Apple brown spot mainly damages the leaves, which is the main disease causing apple early defoliation. In recent years, brown spot disease has been aggravated year by year in the main apple producing areas in the Guanzhong region and has become a major disease affecting apple production. The recurrence of brown spot disease is easy to form early defoliation, which seriously affects the later growth of the fruit and reduces the grade of the fruit; affects the flower bud differentiation, makes the quality of flower buds decline in the coming year, and the poor anti-resistance capacity seriously weakens the tree vigor, resulting in aggravation of various pests and diseases. .
I. Occurrence and harm symptoms of brown spot disease Apple brown spot pathogens mainly overwinter on diseased leaves with hyphae and conidia. The pathogenic bacteria that survived the overwintering season produced a large number of conidia under suitable climatic conditions in the following spring.
The initial infection of lesions occurs mainly in the lower part of the tree, close to the ground on the leaves, and then the infection spreads gradually with the rain splashing. Therefore, the order of occurrence of brown spot disease is: the leaf near the ground → the inner leaf of the inner church → the inner church leaf → the outer leaf of the crown. The field distribution of brown spot mainly depends on the distribution of the overwintering bacterium, and there is a clear epidemiological center. Due to the close distance of pathogenic bacteria, the number of bacteria per unit area is often very large. At the onset of endodermis, there are often hundreds of lesions on one leaf, and the leaves fall off soon after onset.
In the Guanzhong West apple production area, the initial infestation period of brown spot disease was observed from May to June. The brown spot disease leaf was seen in the middle and mid-May. In June, the period of rapid accumulation of the pathogenic bacteria, and the lesions formed by the initial infection occurred. A large number of conidia continue to be re-infected, resulting in a large number of pathogenic bacteria accumulation and disease epidemic, severe disease, resulting in a large number of fallen leaves.
Second, brown spot control and control of brown spot disease, agricultural measures should be used and the prevention and treatment of drugs, comprehensive prevention and control.
1, remove the source of the disease. Brown spot pathogens mainly overwinter on deciduous trees. Clearing diseased leaves in orchards and near orchards can greatly reduce the source of overwintering bacteria. Before the apple sprouts, completely clean up the fallen leaves of the orchard and burn them centrally or deeply. When sporadic patches of brown spot occur in May-June, early lesions are more concentrated, mostly in the lower part of the canopy, and diseased leaves are removed, and diseased leaves are picked up and taken out of the field for destruction, which can greatly reduce re-infested germs. Delay a lot of leaf time.
2. Orchard management. The cut branches of the stem base and branches below 50 cm from the ground in spring can reduce the number of initial infections and effectively control the occurrence of diseases. Reasonable pruning can increase the light conditions of the orchard, reduce the relative humidity in the garden, shorten the condensation time of the foliage, and effectively reduce the amount of pathogenic bacteria. Reasonable fertilizer can increase tree vigor and delay the shedding speed of diseased leaves.
3, chemical control. Although the high incidence period of apple brown spot occurred in July-August, the key period of prevention and control was the growth period before the arrival of the rainy season. General prevention and treatment should do a good job at the same time, do a good job after the apple fell to the end of May this period, if there is more than 5mm rainfall during this period, continuous duration of more than 24hr continuous rain, spray within 1 week after the system should be sprayed therapeutic agent, The interval between consecutive medications should be no less than 10 days. In early June, a systemic therapeutic agent should be administered. The time should be selected after the rain. In the middle of June, a protective agent should be sprayed before the rainy season. The ideal agent is Bordeaux mixture. Before the end of the rainy season in July-August, prevention and control should be carried out according to the disease conditions in the orchard. If the diseased leaf rate reaches or exceeds 1%, continuous medication should be administered 1-3 times, once every 10-15 days, and adducts should be promoted. Protectants are used interchangeably.
Prevention and control of apple brown spot production is mainly alternating with the use of protective fungicides and therapeutic therapeutic fungicides. From the beginning of July, it is necessary to administer the medicine every 10-15 days, until the early September, timely spraying in continuous rain, not only can effectively control the brown spot, but also have good prevention and treatment of ringworm disease, anthrax disease effect. Bordeaux fluid is the preferred protective agent. Bordeaux fluid's greatest advantage is its resistance to rain and water, and it lasts for a long period of time. It is particularly suitable for continuous rainy season in July and August. However, using Bordeaux fluid before fruit enlargement is prone to injury. The preferred agent for the systemic therapeutic agent is the triazole fungicide, such as Guinness, Kaige, Difenoconazole, azoxystrobin, etc., followed by benzimidazoles, such as carbendazim and thiophanate-methyl. In order to improve the efficacy and prolong the efficacy of drugs on rainy days, high-efficiency auxiliaries and retardants (such as Roushuitong, Linshengbaoye retardant, and osmotic treasure, etc.) can be added to prolong the effective period of the bactericidal agent for about 10 days. Can reduce the number of applications and pesticide use. Spraying within 7 days after pathogenic bacteria infestation can effectively control the spread of pathogens and the occurrence of diseases. In the spray fungicide at the same time mixed with appropriate insecticides to control aphids, spider mites, gold moth and so on.
