Key Cultivation Techniques and Management Methods for American Plumcot

American plumcot, namely the new intergeneric hybrid cultivar of apricot and plum, is a new cultivar introduced from the United States by the Economic Forest Research and Development Center of the Chinese Academy of Forestry. This cultivar was developed through multiple generations of hybridization between apricot and plum. Its fruit has a unique rich and fragrant aroma, and its sugar content is much higher than that of any single apricot or plum cultivar, with soluble solids content reaching 18-20%. It is one of the emerging fruit varieties with the best market prospects. Currently, 7 cultivars have been introduced: Flavor Rosa, Flavor Queen, Flavor Delight, Flavor King, Dinosaur Egg, Flavor King, Flavor Rich.

I. Excellent Characteristics

1. Large fruit, early fruiting, high yield. American plumcot bears fruit 2 years after planting and enters full fruiting period in 4-5 years. The average single fruit weight is 80-120 g, with the maximum single fruit weight reaching 150 g. In full fruiting period, the yield per mu can reach 1800-2500 kg.

2. The fruit has brilliant color, extremely high sugar content, unique flavor, and rich nutrition. After the fruit ripens, the skin is purplish red, red, red-yellow, or orange-yellow; the flesh is bright red, pink, or orange-yellow, firm and sweet. The soluble solids content is 40%-70% higher than that of Golden Sun apricot and Black Diamond plum. It is rich in vitamins and mineral elements, especially vitamin A, vitamin C, beta-carotene, and potassium, among which beta-carotene has certain anti-cancer effects. It contains no saturated fatty acids or cholesterol.

3. The fruit is storage-tolerant. The fruit can be stored at room temperature for 15-30 days, and at low temperature of 2-5 degrees C for 3-6 months.

4. Few pests and diseases, strong adaptability. American plumcot can adapt to various types of soil conditions, has no strict requirements for soil pH, and has strong resistance to drought and cold. It can be planted in most areas suitable for apricot and plum cultivation.

II. Cultivation Techniques

1. Planting time: Early to mid-November to late February is preferable.

2. Planting density

The planting density of plumcot should be determined according to cultivar characteristics and site conditions. Flavor King has weaker growth vigor and a smaller plant type, so a spacing of 2 m x 3 m or 2 m x 2 m can be used, planting 111-167 plants per mu; for other cultivars, a spacing of 3 m x 3 m, 2 m x 4 m, or 3 m x 4 m is preferable, planting 56-83 plants per mu.

3. Planting method

First, dig planting holes measuring 80 cm square (length, width, and depth all 80 cm) at the planting site. When digging, keep topsoil and subsoil separate. When backfilling, first mix 20-30 kg of decomposed organic fertilizer with the topsoil, then fill it into the bottom of the hole to one-half of the hole depth, then backfill with subsoil to 10 cm below the ground surface to facilitate watering after planting. When planting, first dig a small pit in the center of the planting hole, place the seedling into the small pit, fill with soil and firm it, and water thoroughly. After the water has completely infiltrated, seal the soil. When planting, fill soil while lifting the seedling to allow the root system to spread fully. The planting depth should be such that the root crown is level with the ground surface. Because most plumcot cultivars require cross-pollination, pollinator cultivars need to be configured at planting. For example: the pollinator trees for Flavor Rosa are Flavor King and Dinosaur Egg; the suitable pollinators for Flavor Queen are Dinosaur Egg, Flavor King, and Flavor Rich; Flavor Delight can self-pollinate, but configuring a certain proportion of Flavor King or Flavor Rosa gives better results. According to the cultivation purpose, the configuration ratio of each cultivar to pollinator trees is 5:5 to 8:2.

4. Trunk heading

The time for trunk heading is from after planting to before bud break. The trunk heading height is generally 60 cm.

5. Pinching of main branches

From late April to early May, when the young shoots of the plumcot trunk grow to 60-70 cm, pinch off the tips to promote lateral branches and cultivate main branches. From late May to early June, when lateral branches grow to 50-60 cm, select three main branches with strong growth vigor and suitable orientation and pinch them at 40 cm; pull flat the branches that have space to facilitate early flower bud formation; remove other overly dense branches.

