Latest Cultivation Techniques and Methods Tutorial for Sweetgum

Sweetgum is a deciduous tree of the genus Liquidambar in the family Hamamelidaceae. It prefers a warm and humid climate, is fond of light, and tolerates drought and poor soil. It is produced in the provinces south of the Qinling Mountains and the Huai River in China. Its resin is used medicinally to detoxify and relieve pain, stop bleeding and promote tissue regeneration. Its roots, leaves and fruits are used as medicine to dispel wind and dampness and to promote blood circulation. Its wood can be used to make furniture and packing cases for valuable goods. Let us take a look at the cultivation techniques for sweetgum below!

Growth Habits of Sweetgum

Sweetgum prefers a warm and humid climate, is fond of light, and the young trees are slightly shade-tolerant. It tolerates drought and poor soil but not waterlogging. It mostly grows on flat land, near villages, and in secondary forests on low hills, and grows well on moist, fertile and deep red-yellow loam. It has a deep root system, with a thick and long main root, and is strongly resistant to wind, but is not tolerant of transplanting or pruning. The seeds have the habit of germinating in the following year. It is not cold-tolerant and cannot overwinter in the open north of the Yellow River, and is not tolerant of saline-alkali soil or drought. On Hainan Island it often forms the dominant species of secondary forests, is resistant to fire, and has extremely strong sprouting ability.

Seed Propagation of Sweetgum

1. Seed collection: Select superior trees that have grown for more than 10 years, are free of pests and diseases, grow vigorously, and have straight trunks as mother trees for seed collection. When the color of the fruit changes from green to yellow-brown (slightly greenish) and before it splits open, it should be knocked down for easy collection. The collected fruits should be placed in the sun to dry, generally for 3 to 5 days. During the drying process, the fruits should be frequently turned with a wooden shovel. After the capsules split open, the seeds are taken out, and then the impurities are removed with a fine sieve to obtain pure sweetgum seeds.

2. Nursery site selection: For the sweetgum seedling nursery, it is best to choose a site with good transportation, close to a water source, deep soil layers, loose soil, relatively fertile soil, and sandy loam with a pH value of 5.5 to 6.0. To reduce disease, it is best to choose a plot that was previously a paddy field for raising sweetgum seedlings. It is not advisable to choose overly clayey soil or vegetable plots, as these soils contain more bacteria and can easily cause root rot in seedlings.

3. Sowing and seedling raising: Sweetgum seeds are small, and no treatment is needed before sowing. Sowing can be done in winter or in spring, but comparatively, seeds sown in winter germinate earlier and more uniformly, while spring sowing is generally done in mid-March. Sowing can be done in 2 ways, namely broadcast sowing and drilling, and broadcast sowing is generally used more often.

Seedling Stage Management of Sweetgum

1. Timely removal of the covering grass: About 25 days after sowing, the sweetgum seeds begin to germinate, and after 45 days the seedlings basically emerge completely. The nursery germination rate is 12.3 to 57%, with an average of 35.6%. When the seedlings have basically emerged completely, the covering grass should be removed in time. It is best to remove the grass in two stages: remove 1/2 the first time, and remove the rest 5 days later. The action should be gentle to prevent pulling out the seedlings.

2. Thinning and replanting: After the grass is removed, when the seedlings grow to 3 to 5 cm, thinning and replanting should be carried out in time on cloudy or light rainy days. Move out the denser seedlings with a bamboo stick, remove the soil, soak the roots in a 0.01% ABT No. 3 or ABT No. 6 rooting powder solution for 1 to 2 minutes, and then replant them in the seedling beds where seedlings are missing. The spacing between plants and rows is generally 5×8 cm, and water thoroughly immediately after planting. After thinning, the density of sweetgum seedlings is controlled at about 100 plants per square meter.

3. Fertilization and irrigation/drainage: 40 days after the covering grass is removed from the seedlings, a suitable nitrogen fertilizer can be selected for topdressing. The concentration of the first topdressing should be less than 0.1%, and the fertilization amount is 22.5 kg per hectare. After that, topdressing should be applied about once every month according to the actual condition of the seedlings, with the concentration controlled at 0.5 to 1.0%, and the fertilization amount at 45 to 60 kg per hectare. When it rains, in order to prevent root rot in the seedlings, standing water in the nursery should be drained in time. In continuous dry weather, the seedling site should be irrigated in time to meet the water needs of seedling growth.

