Detailed Explanation of Key Cultivation and Management Techniques for Papaya

1. Select superior varieties. Varieties suitable for local conditions include Yizhou papaya, Yipinhong papaya, etc., and they can pollinate each other.

2. Field planting and orchard establishment. It is advisable to choose deep, fertile soil with good drainage, neutral or slightly alkaline loam or sandy loam. Plant spacing 2.5 m × 4 m. Before planting, dig planting holes 1 m long, 1 m wide, and 0.8 m deep, and apply 10 kg of decomposed organic fertilizer per hole. Before planting, select 2-3 year old superior strong seedlings. Both spring and autumn planting are acceptable. Spring planting is best before the seedlings bud, and autumn planting is carried out from leaf fall until the soil freezes. Autumn planting causes less root damage, heals easily, has a high survival rate, and grows well. When planting, select grafted seedlings with a seedling height of more than 1.2 m, a graft union thickness of more than 1 cm, and good callusing at the graft union. The root system is required to be intact. The planting depth should be such that after planting and watering, the root crown junction is level with the ground surface, and cover the tree base with 1 sq m of plastic film.

3. Fertilizer and water management. Base fertilizer is applied in late September when the orchard is deeply plowed, mainly using barnyard manure and human excrement and urine, mixed with quick-acting N fertilizer. Young trees are given 15-30 kg of base fertilizer per tree, and large trees are given 30-50 kg per tree.

Topdressing: before budding (late March to early April), apply 130 g of urea and 400 g of ternary compound fertilizer per tree in holes or furrows. Two weeks before and after flowering, spray once each with a mixture of 0.3% urea, 1% superphosphate, and 0.3% potassium sulfate to promote fruit cell division; at full bloom, spray 0.2% boric acid or 0.3% borax to help fruit set. In mid-to-late May, apply 100-250 g of urea per fruiting tree by ring broadcasting or furrow application. After fruit harvest, apply a compound fertilizer mainly based on nitrogen fertilizer, 0.5 kg per tree.

Water management. Generally, irrigate once thoroughly before and after flower bud sprouting. During fruit expansion and new shoot growth periods, water appropriately. Before winter, irrigate once with antifreeze water in combination with base fertilizer application. At the same time, papaya is afraid of waterlogging, so drainage should be done in a timely manner.

4. Training and pruning. For the natural round-headed form, the trunk height is set at 70-80 cm. Of the new shoots it produces, select and retain 3-4 as main branches. The main branches should be arranged in 3-4 different directions, with 10-20 cm spacing between them. Each main branch further produces 2-3 lateral branches, and the outer sides of the lateral branches further produce small lateral branches or bear fruit-bearing mother branches and fruiting branch groups.

Summer pruning: mainly adopt measures such as bud removal, pinching, and branch bending. Bud removal: promptly remove buds below the training zone, as well as upright buds on the back of main branches and competitive shoots on the tips of extension branches. Pinching: when the extension branch of a main branch grows to 50-60 cm, pinch it to promote secondary branches and train the main branch. For new shoots in other parts that are vigorous, upright, overlapping with main branches, or crossing, pinch when they grow to 20 cm to promote secondary shoots. Branch bending: generally in late August and early September, bend flat the branches not retained as main branches and keep them as auxiliary nourishing branches.

Winter pruning: for young papaya trees, the purpose is shaping and crown expansion. In the first year of winter pruning, shorten the branches retained as main branches, preferably leaving 30-40 cm. For young trees, light pruning is main, mainly thinning out overly dense branches, competitive branches, crossing branches, and overlapping branches. For branches with space, shorten them, preferably leaving 20-30 cm. When they grow to 40 cm the next year, pinch them promptly to form fruiting branch groups.

5. Flower and fruit management. In order to obtain high and stable yields, suitable pollinator trees need to be planted when establishing the orchard. The ratio of main cultivar to pollinator cultivar is 4:1. Poor management of papaya can lead to alternate bearing, so attention should be paid to flower and fruit management, and flowers and fruits should be thinned during the flowering period. Thinning flowers and fruits is especially important in an on-year. When thinning fruits, first remove branch-tip fruits, deformed fruits, and crossing fruits, and generally retain basal and middle fruits on the branch, with a fruit spacing of about 20 cm, so as to ensure large fruits, high yield, and stable yield.

6. Disease and pest control. Papaya has very few diseases, mainly insect pests. The main insect pests include aphids, papaya borers, red spiders, etc.

(1) In May, for aphids and other pests, spray 10% imidacloprid at 5000-6000 times dilution, once every 15 days, for 2-3 consecutive times. (2) In mid-June and late July, use Taoxiaoling or Taoxiao Yicijing at 1500-2000 times dilution to control papaya borers. (3) For red spiders, use 2000 times dilution of miewangli for control.