How can hickory be cultivated and managed to achieve high quality and high yield?

High-quality and high-yield cultivation and management techniques for hickory

1 Suitable growing environment for hickory

Hickory is suitable for planting in wind-sheltered mid-slope areas at an altitude of 200-700m. The best soil is black limestone soil developed from limestone, followed by mountain yellow soil. It is advisable to choose sites with good light conditions, sufficient rainfall, suitable temperature, deep and fertile soil, and good drainage and irrigation conditions for planting.

Hickory has a relatively long root system, so in areas where hickory is to be developed, soil with a deep and loose layer should be selected, as this is conducive to root development and promotes hickory growth. According to surveys of hickory forest land, the soil of high-yield hickory forests shows a certain degree of slight acidity, with soil in a small number of areas approaching neutral. Therefore, planting should be carried out in slightly acidic to neutral soil, which not only benefits hickory growth but also promotes an increase in hickory yield.

Hickory is relatively tolerant of poor soil but has weak drought tolerance. If there is sufficient moisture during the growing season, hickory not only produces a large fruit yield but also produces high-quality fruit. If a prolonged drought occurs in summer, it will cause physiological fruit drop in hickory, causing patches of hickory to dry at the branch tips and scorch at the leaves, with massive fruit drop and reduced yield. Hickory is very sensitive to climate during the flowering period. If the temperature suddenly drops during flowering, or if continuous rainy weather occurs, it will cause a large number of flowers to drop, resulting in a reduction in hickory yield that year.

Hickory is a wind-pollinated plant. When wind volume is relatively low, it is beneficial for pollen pollination, but strong winds can easily dry out tender leaves, affecting tree growth and yield. At the same time, violent gales can also blow off hickory fruit, greatly affecting yield. Therefore, hickory should be planted in mountain hollows or valleys, which not only helps spread pollen but also blocks damage to hickory from strong winds.

Hickory is not very strict about light requirements; generally, neutral to slightly shaded light is beneficial for its growth. In mountainous areas, the most suitable altitude is 200-700m. Surveys of hickory at different altitudes show that at an altitude of 500-900m, hickory grows vigorously, develops normally, and has strong resistance, is less prone to pests and diseases, and produces high yields of hickory nuts with good quality. In areas below 200m in altitude, pests and diseases occur seriously in hickory, and its growth is affected to a certain extent; above 1200m in altitude, hickory develops poorly and yield is very low. At the same time, the lower the latitude, the higher the vertical distribution of hickory.

Hickory is suitable for growing in wind-sheltered areas. At the same altitude, differences in terrain create differences in microclimate, affecting its growth and fruiting. In hilly areas at lower altitudes, light is stronger and temperature is higher. The main limiting factors for developing hickory there are high temperature and drought, so planting on shady slopes or semi-shady slopes is preferable. In high-altitude areas, due to the influence of high humidity and lower temperatures, hickory is better planted on sunny slopes.

2 Main cultivation measures

2.1 Matching site to tree

Before planting, a survey should be conducted of the natural distribution, growth, and fruiting of hickory in Ningguo City. Only in this way can suitable planting sites be selected by matching site to tree. First, sites should be chosen in wind-sheltered valleys with sufficient rainfall, strong light, and suitable temperature and humidity. In addition, hickory has relatively strong soil requirements, requiring deep soil, loose topsoil, relatively compact subsoil, fertile soil, strong water permeability, good water and fertilizer retention, and slightly acidic soil. In areas with relatively low rainfall, soil with a relatively deep layer should be selected for afforestation.

2.2 Selection of improved varieties

Mother trees of hickory are very important for breeding improved varieties. Before breeding improved varieties, mother trees are used for sowing and raising seedlings, so the selection of mother trees is relatively strict. Select mature trees with excellent characteristics such as vigorous growth, no pests or diseases, good crown shape, high per-plant yield, large and plump nuts, and strong resistance. The seed collection period for mother tree seeds should be delayed by more than one week compared with normal fruit use. After the fruit is harvested, spread the fruit together with the husk in a well-ventilated indoor area, and sow in the forest after mid-October.

2.3 Planting techniques

Site preparation should be carried out before planting, and strip or block methods should be preferred. Strip site preparation is generally suitable for mountainous land with relatively steep slopes; where the slope of the planting site is relatively gentle, block site preparation should be used to improve forest land utilization, generally with a planting spacing of 1 x 1m. To promote the survival of newly planted seedlings, surrounding weeds and shrubs should be retained to provide shade. At the same time, planting holes should be dug slightly deeper to allow root extension and improve seedling survival rate. In addition, planting density has a relatively large impact on hickory. Hickory should be planted appropriately sparsely. In the initial planting period, density should be controlled at 450-600 plants/ha, and after the forest is finally established, 300-450 plants/ha should be maintained to achieve the goal of high quality and high yield.

