted by cutting partially overlapped and crossed branches; bud picking, tip releasing and pinching are carried out on the saplings in summer, flower buds and the saplings are picked off in time, summer tips are picked off on adult fruit trees, and excessive flowering branches are thinned; erasing sporadic early autumn tips and performing trunk girdling in autumn, promoting to put orderly autumn tips in the middle ten days of 8 months, pinching when the early autumn tips grow to 6-8 leaves, and erasing late autumn tips germinated after the middle ten days of 9 months;

s3, reasonably loading, and timely harvesting: removing defective fruits, undersized fruits and top fruits before bagging, controlling the fruit retaining amount to be about 2000 kg/mu, and preferably selecting the fruit retaining positions to be the inner bore and the middle-lower part of the tree body; harvesting fruits in time in each batch, and finishing harvesting in the middle ten days of 11 months;

s4, clearing the garden comprehensively and thoroughly: in the middle 11 th month after the fruit picking, adopting 1500 times of liquid full garden spraying of 25 percent of prochloraz, after extremely low temperature in winter, spraying lime sulfur mixture with Baume 1 degree or 0.5 to 0.8 percent of formula Bordeaux mixture once in the full garden to realize winter garden cleaning; 2, spraying a compound pesticide of 800 times of 40% of tebuconazole and prochloraz or 200 times of 97% of mineral oil 150-;

s5, accurate chemical control: in the early spring stage and the early flowering stage of 3 months, the late spring stage and the pre-flowering stage, the summer stage of 5-6 months, the autumn stage and the autumn stage of 7-8 months, 25% of silazole prochloraz or 40% of pentoxazole, prochloraz or 2% of amino-oligosaccharin and 0.5% of urea or 60% of benzyl propiconazole or 30% of difenoconazole or 45% of prochloraz or 3% of zhongshengmycin or 40% of pyraclostrobin, and the difenoconazole is respectively sprayed on tree crowns, tree trunks and the ground for 1 time. For orchards with serious diseases, the pesticide is sprayed once after fruit picking in 11-12 months and before low temperature comes and before garden cleaning in winter.

Further, the step S1 further includes: spraying 2 thousandth of urea, 2 thousandth of monopotassium phosphate, 2000 times of calcium magnesium boron and 1500 times of brassinolide in the months from 10 to 12, spraying the tree crown once in 10 to 15 days, continuously spraying for 2 to 3 times, and covering with a mulching film.

Further, applying fruit-strengthening fertilizer before spraying the fruit retention agent and the insecticidal bactericide for 3-5 days, spraying the fruit retention agent and the insecticidal bactericide when the diameter of the fruit is about 40mm, and bagging after the sprayed agent and dew are dried.

Further, the step S4 further includes: the scabs, the moss and the tilted bark on the trunk and the main branches are scraped off, and then 10 parts of quicklime, 2 parts of lime sulfur, 1 part of salt and 10 parts of clear water are mixed into paste liquid to brush the trunk white.

Further, the step S4 further includes: after picking fruits and before sprouting in winter and before extracting new shoots and sprouting each time, cutting off secondary fruits, diseased leaves and diseased branches of the hanging trees in time, removing dry branches and fallen leaves, fallen fruits, rotten fruits and dry branches in the garden, and intensively burying or burning down the dry branches deeply.

The invention has the beneficial effects that:

the invention improves the soil fertility, strengthens the tree vigor and enhances the cold resistance and the disease and insect damage resistance of the tree body by reasonably applying fertilizer and balancing nutrition; by reasonably pruning and protecting young shoots, the planting density is proper, the tree crowns are good in ventilation and light transmission, blossoming inside and outside and layered three-dimensional fruit bearing are realized, and the occurrence of diseases is reduced; through reasonable loading and timely harvesting, the burden of the tree body is reduced, and favorable conditions for preventing germs from infecting are provided; the base number of germs in the next year is reduced and the severity of the diseases in the next year is reduced through comprehensive and thorough garden cleaning; chemical prevention and control are timely carried out according to high-temperature and high-humidity climate of the three gorges reservoir area, different treetop periods and fruiting characteristics of the lemons, so that good prevention and control effects are achieved, and the prevention and control effects of the pesticide are further improved through alternate rotation and compound pesticide application.

