This paper mainly introduces the management of walnut trees from four aspects: Winter management, management of early fruit bearing of walnut trees, management of frozen walnut trees, and shaping and pruning management of walnut trees. Friends in need, don't miss it!
Walnut tree winter Management: I. fertilization management:
Base fertilizer is applied in combination with soil deep ploughing, and the base fertilizer is mainly organic fertilizer. Fertilization was carried out according to Walnut yield, site conditions and tree nutrition. Generally, 5kg organic fertilizer is applied for every 1kg walnut, mixed with an appropriate amount of phosphorus and potassium fertilizer. Each young tree is 20-30kg, each initial bearing tree is 30-50kg, and each tree in full fruit stage is 50-80kg. At the same time, 2-5kg calcium superphosphate was applied. The amount of base fertilizer accounts for more than 30% of the annual fertilization. When fertilizing, pay attention to mix the fertilizer and soil well, and do not pile them directly in the pit.
2、 Watering Management:
After fertilization, water should be poured in time, which is conducive to the absorption of base fertilizer and accelerate the decomposition of fertilizer. The overwintering water shall be poured around November 10. When the topsoil is half dry, the rhizome shall be buried and the trunk shall be painted white. Walnut is wet, waterlogging resistant and weak in drought resistance. Watering is an effective measure to increase production. Timely watering should be carried out in all periods of winter and drought. Before overwintering and after falling leaves, the tree stems and trunks shall be sprayed with stone sulfur mixture once.
3、 Trim Management:
The pruning period of walnut tree is the most suitable from the harvest of fruit in autumn to the yellowing of leaves. It is not suitable to prune one month after defoliation and before germination. These two periods are the peak of bleeding, which is not conducive to the early healing of wounds in the current year. Reasonable tree shape is the basis of high yield. Natural open center shape can be adopted for small and medium-sized crown early fruiting dense planting garden, and trunk sparse layer shape should be adopted for sparse trees, scattered trees and intercropping trees. Pruning at this stage will reduce the leaf area and affect the nutrient accumulation of the tree body, but at this time, the tree body has no bleeding. It is suitable for adjusting the tree skeleton structure, mainly pruning large branches, removing over dense branches, pest branches, shading branches and back branches, and retracting sagging branches. Other pruning should be carried out before budding in the second year.
Walnut trees entering the aging period should be renewed and rejuvenated in time to prolong the bearing life. There are three types of updates: large update, medium update and small update. Big renewal is also called trunk renewal, that is, for walnut trees with high trunk and weak tree potential, all crowns shall be sawn off from the appropriate parts of the trunk; Moderate regeneration is also called trunk branch regeneration, that is, sawing off the appropriate part of the main branch; Small update is also called lateral branch update, that is, the lateral branch retracts. The renewal and rejuvenation should be flexibly controlled according to the tree trend. There are many branches after renewal. The renewal branches should be kept and the tree shape should be cultivated.
4、 Pest control management:
Walnut diseases and pests are relatively few, but if the management is improper and no pesticide prevention is carried out, it will often lead to serious diseases and even plant death. The main diseases and pests of walnut trees include walnut rot, walnut branch blight, walnut canker, Monochamus alternatus, walnut limb lifting moth, walnut leaf beetle, walnut inchworm, scale insect, etc. Autumn and winter are the best period to prevent and control diseases and pests. Based on the principle of "prevention first and comprehensive prevention and control", timely prevent and control the specific diseases and pests in walnut garden, trim and cut off the disease and pest branches and burn the dry and dead branches in combination with autumn, and do a good job in clearing the garden to reduce the source of diseases and pests.
