Key Harvesting and Storage Techniques for Eucommia ulmoides Cultivation

The whole Eucommia ulmoides plant is a treasure; its leaves, bark and seeds are not only medicines and natural health products, but also raw materials for extracting eucommia rubber. The harvesting and storage of Eucommia ulmoides directly affect the level of yield and the quality.

I. Harvesting and Storage of Leaves

1. Selection of leaf-harvesting trees. (1) Choose trees that are free of pests and diseases and have not been sprayed with pesticides, to prevent germs, insect spots and pesticide residues on the leaves from poisoning the human body; (2) harvest green leaves, avoid harvesting yellowed leaves, because green leaves have a high content of active ingredients while yellowed leaves have little; (3) Eucommia ulmoides leaves used for extracting eucommia rubber need only be free of rot and deterioration.

2. Timing of leaf harvesting for medicinal use. Generally, leaves can be harvested from July to October, and August is the best period for leaf harvesting. When harvesting Eucommia ulmoides leaves for extracting eucommia rubber, from the perspective of not affecting tree growth, the fallen leaves of November are best.

3. Post-harvest handling of leaves. To prevent rot, after harvesting, Eucommia ulmoides leaves should first be spread out indoors and promptly subjected to fixation (de-enzyming) treatment. A common fixation method is to use an ordinary iron wok as a roasting pan, stirring and roasting until the leaf surface loses its luster, the leaf color turns dark green, the leaf texture becomes soft, the leaves do not stick to the hand when held, and the weight loss is about 30%; fixation can also be done in a fixation pot at a temperature of about 200°C for 5 minutes. Eucommia ulmoides leaves specifically used for rubber production are not subjected to fixation treatment, but leaves that have undergone fixation can still be used to extract eucommia rubber.

4. Storage. After fixation treatment, Eucommia ulmoides leaves should be promptly dried by baking or air-dried, cleaned of impurities and bagged. Leaves used for rubber production should also be air-dried and bagged, and stored in a dry, ventilated warehouse, with attention to moisture-proofing, sun-proofing, insect-proofing and rat-proofing.

II. Harvesting and Storage of Bark

1. Harvesting time. Generally between spring and summer; because climatic conditions vary from place to place, the specific time differs. Peeling is most suitable when the sap flows freely and the phloem is most easily separated from the xylem.

2. Harvesting method. Select robust plants with a diameter at breast height of more than 12 cm, first make a ring cut at the base of the trunk with a sharp knife; using this as the starting point, make a ring cut every 40-80 cm above it, and make one straight longitudinal cut between the two rings; after cutting, gently pry with a bamboo strip from the longitudinal cut to separate the bark from the xylem, prying while peeling, so that the whole sheet of bark can be peeled off; for young trees with a diameter at breast height of less than 12 cm, peeling is strictly prohibited.

3. Post-harvest handling. After the bark is peeled off, scald it with boiling water, then spread it out and place it on a straw or wheat straw mat in a ventilated place sheltered from rain, so that the Eucommia ulmoides bark closely overlaps on it, then press it flat with wooden boards weighted with stones, and cover and press the surroundings with straw bags or gunny bags. Check after 7 days; if the inner bark is dark brown or purple-brown, it can be taken out, sun-dried and pressed flat; the sun-dried Eucommia ulmoides bark should have its outer bark shaved off with a plane, taking care to shave it flat, and finally brush the mud and dust clean with a palm brush.

4. Grading and packaging. Eucommia ulmoides bark varies in size, thickness and quality, so it must be packaged by grade. The current standard for state purchasing of Chinese medicinal materials uses width and thickness as the main indicators for determining grade, with length as a secondary indicator. Eucommia ulmoides bark is divided into 4 grades: (1) Special grade: dry goods, flat slab shape, both ends cut even, coarse bark removed, surface grayish-brown, interior dark brown, brittle, with rubber threads connecting at the break. Taste slightly bitter, length 70-80 cm, width more than 50 cm, thickness more than 0.7 cm, broken pieces not exceeding 10%, no curled shape, impurities or mildew; (2) First grade: dry goods, flat slab shape, both ends cut even, coarse bark removed, surface grayish-brown, interior dark brown, brittle, with rubber threads connecting at the break. Taste slightly bitter, length more than 40 cm, width more than 40 cm, thickness more than 0.5 cm, broken pieces not exceeding 10%, no curled shape, impurities or mildew; (3) Second grade: dry goods, flat slab shape or curled shape, surface grayish-brown, interior greenish-brown, brittle, with rubber threads connecting at the break. Taste slightly bitter, length more than 40 cm, width more than 30 cm, thickness more than 0.3 cm, broken pieces not exceeding 10%, no impurities or mildew; (4) Third grade: does not meet the standards of special, first or second grade, with the thinnest thickness not less than 0.2 cm, including branch bark, root bark and broken pieces, all belonging to this grade, but also should be free of impurities and mildew.

5. Storage. Pack the graded Eucommia ulmoides bark separately by category, arrange neatly, bundle into pieces, 50 kg per piece, and store in a dry place.

III. Harvesting and Storage of Seeds

1. Selection of seed trees. Seed trees should be selected from trees more than 15 years old that grow robustly, receive sufficient light, have smooth bark, are free of pests and diseases, and have not been peeled. Special attention should be paid not to harvest seeds from mother trees that have been peeled, because after the Eucommia ulmoides tree has borne fruit and been peeled, the nutrient transport system is destroyed; the seeds appear similar to mature ones on the outside, but in fact are not fully developed, the seed kernel is not plump, the vitality is weak, and the content of physiologically active substances is low.

2. Seed collection time. The collection of Eucommia ulmoides seeds must be timely, generally harvested from October to November. If too early, the embryo is not fully developed, the seeds are not fully mature, the oil content is low, the water content is high, respiration is vigorous, and mildew is likely; if too late, the seeds are easily scattered by the wind. The characteristics of mature seeds are: pericarp brown, brownish-brown or yellowish-brown, glossy, seeds plump, endosperm white, cotyledons oblate, rice-yellow.

3. Harvesting method. Choose a sunny day with no wind or little wind, when the seeds are not easily blown down and scattered. Tap lightly with a bamboo pole or shake the branches by hand to make them fall off. At the same time, spread bamboo mats or cloth screens on the ground at a certain distance from the mother tree in the downwind direction to catch the falling seeds. Never cut branches to collect seeds; cutting branches not only affects the fruit yield of the next year, but also affects the growth of the mother tree.

4. Seed handling and storage. After the seeds are collected, they should be placed in a ventilated, cool place to dry in the shade; do not dry them by fire or in the scorching sun. After the seeds are dried in the shade and cleaned, they can be stored in a cool, ventilated place; do not pile them too thickly, to prevent heating.