Drawings

Fig. 1 is a flowchart of a green method for controlling a lemon blotch according to an embodiment of the present invention;

FIG. 2 is a representation of lemon fruit at the onset of verticillium wilt;

FIG. 3 is a diagram showing the serious defoliation of fruit trees when the alternaria leaf spot is attacked;

FIG. 4 is a diagram showing the branch tips of fruit trees when the wheel spot disease occurs.

Detailed Description

The invention is described in further detail below with reference to the following figures and embodiments:

analysis of causes of (I) orbicular leaf spot

1. Variety resistance

Resistance differences between citrus varieties. At present, the varieties of the diseases are mainly the varieties of Xingjin, Gongchuan, Wenzhou mandarin oranges, kumquats, Euleke mandarins, Fengjie navel oranges, granulated sugar oranges, Beijing oranges and the like, through early disease resistance identification, the miscellaneous oranges such as 091 seedless wonder oranges and the like are relatively most susceptible to diseases, and the oranges, oranges and oranges have the second resistance, and the pomelo varieties have the strongest resistance.

2. Geographical climate conditions

According to investigation, the first place where the citrus verticillium spot occurs, such as the city county in Shaanxi, is a region with a periodic ice and snow disaster and severe frost, while the town of Bai sheep in Chongqing, Tenn, has long frost duration although severe frost is not generated in winter. Therefore, the freezing injury caused by the positions with lower air temperature, such as windward slopes with the altitude of more than 500 meters, valley low-lying areas, flat paddy fields and air ports, or low-temperature wind damage is the main cause of serious wheel spot disease.

3. Mismanagement

Excessive load, wet damage and improper fertilization neglect the protection of each young sprout and the cleaning of the garden, which leads to serious occurrence of the lemon wheel spot.

(II) the wheel spot disease prevention and control method comprises the following steps:

s1, fertilizing reasonably, and cultivating strong tree

According to investigation and analysis of fertilization conditions of lemon gardens with different tree vigors, the lemon wheel spot disease belongs to weak parasitic pathogen like anthracnose, and can only cause great occurrence under the condition that lemon trees are weak. 2019. 2021 in winter, frost is light, and lemon gardens with serious diseases are most orchards for farmers to lose control, and are severely weakened in tree vigor, and enterprise orchards with good management have strong tree vigor and relatively light diseases. The farmers lose management of the orchard, the nitrogen fertilizer is excessively applied, the organic fertilizer is less in dosage, the phosphorus-potassium fertilizer is insufficient in dosage, and the nutrient proportion is seriously imbalanced, so that branches are vigorous and long, the development of the branches and the leaves is insufficient and not robust, the deficiency-fat phenomenon is formed, and a great amount of favorable conditions are provided for the invasion harm of the alternaria alternata.

Increase soil organic matter, pay attention to balanced application of nitrogen phosphorus potassium fertilizer and microelement fertilizer, loosen the soil, balance nutrition, improve soil fertility. Applying high nitrogen (nitrogen content is more than or equal to 20%) sprouting fertilizer 2 jin/plant for 2-3 months, and supplementing medium and trace element leaf fertilizer containing boron, zinc, magnesium and the like and brassin for 1 time; 2 jin of strong fruit fertilizer (the content of potassium is more than or equal to 20%) is applied for 6-7 months, and foliar fertilizer containing potassium, magnesium and zinc elements is sprayed on the leaf surface for 1 time; 5 jin/plant of organic fertilizer is applied in 9-10 months, and foliar fertilizer containing phosphorus, potassium, boron, zinc and magnesium elements is sprayed for 1 time; pruning for 11-12 months, applying 1 time of 1.5 jin/plant of fertilizer (low-nitrogen high-phosphorus potassium fertilizer), and spraying brassin and foliage fertilizer containing B, Zn and Mg for 1-2 times.

