Scientific name: Robinia pseudoacacia L. The leaves are like locust trees, and there are stipules on the branches, hence the name Robinia pseudoacacia. The genus Robinia (about 20 species, native to temperate and subtropical North America, has been introduced all over the world. China introduced 3 species).

Form and use

Deciduous tree, with a height of 25m and a DBH of 1. 1 m. The bark is deeply longitudinally split to shallowly split. Branchlets are smooth and brown. No terminal bud, subsessile bud. Odd pinnate compound leaves, alternate; Leaflets 7 ~19, long1.5 ~ 4.5 cm, smooth and hairless on both sides, opposite or nearly opposite, entire, with small stipules; There are often 2 stipules with unequal size and hardness at the base of the total petiole. Racemes are white, fragrant, axillary, and the inflorescence axis is thin and drooping. The pod is flat, oblong, 4 ~10 (20) cm long, with narrow wings along the abdominal suture. The seeds are flat kidney-shaped, brownish green, purplish brown to nearly black, with light markings. Flowering from April to May, pods mature from July to September. There are two cultivation variants in China: ① Robinia pseudoacacia L.F. Inermis (Mirb.) Rehd.: the crown is open, broom-shaped, neat and beautiful. The branches are stiff and spineless. ② Robinia pseudoacacia L.F. umbraculifera (DC.) Rehd.: Fine branches, oval crown, and pruning resistance. Branches have no thorns, or the thorns are small and soft. No or few flowers, few fruits.

The material is hard and heavy, and the compressive strength and impact strength along the grain are very high. It is corrosion-resistant, water-resistant and wet-resistant, with glossy planed surface and beautiful patterns. It is an excellent material for piles, pits, sleepers, farm tools, vehicles, tool handles, sports equipment, floors and kelp culture. Branches, wood and roots are flammable and have strong firepower, so they are excellent firewood. Leaves contain a variety of nutrients and are excellent feed and fertilizer. Robinia pseudoacacia flower is an excellent honey source and contains aromatic oil. Bark fiber is tough, shiny, easy to bleach and dye, and is used for papermaking, weaving and rope making. Robinia pseudoacacia has strong soil and water conservation ability, and can also improve soil and increase aggregate structure and organic matter.

(Li Jianwen Xu Munong)

Geographical distribution and biological characteristics

Robinia pseudoacacia is native to Appalachian and Ozank Mts in the eastern United States. In the third or fourth year of Guangxu in Qing Dynasty (1877 ~1878), Zhang Sigui, deputy envoy of Japanese Embassy in China, sent seedlings to Zuo Zongtang to plant in Nanjing. At the beginning of the 20th century, it was introduced from Europe (Germany) in large quantities, and planted in the hills and beaches on both sides of Qingdao and Jiaoji Road in Shandong Province. Later, it gradually expanded to East China, North China, Northwest China and Liaodong Peninsula. The northern boundary of Robinia pseudoacacia planted in China is roughly Tieling and Shenyang in Liaoning, Chengde and Zhangjiakou in Hebei and Yinchuan in Ningxia. Northwest to Shihezi, Kuicheng, Yining, Aksu, Yecheng and Hotan in Xinjiang; Xining in Qinghai in the west; Southwest to Ya 'an, Sichuan and Kunming, Yunnan; South to Guangdong and Guangxi; East to Dandong, Liaoning, Yantai, Shandong, the northern coast of Jiangsu Province and Taiwan Province Province. That is, it is planted in a wide area of 23 ~ 46 north latitude and 810 ~124 east longitude. In the south of the Yangtze River, it is mostly planted sporadically. The middle and lower reaches of the Yellow River, the leeward valleys of the Huaihe River basin and the Loess Plateau, the middle and lower parts of rock and soil slopes, ravines, fine sandy land, light saline-alkali land, floodplains, coastal beaches and dams on both sides of the river are the most suitable places for Robinia pseudoacacia. The highest altitude limit of the planting area: Lintao County, Gansu Province, 2 100 m, south-central Shanxi 1400 m, Yan 'an, Shaanxi 1600 m, Zhangjiakou, Hebei 1000 m, Shandong 1000 m, and Anhui and Jiangsu 500 m.

