Occurrence and control of peach gum disease

Peach gum disease is a common disease in peach trees at present, and the disease is serious, especially in peach orchards with extensive management and weak tree strength, the incidence rate can reach more than 90%. The disease seriously weakens the tree situation, affects yield and quality, and seriously leads to dead branches and dead trees. it threatens the production and development of peach trees, and it is also the most head-scratching disease for fruit farmers.

First, the cause of the disease. There are two causes of peach gummy disease: one is the non-infectious pathogen, such as mechanical injury, pest injury, frost injury, frost injury and other wounds caused by extensive management, heavy pruning, too much fruit, improper fertilization, soil stickiness and so on. The other is infectious pathogen, which is caused by fungi, belonging to ascomycete subphylum in sexual stage and semi-knowing subphylum in asexual stage.

Symptoms and regularity of the disease

The main results are as follows: 1. the non-invasive glue mainly occurs on the trunk and big branches, and the branchlets can also occur in severe cases. The disease department swelled slightly at the initial stage, and then secreted translucent and soft gum, which flowed heavily after rain, then turned brown in contact with the air and became a crystal soft glue block, and then dried into a reddish brown to tea-brown hard glue block, with the increase in the amount of glue flow, the cortex and xylem of the disease gradually turned brown and rotten (but no pathogen was produced). As a result, the trees become weaker and weaker, the serious ones cause the dead trees, the disease of the rainy season is serious, the disease of the older trees is serious, and the disease of young trees is light.

2. The infective glue mainly harms the branches and also infects the fruit. The pathogen invades the new shoots of peach trees in the same year, and the new shoots produce tumor-like disease spots with lenticels as the center, but not glue. In May of the next year, the tumor skin cracked and overflowed the glue, which was colorless and translucent, and then turned into a tea-brown hard lump, and the diseased part was sunken into round or irregular patches with small black spots scattered on it. Perennial branches are susceptible to disease, resulting in blisters, and brown glue can be oozed from the diseased parts, which can lead to branch ulcers and even death. Peach fruit is susceptible to brown rot, with dense small grains and white lumps when it is wet.

Infectious gummosis overwintered with mycelium and conidia in diseased branches. Conidia scattered from late March to mid-April of the following year, which spread with the wind, mainly through wounds and from lenticels and lateral buds. Especially in rainy days, a large number of bacteria overflow from the diseased part, flow down the branches or splash on the new shoots, invade from lenticels and wounds, and become the main source of bacteria for the first time of the new shoots, and the activity of latent bacteria in the branches is related to temperature. When the temperature is about 15 ℃, the glue can be exudated from the disease part. with the increase of the temperature, the gum spots of the tree increase and the disease becomes worse. The incidence of infectious rheumatosis has two peaks in one year, the first from early May to early June and the second from early August to early September. The most favorable time for invasion is the gradual corking of cortical cells of branches and the formation of lenticels. Therefore, it is better to prevent the disease in the shoot growth period.

Third, comprehensive prevention and control measures. According to the above symptoms and the law of the disease, in the actual production, the prevention and control of the disease should be based on agricultural control and artificial control, supplemented by chemical control, which mainly controls the two peak periods of spore spread and spore invasion. The specific measures are as follows.

The main results are as follows: 1. Strengthen the cultivation management, enhance the tree potential and improve the disease resistance of peach trees.

More organic fertilizer was applied to diseased trees, appropriate amount of phosphorus and potassium fertilizer was applied, and nitrogen fertilizer was controlled in the middle and later stage. Reasonable pruning, reasonable load, coordinate the contradiction between growth and fruit, and maintain a stable tree potential. Do a good job of drainage in the rainy season to reduce the humidity of peach orchards. Timely summer cutting, improve ventilation and light transmission conditions, at the same time control other diseases and pests, especially peach branch pests, reduce diseases and insect wounds and mechanical wounds.

2. Eliminate the source of overwintering bacteria: clear the garden to disinfect the garden from December to January, scrape off the glue lump and its lower rotten skin and wood, burn it together, then spray 5 °Be stone-sulfur mixture to disinfect the tree trunk and big branches, eliminate the overwintering bacterial source and insect eggs, and prevent frost injury and sunburn.

3. Before the peach tree germinates, spray 5 °Be stone sulfur mixture on the tree to kill the active bacteria.

4. Prevention and control method of quicklime powder: in recent years, experiments have been carried out with quicklime powder to control the gum flow of peach, apricot, plum and other fruit trees, and the effect is very good, and the cure rate is up to 100%. The specific approach is: the raw lime powder can be applied to the glue, 5-7 days after the smear all stop the flow of glue, the symptoms disappear, no longer relapse. The most suitable period for powder application is when the sap begins to flow, that is, at the end of March, which is the initial period of glue flow, and the number of trees is small and the range of glue flow is small, which is convenient for prevention and control and reduce the nutrient consumption of trees. Later, with the discovery of manual powder control, the prevention and control is the best in overcast and rainy days, when the glue from the bark has high viscosity and is easy to be stained with quicklime powder. Serious gum flow of fruit trees or aging trees with a knife scraped off the dry glue and old skin, exposed the tender skin, the powder effect is better. This method is simple and effective.

5. timely spraying in the growing season: the period from late March to mid-April is the period when conidia pop out of infectious gum disease, which can be prevented by spraying 1500-fold methyl topiramate or 1000-fold doxorubicin or Guoshangling combined with the control of other diseases. The two peak periods of infectious rheumatosis were from early May to early June and from early August to early September. On the eve of each peak, 1000-fold liquid fungus was sprayed every 7-10 days, such as bactericidal or bacteriocin, bacteriocin, etc., alternately for 2-3 times, so as to eliminate the disease in the budding state and minimize the times of spraying according to the condition.