Aiming at the current high emergence situation of the leaf spot of the Wanzhou lemon, which causes large-area dead branches and leaves and even dead trees, 2 thousandths of urea, 2 thousandths of dihydrogen phosphate, 2000 times of potassium, calcium, magnesium and boron and a certain proportion of plant growth regulators such as brassin and the like are sprayed on the tree crowns from immediately before winter (before and after fruit picking) in the current 10 months, and the tree crowns are sprayed once at 10-15d and continuously sprayed for 2-3 times. The mulching film is covered in winter, the prevention and the treatment of plant diseases and insect pests are enhanced, the resistance of leaves is improved, and the morbidity and the fallen leaves can be effectively reduced.

1. Experimental protocol

In 2021-2022 years, in the lemon wheel spot disease area of white sheep town Yancun in Chongqing Wanzhou district, winter leaf protection test was carried out for three consecutive years, no rain occurred within 7h after drug application, and the time and climate of drug application are listed in the following table one.

Watch 1

The pesticide application adopts a 3WBD-16HBA type knapsack electric sprayer of Taizhou city road bridge Fuda sprayer factory, the operation is carried out by double hollow conical spray heads, the inside and the outside of the tree crown are evenly sprayed until the spraying is wet, the spraying pesticide liquid amount is 50 kg/treatment, 3 trees are treated in each way, 3 times of treatment are set, and 9 trees are treated in each way. The cells are randomly distributed. When the medicine is applied, the lemon is just in the period of lowest temperature in the state of ten thousand, and the wheel blotches and fallen leaves begin to appear. During the test, the test area is cleared of the garden in winter and is beaten with lime sulfur mixture once.

Treatment 1: spraying the tree crown with 2 per mill urea, 2 per mill monopotassium phosphate and 1500 times of brassinolide before winter (before and after picking fruits) in 10 months, and continuously spraying for 2-3 times at 10-15 days.

And (3) treatment 2: spraying the tree crown with 2% of urea, 2% of monopotassium phosphate and 1500 times of brassinolide before winter (before and after picking fruits) in 10 months, spraying the tree crown once in 10-15 days, continuously spraying for 2-3 times, and covering with a plastic film.

And (3) treatment: before winter in 10 months (before and after picking fruits) to 12 months, spraying 2 per mill urea, 2 per mill monopotassium phosphate, 2000 times of calcium magnesium boron and 1500 times of brassinolide on tree crowns, spraying for one time at 10-15 days, continuously spraying for 2-3 times, covering with mulching film in 12 months, and removing withered branches and fallen leaves in the garden and rotten fruits to intensively burn or deeply bury after picking fruits in 11 months. 10 parts of quicklime, 2 parts of lime-sulfur mixture, 1 part of salt and 10 parts of clear water, and the mixture is blended into pasty whitening agent for whitening.

And (4) treatment: after 11 months, the fruits are picked, and the withered branches and fallen leaves in the garden and rotted fruits are intensively burnt or deeply buried. 10 parts of quicklime, 2 parts of lime-sulfur mixture, 1 part of salt and 10 parts of clear water.

And (4) treatment 5: and (5) spraying clear water.

The specific drugs used are listed in table two.

Watch two

2. Investigation method

The control effect is investigated in 3 months and 20 days when the incidence of the alternaria leaf spot is basically stable. And (3) repeatedly investigating 3 fruit trees, wherein each fruit tree investigates 5 points according to 5 directions in east, west, south and north, each point has 1 tip and 15 tips in total, investigates all the leaves of each tip, records the grade number of the damaged leaves, and calculates the damage index and the leaf protection effect of the leaves.

