Large-fruited, late-maturing, storage-tolerant peach cultivar Yuxi Hongmi: characteristics and cultivation techniques

Yuxi Hongmi (tentative name) was bred by the College of Forestry, Henan University of Science and Technology in 1996 by crossing Wanhongmi as the female parent with mixed pollen from the local cultivars Bayuexian and Meixian Dongtao as the male parent. The fruit is extremely large, round-spherical, with an average single-fruit weight of 350 g. The sun-exposed side of the fruit is rose-red and attractive; the flesh is fine and firm, sweet, clingstone, and very hard. It has good stress resistance, with no fruit cracking or fruit drop. The fruit ripens in mid-September, coinciding with the Mid-Autumn Festival and National Day, giving it good market prospects. Its cultivar characteristics and cultivation techniques are described below.

1 Main traits

1.1 Botanical characteristics

The tree is medium-large, with a naturally semi-circular canopy and a semi-spreading growth habit. One-year-old branches are dark red on the sun-exposed side; new shoots are green with a red blush on the sun-exposed side, with an average internode length of 2.3 cm. Leaves are narrowly lanceolate, with acuminate tips, narrow cuneate bases, finely serrate margins, and dark green color, averaging 18 cm long and 4 cm wide. Nectaries number 2-4, kidney-shaped. Flowers are rose-form, with pink petals.

1.2 Fruit economic traits

The fruit is round-spherical and uniform in size, with an average single-fruit weight of 350 g and a maximum of 500 g. The fruit apex is slightly concave, the suture is shallow and distinct, and the two halves are relatively symmetrical. The ground color of the skin is yellowish-white, with rose-red on the fruit surface, and the fuzz is sparse and short. The skin is thin and easily peeled when fully ripe. The flesh is milky white, with red pigment beneath the skin (the red pigment increases during storage or delayed harvest), and dark red near the stone. The flesh is hard-melting, juicy, crisp and sweet, with a slight aroma and few fibers; soluble solids content is 16%-17%. Clingstone, with an edible rate of 96%.

1.3 Growth and fruiting characteristics

The tree is vigorous. A 5-year-old tree is 2.5 m tall, with a crown spread of 3.0 m x 2.5 m, a trunk diameter of 10.5 cm, and an average new shoot length of 75 cm. Budbreak capacity is moderate and branching capacity is strong; long, medium, and short fruiting branches can all bear fruit. The starting node of flower buds on short fruiting branches is the 1st node, and on long and medium fruiting branches it is the 2nd-3rd node. There are many compound flower buds; a 20 cm fruiting branch averages 20 flowers. In the 2nd year after planting, the average yield per tree is 5 kg; in the 3rd, 4th, and 5th years, the yields per tree are 35 kg, 60 kg, and 75 kg respectively.

1.4 Phenological period

In the Henan region, the leaf bud swelling stage is in mid-March, the first bloom stage is at the end of March, and the full bloom stage is in early April; the flowering period is 8-9 d (days). The leaf expansion stage is in mid-April, and the rapid new shoot growth stage is in late April. The fruit begins its first rapid expansion in early to mid-May, and begins its second expansion from mid-August to early September. In early September, all fruit on the outer canopy is colored; in mid-September, fruit in the inner canopy colors and the fruit ripens; the fruit development period is 160-170 d (days). The leaf fall period is in mid-November.

1.5 Stress resistance

This cultivar is relatively drought-tolerant and waterlogging-tolerant, and also has relatively strong disease resistance. From winter 2001 to July 2002, no watering was done and no rain fell, yet it still produced a high yield. From May to August 2003, heavy rain fell continuously and prolonged overcast days occurred, yet it still produced a high yield. This cultivar has no special diseases or pests. Diseases already found include peach bacterial shot hole, anthracnose, scab, and powdery mildew; insect pests include aphids, leafminers, red spider mites, oriental fruit moths, and red-necked longhorn beetles. This cultivar rarely has brown rot and shows no preharvest fruit drop.

2 Key cultivation techniques

2.1 Soil selection and planting density

Yuxi Hongmi peach has strong adaptability and is especially drought-tolerant and tolerant of poor soil. It can be successfully planted in mountainous areas, hills, and flat land. The suitable soil pH is between 5.5 and 7.5, but replanting in old peach orchards should be avoided.

This cultivar has a spreading growth habit. The suitable planting density is a spacing of 3 m x 4 m or 2 m x 4 m between rows and plants, with pollinizer trees arranged at a ratio of 5:1.

