Dandong Azalea

Dandong Azalea

Dandong Azalea is a geographical indication agricultural product.

　　China is the homeland of azaleas. The azaleas of Dandong, Liaoning, have spread their unique charm to Sichuan, Shanghai, Xinjiang, Zhejiang, Beijing, and even the "City of Flowers," Guangzhou. Of the more than 800 species of azaleas found worldwide, 650 are distributed in China, with over 240 species in Dandong alone. After more than 60 years of cultivation, Dandong azaleas have developed their own superior characteristics.

　　Dandong azaleas have a long history and enjoy a high reputation both domestically and internationally. Currently, Dandong has over 5,000 acres of azalea planting bases, employing more than 50,000 people, and cultivates over 300 varieties of azaleas, with large quantities sold across the country every year.

　　The soil, climate, and water quality conditions in Dandong are particularly suitable for azalea growth. As a result, governments at all levels in Dandong actively support the development of the azalea planting industry, establish flower markets, and while expanding publicity, promote large-scale, technologically advanced, and high-quality azalea cultivation, making azaleas a specialty product of Dandong.

　　Azaleas (Rhododendron), also known as Yingshanhong, Shan Zhizhu, Hong Zhizhu, Shan Shiliu, and Shan Juan, are evergreen or deciduous shrubs or evergreen trees of the Rhododendron family. The genus comprises about 900 species, with 530 species native to China, mainly distributed in Yunnan, Tibet, Sichuan, and cultivated garden varieties numbering around 300. They are generally divided into: Spring Azaleas (Oriental Azaleas), originating from Japan, with smaller flowers, blooming in April, and numerous varieties; Mao Azaleas (Large-leaf Azaleas), robust and growing up to 2–3 meters tall, serving as excellent rootstocks for Western Azaleas, with mostly single-petaled large flowers and about 10 varieties; Western Azaleas, first bred in the Netherlands and Belgium in Western Europe, known for their diverse colors and shapes, the most beautiful category, compact and dense in form, sensitive to frost, blooming from April to May with flower diameters of 6–10 cm, and numerous varieties; Summer Azaleas (known as Satsuki Azaleas in Japan), the latest to bloom from May to June, with slender branches and leaves, full tree crowns, and heights of around 1 meter. The azalea is the national flower of the Kingdom of Nepal. Fine varieties are propagated through grafting, cuttings, or seeds of the original species. It is one of the world’s famous flowers and one of China’s ten traditional famous flowers. Suitable for planting in gardens, it is a major flower in winter, spring, and early summer.

　　Geographic Scope

　　The geographic scope of Dandong Azaleas covers the current administrative regions of Dandong City, namely Donggang City, Fengcheng City, Kuandian County, Zhen’an District, Zhenxing District, and Yuanbao District. The geographical coordinates are between 123°22′–125°41′ east longitude and 39°43′–41°09′ north latitude. The production area within this scope is 350 hectares, with an annual output of 30 million plants.

　　Natural Ecological Environment and Humanistic Historical Factors

　　(1) Soil and Topography: The soil types and their combinations vary significantly across Dandong’s regions. The city has six soil types: brown soil, dark brown soil, meadow soil, saline soil, marsh soil, and paddy soil; 13 subtypes, 45 soil genera, and 102 soil species. Brown soil is the most prevalent, accounting for 86.24% of the total soil area, followed by meadow soil at 6.72%, and then paddy soil, dark brown soil, saline soil, and marsh soil. The average nutrient content of the city’s soil is: organic matter 2.12%, total nitrogen 0.123%, available nitrogen 6 ppm, available potassium 143 ppm, with a soil pH between 6.0–6.5, making it highly suitable for the growth and development of Dandong Azaleas. Dandong is part of the Liaodong mountainous hills, belonging to the southwestern extension of the Changbai Mountain range or its residual ranges. The terrain gradually descends from northeast to southwest. Based on elevation and topographic features, it can be divided into three major landform units: the central and low mountainous areas in the north, the hilly areas in the south, and the coastal plain areas along the southern edge. Mountainous and hilly areas dominate, with some smaller landforms such as terraces, basins, and plateaus. The general topography is described as “seven parts mountains, one part water, half a part fields, and half a part roads and estates.” The northern edge of Fengcheng City and the northern part of Kuandian County belong to the central and low mountainous areas, with elevations generally between 400–1000 m and erosion depths of 300–500 m. The area from northern to central Fengcheng City and central Kuandian County belongs to the low mountain and hilly area, with elevations typically between 300–800 m and erosion depths of 100–300 m. The southern parts of Fengcheng City and Kuandian County...

