Field Management Methods and Technical Key Points for Dahurian Angelica

① Thinning and final thinning: For autumn-sown Dahurian angelica, after the seedlings turn green in early spring, begin thinning when the seedlings are about 5 cm tall. The first thinning is at a plant spacing of 5 cm, the second at 10 cm; when the seedlings are about 15 cm tall, carry out final thinning at a spacing of 12-15 cm, removing small, weak and overly vigorous seedlings. The thinning and final thinning of spring-sown Dahurian angelica are carried out in the same way.

② Cultivation and weeding: Carry out cultivation and weeding at the same time as thinning. The first cultivation should loosen the surface soil shallowly, and thereafter the depth can be increased gradually, with the number of times depending on soil moisture and weed growth. Once the plants have grown large and closed the rows, cultivation and weeding should no longer be carried out. When loosening the soil, take care not to damage the main root, otherwise the main root tends to branch; if any individual plant is found to bolt early, it should be pulled out promptly.

③ Topdressing: Dahurian angelica likes fertilizer, but generally little or no fertilizer is applied before spring to prevent overly vigorous growth during the seedling stage and premature bolting and flowering. Before the rows close, calcium-magnesium-phosphorus-potassium fertilizer can be applied; per 667 sq m, apply 25 kg of calcium-magnesium-phosphate fertilizer and 5 kg of potassium chloride. Immediately after application, earth up the soil to prevent lodging and promote growth. The number of topdressings and the amount applied each time can be determined according to the growth of the plants. If, when the rows are about to close, the leaves are light green and growth is not very vigorous, topdressing can be applied once more; if at this time the leaves are dark green and growth is vigorous, no further topdressing is needed.

④ Irrigation and drainage: Dahurian angelica likes water but is afraid of soil waterlogging. After spring of the following year, timely irrigation can be carried out together with topdressing, and especially during the dog days, sufficient moisture should be maintained. If water accumulates in the field during the rainy season, ditches should be opened promptly for drainage to prevent root rot and disease occurrence caused by standing water.

⑤ Removal of bolting plants: In May of the second year after sowing, if any plants bolt and flower, they should be pulled out promptly.

⑥ Pest and disease control: The main diseases of Dahurian angelica include leaf spot and violet root rot. For leaf spot (white spot disease), spray 1-2 times with Bordeaux mixture at 1:1:100 or 65% zineb wettable powder at 400-500 times dilution to control the development of the disease. For the control of violet root rot, per 667 sq m, use 200 g of 50% tecmazine wettable powder plus plant ash, broadcast it into the soil, and then plow before sowing. The main insect pests of Dahurian angelica include the yellow swallowtail butterfly, aphids and red spider mites. For the yellow swallowtail butterfly, spray 90% trichlorfon at 800 times dilution, Qingchongjun (each gram of powder contains 10 billion spores) at 500 times dilution, or Bt emulsion at 200-300 times dilution, once every 5-7 days for 3 consecutive times. During the occurrence period of aphids, spray 40% dimethoate at 1,500-2,000 times dilution or 50% fenitrothion at 1,000 times dilution, once every 5-7 days for 2-3 consecutive times. For the control of red spider mites, begin spraying 0.2-0.3 degree Beaume lime-sulfur mixture in April, once a week for several consecutive times.