4. Loosening soil and weeding: During the seedling growth period, loosen the soil and weed in time. When the seedlings are small, hand weeding must be used. When they grow to more than 30 cm, chemical weeding can be carried out with a 1/3000 concentration of Goal herbicide, with a dosage of 15 ml per mu each time. When applying the pesticide, point the sprayer head at the middle of the drilled row spacing, and be careful not to spray the medicinal solution onto the tender leaves and young stems.

Cultivation Techniques of Sweetgum

1. Site selection and land preparation: Choose warm and humid valleys with deep soil, and the lower and middle parts of mountain slopes. In low mountain and hilly areas, shady slopes and semi-sunny slopes are preferable. Land preparation should be completed before winter. For gentle slopes, full reclamation plus hole-shaped land preparation is preferable. For steep mountain slopes, fish-scale pits or hole-shaped land preparation should be adopted, with hole specifications of 50×50×40 cm.

2. Planting and establishment: Afforestation should be carried out in early to mid-March when the climate is relatively stable. The general spacing between plants and rows is (1.5 to 3.0)×(1.5 to 3.0) m, with 1110 to 4440 plants per hectare. For timber forests, sparse planting can be used; for mainly raising fodder forests, raw material forests, and combined timber-seedling forests, dense planting can be used. In hilly and low mountain areas, mixed forests can be created, mixed with species such as Masson pine and Chinese fir, with the mixed method being strip-shaped or block-shaped, and sweetgum accounting for 30 to 40% of the mixture.

3. Weeding and fertilization: Newly established forests should be continuously weeded and loosened for 2 to 3 years, with tending carried out twice in May to June and September to October. In the first year, weeding is the main task; in the second and third years, expanding the holes is the main task, with a hole diameter of 60 cm and a depth of 15 cm. Young forests should be fertilized in combination with tending from September to the following May, using organic fertilizer or compound fertilizer applied in strip-shaped trenches. For mature forests, fertilization is best carried out in winter.

4. Pruning and thinning: Starting from the second year after afforestation, prune branches below 1/3 of the base of the trees as well as double-forked branches and competing branches, until the forest becomes closed. Pruning should be carried out during the tree dormancy period. Pruning cuts should be smooth, without damaging the bark or leaving stubs. When the stand canopy density reaches above 0.9 and suppressed trees account for 20 to 30% of the total trees, thinning should be carried out. The starting period is about 10 years, and the first thinning intensity is 25 to 35% of the total stand trees. After thinning, the canopy density should not be less than 0.7, and the thinning interval should not be less than 8 years. Thereafter, the thinning intensity is 20 to 30%, and final felling is carried out after 30 to 40 years.

5. Pest and disease control: Clear away dead branches and fallen leaves on the afforestation site to eliminate sources of pests and diseases, create mixed forests, improve the forest site ecological environment, remove diseased and pest-infested trees, and destroy the habitat of pests and diseases: fertilize scientifically and thin reasonably. For the control of the brown tent caterpillar, the following methods should be used:

① Manual control: manually remove cocoons. Protect natural enemies: pick out parasitized pupae from cocoons collected in the field and put them back into the forest, or do not collect them. Poison rope method: mix 20% fenvalerate with machine oil at 1:8, soak paper rope for 0.5 hours, take it out and dry it, then tie it at breast height on the tree trunk. The control effect is above 90%. Light trapping of moths: set up insect traps in concentrated areas of more severely damaged forest land to trap and kill adult moths, with good effect.

② Chemical control: Use 25% diflubenzuron III at 3500 times dilution, or 20% fenvalerate at 2000 times dilution, or 25% deltamethrin at 2000 times dilution, or 40% omethoate at 800 times dilution, and spray the tree crowns with a motorized sprayer in the evening. The control effects are all above 90%. Pyrethroid medicinal solutions can also be sprayed into the web nests, with a control effect of more than 95%.