2.4 Water and fertilizer management

2.4.1 Weeding and fertilizing

Weeding can reduce competition for water and nutrients during the growth of weeds in hickory forest land and can significantly improve yield and quality. Because herbicides have a certain impact on soil and the environment, manual weeding is advocated and can be combined with intertillage for weed control. When the amount of grass is too large and manual weeding is inconvenient, pollution-free chemical agents may be appropriately selected for weed control.

Hickory fertilization should mainly use nitrogen fertilizer and phosphorus fertilizer. Fertilize before flowering and after fruit drop respectively to promote flower bud differentiation and fruit development and increase fruiting. Hickory fertilization should apply more organic fertilizer and biological fertilizer and less chemical fertilizer. Fertilization can reduce the alternate bearing of hickory, maintain high and stable yield, and also improve the quality of hickory. According to the growth condition of hickory, open ring-shaped trenches around the base of the hickory tree, appropriately broadcast urea or compound fertilizer evenly or deeply bury base fertilizer, and then cover with soil.

2.4.2 Water management

Hickory has relatively high water requirements. It fears both prolonged drought and soil waterlogging. Soil moisture content greatly affects the growth and development of hickory. Too much water can easily make hickory growth and fruiting unfavorable, and roots soaked in water for a long time can cause tree death. Forest surveys show that hickory grown in well-drained soil has a large crown, high yield, and good quality; prolonged drought can also cause poor growth in hickory, early fruit drop, and even tree death. Therefore, watering and drainage for hickory should be done promptly according to soil moisture conditions.

2.4.3 Intercropping

According to surveys, intercropping has a significant impact on hickory. Hickory grows relatively slowly and generally takes 20 years to enter the full fruiting period. At the same time, young trees prefer shade, and interplanting can effectively block strong light and improve summer soil drought. In the first few years after hickory is planted, when the trees are relatively small, economic crops such as corn, beans, and tea can be planted in idle spaces in the forest to increase the income from interplanted crops.

2.5 Training and pruning

Training and pruning have a relatively large impact on hickory growth and yield. The quality of pruning has a relatively large impact on hickory growth and the following year's yield. First prune crowded crossing branches and overlapping branches on the periphery, with emphasis on removing weak branches and diseased and pest-infested branches, and thin out vigorous water sprouts in the inner canopy. After that, remove excessive large branches irregularly each year, and generally the pruning amount should be controlled at about 25% of the total branch amount.

2.6 Flower and fruit retention

During the flowering and young fruit stages of hickory, pollination failure or premature fruit drop often occurs. The use of chemical agents and exogenous hormones for spraying and trunk painting can significantly increase the fruit-setting rate of hickory. For the agents used, use a slightly lower concentration during the fruit growth period, and appropriately increase the application concentration in the later growth stage, which can effectively retain flowers and fruit. At the same time, during the peak blooming period of female hickory flowers, especially during long periods of rainy weather, artificial supplementary pollination can also significantly increase the fruit-setting rate of hickory.

2.7 Harvesting

Harvest should be carried out in late September, about one week after White Dew. At this time, hickory has basically reached physiological maturity, the outer fruit skin turns yellow-brown, and the fruit begins to drop. When harvesting hickory, pay attention to personal safety, and at the same time be careful not to damage branches and buds, so as not to affect the next year's hickory yield. In addition, fruit-drop accelerators can be used to harvest hickory. Spraying ethephon is currently a relatively ideal method for accelerating hickory fruit drop, commonly using a concentration of 300,000 mg/kg of ethephon to spray hickory fruit.

2.8 Pest and disease control

The main insect pests of hickory include leaf-eating pests and trunk-boring pests. Among them, leaf-eating pests mainly include hickory leaf aphid, hickory prominent moth, and green slug moth, while trunk-boring pests mainly include cloud-patterned longhorn beetle, mulberry longhorn beetle, and coffee wood leopard moth. If leaf-eating pests occur severely, they can consume hickory leaves almost completely, causing weakened tree vigor, reduced hickory yield, and inducing disease occurrence; trunk-boring pests are even more harmful to hickory, can cause branches to dry and die, are easily broken by wind, and if severe can even cause the death of the whole plant. The hickory diseases that occur severely and commonly in this area include hickory canker, branch blight, and leaf blight. Hickory diseases cause the greatest losses to hickory, occur over a wide area, and are severely damaging, causing trees to die within a few years of fruiting.

Pest and disease control for hickory should implement a strategy of prevention first. Adopt the method of matching site to tree, choose a site environment suitable for its growth to plant hickory, do not blindly expand the hickory planting area, reasonably control water and fertilizer, naturally form alternate bearing, strengthen tree vigor, improve its stress resistance, and enhance the ability of hickory to resist pests and diseases. For severe outbreaks of pests and diseases, timely prevention and control should be carried out promptly with pollution-free agents to avoid further expansion of losses.