Grading standard of leaf diseases: grade 0, no disease; grade 1, the lesion area accounts for less than 5% of the whole leaf area; grade 3, the lesion area accounts for 6 to 10 percent of the whole leaf area; grade 5, the lesion area accounts for 11% -25% of the whole leaf area, grade 7, the lesion area accounts for 36% -50% of the whole leaf area; grade 9, the lesion area accounts for more than 51% of the whole leaf area.

The efficacy calculation method is as follows: disease index ∑ [ leaf number of disease (fruit) of each grade × relative grade value ] ÷ [ survey total leaf (fruit) number × 9] × 100

Preventing and treating effect (%) [ control region disease index-treatment region disease index ] ÷ control region disease index x 100

Statistical data were analyzed using the SPSS 20 software system and differential significance analysis was performed using the duncan new repolarization technique (DMRT).

3. Test results

Winter nutrition leaf-protecting test survey result table (third table)

The results show that before winter, in 12 months after fruit picking, 2 thousandth of urea, 2 thousandth of monopotassium phosphate, 2000 times of calcium magnesium boron and 1500 times of brassinolide are sprayed on the tree crown, and the tree crown is sprayed for 2-3 times continuously after 10-15 days, and is covered with a mulching film, so that the tree trunk is whitewashed, the resistance of the tree body can be effectively enhanced, the fallen leaves and the disease can be reduced, and the control effect can reach 87.71%. The measure is particularly important for orchards with serious diseases, can help resist the coming wheel spot outbreak in the last 12 months, and reduces the disease incidence degree.

S2, trimming reasonably and keeping young sprout

According to early observation, the occurrence of the leaf spot of the lemon is mainly harmful to leaves, fruits and branches of the whole tree in winter, and the occurrence of the leaf spot of the branches, the leaves and the fruits which are not aged in winter and the leaves at the middle and lower parts of the tree in spring and autumn is particularly serious. In order to reduce the occurrence of diseases, the tree crowns are kept ventilated and transparent, key young shoots are well protected, and summer shoots are treated in time. Aiming at the current climate situations of high temperature, much humidity and much and little fog in the three gorges reservoir area, the lemons adopt a natural open heart-shaped tree form, and after fruit picking, before sprouting in the next spring, the fruit bearing trees are subjected to short-cut, thinning-shear, retraction and big-branch sawing, dead branches, insect-plague branches, thin and weak bore branches, anywhere branches, overgrown branches and the like, so that the canopy closure is prevented. The flower amount is fully considered in the pruning of other seasons, the light pruning is mainly used, the tree vigor is strong and weak in spring according to the size of the tree, the ratio of spring shoots to flower buds and young fruits is adjusted through the overlapping and crossing branches of the short sections, and the fruit retaining amount is determined, so that the purpose of strengthening the tree vigor is achieved; bud picking, tip releasing and pinching are carried out on the saplings in summer, flower buds and the saplings are picked off in time, summer tips are picked off on adult fruit trees, and excessive flowering branches are thinned; erasing sporadic early autumn tips and trunk girdling in autumn, advancing the tip-releasing time to the middle of 8 months, promoting the orderly release of the early autumn tips, timely pinching when the early autumn tips grow to 6-8 leaves, simultaneously enhancing fertilizer and water management, and spraying 1-2 times of monopotassium phosphate to ensure early lignification. The late autumn shoots sprouting after 9 th of the middle ten days are erased in time, malformed fruits and over dense fruits are thinned out, and the cold resistance and the disease resistance are enhanced. Aiming at the saplings, the method mainly cultures crowns, is little or no in shearing, can cut off long summer shoots for a short time, cultures tree forms early and cultures enough mother branches with good results.

Meanwhile, reasonable thinning, plant separation or interlaced thinning are adopted for orchards with overlarge density and orchard construction in the early stage, so that ventilation and light transmission of trees are enhanced.

