Decline Reason and Rejuvenation Technical Measures of Myrica rubra

Causes of decline and technical measures for rejuvenation of bayberry trees

The area of red bayberry in the northern mountain area of Chaoan is about 1 173.3 hm2, which is an important fruit tree in the mountainous and semi-mountainous areas of Chaozhou. The 'Dongkui' bayberry introduced at the end of the last century has significant causal, high-quality and high-quality benefits, and the cultivation of bayberry has become an important source of agricultural income for literary temples, Guihu and other towns. However, since 2010... At the beginning, the bayberry tree appeared withered branches, decline and even death, and the area gradually expanded, more than 800 hm2 has been seriously declining, affecting the development of Chaozhou bayberry industry, resulting in great losses. In view of this phenomenon, since 2014, through in-depth investigation, experiments and research, the author has selected corresponding chemicals to implement prevention and control, combined with scientific cultivation measures, which has effectively curbed the decline of bayberry, and the mortality rate of bayberry has been controlled below 2%. Reduce the cost by 40% and return to normal growth within 3 years, with good results.

1 Analysis of the causes of the decline of bayberry trees

1.1 caused by root-knot nematode

With the support of the superior scientific research department, the agricultural technicians of Chaoan District Agricultural work Station in Chaozhou City tested the soil and fine roots of some declining bayberry orchards in Guihu Town and Wenci Town. The main cause of large-scale decline and even death of red bayberry is bayberry root-knot nematode disease. The root-knot nematode disease of bayberry, which has not been paid attention to for a long time, has become the most serious harm, which directly leads to the decline of bayberry tree and even the death of dead branches.

After Myrica rubra was damaged by root-knot nematode, the leaves at the end of the main branch were yellowed, fell off, the branches died, and the withered branches increased gradually until the withered branches spread all over the plant. Dig out the root system, you can see the end of the root system blackened, rot, and sometimes nodule-like pimple, expanding from the branch root system to the main root system. The roots were seriously damaged, and the ability of the roots to absorb and store nutrients decreased, so that the tree could not get the necessary nutrient supply, thus affecting the growth of bayberry. In the later stage of damage, the diseased trees even wilted and withered to death. At the same time, it will also induce root rot, Fusarium wilt and other diseases.

Because the root-knot nematode is small and can not be detected by the naked eye, and the initial symptoms of Myrica rubra are not obvious, coupled with the weak control awareness of fruit farmers, the disease is often confused with lack of water, fertilizer or other diseases, thus delaying the best time for control.

1.2 unscientific management measures

1.2.1 abuse of herbicides, especially glyphosate, directly harms the roots and destroys the soil structure. Weeding often leads to soil erosion, resulting in relative drought and water shortage of soil, and injury of shallow roots in high temperature season in summer and autumn.

1.2.2 fertilization methods are unscientific. Most fruit farmers use chemical fertilizer for a long time, using only nitrogen fertilizer and phosphate fertilizer, less potassium fertilizer, and almost no organic matter fertilizer, which leads to the aggravation of soil acidity, which is an important reason for the spread of root-knot nematode.

1.2.3 abuse of plant regulators in order to be put on the market early, fruit growers use a large number of plant growth regulators, which seriously damage the law of plant growth. Disorderly emergence of new shoots induces a large number of pests, such as leaf roll moth (hanging filaria) and shell insects. Disordered growth affects the normal flowering and fruiting, resulting in unstable yield and decreased quality.

1.3 Climatic factors

Due to the global warming, the annual accumulated temperature increases, which is the main reason for the damage of root-knot nematodes. The suitable temperature for nematode growth and reproduction is 25 ~ 30 ℃, which is lower than 10 ℃ to stop activity. In Chaozhou, the time when the temperature is lower than 15 ℃ is relatively short, and root-knot nematodes often maintain strong reproductive capacity.

2 technical measures for rejuvenation

2.1 Control of root-knot nematodes and promotion of new roots

If nematode damage is common in bayberry orchards, 1000 times liquid 10% thiazolyl phosphine mixed organic liquid fertilizer should be used in time to drench the roots as far as possible, especially in the dense areas of fine roots, which can eliminate most of the nematodes and promote the growth of new roots. Drenched twice in the first year, the interval is 4 ~ … The times of prevention and treatment were determined according to the situation in the second year. After more than 2 times of pesticide application, the bayberry tree can basically recover its vitality. If there are the same damaged bayberry trees above the orchard, control should be carried out at the same time, otherwise measures should be taken to isolate and prevent Rain Water from spreading root-knot nematodes. The neighboring orchards should also implement unified prevention and control at the same time to prevent the spread of Rain Water.

2.2 protect vegetation and control weeds without weeding

Good vegetation can reduce soil water loss and maintain soil relative humidity, which is beneficial to the root growth of red bayberry. Except for small shrubs, annual grass is usually retained. A lawn mower can be used to control weeds, or a lower concentration of herbicide can be used to control the growth rate. The garden is cleared in winter every year, and lime can be applied for 50 kg per 667m2.

2.3 pruning and reshaping to rebuild the crown

When the withered branches are serious, they must be retracted and reshaped and the crown must be re-cultivated. For bayberry trees with serious decline, the damage of root-knot nematodes should be controlled at first, and the new shoots should be re-sprouted and turned green before the first pruning. The bayberry trees with few withered branches and no serious decline can be pruned at the same time to promote the sprouting of new shoots. For some particularly serious bayberry trees, heavily truncated branches are bandaged to prevent sunburn.

2.4 rational fertilization to restore tree potential

When the tree potential has just recovered, the root system is underdeveloped, and the amount of fertilizer application should be controlled. The adult tree should apply 200 kg organic fertilizer per 667m2. Every time you smoke new shoots and top dressing... One time, 10 kg of ternary compound fertilizer was applied every 667m2. The recovery of tree potential in the second year can increase the application of compound fertilizer with high potassium content and promote flower bud differentiation.

2.5 Integrated control of diseases and insect pests and protection of branches and leaves

Declining trees need enough green leaves to restore their growth, and it is very important to protect their branches and leaves. The main pests of red bayberry are bark moth, leaf roll moth, inchworm, shell insect and so on. The larvae of bark moth are mainly harmful to branches, and the control methods are to cultivate strong trees, dry and whiten them and kill them artificially. It is the best measure to control the harm of bark moth and longicorn beetle by drying and whitening the main branches in April every year. Leaf roll moth, inchworm and shell worm are mainly harmful to new shoots and young leaves, and the control method is to use 22.4% ethyl ester 4000 times solution at the initial stage. The agent is selective to many kinds of natural enemies such as ladybugs and parasitic wasps, and can protect the natural enemies to the greatest extent when used in the early stage of the occurrence of insect pests. There are many biological natural enemies in orchards with good ecological environment, such as Chrysophora botrytis and Eriocheir sinensis, which are the hosts of leaf roll moth, wood beetle moth and inchworm; red-shouldered lady beetle leopard variant, six-spotted ladybug, Chrysopus chinensis and Chrysopus chinensis are the natural enemies of aphids and shell insects, so we should pay attention to the protection and utilization.