Disease prevention measures of walnut tree in winter management of walnut tree in the early stage of fruit bearing: in the early stage of walnut fruit bearing, the tree body is in the stage of vegetative growth is greater than reproductive growth. The good ring of growth and development in this stage directly affects the formation of tree shape and the improvement of yield. In order to ensure the normal development of the tree, prevent the occurrence of "small old trees" or withering, and lay a good foundation for high and stable yield in the future. Therefore, after the establishment of the garden, the comprehensive management of young walnut trees should be strengthened. 1、 Soil management:
Soil is one of the important environmental conditions for walnut growth. Soil condition and management level restrict the growth and fruit of walnut trees. In order to promote the growth of young trees, intercropping, weeding and soil loosening shall be carried out for many times every year to reduce soil water evaporation, improve soil ventilation, promote the decomposition of soil insoluble nutrients and improve soil fertility. In general, during the growing season every year, "grass must be removed, hoed after rain, and hoed after irrigation". If the manpower is not enough, weeding must be carried out twice a year. One is after flowering and the other is before lodging. These two weeding should not only be timely, but also be deeply hoed. Thus, the grassland can be effectively controlled and the purpose of loose soil water storage and moisture conservation can be achieved. 2、 Fertilization management:
Type of fertilizer: different types of fertilizer are applied at different times. According to the different nutrients contained in fertilizers, fertilizers are divided into two categories:
(1) Organic fertilizer: manure, compost, human excrement and urine, cake fertilizer, green manure, etc. Organic fertilizer contains a wide range of nutritional elements, including not only the main elements of nitrogen, phosphorus and potassium, but also a variety of trace elements. Organic fertilizer has high fertilizer efficiency and long-term effect. It can improve soil structure and regulate soil temperature. Organic fertilizer shall be the main fertilizer every year. Walnut orchards are mostly mountainous and hilly areas, with barren soil layer and lower organic matter content. In order to ensure high and stable yield of walnut, a large amount of organic fertilizer should be applied every year.
(2) Inorganic fertilizer: commonly known as "chemical fertilizer". Generally, it has the characteristics of high content of a certain nutrient, strong quick availability and convenient application. However, this fertilizer does not contain organic matter, but only one or several main nutrient elements. Long-term use alone will harden the soil on the one hand and imbalance the nutrition of plants on the other. Therefore, it should generally be used in combination with organic fertilizer. The effect of inorganic fertilizer is rapid, but its duration is short.
Fertilization management of walnut trees
Fertilization period: Walnut continuously absorbs various nutrients in the soil during the whole growth period. Its absorption of nutrients is not balanced at different ages in a year, and it has the key period with the largest absorption. Generally, from mid August to October, the soil water status is also good. The root system is in the peak period of autumn growth activities. The tree body accumulates and stores more nutrients, which is conducive to growth and fruit. Applying organic fertilizer in autumn can improve soil porosity, help orchard snow to preserve moisture, prevent soil drought in winter and spring, increase ground temperature and reduce rhizosphere freezing injury. Topdressing: mainly topdressing chemical fertilizer, especially nitrogen fertilizer. Topdressing is applied in the critical period of walnut fertilizer demand or in order to adjust the relationship between growth and fruit. It is a supplement to the lack of base fertilizer. Topdressing is mainly carried out during the tree growth period to ensure the high yield and robust growth of Walnut in that year. According to the growth and fruiting characteristics of young walnut trees, topdressing can be carried out in the following three periods:
(1) Before flowering: this period is the first growth period of root system and the nutrient competition period for germination and flowering. Topdressing at this stage is beneficial to promote growth, reduce flower falling and improve fruit setting rate. This topdressing is mainly quick acting nitrogen fertilizer, including ammonium sulfate, ammonium nitrate, urea, etc. The time is late March. The fertilization amount is 30% of the annual fertilizer amount.
(2) After flowering: the main function is to reduce fruit drop, promote the rapid expansion of young fruits and the growth of new shoots, and prepare for flower bud differentiation. The top dressing type is mainly quick acting nitrogen fertilizer, and an appropriate amount of phosphorus and potassium fertilizer should be applied at the same time. The topdressing amount accounts for 20% of the annual topdressing amount.
(3) Hard core stage: generally, after entering the hard core stage, the fruit growth slows down gradually and the kernel begins to enrich. At this time, topdressing can meet a large amount of nutrients required for kernel development. At the same time, this is also the key period of flower bud differentiation. Sufficient carbohydrate accumulation is also conducive to flower bud differentiation, laying the foundation for high and stable yield in the second year. It is mainly nitrogen, phosphorus and potassium compound fertilizer. The topdressing amount accounts for 20% of the annual topdressing amount.