Robinia pseudoacacia is a warm temperate tree species, which is suitable for the climate with annual average precipitation of 600 ~1200mm and annual average temperature of/kloc-0 ~14℃, with annual precipitation of 500 ~ 600mm, annual average temperature of 6 ~ 9℃, absolute minimum temperature of-24 ~-26℃. Where the annual precipitation is less than 500 mm, the annual average temperature is below 6℃, and the absolute minimum temperature exceeds -26℃, it can't grow into a big tree, and the ground freezes to death every year, sprouting and shrubby every year. Robinia pseudoacacia planted in the tuyere grows slowly, and is prone to wind bending, wind falling, tilt or crown deviation. Robinia pseudoacacia has developed root system, wide absorption area and strong drought tolerance. Robinia pseudoacacia is very sensitive to moisture, and it shows fast-growing characteristics in the coastal fine sand land of the Yellow Sea and Bohai Sea, and the floodplains, valleys, ditches, roadsides, dams and other places in the Yellow River, Huaihe River and Haihe River basins. The dry shape is straight and complete, and it can grow into small-diameter timber in 8 ~12 years, and medium-diameter timber in15 ~ 20 years. However, it is not tolerant to waterlogging, and the stagnant water will be waterlogged to death in 2 days. Where the groundwater level is less than 1.0 m, the root rot rate is as high as 45 ~ 70%, and the dead tip is serious. The requirements for soil are not strict, and it can grow on sandy soil, loam, clay, and even gravel weathered by slag piles and shale for many years, but it grows slowly and has a low tree shape in dry and barren middle sandy land and poorly structured clay land. It can grow normally in acid soil, calcareous soil and saline-alkali soil with salt content below 0.3%, and it grows fastest in loose, moist and fertile fine sand land and loam land. Roots have nodules, which can fix nitrogen in the air into the soil. Robinia pseudoacacia is photophobic and intolerant of shade. The high-speed growth period of trees mostly occurs in 2 ~ 6 years, a few in 6 ~10 years, and the maximum annual growth is1.5 ~ 2.0 meters. The fast-growing period of diameter growth is 3 ~15 years, and the maximum annual growth is1.0 ~ 3.0 cm. The fast-growing period of the volume occurs in12 ~ 30 years, and the maximum annual growth is 0.00173 ~ 0.05093 cubic meters.

(Xu Munong)

breed

The main goal of Robinia pseudoacacia breeding is to grow fast and improve the dry shape. Robinia pseudoacacia is not the main afforestation tree species in its origin and European countries, and there is little breeding work, but foresters in various countries have long paid attention to the existence of intraspecific variation of Robinia pseudoacacia. The excellent types recorded are: ① pagoda-shaped Robinia pseudoacacia: the lateral branches are upright and the crown is in the shape of a steeple; ② Robinia pseudoacacia with mast: fast growth, straight trunk and few seeds; ③ Ornamental Robinia pseudoacacia. In addition, Hungary selected excellent types with high honey production and late flowering. The breeding of Robinia pseudoacacia in China only started in 1960s, mainly selective breeding. Good phenotypes include "Robinia pseudoacacia" (the trunk is straight), "Shilin" and other excellent clones, and the volume per plant exceeds 30% of the control, which has been widely popularized.