S3, reasonable loading, timely harvest

The lemon has the characteristics of blooming in four seasons and bearing fruits, and long picking period. According to earlier investigation, most fruit growers in white sheep towns in the Wanzhou area blindly pursue current-year yield, the yield is usually over 3000 kg/mu, and the high fruit growers exceed 3500 kg/mu and exceed the load capacity of trees for a long time, so that serious leaf fall, tree weakness and serious reduction of the resistance of various diseases are caused.

1. Reasonable load and adjustable yield

In order to reduce the occurrence of diseases, proper planting density is required to be kept, and the tree crown is ventilated and transparent, blooms inside and outside, and can fruit in a layered and three-dimensional manner. The residual fruits, the small fruits and the top fruits are thinned and removed before bagging of the lemons, so that the fruit retention amount is controlled, the fruit retention amount is controlled to be about 2000 kg/mu, the tree vigor recovery is facilitated, the big and small years are reduced, and the high yield and stable yield are ensured. The fruit-remaining part is preferably the inner bore and the middle-lower part of the tree body.

2. Harvesting in time after fruit ripening

In a Wanzhou lemon production area under the unique geographical climate condition of the Sanxia reservoir area, the fruits are harvested for 3 times in four seasons of one year, namely spring flowers and fruits, summer flowers and autumn flowers and fruits, mature fruits, immature fruits, young fruits and flowers exist in each season, the picking workload is large, and the fruits are not easy to distinguish, so that each batch of fruits are particularly paid attention to timely harvesting, the harvesting of early and middle mature varieties such as lemon, Fengjie navel orange, granulated sugar orange and the like is finished in the middle and middle ten days of 11 months, firstly, the harvesting is timely carried out, the tree burden is reduced, secondly, the late low temperature is prevented from coming, the physalospora piricola shows spots on the surfaces of the fruits, and the fruit commodity is reduced. After harvesting is finished, the defective fruits and the winter flowers which are not picked are timely picked, so that favorable conditions are provided for avoiding germ infection.

3. Enhanced post-harvest management

After each fruit picking, 1.0-1.5 jin/plant of fertilizer is applied to supplement nutrients to the tree, which is favorable for recovering the tree vigor and enhancing the disease resistance of the tree. If young shoots are taken out in autumn, foliage fertilizer is sprayed timely to supplement medium trace elements such as phosphorus, potassium, calcium, magnesium, boron and the like, so that the young shoots are accelerated to be mature, if young shoots are taken out vigorously in summer, the young shoots are wiped off timely, and the young shoots can be picked or cut off to promote the growth of regular young shoots and culture mother branches with excellent fruiting.

S4, clearing garden thoroughly

1. And (4) intensively treating the diseased tissues. In an orchard where the lemon wheel spot occurs, after fruit picking and before sprouting in winter and before sprouting of each new shoot, timely pruning secondary fruits, diseased leaves and diseased branches of the hanging trees, removing dry branches, fallen fruits, rotten fruits and dry branches in the orchard, and intensively burying or burning the dead branches deeply.

2. Cleaning the garden with the pesticide in winter. According to earlier observation, the occurrence of the verticillium wilt of the lemon trees is mainly in winter, all leaves, fruits and branches of the whole trees can be damaged, the occurrence of the branches, leaves and fruits which are not aged in winter and the leaves at the middle and lower parts of the trees in spring and autumn is particularly serious, the occurrence of the verticillium wilt in the same year cannot be reduced by clearing the orchard with the pesticide in winter, the base number of germs in the next year is reduced, and the severity of the occurrence of the diseases in the next year is reduced. After fruit picking (11 last ten days), 25% prochloraz 1500-fold liquid is sprayed in the whole garden, after extreme low temperature in winter, 1-degree Baume lime sulphur or 0.5% -0.8% of Baume Bordea liquid is sprayed in the whole garden thoroughly on the crown and the ground, meanwhile, scabs, lichens and tilted skins on the trunk and the main branches are scraped, and then 10 parts of quicklime, 2 parts of lime sulphur, 1 part of salt and 10 parts of clear water are mixed into pasty liquid to brush the trunk white. Therefore, the sterilization, warming and warming effects are achieved, and the freezing injury is reduced.