6. Branch bending

Branch bending is carried out in mid-October. For auxiliary branches, temporary branches, and competitive branches, the bending angle is relatively large and they can be pulled flat. For extension branches and lateral branches, the bending angle is generally 60-80 degrees. The branches of Flavor Rich and Flavor Rosa are relatively soft, so the bending angle should be smaller, using fruit to suppress the canopy.

7. Pruning and training

The suitable tree shape for American plumcot is preferably the natural open-center shape or the two-tier sparse open-center shape. The structure of the natural open-center shape is: trunk height 40-50 cm, with three main branches extending at an angle of 40-45 degrees, and 2-3 lateral branches evenly distributed on the main branches. The structure of the two-tier sparse open-center shape is: three main branches in the first tier with a tier spacing of 80 cm, and two main branches in the second tier, with the top removed to open the center. When pruning one-year-old young trees in winter, light pruning and delayed heading should be the main approach, with light pruning intensity to avoid excessive pruning; branches should mainly be left unpruned and allowed to grow, with few or no heading cuts. Specific pruning methods: cut the main branch extension branches back to 50 cm; for lateral branches on the main branches, select lateral branches with suitable orientation and angle and cut them back to 30 cm to promote the formation of fruiting branch groups. Leave auxiliary branches unpruned. In summer pruning, branch thinning should be the main approach, with few heading cuts or heading cuts, removing dense inner-canopy branches, overlapping branches, and sprout branches to improve tree structure and enhance ventilation and light penetration.

8. Flower and fruit management

Before plumcot flowering, supplementary pruning should be carried out to thin out slender and weak flowering branches. During full bloom, release bees, and combine with foliar spraying of 0.3%-0.5% borax plus 0.3% urea water to significantly increase fruit set rate. Fruit thinning of plumcot should be carried out after the first physiological fruit drop, generally leaving one fruit every 10 cm. During the fruit enlargement period, applying 100-150 g of potassium sulfate compound fertilizer per plant can increase fruit weight. During the coloring period of plumcot, spraying 0.3%-0.5% monopotassium phosphate solution once every week can significantly increase sugar content and promote coloring. After fruit harvest, fertilizer and water management should be strengthened to promote recovery of tree vigor. At the same time, foliar spraying of 500-800 times paclobutrazol 2-3 times can be used to control excessive vegetative growth and promote flower bud formation.

9. Water and fertilizer management

Plumcot is not tolerant of waterlogging. To facilitate drainage, ditches 20 cm deep and 20 cm wide should be dug along the planting rows with the trunk as the center line, 50 cm away from both sides of the center line. At the same time, soil should be mounded under the tree canopy in an arc shape to facilitate drainage and irrigation. Water once each year before flowering, after flowering, during the young fruit enlargement period, and before freezing, and in July-August carry out timely drainage or irrigation depending on soil moisture conditions. After fruit harvest, water and fertilizer management should be strengthened, applying 0.5 kg of N, P, K compound fertilizer per plant to increase nutrient accumulation in the tree and promote recovery of tree vigor and the formation of plump flower buds. From late October to early November, dig ditches or trenches 40 cm deep and 30 cm wide on both sides of the tree rows, and apply 30-50 kg of decomposed organic fertilizer or 2-3 kg of superphosphate and 0.5-1 kg of urea per plant.

10. Pest and disease control

(1) Shot hole disease generally begins to occur from late March to early April. In mid-March, spray 70% thiophanate-methyl wettable powder at 1000 times plus 65% mancozeb wettable powder at 500-800 times, or 50% carbendazim wettable powder at 800-1000 times.

(2) From late March to mid-April in spring, aphids often damage young plumcot shoots, causing the young shoots to stop growing. Spray 40% Likete wettable powder at 1000-1200 times for control.

(3) The peach fruit moth generally begins to cause damage in June-July. Spraying 50% fenitrothion emulsion at 1500 times has good killing effects on eggs and emerged adults.

(4) In June-July, scarab beetles cause relatively serious damage. Based on the death-feigning habit of scarab beetles, a combination of manual and light trapping can be adopted, manually shaking trees to dislodge or capture adults, and where conditions permit, black light traps can be used.

(5) In August, red spider mites cause relatively severe damage and can be controlled with 60% propargite.