New techniques for preventing and controlling Root Rot of Peach trees

New techniques for preventing and controlling Root Rot of Peach trees

1 harmful symptoms of root rot of peach trees

The main symptom of root rot is that the hyphae between cortex and xylem are full of white to yellowish mycelium, the hyphae expand outward like a fan, the fresh mycelium has blue-green fluorescence in the dark, and the root of the disease has a strong mushroom smell (figure 1) [Yoshanayama Huayao]. In the later stage of the disease, the cortex decayed and the xylem decayed; in the rainy season or wet environment, clusters of beige mushroom-like fruiting bodies could be produced at the diseased part or the broken root. The leaves of lightly diseased trees are small, the leaves are yellow, and the growth of new shoots is small (figure 2). The leaves of seriously diseased trees fall early, branches die, and even the whole tree dies (figure 3).

Fig. 1 peach root rot disease spot

Fig. 2 peach tree with root rot and disease

Fig. 3 peach tree with root rot, disease and death

2 the pathogen of root rot of peach trees

2.1 pathogen of root rot of peach trees

The pathogen of peach root rot is Pseudomonas mellea, which is a fungus with a wide range of hosts, which mainly harms the root neck of fruit trees, such as peach trees and apples, causing root cortex rot. The initial location of the disease is uncertain, but no matter where it begins, it rapidly extends to the root neck, and then spreads around from the root neck.

2.2 routes of transmission and conditions of onset

The pathogens overwintered mainly as mycelia on the diseased plants and residues in the field, and the pathogens died after decay and decomposition. The contact of diseased roots and the movement of diseased bodies are the main ways of disease transmission. When the healthy root comes into contact with the diseased body or the healthy root comes into contact with the diseased body, the pathogen can invade directly through the wound and rapidly expand the harm. Root rot disease often occurs in orchards rebuilt from old woodlands or river beaches, and rarely occurs in orchards where previous trees have not been planted.

(3) traditional prevention and control methods.

3.1 Agricultural control

When building a new orchard, avoid places such as old woodland, river beaches and ancient graveyards with more trees. If it is necessary to build a garden on such land, first of all, we should thoroughly remove tree stumps, residual roots, rotten bark and other diseased bodies; secondly, we should irrigate, plough and air the soil to promote the decay and decomposition of the residual remains; if possible, plastic film can also be used to cover the soil for the summer and use solar heat to kill pathogens. You can also use 200 times formalin solution to irrigate the soil for fumigation and sterilization, and then plant seedlings after formalin is fully dispersed. After discovering the diseased tree, the diseased tree should be dug up around the root neck to find the diseased site, and the main, lateral and branch roots should be found according to the diseased spot (figure 4); according to the severity of the disease, the diseased tissue should be scraped or sawed off thoroughly, and the diseased body should be thoroughly cleared, in order to avoid spread, trenches can be dug around the diseased tree to seal off, generally, the ditch is 50 cm deep and 30 cm wide.

Fig. 4 check the root neck of peach tree

3.2 Pesticide control

Apply medicine to protect the wound, effective agents such as Bordeaux solution, 1% 2% copper sulfate solution, 2-3 Bomedo stone sulfur mixture, etc.; cover the root with disease-free soil or medicinal soil. The trees with mild disease or those which are difficult to find the disease site can also be treated by direct drug administration.

The above two kinds of methods have poor maneuverability, poor control effect and high control cost. Therefore, after searching in many ways, we finally found a simple, practical, effective and low-cost method-biological bacteria organic fertilizer prevention and treatment method.

4 methods of biological bacteria organic fertilizer for the control of peach follow-rot disease

Biological bacteria organic fertilizer is provided by Xinji Fangsheng Agricultural Science and Technology Co., Ltd., which contains 10 kinds of probiotics, the number of probiotics is 400 million / g, and the fertilizer has double effect. Among them, the probiotics which have effect on the pathogen are Bacillus megaterium, Bacillus subtilis and Bacillus amylolyticus. These three bacteria have good inhibitory effect on the pathogen of peach root rot, especially the large number of Bacillus amylolyticus. It can induce plants to produce disease resistance and produce a variety of physiologically active substances and amino acids, such as gibberellin, indoleacetic acid, cytokinin and so on. Promote the root system and plant growth of peach trees and restore the health of diseased trees.

The peach orchard in Dongliuzhuang, Qianying Township, Xinji City, covers an area of 20 mu, involving 4 fruit farmers, planted in 2010, varieties of late Jinghong and yellow peaches, which began to bear fruit in the third year, six or seven trees died every year since the fourth year, and problems were found in many trees in June 2017. some of the whole trees wilted, some of the main branches dried up, cut open the neck of the roots, you can find that the disease part is rotten, there are obvious white germ tissue. The garden planted peach trees 15 years ago, the variety is peach, peach orchard decline after the planing, mainly planting Chinese wolfberry.

Peach trees grew well in the young stage, no root rot and other root diseases were found, and continuous disease and even death were found in the fruiting stage.

On the afternoon of June 14, the diseased tree was dug up and the diseased spot was found (figure 1). Without dealing with the diseased spot, the biological bacteria organic fertilizer (figure 5) was directly applied to the diseased spot, with a dosage of about 2 kg, buried in the soil and watered. It was observed on the 29th that the leaves of the treated trees changed from yellow to green, while the untreated trees became more withered and did not die. It was observed on July 5 that all the treated leaves turned green, and new shoots grew again, and the untreated tree trunks withered and died (figure 6). According to the investigation at the end of July, more than 10 trees recovered and grew normally after treatment (figure 7).

Fig. 5 Biological bacteria organic fertilizer being fermented

Fig. 6 treated trees and control trees after 20 days of treatment

Fig. 7 treated peach trees