3. Cleaning garden with the medicament in spring. Spring clearing of lemon blotch is critical to reducing the severity of the occurrence of the blotch. The incidence time of the cercospora leaf spot is from the first 12 middle months to the last 3 middle months of the following year each year, and the development is not continued. In the first winter, germs infect tissues in the early spring, summer, autumn and other shoot eruption periods, and the harm is caused only when the temperature is reduced, and at the moment, the current year development of the germs cannot be prevented by spraying more chemicals. Therefore, the cleaning of the disease in spring is more critical than the cleaning in winter. In the middle ten days before the lemon sprouts, namely the disease degree caused by the early alternaria alternata is fixed and does not continue to expand, and when the young shoots are not sprouted in the year, the spring garden is cleaned by adopting 40% of pentoxazole, 800 times of prochloraz or 97% of mineral oil 150 and 200 times of liquid or 40% of pyridaben, 5000 times of etoxazole or 5000 times of 22.4% of spirotetramat for 5000 times. Attention is paid to alternate and compound medication to improve the prevention and treatment effect of the medicament.

S5, prevention and treatment by accurate chemical agent

According to a great deal of investigation on the occurrence condition of wheel spot in an orchard in the early period, the characteristics of the wheel spot of the lemon in special climates in the three gorges reservoir area are mainly shown as the onset period from 12 middle ten days to 3 middle ten days, the disease spots basically do not continue to expand after 3 middle ten days, and the severity is also shown to be stable. The disease parts are mainly expressed in the spring tips and autumn tips of the middle and lower parts of the tree body, the aged leaves of the autumn tips, the summer tips of the upper parts, the un-aged leaves of the autumn tips and the leaves. In winter, if the fruit is not picked, the ripe fruit and part of immature young fruit are infected with the alternaria leaf spot. Therefore, the prevention and control of the lemon wheel spot are based on prevention and comprehensive prevention and control, and chemical prevention and control are timely and accurately carried out according to different tip pulling periods and fruiting characteristics.

In 2019 to 2022, field efficacy tests are carried out in Huimin village, double-stone community and Baiyancun of sheep town, 4 effective medicaments are screened, and 4 combinations with better control effect are screened. The specific scheme is as follows:

1. method of administering a drug

Selecting different medicaments, and spraying tree crowns, tree trunks and the ground for 1 time respectively after picking fruits in 3 months middle and late ten days and before blossom, in 5-6 months summer early season, in 7-8 months autumn and autumn early season, in 11-12 months and before low temperature comes, and spraying the medicaments for 5-6 times in total.

2. Investigation method

The investigation was carried out when the onset was stable and no longer extended. Trees were planted per plot in 3 replicates each. Sampling at east, south, west and north 4 points, and randomly investigating 1-2 branches at least 30 leaves at each point. Calculating disease index and preventing and treating effect.

Grading standard of leaf diseases: grade 0, no disease; grade 1, the lesion area accounts for less than 5% of the whole leaf area; grade 3, the lesion area accounts for 6 to 10 percent of the whole leaf area; grade 5, the lesion spot area accounts for 11-25% of the whole leaf area, and grade 7, the lesion spot area accounts for 36-50% of the whole leaf area; grade 9, the lesion area accounts for more than 51% of the whole leaf area.

Disease index ∑ [ leaf number of disease (fruit) of each grade × relative grade value ] ÷ [ survey total leaf (fruit) number × 9] × 100

Preventing and treating effect (%) [ control region disease index-treatment region disease index ] ÷ control region disease index x 100

Watch four

Investigation data of field control effect of different medicament treatment on lemon wheel spot disease (table five)