　　...and the northern part of Donggang City are hilly areas, generally below 500 m in elevation, with relative height differences of 50–150 m. The southern part of Donggang City features a coastal plain extending east-west in a belt-like pattern, with an elevation of 2–5 m and a slight incline toward the Yellow Sea.

　　(2) Hydrology: Dandong has abundant water resources. There are 1,361 rivers of various sizes (over 2 km in length) in the city, including four major rivers with drainage basins exceeding 5,000 km²: the Yalu River, Hun River, Yu River, and Dayang River. There are 54 reservoirs, 31 hydropower stations, five large irrigation districts, over 200 small irrigation districts, and over 3,000 km of artificial river embankments. The city’s total surface water resources amount to 8.932 billion cubic meters, including 3.990 billion cubic meters in Kuandian County, 3.364 billion cubic meters in Fengcheng City, 1.211 billion cubic meters in Donggang City, and 0.367 billion cubic meters in the Dandong urban area (including Zhen’an District).

　　(3) Climate: Located in a mid-latitude region, Dandong has distinct seasons and a warm temperate continental monsoon humid climate. Winters are the longest, followed by summers, with spring and autumn transition seasons being the shortest. The main climatic features are mild winters and cool summers, humid weather, abundant precipitation, clean and fresh air, ample sunlight, and suitable temperatures. The average annual temperature in the southern part of the city is 8–9°C, with a frost-free period of 180–200 days and an annual effective accumulated temperature above 10°C of 3,200–3,500°C; the northern part has an average annual temperature of 6–7°C, a frost-free period of 135–180 days, and an annual effective accumulated temperature above 10°C of 2,800–3,200°C. The annual average sunshine duration in the region is 2,350–2,530 hours, with an average annual rainfall of 900–1,200 mm. Over 85% of the annual precipitation occurs from April to September, and the average annual humidity is 60%. Dandong lies in the westerly wind belt of atmospheric circulation, with predominantly northerly winds in winter and southerly winds in summer, allowing warm and moist air currents from southern low-pressure systems to frequently move northward, resulting in frequent overcast, foggy, and rainy weather in the Dandong area.

　　(4) Humanistic History: Dandong has a long history of azalea cultivation. In the 1930s, potted azaleas were already present in Dandong, and by the time of the liberation of the Northeast, the "Old Eight Varieties" of Dandong azaleas had been established. In the 1960s, through the collection of superior folk azalea varieties and artificial pollination, the "New Eight Varieties" and "Special Eight Varieties" of Dandong azaleas were cultivated. Varieties such as "Wubaozhu," "Sihai Bo," "Wangguan," and "Fen Tianhui" are among the finest in China’s azalea family, forming a unique population of Dandong azaleas. On March 27, 1984, the second session of the ninth Dandong Municipal People’s Congress reviewed and approved the Dandong Municipal Government’s proposal to designate the azalea as the city flower of Dandong. Since then, the azalea has officially become the city flower of Dandong. In recent years, the municipal government has correctly guided the development of the azalea industry, not only listing Dandong azaleas as one of the city’s specialty industries but also making long-term plans for its development. Through rational production structure layout, introduction of new varieties, increased floral diversity, promotion of low and compact crown shaping, and flowering period regulation techniques, Dandong azaleas have become more aesthetically pleasing, with extended flowering periods, and have formed large-scale commercial bases. Currently, Dandong azaleas, as an emerging industry in Dandong’s rural areas, are developing rapidly and showing promising momentum, becoming a branded flower with Dandong regional characteristics. Dandong has also become the only city in China that is a dedicated azalea production base. Dandong azaleas now have six color series and over 120 precious varieties, and have been awarded "Gold Awards" multiple times at national flower expos.

　　It has become a brand flower with characteristics unique to the Dandong region, and Dandong City has also become the only city in China designated as a rhododendron production base. Currently, Dandong rhododendrons come in 6 color series and over 120 precious varieties, and have been awarded the "Gold Award" multiple times at national flower expos.

