Cultivation Techniques for the Medicinal Herb Cornus officinalis and Methods for Controlling Anthracnose
Cornus officinalis, also known as zaopi or yurou, is a plant of the family Cornaceae. Its seedless flesh is used as medicine and has the functions of tonifying the liver and kidneys and astringing essence and stopping sweating. It is one of the main economic crops in Huoshan County.
I. Cultivation Techniques
1. Characteristics and growth habits. Cornus officinalis is a deciduous tree or shrub, 2-10 m tall, with alternate simple leaves, elliptical leaf blades, acuminate apex, cuneate base, axillary umbel-like inflorescences, flowers appearing before the leaves, and yellow flowers. The drupe is elongated-elliptical and red when mature. The flowering period is February to March, and the fruiting period is April to October. Cornus officinalis is generally distributed on gentle slopes of low hills at an altitude of 250-800 m in limestone soils with a relatively thick humus layer. Wild Cornus officinalis is rarely found on barren land. It prefers a warm and humid climate. Frost damage during the flowering period can cause severe yield reduction.
2. Site selection and land preparation. Choose sandy loam soil with good drainage and a deep soil layer. Idle land in front of and behind houses and beside fields and ditches can also be used for planting. Apply 4000-5000 kg of organic fertilizer per 667 sq m, then plow deeply, harrow finely, and level.
3. Propagation methods
(1) Seed propagation. Select fruits that are large, have plump seeds, and are free of pests and diseases. Remove the flesh, soak in human urine for 15-20 days, and in November dig a deep pit in a sunny spot. Apply sufficient organic fertilizer at the bottom of the pit, spread the seeds on it, then cover with pig or cattle manure or mixed fertilizer to a depth of 15-20 cm. Wait until early April of the following year, then dig open to check. Once the embryos of the seeds have begun to swell and split, they can be taken out for sowing and seedling raising. The seedling nursery should be chosen in moist, fertile, loose soil, deeply plowed and finely prepared, with weeds completely removed, sufficient base fertilizer applied, and raked level to make beds. The bed width is 1.4-1.7 m. On the bed, open drill sowing furrows 20 cm deep, with a row spacing of 35 cm and a width of 25 cm. Apply base fertilizer in the furrows again at 1500-2000 kg per 667 sq m. Sow seeds on the base fertilizer at a seed spacing of 3-5 cm. After sowing, cover well with burnt soil ash and then cover with fine soil level with the bed surface. After sowing, prevent trampling by people and livestock. Seedlings can emerge in the same year. If seeds that have not undergone base fertilizer and germination acceleration treatment are directly sown in the nursery, they will not emerge in the first year and will only emerge gradually after April of the second year, and the seedlings will be uneven. After emergence, carry out timely intertillage and weeding and apply appropriate fertilizer. When the seedlings are about 1 m tall, they can be transplanted.
(2) Cutting propagation. Select healthy, disease-free mother plants with heavy fruiting. In February to March, cut branches about 66 cm long, soak them in a 1:20000 sodium naphthaleneacetate solution for a full day and night, and insert them into the soil at a row spacing of 33 cm and a plant spacing of 10-13 cm, with the branches inserted about 13 cm into the soil. The nursery bed should be given sufficient base fertilizer and kept moist. If conditions permit, a small arched shed can be used to retain moisture and heat. Transplant only after the branches have grown fibrous roots and survived.
(3) Field planting. The transplanting and field planting time for both seed-raised and cutting-raised seedlings is winter and spring, with a higher survival rate in winter. Choose sunny, fertile land with a deep soil layer for planting. The depth of the planting holes depends on the length of the main roots of the saplings. During field planting, the roots of the saplings should be spread out smoothly, not bent, and not damaged. Each plant should be 2.7-3 m apart. Generally, 60 plants are planted per 667 sq m of mountain land. After planting, cover with soil and press firm, then water with an appropriate amount of water and diluted manure.
4. Field management. Field management of Cornus officinalis must achieve the "four diligences and one prevention," namely frequent weeding, frequent earthing up, frequent pruning, frequent fertilization, and prevention and control of pests and diseases. Specifically, it can be carried out in stages.
(1) Management during the seedling stage. Before emergence, keep the soil moist frequently, prevent the ground from drying and crusting, and cover with grass. Water during drought. After the seedlings emerge, remove the covering grass and frequently pull weeds. When the seedlings are about 15 cm tall, apply dilute manure fertilizer once to accelerate seedling growth. If the seedlings are too dense, thin them when they are 12 cm tall. If the current-year seedlings do not reach the height for field planting, cover with weeds and pig or cattle manure before winter to help retain heat and moisture so that the seedlings can overwinter safely.
(2) Management after field planting. After field planting, carry out intertillage and weeding 4-5 times each year to keep the area around the plants free of weeds. If sufficient base fertilizer was applied at transplanting, no additional fertilization may be needed in the same year. Thereafter, apply fertilizer once each year in spring and autumn. The amount of fertilizer applied depends on the age of the tree: apply less to small trees and more to large trees. A large tree over 10 years old can be given 10-15 kg of human and livestock manure per plant. The method is to open a ditch around the tree, apply the fertilizer, then water, and after the water infiltrates, level the ditch. In the first year after field planting and once the fruiting stage begins, attention should be paid to watering. Drought during the flowering period or summer can cause flower and fruit drop. Before early February of the second year after planting, cut off the terminal branches to promote the growth of lateral branches. During the young tree stage, cut off the clustered branches at the base of the tree every early spring to promote trunk growth. Pay attention to shaping the crown and thinning the lower lateral branches so that the branches of the crown are evenly distributed, which facilitates ventilation and light penetration and increases the fruiting rate. Young trees should be earthed up 1-2 times each year, while mature trees can be earthed up once every 2-3 years. If roots are found exposed above the ground, promptly mound soil around the roots.
II. Control of Cornus officinalis anthracnose. Cornus officinalis anthracnose, also known as black fruit disease, can have a diseased fruit rate of more than 50%, and the tree vigor declines, reducing fruiting in the second year and affecting yield and quality.
1. Disease symptoms. When young fruits are affected, the pathogen mostly invades from the top of the fruit, and the lesion expands downward. The diseased part is black, and the edge is reddish-brown. The lesion gradually expands to the whole fruit, which then turns black and shrinks, and most do not drop. When mature fruits are affected, brownish-red small spots appear first, then expand into circular or elliptical black sunken spots. The edges of the lesions are reddish-brown, with a red halo on the outside. Under moist conditions, small black dots and orange-red spore masses are produced on the diseased part. When the lesions unite, the whole fruit turns black, dries up, and drops.
2. Disease occurrence pattern. The pathogen overwinters on diseased fruits as mycelium and acervuli, and produces conidia for infection in mid-to-late April of the following year. During the growing season, conidia are produced and spread by wind and rain, expanding the damage. The peak period of fruit anthracnose is July to September. In years with a large amount of overwintering inoculum, abundant rain, and high humidity, the disease occurs earlier and more severely. Older trees and trees with weak growth are more severely affected, while vigorously growing trees are less affected. Extensive management leads to severe disease, while pruning and fertilization reduce disease severity.
3. Control methods
(1) Agricultural control. After fruit harvest in autumn, prune off diseased fruits and diseased branches, bury diseased fruits on the ground, and reduce overwintering inoculum. Strengthen field management by pruning, watering, and fertilizing to promote robust growth and enhance disease resistance.
(2) Chemical control. In the early stage of disease onset, promptly spray 25% prochloraz emulsifiable concentrate at 1000 times dilution, or 50% prochloraz wettable powder at 1000-2000 times dilution for control.