Fertilization amount: the fertilizer demand of walnut trees changes due to changes in tree age, tree potential, fruit yield and environmental conditions. On medium fertility soil, about 100g urea, 30g calcium superphosphate and 10g potassium nitrate are applied to each plant every year; Results in the initial stage, about 300g urea, 250g calcium superphosphate and 80g potassium nitrate were applied to each plant every year. The amount of base fertilizer is equivalent to 50 ~ 100kg per plant, and it shall be applied every year.
Fertilization method:
(1) Root fertilization can adopt ring fertilization, inter row furrow fertilization, hole fertilization and radial furrow fertilization.
(2) Foliar fertilizer spraying: 0.3 ~ 0.5% urea, 0.3 ~ 0.5% potassium chloride and 1.0 ~ 3.0% calcium superphosphate leaching solution can be sprayed.
3、 Irrigation management:
During the growth period of walnut trees, the annual rainfall reaches 600 ~ 700mm, and is evenly distributed, which can basically meet the needs of growth and development. If the rainfall is insufficient or unevenly distributed, it needs to be supplemented by irrigation. Whether young trees or big trees, we should strengthen the regulation of soil moisture. The time, quantity and method of irrigation can be determined according to the local climate conditions, soil moisture, rainfall and walnut growth and development. Generally, irrigation can be carried out 3 ~ 4 times a year.
Irrigation time:
(1) In early spring irrigation, before and after walnut germination, it is necessary to complete the complex processes of bud germination, leaf expansion, flowering and new shoot elongation. During this period, the northern region is in the spring drought season. Paying attention to early spring irrigation before sprouting is very beneficial to promote early growth and prevent the harm of spring cold and late frost.
(2) In the northern region, high temperature and dry weather is easy to occur after the beginning of summer. At this time, the leaves are easy to wilt, which hinders the normal transpiration and photosynthetic function. Especially for 1 ~ 2-year-old trees after planting, the root system is relatively shallow and the early resistance is poor, so irrigation is needed at this stage.
(3) Irrigation before winter, full irrigation before soil freezing, combined with the application of base fertilizer in autumn, can promote root absorption, increase the accumulation of stored nutrients and improve the level of tree volume accumulation.
Management of walnut trees after freezing: after the walnut trees are frostbitten, anti freezing measures must be taken as soon as possible to avoid affecting the output and diseases of the next year. The following are specific practical measures:
1、 Trunk protection measures:
(1) In order to prevent the aggravation of freezing injury and the occurrence of rot disease, walnut trees with freezing injury of grade 4-5 shall be painted with tree protection immediately or the trunk shall be painted white.
(2) After snow, the snow around the trunk shall be removed in time, and the ground temperature rises. After the surface thaws, the trees under 4 years shall be centered on the trunk and laid with about 1 square meter of plastic film.
2、 Fertilization and watering Management:
(1) Fertilize and water the soil immediately after thawing and before germination (in the first and middle of March). Using circular or radial fertilization ditch method, apply 50kg organic fertilizer and 1-2kg urea to big trees; Young trees shall be applied with urea of 0.2-0.5kg and watered immediately after fertilization. After spreading leaves, the trees were sprayed with a mixture of 0.1-0.3% urea and potassium dihydrogen phosphate for external topdressing.
(2) After the soil thaws, loosen the soil on the tree tray as soon as possible, and fully plough and loosen the soil on the forest land where conditions permit.
3、 Trim Management:
(1) For trees with frost damage above grade 2, the frost damage parts of branches and stems shall be distinguished from bud germination to leaf spreading (from mid and late March to mid April), and timely and appropriate pruning shall be carried out. Cut off the dead part of the branches, and apply 3-5 degree stone sulfur mixture or 50% methyl tobuzin wettable powder 50 times solution to the cut mouth for disinfection. Transport the cut branches out of the forest land for centralized burning.
(2) In the first and middle of May, the sprouts and new shoots on the pruned branches shall be selected and retained. Select and cultivate new backbone branches and fruiting branch groups, cut off dorsal branches, upright branches, over dense branches, Cross branches, etc., and restore tree vigor and tree shape as soon as possible.
(3) In the middle and late May, select and retain the new sprouting branches on the branches of the young trees frozen to death on the ground and the trees frozen to death at the grafting site