6-8 How to prevent and control monthly apple anthracnose blight? What are the symptoms? What are the specific drugs?

Speaking of apple anthracnose leaf blight, many fruit growers will have a headache. Anthracnose leaf blight pathogen because of its short incubation period, fast spread, once susceptible, control is not timely, from infection to defoliation only three days, resulting in a large number of early fruit trees defoliation, reduce fruit quality, and even destroy the garden. How to control apple anthracnose leaf blight? What specific drugs do you have?

Recently, there has been a trend of large-scale outbreak of apple anthracnose leaf blight, and it has shown several new characteristics: first, it has developed from early-maturing varieties to medium-maturing varieties (including Marshal apples), and second, from leaf disease to all leaf and fruit disease. third, once the disease causes serious defoliation, and drugs are difficult to cure.

Why anthrax leaf blight is so difficult to prevent

1. The harm is serious

It mainly harms leaves and fruits, causes a large number of early fallen leaves, reduces fruit quality, and even destroys the garden.

two。 The incubation period is short

Once infected, prevention and treatment is not timely, from infection to fallen leaves only three days

3. Spread a long distance

The spores spread with the air and spread outward at a rate of 200 kilometers a year.

4. There are great differences in varieties.

There are great differences in disease resistance among different apples. Gala, Qin Guan and Jin Guan are easy to infect varieties, while Fuji is difficult to infect.

Incidence characteristics of apple anthracnose leaf blight

At the beginning of anthrax leaf blight, a number of dry disease spots were distributed on the leaves, and the disease spots were brown at the beginning. Under the condition of high temperature and high humidity, the disease spots expanded rapidly and spread to the whole leaf in about 2 days. The whole tree leaves withered and shedded in 2-3 days, and the withered leaves were dark in color, mostly dark brown, just like being burned by fire. When the environmental conditions are not suitable, dead spots of different sizes are formed on the leaves, and the healthy tissues around the disease spots turn yellow, and the seriously sick leaves fall off quickly. When the disease spot is small and more, the disease symptoms of the diseased leaves are similar to those of brown spot disease. There are many round brown sunken disease spots 1-2 mm in diameter on the fruit surface of the damaged fruit, the fruit surface around the disease spot is red halo, the pulp under the disease spot is brown spongy, the depth is about 2 mm, the number of disease spot is large, and the number of disease spot on a single fruit is up to hundreds. The diseased fruit becomes "hemp noodle fruit", and the disease spot no longer expands. Under natural conditions, there are few spores on the fruit spot, which is obviously different from the common apple anthracnose.

Onset time of apple anthracnose leaf blight

June to August is the most suitable month for the occurrence of apple anthracnose leaf blight, when the temperature is about 30 ℃, Rain Water is abundant, which can fully meet the conditions of transmission, infection and disease of apple leaf anthracnose, and is the peak period of the disease. Compared with brown spot, anthracnose leaf blight has the characteristics of short incubation period, large spore production, rapid onset, fast speed and fierce coming force. There are no small black spots on the disease spot, and most of the disease is caused by yellowing and shedding of the leaves at the periphery of the crown or at the base of the upper shoot, gradually upward and inward, and in serious cases, the whole tree leaves are bare, leaving only the fruit.

Causes of apple anthracnose leaf blight

1. Due to the reduction of production due to frost in a large area of the country this year, coupled with more precipitation in the early stage, the load of fruit trees is relatively light and prosperous, which leads to poor ventilation and light transmission of fruit trees.

two。 The orchards with anthrax leaf blight over the years have not been completely cured, and the number of pathogens is large.

3. Rainfall in spring and summer increases the humidity of orchards, which is conducive to the propagation and infection of pathogens.

4. The reduction of yield in frozen orchards leads to the abandonment of management by fruit growers, resulting in inadequate prevention.

5. The early freezing injury caused some rotten leaves and was easily infected by various bacteria.

Suggestions on prevention and control of apple anthracnose leaf blight

1. Strengthen agricultural prevention and control. The drainage facilities should be renovated before the rainy season to ensure that the stagnant water in the orchard can be removed in time. Closed orchards should be pruned in summer to improve ventilation and light transmission. After the occurrence of the disease, the fallen leaves should be removed in time and taken out of the garden for sterilization, and the trees should be sterilized by spraying. Remove the diseased fruit as early as possible to avoid excessive consumption of tree nutrients. Strengthen the management of ploughing and fertilization, improve the quality of flower buds, and strive to have a higher yield in the coming year.

two。 Regular spray protection. Change the misconception that you don't see the disease or spray. From the first ten days of May, pyrazole and complexed mancozeb plus imipramine were sprayed once every 10-15 days to ensure that the leaves and branches were protected by chemicals before each continuous overcast and rain for more than 2 days.

3. Pay attention to the quality of medicine and spray. At present, the main effective agents against anthracnose leaf blight are: pyrazolyl ester, prochloraz, dicyanogen anthraquinone (note: early-maturing varieties such as Gala are at risk), bromofenitrile and other chemical agents, and biological agents such as polyantimycin, Chunramycin and allicin (biological agents are not effective alone and need to be used in conjunction with the previous chemical agents). Some copper preparations such as nonomycete copper, quinolinone, oleic acid copper, thiocarbamate copper and so on also have a certain preventive effect. In addition, spray must be meticulous and thoughtful, do not leak a branch, especially spray the inner branches of the crown, should ensure that the front, back and fruit of the leaves are evenly applied. At the same time, the higher the degree of atomization, the better the control effect.