　　Production Technical Requirements

　　(1) Site Selection: A. Facility Requirements. Azaleas should be cultivated in ventilated, light-permeable, sunlit greenhouses equipped with misting facilities and shading. The greenhouse and surrounding environment should be free from air and water pollution. B. Substrate Selection. The substrate should be loose, well-drained, breathable, and have a slightly acidic pH between 4.5–6.5. C. Temperature. Azaleas prefer cool climates and are not suited to high temperatures. The optimal growth temperature is 25–28°C during the day and 10–15°C at night. Growth is hindered when temperatures exceed 30°C or fall below 5°C, and frost damage can occur below 1°C. D. Water Quality and Humidity. The water used for azaleas should have a pH between 4.5–6.5, with air relative humidity of 70–80% and substrate relative humidity of 50–60%. E. Light. Azaleas are long-day plants, and insufficient light affects flower quality, but they are sensitive to intense sunlight. Shading is required in summer and autumn, with direct light reduced to 40–60%. F. Ventilation. Ensure good ventilation and proper planting density.

　　(2) Variety Selection: Choose robust, adaptable Dandong azaleas that meet market demand.

　　(3) Production Process: A. Cultivation Methods. ① Selection of Pots and Substrate. Choose pots suitable for azalea growth; the substrate should be breathable, moisture-retentive, and conducive to root development. ② Propagation. Azalea cultivation primarily uses asexual propagation. Breeding can involve sexual reproduction or the use of bud mutations to develop new varieties. Rootstock Cuttings: Use robust, fast-growing, and highly compatible Mao Azaleas (with strong root systems) as rootstocks. Cut 6–8 cm semi-woody new branches from healthy plants during April–June and September–October, remove lower leaves, retain the top 2–3 leaves, dip the base in a rooting agent, and then insert into sandy soil (spring) or peat soil (autumn) under shaded conditions. Maintain a temperature of 25–28°C and humidity of 80–85%. Water thoroughly after insertion, then use misting to maintain moisture when leaves are dry. Gradually remove shading after 20 days, allow slight ventilation after 40–50 days, and remove the cover after 60 days. Water only when necessary to prevent root rot. Transplanting and Shaping: Transplant rooted Mao Azaleas into nutrition pots or prepared beds, shade them, and prune after 80–120 days by cutting 10–20 cm from the base (longer for larger plants). New axillary buds will grow after about 30 days; retain 3–4 buds, remove excess ones, and prune again based on growth, keeping 8–9 buds. For larger plants, continue pruning; for smaller ones, proceed to grafting. Grafting Methods and Post-Grafting Management: Use superior varieties as scions, cut 3–4 cm of tender branches as scions, and trim the lower part into a wedge shape using a sharp knife. Use semi-woody tender branches as rootstocks, split them 0.3–0.6 cm deep with a blade, insert the prepared scion, and secure tightly with plastic twine. Water thoroughly, place in a plastic greenhouse, and shade to maintain temperature and humidity for wound healing. Gradually allow ventilation and remove shading after 30 days, and remove the greenhouse after 50 days. Mist as needed if leaves dry, and water slightly if soil dries—avoid overwatering to prevent root rot. After 70–80 days out of the greenhouse, remove binding twine and eliminate nutrient-consuming Mao Azalea axillary buds. B. Field Management. ① Fertilization. Avoid alkaline, concentrated, or uncomposted organic fertilizers. Use fertilizers suitable for