Key Technical Points for Olive Cultivation and Management in Mountainous Areas

    Olive, also known as green olive, white olive, or Chinese olive, is a plant of the genus Canarium in the family Burseraceae. It originated in southern China and is abundantly produced in Guangdong, Guangxi, Sichuan, and other provinces. It is one of the famous high-quality fruits of tropical and subtropical regions. It can be eaten fresh or processed into various preserved fruits. Olive also has multiple health benefits; both its roots and fruits can be used as medicine, possessing functions such as dispelling wind, promoting qi circulation, relieving cough, relieving pain, and treating bone stuck in the throat.
 
Olive is an evergreen tree with a long lifespan and a long high-yield period. It has low soil requirements and is relatively drought-tolerant and tolerant of poor, barren soil. It grows easily and vigorously, making it one of the excellent fruit trees for transforming low-yield forests, greening mountainous and barren hills, adjusting agricultural structure, and increasing farmers' income. Olive prefers warmth and requires appropriately high temperatures during the growing season to grow vigorously and bear fruit well. Areas with an annual average temperature above 20°C and without severe frost damage in winter are more suitable for its growth. Most areas of Guangdong are suitable for cultivation. Gaopi Town in Dabu County has a long history of olive cultivation. In 1992, the town Party committee and government made olive cultivation one of the leading projects for adjusting agricultural structure and increasing agricultural income. To date, the annual olive planting area has reached over 12,000 mu. Based on my years of practical experience at the Gaopo Town Agricultural Station, the key technical points for olive cultivation are summarized as follows. 

    I. Orchard Site Construction 

Before planting, a suitable mountain site must first be selected. Any hillside with red or yellow soil and alluvial land along rivers and streams can be used for planting. Sandy soil with relatively deep soil layers and fertile texture is ideal for planting. At the same time, there should be a water source around the mountain area. If conditions permit, a water storage pond can be built to ensure water supply for the orchard. Then terraces should be built, with a terrace width of 1.5-2 m. The terrace surface should be higher on the outside and lower on the inside to prevent soil and water loss. Planting row spacing should be 5-7 m, and plant spacing should be 6-8 m. Dig large holes deeply, with a depth of 0.8-1 m and a length and width of 1 m each. After digging, let the holes and soil dry in the sun for a period of time, then backfill with base fertilizer. Generally, rice straw, reed, or other crop stalks, or 50-100 kg of pig and cattle pen manure, garbage compost, etc. are used. On the top layer, add 1.5 kg of superphosphate and 2 kg of cake fertilizer. Organic fertilizer should be mixed evenly with the soil, then piled into a small mound about 30 cm high. Planting can be done only after it has settled. 

    II. Timely Planting 

Olives are generally best planted from March to June, and the survival rate is highest when planted before the spring shoots have emerged. For many years, our town has mainly used nutrition cups to raise rootstock seedlings, sowing from October to December. By April to June of the following year, when the seedlings reach over 20 cm in height, they can be planted. When planting seedlings in nutrition cups, the nutrition bag must be torn open, because the bag does not rot easily and will affect root development if not removed. Olive roots are very fragile. When planting, first dig a hole on top of the soil mound, then place the seedling into the hole, cover the roots with relatively fertile fine soil, press the root area firmly with the foot, and water with settling water. Prevent the roots from contacting fresh animal manure, which can cause new roots to rot. With this planting method, the survival rate can generally reach over 95%. 

    III. Timely Grafting 

Timely grafting of olives is one of the important measures to promote early fruiting and high yield. Generally, for fruit trees planted from nutrition cup seedlings, grafting begins in the third year after planting; for 3-year-old large seedlings, grafting begins in the second year after planting. Grafting should generally be carried out during the two solar terms "Spring Equinox" and "Qingming". The grafting methods generally used are the double-bud cut grafting method or the short-scion cut grafting method, which help increase the grafting survival rate. 

    IV. Fertilizer and Water Management 

Young trees should be given light fertilizer frequently to promote shoot growth. In principle, apply fertilizer once for each new shoot flush. Generally, choose to fertilize when the soil is fully moist after rain. Mix a small amount of farmyard manure with compound fertilizer and place it into small holes dug on the west side of the young tree. When fertilizing, be careful not to damage the roots, and rotate the positions. Bearing trees are generally fertilized 3-4 times per year. These are pre-flowering fertilizer (March-April), fruit-strengthening fertilizer (July-September), and post-harvest fertilizer (November). The first two applications should mainly use quick-acting fertilizers to promote flower bud differentiation and fruit ripening. The last application, after "Start of Winter", is a "wintering fertilizer" applied together with orchard clearing and weeding, mainly using farmyard manure and plant ash. Fertilization is generally done by digging holes or opening ring-shaped trenches along the drip line at the outer edge of the canopy, and the type and amount of fertilizer should be adapted to local conditions and individual trees. 

    V. Shaping, Dwarfing, and Pruning 

When planting olives, cut off the main trunk, keeping the trunk height at 30-50 cm, and retain 3-4 buds on the main trunk at different positions and orientations to promote the growth of 3-4 first-level main branches. When the first-level main branches grow to about 50 cm, pinch the tips again to promote the growth of second-level main branches. During the growth process, continuously remove overly vigorous, overly weak, and overly dense branches. Control the entire tree shape to 4-5 tiers, with a tree height of about 4-5 m. By cutting back water sprouts, thinning out inner canopy branches, overlapping branches, and diseased and pest-damaged branches, ensure the tree shape forms a semi-round dwarf canopy, laying a good foundation for high yield.