I. Occurrence and harm symptoms of brown spot disease Apple brown spot pathogens mainly overwinter on diseased leaves with hyphae and conidia. The pathogenic bacteria that survived the overwintering season produced a large number of conidia under suitable climatic conditions in the following spring.
The initial infection of lesions occurs mainly in the lower part of the tree, close to the ground on the leaves, and then the infection spreads gradually with the rain splashing. Therefore, the order of occurrence of brown spot disease is: the leaf near the ground → the inner leaf of the inner church → the inner church leaf → the outer leaf of the crown. The field distribution of brown spot mainly depends on the distribution of the overwintering bacterium, and there is a clear epidemiological center. Due to the close distance of pathogenic bacteria, the number of bacteria per unit area is often very large. At the onset of endodermis, there are often hundreds of lesions on one leaf, and the leaves fall off soon after onset.
In the Guanzhong West apple production area, the initial infestation period of brown spot disease was observed from May to June. The brown spot disease leaf was seen in the middle and mid-May. In June, the period of rapid accumulation of the pathogenic bacteria, and the lesions formed by the initial infection occurred. A large number of conidia continue to be re-infected, resulting in a large number of pathogenic bacteria accumulation and disease epidemic, severe disease, resulting in a large number of fallen leaves.
Second, brown spot control and control of brown spot disease, agricultural measures should be used and the prevention and treatment of drugs, comprehensive prevention and control.
1, remove the source of the disease. Brown spot pathogens mainly overwinter on deciduous trees. Clearing diseased leaves in orchards and near orchards can greatly reduce the source of overwintering bacteria. Before the apple sprouts, completely clean up the fallen leaves of the orchard and burn them centrally or deeply. When sporadic patches of brown spot occur in May-June, early lesions are more concentrated, mostly in the lower part of the canopy, and diseased leaves are removed, and diseased leaves are picked up and taken out of the field for destruction, which can greatly reduce re-infested germs. Delay a lot of leaf time.
2. Orchard management. The cut branches of the stem base and branches below 50 cm from the ground in spring can reduce the number of initial infections and effectively control the occurrence of diseases. Reasonable pruning can increase the light conditions of the orchard, reduce the relative humidity in the garden, shorten the condensation time of the foliage, and effectively reduce the amount of pathogenic bacteria. Reasonable fertilizer can increase tree vigor and delay the shedding speed of diseased leaves.
3, chemical control. Although the high incidence period of apple brown spot occurred in July-August, the key period of prevention and control was the growth period before the arrival of the rainy season. General prevention and treatment should do a good job at the same time, do a good job after the apple fell to the end of May this period, if there is more than 5mm rainfall during this period, continuous duration of more than 24hr continuous rain, spray within 1 week after the system should be sprayed therapeutic agent, The interval between consecutive medications should be no less than 10 days. In early June, a systemic therapeutic agent should be administered. The time should be selected after the rain. In the middle of June, a protective agent should be sprayed before the rainy season. The ideal agent is Bordeaux mixture. Before the end of the rainy season in July-August, prevention and control should be carried out according to the disease conditions in the orchard. If the diseased leaf rate reaches or exceeds 1%, continuous medication should be administered 1-3 times, once every 10-15 days, and adducts should be promoted. Protectants are used interchangeably.
Prevention and control of apple brown spot production is mainly alternating with the use of protective fungicides and therapeutic therapeutic fungicides. From the beginning of July, it is necessary to administer the medicine every 10-15 days, until the early September, timely spraying in continuous rain, not only can effectively control the brown spot, but also have good prevention and treatment of ringworm disease, anthrax disease effect. Bordeaux fluid is the preferred protective agent. Bordeaux fluid's greatest advantage is its resistance to rain and water, and it lasts for a long period of time. It is particularly suitable for continuous rainy season in July and August. However, using Bordeaux fluid before fruit enlargement is prone to injury. The preferred agent for the systemic therapeutic agent is the triazole fungicide, such as Guinness, Kaige, Difenoconazole, azoxystrobin, etc., followed by benzimidazoles, such as carbendazim and thiophanate-methyl. In order to improve the efficacy and prolong the efficacy of drugs on rainy days, high-efficiency auxiliaries and retardants (such as Roushuitong, Linshengbaoye retardant, and osmotic treasure, etc.) can be added to prolong the effective period of the bactericidal agent for about 10 days. Can reduce the number of applications and pesticide use. Spraying within 7 days after pathogenic bacteria infestation can effectively control the spread of pathogens and the occurrence of diseases. In the spray fungicide at the same time mixed with appropriate insecticides to control aphids, spider mites, gold moth and so on.