azaleas, preferably applied on overcast days or in the evening, followed by watering to aid dissolution. Stop fertilizing during the semi-dormant summer period and apply 1–2 phosphorus fertilizations during the reproductive growth phase. ② Watering. Supply sufficient water without waterlogging. Keep the substrate moist but not soggy. In summer and autumn, water 1–2 times daily to maintain air humidity, focusing on foliar spraying. Extend watering intervals in winter. ③ Finished Flower Pruning. Azalea shape depends entirely on pruning. Prune 2–3 times annually: in March, prune semi-finished or post-bloom azaleas, removing weak, diseased, and excess branches, shaping them as desired, with cuts kept short (3–5 cm). June pruning is mainly for flowers intended for the Spring Festival market, focusing on retaining flower density while removing weak branches. If not for market, prune again in October—market-bound flowers are pruned twice yearly, others three times. ④ Flowering Period Control. Pruning controls the flowering period based on variety and bud development stages. Temperature and Humidity Control: To advance flowering, maintain temperatures of 25–30°C during the day and above 15°C at night, with over 80% humidity, advancing the flowering period by 20–40 days. To delay flowering, keep budded plants at 2–4°C in shade, maintaining a low-temperature semi-dormant state without drying out or watering, thus postponing the flowering period accordingly. C. Pest and Disease Control. Follow the principle of "prevention first, integrated control." Prohibit the use of highly toxic, persistent, or teratogenic/carcinogenic/mutagenic pesticides. ① Black Spot Disease (Brown Spot). Symptoms: A fungal disease causing black or brown spots on leaves, which enlarge rapidly, leading to leaf drop, stunted growth, or death. Optimal conditions: 18–23°C and over 90% humidity. Control: Lower temperatures, reduce watering, ensure proper ventilation, promptly remove and burn infected leaves. Rotate broad-spectrum fungicides for prevention. ② Chlorosis (Yellowing, Iron Deficiency). Symptoms: A physiological disorder where leaves turn yellow or yellow-white due to iron deficiency, dark yellow from overwatering, or yellow/brown from overfertilization. Solutions: For iron deficiency, spray 0.1% ferrous sulfate solution twice, 10 days apart, or preventatively. For root rot yellowing, reduce watering, spray GreenBang 98 and Rare Earth at 600x to boost resilience and root growth. For overfertilization, flush with water if yellowing appears 5–6 days after fertilization, stop fertilizer use, and wait for new branches to lignify before re-fertilizing. For newly transplanted plants, wait 30 days before fertilizing, using Yellow Leaf Enemy at 400x to regulate growth. ③ Root Rot. Symptoms: Infects roots and stems, initially water-soaked, then rotting with brown vascular bundles, not spreading upward. Later, affected areas deteriorate, with plants wilting at noon and recovering at dawn, potentially dying in severe cases. Control: Strictly disinfect substrate before repotting; maintain loose, moist, well-draining substrate to avoid waterlogging. Remove and treat infected plants, debris, and soil. Wash and repot affected plants, or spray treated soil with a 70% Thiophanate-Methyl solution at 1000x. ④ Red Spider. Symptoms: Hinders tender leaf growth, causing curling, shrinking, or rust-colored leaves. Control: Use acaricides like Abamectin or Kelthane. ⑤ Mealybugs. Symptoms: White, powdery pests on leaf buds, branches, and stems, sucking nutrients and hindering growth, potentially killing plants. Control: Use Lorsban for effective treatment.