2.2 Training and pruning

For a 4 m x 2 m row-to-plant spacing, the "V" trellis tree form is suitable. This tree form is formed in 2-3 a (years), and when formed, the main branches and their extension branches are 1.4-1.5 m long. At least a 60-80 cm ventilation and light-transmission band should be maintained between rows.

Because this line easily forms flower buds, branch number and fruit number should be strictly controlled. Per 667 sq m (mu), branches should be controlled at 8000-10000, with 2-3 fruits retained per branch. In pruning, light pruning and long shoot training should be used, mainly to develop long and medium fruiting branches; the suitable thickness of fruiting branches is 0.3-0.4 cm.

2.3 Flower and fruit management

For this cultivar, flower and fruit thinning should be strict, and the number of retained fruits should be controlled. Remove double fruits, deformed fruits, pest- and disease-damaged fruits, small fruits, upright fruits, and fruits on branches thicker than 0.6 cm, and retain good fruits with regular shape, uniform size, and on fruiting branches 0.3-0.4 cm thick. Maintain a fruit spacing of 8-10 cm, a leaf-to-fruit ratio of 50:1, and a yield per 667 sq m (mu) of more than 3000 kg. After fruit set is finalized (late May), bag with white plastic film bags to prevent pest and disease infection of the fruit, prevent fruit cracking, and promote fruit coloring. Spray insecticide and fungicide once before and after bagging.

2.4 Strengthen fertilizer and water management. Promote growth and flower formation

In the first year after planting, apply the first fertilizer when buds sprout in spring, and thereafter apply fertilizer once every 15 d (days), using quick-acting nitrogen and phosphorus fertilizers combined with organic fertilizer applied with irrigation. Each time, apply 10-25 g urea, 10 g superphosphate, and 5-10 kg organic fertilizer per tree; as the canopy expands, the fertilizer rate gradually increases. Stop fertilizer application in early July to control excessive shoot growth and favor flower formation. Apply autumn fertilizer once in late September (mainly organic fertilizer).

For high-yielding trees, fertilizer application should be based mainly on base fertilizer, applied together with deep plowing in late autumn. Generally, apply 7000 kg organic fertilizer per 667 sq m (mu), accounting for more than 80%-90% of the annual total. The second application is fruit-swelling fertilizer, mainly nitrogen fertilizer combined with phosphorus and potassium fertilizers, applied after fruit set is finalized (late May). The third application is before the fruit rapidly expands (mid- to late August), mainly quick-acting phosphorus and potassium fertilizers. In addition, after fruit harvest, if conditions permit, apply a supplementary fertilizer mainly of nitrogen in late September to help branches and shoots mature and increase the level of stored nutrients in the tree. Attention should also be paid to supplementing trace elements.

Although peach trees are highly drought-tolerant, during the flowering period and fruit expansion period, if there is a long drought without rain, irrigation should be done in time to promote normal fruit set, development, and expansion. In addition, irrigation should also be done in time after each fertilizer application. Peach trees are most afraid of waterlogging, so in rainy seasons, ditches should be cleared in time for drainage to prevent waterlogging damage.

2.5 Pest and disease control

For the pests and diseases found on this cultivar, control can be achieved by seizing 7 key control periods throughout the year. Specifically: 1) Before budbreak, spray 3degBe-5degBe lime sulfur mixture, mainly to control bacterial shot hole, powdery mildew, peach aphids, red spider mites, leafminers, and fruit borers; 2) Before flowering, spray Aoke 2000-2500x solution (or imidacloprid 2000x solution) + carbendazim powder (or thiophanate-methyl) 1000x solution, mainly to control aphids and also control mirids; 3) 10 d (days) after flowering (early April), spray methomyl 2500x solution + Hao'aisheng 1000x solution to control mirids, aphids, and peach shot hole; 4) In early May, use diflubenzuron No. 3 (1500-2500x solution) + kungfu (2000x solution) + fungicide to control peach leafminer; 5) In late May, use clofentezine (1500-2000x solution) + Taoxiaojing(ling) 1500x solution to control fruit borers and red spider mites; 6) In early June, spray Hongbaiman Lisha 2000x solution + Taoxiaoling (or kungfu) to control red spider mites; 7) From late June to early July, use Taoxiaoling(jing) + cypermethrin 2000x solution + mancozeb 1000x solution or carbendazim to control bacterial shot hole, powdery mildew, and scab. At the same time, control aphids, mites, and white peach scale, etc.

When applying pesticides, alternate the use of various types of chemicals to prevent pests and diseases from developing resistance.