The disease condition of the leaves is stable in 25 days in 3 months, the wheel blotch symptom is obvious, and the extension is stopped, at the moment, the investigation is easy and feasible. According to investigation data, the selected medicament has certain prevention effect on the lemon wheel spot, wherein the treatment amount of 16, 4, 14, 11, 1, 5, 6, 8, 3, 17, 2, 9, 10, 12, 13, 7 and 18 is 25% of silazole, the maximum prevention effect of prochloraz is 94.73%, 40% of pentazole, prochloraz, 2% of amino-oligosaccharin and 0.5% of urea are treated, the prevention effects are 91.63%, 60% of benzyl chloride and propiconazole are treated, the prevention effect is 91.51%, the prevention effect is 5 medicaments with 80% -89%, and the treatment amount of 3% of zhongshengmycin and 29% of lime sulfur mixture/99% of mineral oil is also included. The two types of medicaments are green prevention and control main push medicaments, are cost-saving and synergistic and green environment-friendly medicaments, and can be popularized and used for production in a large area as long as the application period is mastered. The effective prevention rate is 60% -70% of 4 kinds of medicine, including 2%. 8 hundred million/g Jinggang wax bud fungus and novel plant immune protein regulator, also is biological bacterial agent and nutrition supplement product with relatively good effect. The result of the control proves that the control effect of the lemon wheel spot is improved again, and the control method can be started from the aspects of supplementing plant nutrition and increasing stress resistance. The control effect is less than 60% of 4 medicaments which are common medicaments in production, the control effect of 13% of thia-flutriafol is 59.91%, but the control effects of 70% of thiophanate methyl, 25% of pyraclostrobin and 33% of kasuga copper are less than 32%, and the control effect is poor.

The results show that after fruit picking in 11-12 months and before low temperature comes in 3 months middle and late in spring and early blossoming, 5-6 months summer and early blossoming, 7-8 months autumn and late blossoming, orchards with serious morbidity, 25% of silazole, prochloraz or 40% of pentoxazole, prochloraz or 2% of amino oligosaccharin and 0.5% of urea or 60% of benzyl propiconazole are used, the prevention effect is more than 90%, wherein the 25% of silazole and prochloraz have the highest prevention effect which reaches 94.73%. 30 percent of difenoconazole or 45 percent of prochloraz or 3 percent of zhongshengmycin and 40 percent of pyraclostrobin are adopted, and the prevention effect of the difenoconazole is also high and reaches more than 85 percent. The alternating and compound application is noticed, the supplement of trace elements in the medicine is reasonably matched, and the prevention and treatment effect of the medicine is improved. Therefore, in the prevention and control of the lemon wheel spot, the best prevention and control period is selected, the medicaments with good prevention and control effects are alternately used, auxiliary agents such as mineral oil or vegetable oil are matched, the medicament is also required to be alternately used, the nutrition is supplemented, and the better prevention and control effect can be achieved.

The foregoing is merely an example of the present invention and common general knowledge in the art of designing and/or characterizing particular aspects and/or features is not described in any greater detail herein. It should be noted that, for those skilled in the art, without departing from the technical solution of the present invention, several variations and modifications can be made, which should also be regarded as the protection scope of the present invention, and these will not affect the effect of the implementation of the present invention and the practicability of the patent. The scope of the claims of the present application shall be determined by the contents of the claims, and the description of the embodiments and the like in the specification shall be used to explain the contents of the claims.

Claims (5)

1. The green prevention and control method for the leaf spot of lemon is characterized by comprising the following steps of:

s1, reasonably applying fertilizer, and strengthening tree vigor: 2 jin/plant of high-nitrogen germination fertilizer is applied in 2-3 months, and foliar fertilizer and brassin are supplemented and sprayed for 1 time; applying 2 jin/plant of strong fruit fertilizer in the last ten days of 6 months, and spraying foliar fertilizer for 1 time; applying 1.0-1.5 jin of Huanyang fertilizer per plant after the first batch of fruits and each subsequent batch of fruits in 8 months; applying 5 jin/plant of organic fertilizer in 9-10 months, and spraying foliar fertilizer for 1 time; pruning for 11-12 months, then applying 1 time of 1.5 jin/plant of fruit picking fertilizer, and spraying brassin and foliar fertilizer for 1-2 times;