　　Cut 3-4 cm of tender branch to use as scion, and shave the lower part of the tender branch into a wedge shape with a sharp knife. The rootstock should be a semi-lignified tender

　　branch. Use a blade to split the rootstock 0.3-0.6 cm deep, insert the prepared scion, and secure it tightly with plastic string. Water thoroughly, place it in a plastic greenhouse, and provide shade to maintain temperature and humidity, promoting wound healing. After 30 days, gradually allow ventilation and remove shading materials; after 50 days, the greenhouse can be removed. During this period, if leaves dry out, you can mist them to maintain moisture. If the soil dries out, water appropriately but not excessively to avoid root rot. Seventy to eighty days after removing the greenhouse, cut off the binding strings and remove the axillary buds of the nutrient-consuming Rhododendron mucronulatum. B. Field Management. ① Fertilization. Rhododendrons are sensitive to alkaline fertilizers, concentrated fertilizers, and uncomposted organic fertilizers. Choose organic fertilizers or compound fertilizers suitable for rhododendron growth. It is best to fertilize on overcast days or in the evening, and water after applying fertilizer to aid dissolution. During the peak summer season, when rhododendrons are in a semi-dormant state, stop fertilizing. When entering the reproductive growth phase, apply 1-2 additional phosphorus fertilizers. ② Watering. Rhododendrons require ample water but cannot tolerate waterlogging. The growing medium should be allowed to dry out between waterings. In summer and autumn, to maintain air humidity, water once or twice a day, mainly spraying the leaves to increase humidity. In winter, extend the intervals between watering. ③ Pruning of Finished Flowers. The shape of the rhododendron flower is entirely dependent on pruning. Prune 2-3 times a year. In March during spring, prune semi-finished or post-bloom rhododendrons, removing diseased, weak, and excess branches, shaping them as desired. Keep the branches no longer than 3-5 cm. Pruning in June is mainly for flowers intended for the Spring Festival market. At this time, prune to remove weak branches while maintaining flower density. If not for market release, continue pruning in October—that is, market-bound flowers are pruned twice a year, while non-market flowers are pruned three times. ④ Flowering Period Control. Pruning Control: Adjust the flowering period through branch pruning, determining the timing based on variety and bud development stages. Temperature and Humidity Control: To advance blooming, maintain temperatures of 25-30°C during the day and above 15°C at night, with relative humidity above 80%. This can advance the flowering period by 20-40 days. To delay blooming, place plants with formed flower buds in a cool location at 2-4°C, keeping them in a low-temperature semi-dormant state without watering until dry. This delays the flowering period accordingly. C. Pest and Disease Control. Rhododendron pests and diseases should be managed according to the principle of “prevention first, integrated control.” The use of highly toxic, acutely poisonous, high-residue, and teratogenic (carcinogenic, mutagenic, teratogenic) pesticides is prohibited. ① Black Spot Disease (Brown Spot Disease). Symptoms: A fungal disease where symptoms include black or brown spots on the leaves. The spots expand rapidly, and in severe cases, leaves fall off, growth halts, or the plant may die. The optimal temperature for black spot disease is 18-23°C, with relative humidity above 90%. Control Methods: Lower temperatures, reduce watering frequency, practice reasonable planting density, improve indoor ventilation and light penetration, and promptly remove and burn any infected leaves. For chemical control, alternate broad-spectrum fungicides and apply them regularly for prevention. ② Chlorosis (Yellowing Disease, Iron Deficiency). Symptoms: A physiological disorder. Symptoms include yellowing or yellow-white leaves due to iron deficiency; dark yellow leaves caused by waterlogging and root rot; and yellowing or yellow-white withering of central leaves due to over-fertilization. Solutions: For iron deficiency, spray a 0.1% ferrous sulfate solution every 10 days, for two consecutive sprays or as a preventive measure. For yellowing due to root rot, reduce watering frequency, spray GreenBang 98 and rare earth elements at 600x dilution to enhance stress resistance and promote root development. For over-fertilization issues, if yellowing is noticed 5-6 days after fertilization, promptly water thoroughly to dilute the fertilizer concentration, stop using fertilizer, and wait until new branches lignify before re-fertilizing to prevent further damage. For transplanted plants whose roots haven’t yet acclimated, wait 30 days before fertilizing. You may use Yellow Leaf Enemy at 400x dilution to regulate plant growth. ③ Root Rot. Symptoms: Primarily infects roots and stems, initially appearing water-soaked, then decaying. The vascular bundles in decayed areas turn brown but do not spread upward. In later stages, affected areas often deteriorate. Initially, above-ground symptoms are not obvious, but later leaves wilt at noon and recover in the morning and evening. Severe cases can lead to plant death. Control: Thoroughly disinfect the growing medium before repotting; keep the medium loose, moist, and well-aerated to avoid waterlogging. Upon detecting infected plants, promptly remove and dispose of diseased plants, residues, and potting soil. For treatment, rinse with water and repot. Spray a solution made from 70% thiophanate-methyl wettable powder diluted 1000x onto the potting soil. ④ Red Spider Mites. Symptoms: Tender leaves show hindered growth, curling and shrinking, or turn rust-colored. Control Method: Use acaricides such as abamectin or kelthane. ⑤ Mealybugs. Symptoms: Attach to leaf buds, branches, and stems, appearing as a white powdery substance. They suck plant nutrients, affecting normal growth, and can cause severe damage or death. Control Method: Lorsban provides effective control.