(Pang Jinxuan)

Afforestation technology

(1) Seed collection: Seed should be collected on a robust tree that is over15 ~ 20 years old. The pod is reddish brown and the peel is dry, so it can be collected. Due to the damage of pod borer, seed wasp and seed wheat moth, it is necessary to collect seeds in late August to early September. After the pods are collected, they are spread on the ground in the sun, threshed by rolling or threshing machine, and the peels, grains and sundries are removed to obtain pure seeds, which are put into bags for dry storage. Pod seed rate10 ~ 20%. The 1000-seed weight is 21.8g.. ② Seedling raising: Choose sandy loam with good drainage, moisture and fertility as nursery. Saline-alkali soil should be planted where the salt content is below 0.2% and the groundwater level is above 1.0 meters. Do not use vegetable land as nursery. Disinfect soil with ferrous sulfate powder in combination with soil preparation. Robinia pseudoacacia seed coat is thick and hard, with poor water permeability, and there are many hard seeds, so it must be soaked in hot water for many times. First, pour boiling water at 90 ~100℃ into the jar, then pour the seeds, stir them while pouring until the water is not hot, soak them for one day and night, use yellow mud slurry to float the seeds that absorb water and swell, and continue to soak the remaining hard seeds with the above method. Finally, put the remaining hard seeds into a fine-mesh iron sieve, and then put the iron sieve into a hot water pot for about1. Lift the iron sieve, pour the seeds into cold water, and soak for one day and night. Most seeds can absorb water and swell. Mix the water-absorbing and swelling seeds with sand, put them in a sand pit or a straw bag or a jar (covered with a straw curtain) to accelerate germination, spray water and stir 1 twice a day, and take them out for sowing when the seeds of 1/3 crack. Spring sowing is about before and after Qingming Festival. Sowing in rainy season is changed in places with severe spring drought, and sowing in saline-alkali land is in the late rainy season (middle and late August). Wide row sowing (ditch width10cm, ditch depth 2 ~ 3cm), with seed consumption of 37.5 ~ 60kg per hectare. It is also possible to cultivate root tiller seedlings after seedling emergence and propagate excellent types by bag grafting. Pay attention to intertillage weeding after emergence, except for breeding flies, scarabs and elephants? Rhizoctonia solani and anthracnose. For seedlings with strong lateral branches, pick the core or knock off some leaves in summer to promote the root system development of seedlings. Interplanting in time, generally leave12 ~150,000 seedlings per hectare, and leave 30,000 ~ 60,000 seedlings per hectare for "four sides" tree planting. (3) Afforestation: in plain land, hole-shaped or strip-shaped soil preparation is mostly used, and the depth is 0.6 ~1.0 m; Narrow terraces, horizontal steps, horizontal ditches, fish scale pits and cave-like soil preparation in mountainous areas, with a depth of 0.4 ~ 0.6 meters; In saline-alkali land, land preparation methods such as building terraced fields, strip fields and furrowing and ridging are adopted (see land preparation for afforestation). Planting with stems is mostly carried out from "shocking" to "Qingming" when the buds just crack and show green. The taller the seedlings are, the later the afforestation time should be. The height of the stem should be1~ 3cm. In autumn, winter or early spring, the stem should not be exposed to the ground, and the buried soil should be 2 ~ 3cm higher than the root neck, not too deep. Water after planting, otherwise the soil will be trampled or compacted. Soil and water conservation forest and firewood forest are planted with 3,300 ~ 4,950 plants per hectare, and timber forest with medium site conditions is planted with 2,490 ~ 3,300 plants per hectare. Fast-growing and high-yield forest with good site conditions and intensive management1665 ~1995 plants. The terminal buds of Robinia pseudoacacia have weak germination ability, and strong strips are extracted from side buds every year to replace the top tips, so there are many branches of Robinia pseudoacacia planted sparsely, and the trunk shape is not straight and complete. The young forest can maintain a large canopy density (about 0.7) and cultivate excellent trunk shape. Robinia pseudoacacia is an excellent companion tree species, which can be mixed with many kinds of poplar, Salix, Paulownia, Ulmus pumila, Melia azedarach, Quercus acutissima, Ailanthus altissima, Pinus tabulaeformis, Platycladus orientalis and Amorpha fruticosa. In addition to being mixed with European and American poplars in the plain, they are mixed with other tree species in strips (4-6 rows) or blocks. If Robinia pseudoacacia inhibits the growth of other tree species, it can also be cut early or stubbled into shrubs to protect the ground. ④ Tending management: timely intertillage, weeding, pruning, thinning and pest control after afforestation. Pruning can be done in autumn, winter, early spring or before wheat harvest (May). The time of thinning of Robinia pseudoacacia forest is about 4 ~ 6 years after afforestation. In the pure forest of the same age, the lower layer thinning method (see thinning) is adopted, in the stands with neat row spacing in the plain, the mechanical thinning method (see thinning) is adopted, and in the mixed forest with different ages, the upper layer thinning method or comprehensive thinning method (see thinning) is adopted. The main cutting age of small-diameter timber stands can be set at10 ~15 years, and that of medium-diameter timber stands can be set at 20 ~ 30 years. The fast-growing and high-yield forest can be cut in10 ~15 years. After the main cutting, the tillers can be regenerated, and the root plants can be dug out before the rainy season, so that the roots can germinate more and the seedlings can grow vigorously. In the early spring of the second year of harvesting, 2,490 ~ 3,300 plants are reserved per hectare.

