Detailed Explanation of Key Points for High-Yield Cultivation Techniques of Angelica dahurica

I. Land selection and land preparation:

Angelica dahurica is a deep-rooted plant, so it is advisable to choose sandy loam soil with deep soil layers, medium fertility, and good drainage for planting. Apply 4000 kg to 5000 kg of farmyard manure per 1000 sq m, together with 80 kg of superphosphate, plow deeply to 30 cm, harrow finely and level, and make flat beds 1.5 m wide.

II. Propagation method:

Seed propagation is used, mostly by direct sowing. For autumn sowing, generally sow in September to October. For drilling, open shallow furrows at a row spacing of 35 cm and sow; for hole sowing, open holes at a hole spacing of (15-20) cm X 30 cm and sow. After sowing, cover with a thin layer of soil and press firm. Seedlings can emerge 15-20 days after sowing. Seed rate per 1000 sq m: about 2 kg for drilling; about 1 kg for hole sowing. If before sowing the seeds are sprayed with a 2% potassium dihydrogen phosphate aqueous solution, stirred, and moistened in a closed state for about 8 hours before sowing, emergence can be advanced and the emergence rate greatly increased.

III. Field management

1. Thinning and final thinning: In the following spring, when the seedlings are about 5 cm tall, begin thinning, generally carried out 2 times. When the seedlings are 15 cm tall, do final thinning. For drilling, thin to a plant spacing of 12 cm to 15 cm; for hole sowing, keep 1-3 strong seedlings per hole. At the same time, remove exceptionally large seedlings to prevent early bolting.

2. Intertillage and weeding: Each thinning should be combined with intertillage and weeding. The first time, only loosen the surface soil lightly, and thereafter gradually deepen. After the plants close the rows, stop intertillage.

3. Topdressing: Generally topdress 3-4 times. It is often carried out after thinning and final thinning and before row closure. The main fertilizer types are decomposed human manure and urine, cake fertilizer, etc., first light and then concentrated. After the last topdressing before row closure, earth up promptly to prevent lodging.

4. Drainage and irrigation: If the soil is dry after sowing, water once. Thereafter, keep the bed surface moist before the seedlings emerge to favor emergence. After final thinning, water less and cultivate more to promote downward root growth. Pay attention to drainage after rain.

IV. Pest and disease control

1. Septoria leaf spot: Mainly damages leaves. Control methods: Remove diseased and residual tissues and burn them in a centralized manner; in the early stage of the disease, spray with 1:1:100 Bordeaux mixture or polyoxin 100-200 units.

2. Papilio machaon: The larvae damage leaves. In addition, aphids, red spiders, and root-knot nematode disease also damage the aboveground parts and roots, so timely selection of appropriate pesticides for control is necessary.