Symptom characteristics and control measures of jujube leprosy

Symptom characteristics and Control measures of Jujube Mad Disease

Jujube mad disease, also known as "jujube cancer disease", witches' broom disease, is a destructive infectious disease on jujube trees. Once jujube trees are infected with the disease, the whole tree can die after 2-6 years of disease. In recent years, jujube mad disease occurred seriously in Cangxian County, and showed a trend of outbreak. according to the investigation of the technical staff of the Forest Prevention Station of Cang County Garden and Greening Bureau, jujube madness disease is common in Cangxian jujube area, and the annual incidence rate of many jujube orchards is more than 70%. Caused great losses to jujube production.

1 characteristics of symptoms

In Cang County, the incidence of jujube mad disease was higher in Jinsi jujube, Po jujube and other varieties, but no diseased plant was found in Dongzao jujube. When the disease occurs, the flower organ degenerates, and the buds and flowers become leaflets (figure 1). The leaflets can produce short branches with short internodes (figure 2), and the branchlets are clustered with leaves. First there are individual crazy branches in the crown, and then the whole tree is covered (figure 3). The tufted branchlets are slender, the internodes are short, the leaves are small, and they are not easy to fall off in winter (figure 4). The leaves on the diseased branches first turn yellow, and the veins are still green, then the whole leaf yellowed, the leaf margin curled up, dull, hard and brittle. The late-onset branches can still bear fruit, the size of jujube fruit on the diseased branch is very different, the fruit surface is uneven, uneven, convex red, concave green, soft pulp tissue, can not be eaten.

2 the regularity of the disease

2.1 pathogen

Jujube mad disease is caused by phytoplasma (that is, bacteroid). After the pathogen invades the tree, it first runs to the root, and after proliferation, it is transmitted upward through the phloem to the growing point. The pathogen transports through the sieve tube of the phloem and transmits from the root to the crown when sprouting in spring and from the crown to the root when the branches and leaves stop growing in autumn. In the growing season, there were pathogens in the crown and roots. At the end of dormant season (April), there were almost no pathogens in the aboveground diseased branches, but there were pathogens in the roots all the time.

2.2 ways of transmission

There are two ways to spread jujube mad disease, one is asexual reproduction. Whether the diseased plant is used as rootstock or scion, the disease can be transmitted by grafting (including branch grafting, bud grafting, root grafting), and the root tillering seedlings of infected trees can spread in different places with transportation. The other is through the transmission of insects (such as leafhoppers). Once the leafhopper ingests the mycoplast of jujube leprosy disease, it will carry bacteria for life and can infect many jujube trees one after another. When the greening tree species with vector insects are planted in different places, the pathogen can be transmitted to the local jujube trees, causing the occurrence and spread of jujube mad disease in the local area.

2.3 the course of disease

The pathogenesis of jujube mad disease can be divided into five stages: leaf change, flower change, branch change, crazy tree and decline (figure 5).

Fig. 5 the course of disease

2.4 morbidity condition

According to the investigation, the ecological environment of jujube orchard plays an important role in the occurrence and spread of jujube mad disease. The disease is serious in the jujube orchard with barren soil, extensive management and weak tree potential; the disease is serious in the jujube orchard surrounded by pine and cypress trees. In jujube areas with high level of management, due to timely cleaning of diseased trees and reduction of pathogens, effective control of diseases and insect pests and reduction of the number of vector insects, the incidence of jujube mad disease is low and the spread speed is slow.

For many years, jujube mad disease rarely occurred in the jujube area of Cangxian county, the reason is not that saline-alkali soil conditions have an inhibitory effect on jujube mad disease, but that the ecological environment and management methods are not conducive to the spread of jujube mad disease. With the continuous decline of jujube production efficiency, the enthusiasm of jujube farmers to manage jujube trees has declined, resulting in simple and extensive jujube garden management. At the same time, a large number of urban and rural greening are transferred to non-local seedlings (especially scattered pine and cypress seedlings). These seedlings are likely to carry leafhoppers, the pathogen of jujube mad disease, and become the direct transmission source of jujube mad disease. it has created conditions for the introduction of the pathogen of jujube mad disease, resulting in the occurrence of the disease in a large area in Cangxian County.

3 Prevention and control measures

3.1 Quarantine

We will strengthen quarantine and law enforcement and strictly prohibit jujube leprosy seedlings from entering the jujube area. The disease-free mother plant was selected to collect scions, cuttings and propagate root tillers. During the local greening and afforestation, the seedlings from the epidemic areas, especially the pine and cypress, should be quarantined and disinfected in time in order to remove the vectors that spread the pathogen of jujube mad disease.

3.2 strengthen the management of jujube orchard and enhance the tree potential

Strengthen the water and fertilizer management of jujube orchard, reasonable pruning, appropriate load, timely removal of weeds in and around jujube orchard, combined with spraying, reduce the occurrence of diseases and insect pests, and enhance the disease resistance of trees [Jishan Huayao].

3.3 step up publicity

Through the distribution of posters, media broadcasts and other means, let the common people understand the harm of jujube mad disease and prevention knowledge, if not timely prevention and control, the disease will quickly spread to other jujube trees, affecting their own and neighbors' economic income.

3.4 thorough elimination of jujube mania disease

In the growing season, for the diseased jujube, glyphosate and other internal herbicides can be used to completely kill the diseased plant by daubing or spraying branches and leaves, leaving no roots and tillers, and the nail mouth width is more than 5 centimeters. Spray care not to spray on the surrounding healthy jujube trees and crops.

3.5 timely control of vector insects and cut off the route of transmission

The leafhopper can spread the disease by feeding on the disease-free tree after feeding on the mad tree. The jujube was sprayed uniformly in late April, mid-May and late June respectively. Pine and cypress species should not be planted around the jujube orchard as far as possible. if pine and cypress are planted, after the leafhopper moves to the pine and cypress in October and before the leafhopper moves to the jujube tree in spring, the insecticide is sprayed to the pine and cypress to reduce the population base and the probability of infection. The medicament can be mixed with 10% (mass fraction) cypermethrin 5000 times + 10% imidacloprid 3000 times.