s2, reasonably trimming, and preserving young shoots: adopting a natural open-heart tree shape, and performing short-cut, thinning, retracting and big branch sawing on fruit trees after picking fruits in winter and before sprouting in spring of the next year; in spring, the ratio of spring shoots to flower buds and young fruits is adjusted by cutting partially overlapped and crossed branches; bud picking, tip placing and core picking are carried out on the saplings in summer, flower buds and the saplings are picked off in time, summer tips are picked on adult bearing trees, and excessive flower branches are removed; erasing sporadic early autumn tips and performing trunk girdling in autumn, promoting to put orderly autumn tips in the middle ten days of 8 months, pinching when the early autumn tips grow to 6-8 leaves, and erasing late autumn tips germinated after the middle ten days of 9 months;

s3, reasonably loading, and timely harvesting: removing defective fruits, undersized fruits and top fruits before bagging, controlling the fruit retaining amount to be about 2000 kg/mu, and preferably selecting the fruit retaining positions to be the inner bore and the middle-lower part of the tree body; harvesting fruits in time in each batch, and finishing harvesting in the middle ten days of 11 months;

s4, clearing the garden comprehensively and thoroughly: in the middle 11 th month after the fruit picking, adopting 1500 times of liquid full garden spraying of 25 percent of prochloraz, after extremely low temperature in winter, spraying lime sulfur mixture with Baume 1 degree or 0.5 to 0.8 percent of formula Bordeaux mixture once in the full garden to realize winter garden cleaning; 2, spraying a compound pesticide of 800 times of 40% of tebuconazole and prochloraz or 200 times of 97% of mineral oil 150-;

s5, accurate chemical control: in the middle and late spring blossoming periods of 3 months, before blossoming, in the summer blossoming period of 5-6 months, in the autumn bloom period of 7-8 months and in the autumn blossoming period, 25% of silazole, prochloraz or 40% of pentoxazole, prochloraz or 2% of amino-oligosaccharin + 0.5% of urea or 60% of benzyl-propiconazole or 30% of difenoconazole or 45% of prochloraz or 3% of zhongshengmycin or 40% of pyraclostrobin are respectively sprayed on the crown, the trunk and the ground for 1 time. For orchards with serious diseases, the pesticide is sprayed for 1 time after fruit picking in 11-12 months and before low temperature comes and before garden cleaning in winter.

2. The method for preventing and controlling lemon blotch as claimed in claim 1, wherein the step S1 further comprises: spraying 2 per mill urea, 2 per mill monopotassium phosphate, 2000 times of calcium magnesium boron and 1500 times of brassinolide in the months from 10 to 12, spraying the tree crowns once at 10 to 15 days, continuously spraying for 2 to 3 times, and covering with a mulching film.

3. The method for green prevention and control of lemon wheel spot according to claim 1, characterized in that: applying fruit strengthening fertilizer before spraying the fruit retention agent and the insecticidal bactericide for 3-5 days, spraying the fruit retention agent and the insecticidal bactericide when the diameter of the fruit is about 40mm, and bagging after the sprayed liquid medicine and dew are dried.

4. The method for green prevention and control of lemon wheel spot according to claim 1, characterized in that: the step S4 further includes: the scabs, the moss and the tilted bark on the trunk and the main branches are scraped off, and then 10 parts of quicklime, 2 parts of lime sulfur, 1 part of salt and 10 parts of clear water are mixed into paste liquid to brush the trunk white.

5. The method for preventing and controlling lemon blotch as claimed in claim 1, wherein the step S4 further comprises: after picking fruits and before sprouting in winter and before extracting new shoots and sprouting each time, cutting off secondary fruits, diseased leaves and diseased branches of the hanging trees in time, removing dead branches and fallen leaves, fallen fruits, rotten fruits and dead branches in the garden, and intensively burying or burning down the dead branches deeply.

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