　　Spray twice in succession or apply as a preventive measure in advance; for root rot and yellowing, reduce watering frequency and spray with GreenBang 98 and rare earth elements at 600x dilution to enhance stress resistance and promote root development; if caused by over-fertilization, such as when plants turn yellow 5–6 days after fertilizing, promptly water thoroughly with clean water to dilute the fertilizer concentration, stop using fertilizer, and wait until new shoots have lignified before re-fertilizing to prevent further fertilizer damage; for transplanted plants whose roots have not yet acclimated, wait 30 days before fertilizing, and you may use Yellow Leaf Enemy at 400x dilution for spraying to regulate plant growth. ③ Root rot. Symptoms: Primarily infects roots and stems, initially appearing water-soaked, then the roots rot, with the vascular bundles in the rotten areas turning brown but not spreading upward; in later stages, the affected areas often become mushy, and the above-ground symptoms of diseased plants are not obvious at first, but later the leaves wilt at noon and can recover by morning and evening; severe cases may result in plant death. Prevention and control: Strictly disinfect the substrate before repotting; keep the substrate loose, moist, and well-aerated to avoid waterlogging; upon discovering diseased plants, promptly remove the affected plants, debris, and potting soil; for treatment, rinse with clean water and repot; prepare a solution by mixing 70% thiophanate-methyl wettable powder with water at 1000x dilution and spray it on the potting soil. ④ Red spider mites. Symptoms: Growth of young leaves is hindered, becoming curled and smaller, or the leaves turn rust-colored. Control methods: Use acaricides such as abamectin or propargite for control. ⑤ Mealybugs. Symptoms: Attach to leaf buds, branches, and stems, appearing powdery white, sucking plant nutrients and affecting normal growth; severe infestations can cause plant death. Control methods: Lorsban can be used for control with good results.

　　　　600倍，增强抗逆能力，促进根系发育；由施肥过量引起的，如施肥5-6天发现植株变黄，应及时浇透清水，降低肥料浓度，停止肥料使用，等新生枝木质化后再施肥，以防再引起肥害；移植后的植株根系没有缓好，应在30天后施肥，可选用黄叶敌400倍喷洒，调节植株生长。③根腐病。症状：主要侵染根及茎部，初呈水漫状，后腐烂根部，腐烂处维管束变褐，不向上发展，后期病部往往变糟，病株地上部初期症状不明显，后叶片中午萎蔫，早晚尚能恢复，严重的可枯死。防治；换盆前对基质严格消毒；保持基质疏松、湿润，使其有良好的通透性，避免积水；发现植株患病后，及时处理病株、残株及盆土；治疗时，可用清水冲洗后重新上盆；用70％的托布津可湿性粉剂加1000倍水制成溶液喷洒盆土。④红蜘蛛。症状：嫩叶生长受阻，卷曲变小，或叶片呈铁锈色。防治方法：用阿维菌素、克螨特等杀螨类药剂防治。⑤粉介虫。症状：附生在叶芽、枝和杆上，呈白粉状，吸取植株营养，影响正常生长，严重会枯死。防治方法：可用乐斯本防治，效果较好。

　　Product Typical Quality Characteristics and Quality Safety Regulations

　　(1) External Sensory Characteristics: Dandong azaleas are vibrant year-round, with large, brightly colored, and numerous flowers. Their blooming period lasts for months, with densely layered blossoms and evergreen leaves providing a stunning visual experience, making them highly valuable for ceremonial and diplomatic occasions.

　　(2) Internal Quality Indicators: None.

　　(3) Safety Requirements: Prohibit the use of highly toxic, persistent, or teratogenic/carcinogenic/mutagenic pesticides. Comply with the "Azalea Cultivation Technical Regulations" (DB210600/T003-2005) and "Azalea" (DB210600/T002-2005).

　　Packaging, Labeling, and Related Regulations

　　Dandong Azaleas are classified into three grades based on individual plant quality: Grade 1, Grade 2, and Grade 3. The quality of Dandong Azaleas in each grade shall comply with the provisions specified in Appendix 1. The cardboard boxes or other packaging containers used for Dandong Azaleas should have high mechanical strength to protect the plants from damage. During handling, they should be moved with care to avoid significant shaking or compression, while ensuring proper ventilation and moisture retention. Transport vehicles must be clean, hygienic, and free from contamination, and measures should be taken to prevent rain exposure, sun exposure, and physical damage. Temporary storage should be carried out under cool, ventilated, clean, and hygienic conditions, avoiding direct sunlight, rain exposure, extreme high or low temperatures, as well as pollution from toxic or harmful substances. Regular inspections should be conducted during storage.