The main pests and diseases are pod borer, locust seed wasp, seed wheat moth, stinkbug, elephant? , locust aphid, locust foot moth, locust valley moth, skin-jumping worm, purple feather disease, locust skin rot disease, etc.

(Xu Munong)

Robinia pseudoacacia

(Li Kuansheng)

Scientific name: Napocheima robiniae Chu. Lepidoptera, geometridae. The male moth is brown, with a length of14 ~17mm and a wingspan of 33 ~ 42mm. Antennas are biccomb-shaped, the axis is gray-white, the comb is brown, and the length is about1/3 of the antenna; Chest and abdomen are dark brown with long hair; The front wing is brown, and the color between the outer line and the inner line is deeper, forming a curved middle band, which is wide at the front and narrow at the back, with a gray-yellow line between the outer edges of the outer line and a small black spot on the middle room; The hind wings are gray-yellow, with a black spot on the middle chamber and two gray-black horizontal lines outside the point. The female moth is brown, with a body length of13 ~19mm and degenerated wings. (see photo) Distributed in Shaanxi, China. Harm Robinia pseudoacacia, Toona sinensis, Ailanthus altissima, Cotinus coggygria, sumac, Eucommia ulmoides, Ginkgo biloba, Melia azedarach, Gleditsia sinensis, ash tree, walnut, jujube, apple, etc. One year 1 generation, pupae spend the summer and winter in soil cocoons. The overwintering pupae began to emerge in late February of the following year, and the peak of emergence was from late March to early April, and the emergence ended in late April. Eggs began to be seen in early March, and the spawning period was basically the same as the adult occurrence period. Eggs began to hatch in early April, entered the peak period in the middle and ended in the late period. In mid-May, the larvae began to mature, and they went down to the ground to make cocoons. After 30-50 days of pre-pupation, they all pupated in late July and passed the winter. Adults are cold-tolerant, emerge when the surface is thawed, and go out at 22 o'clock in the evening. Male moths have phototaxis. After emergence, the female moth climbs to the treetops along the trunk and mates with the male moth to lay eggs. Eggs are arranged in rows and piled on the shady side of 1 annual shoots. The egg period is usually10 ~12 days. Each female lays an average of 462 eggs with a maximum of 920 eggs. The life span of female moths is 4 ~ 5 days, and that of male moths is 3 ~ 4 days. Larvae * * * 6th instar. 1~ 3 instar larvae eat less and have weak drug resistance; From the 4th instar, the food intake increased sharply, and the drug resistance increased. The newly hatched larvae had the habit of spinning and spreading with the wind. Prevention and control methods: setting lights to trap and kill male moths; Before the female moth emerges, a plastic film is tied to the base of the trunk to prevent the female moth from laying eggs on the tree, and the egg blocks below the barrier zone are treated before hatching; Protecting and utilizing natural enemies; 1~ 3 larval stage, spraying Beauveria bassiana and other microbial agents, 50% chlorpyrifos EC 1000 times, 50% phoxim EC 2000 times, or spraying aerosol.

Adult Robinia pseudoacacia