Pest and Disease Control:
1.猝倒 disease: Also known as "stand-failure disease," it primarily occurs within two months after seedlings emerge or within half a month after seedling transplantation. The pathogen invades through the roots, causing brown spots, expanding lesions, appearing water-soaked, and leading to tissue necrosis. The disease can cause the seedlings to collapse rapidly. The disease is prone to occur when the nursery area has standing water, excessive soil cover, hard surface soil, and high surface temperatures.
Control Methods: Spray 0.5% Bordeaux mixture on the stems and leaves of seedlings, then rinse the seedlings with clean water after spraying.
2. Location: Primarily the larvae of noctuid moths or cutworms, which hide in the soil during the day and emerge to feed at night. They chew on unemerged seedlings, or bite off the base of seedlings at ground level, and may also climb to the upper part of the seedlings to feed on tender stems and buds, affecting the growth of the seedlings.
Control Methods: Remove weeds, destroy eggs, and prevent larvae on the weeds from transferring to seedlings to cause damage. In the morning, around areas with missing or broken seedlings in the seedbed, dig up the soil to capture larvae; spray with a 90_0010_00 dilution or a 300-fold dilution of 20% emulsion oil to kill insects.
3. Anthrax disease: Primarily harmful to leaves, the initial stage shows faint brown-green spots on the leaf surface. As the spots expand, they form circular or irregular lesions with a diameter of 0.6-1 cm. The edges are purple-brown, the center is yellow-brown to gray-white, with occasional annular patterns and scattered small black dots. Lesions can also merge into larger ones. The peak period for occurrence is from June to September when it is humid, rainy, and warm.
Control Methods: In winter, remove and burn the withered branches and leaves to greatly reduce the source of initial infection in the coming spring; promptly remove and destroy any small number of infected leaves; during the early stage of the disease, alternate spraying the plants with a thick solution of 0.125% of 75% Chlorothalonil wettable powder or a 0.1% concentration solution of 70% Metalaxyl wettable powder.
4. Sunscald: During seedling cultivation, intense sunlight after prolonged rain can easily cause sunscald in seedlings. Symptoms include the entire plant and upper leaves losing green color, the leaf surface turning greyish-white to grey-brown, with local discoloration. Mild cases show circular brown spots with brown edges and light coloration, while severe cases result in the entire leaf turning brown, withering, and falling off.
Control Methods: After entering the high-temperature season, promptly cover the seedbed with sugarcane shade; maintain the seedbed moist by frequently spraying water on the plant leaves; spraying with a 0.1% solution of 96% copper can enhance the plant's heat resistance.
Early spring sown Luchang Xiamiao seedlings generally grow from April to May. The climate conditions during this period are favorable, making it suitable for seedling transplantation. The seedlings sown on seedling beds have become relatively dense and need to be sold or transplanted to separate beds during this period. Those sown in field nurseries should also take advantage of the favorable climate to promptly carry out thinning and setting work. Use some thinned seedlings for transplantation and replenishment, eliminate inferior seedlings, adjust seedling density, ensure a certain yield per unit area, and create conditions for seedling cultivation. Irrigation is required after thinning or later to ensure that the loosened root systems of the seedlings are closely combined with the soil.
The growth condition of Leshan Xiangxiao seedlings during their peak growing period essentially determines the seedling quality. During this phase, seedlings grow rapidly with significant height, ground diameter, and root growth, with height increase being particularly pronounced and leading to the formation of lateral branches. The main external factors affecting seedling growth and development are temperature, soil moisture, and nutrients. It is necessary to set up shade houses to prevent leaf scorching from intense sunlight. During dry and hot periods, irrigation should be timely, and during the rainy plum season, drainage should be done promptly to avoid waterlogging. Leshan Xiangxiao is prone to seedling death if the soil remains waterlogged for more than a day. Additionally, tasks such as loosening soil, weeding, and pest control should be conducted. Fertilization should be applied during the two rapid growth phases, excluding the slow growth period from July to August, to meet the needs of vigorous seedling growth.
Cultivation Techniques:
1. Seed Collection: Select seeds from robust female trees aged 20-40 years. From mid-October to early November, when the聚合果turns from green to reddish-brown, harvest them using a seed knife or pruning shears. Spread them thinly in a cool, well-ventilated area for ripening. Once the fruit shells crack, extract the seeds, or leave the fruits outdoors to dry for several days before bringing them indoors. Remove the false seed coat and plant the seeds immediately after collection. The thousand-grain weight is 260-300 grams, with an 80% germination rate.
2. Sowing: Under certain conditions, seeds can be sown indoors on seedling beds or in outdoor nurseries with good irrigation, preferably in deep, fertile sandy loam soil. Prior to sowing, the land should be meticulously prepared, with the topsoil loosened and weeds removed, ensuring the ground is level. Additionally, organic fertilizers with slow release, such as compost, manure, and green manure, can be mixed in as a base fertilizer, along with a small amount of nitrogen and some phosphorus and potassium to improve soil quality and ensure a continuous supply of nutrients for seedling growth. In indoor or warmer regions, sowing can be done in early February. In outdoor or colder areas, it is generally recommended to sow after the soil thaws in March. Before sowing, seeds can be soaked in warm water below 40℃ for 12- hours to absorb sufficient moisture, accelerate germination, and ensure uniform seedling emergence.
According to the different purposes of seedling cultivation by the grower, various sowing methods can be employed. If the grower plans to sell seedlings or transplant seedlings in the seedling stage, the broadcast sowing method can be used, which involves evenly sowing seeds over the entire seedling bed. Broadcast sowing maximizes land use, results in a high seedling density, and a relatively even distribution of seedlings, leading to a high seedling yield per unit area. However, its drawback is that the seedlings remain in the bed for a short period, and the grower must be prepared for transplantation. If the grower does not plan to sell seedlings or transplant them in the same year, the row sowing method can be adopted, where seeds are evenly scattered in grooves created at a certain distance on the seedling bed. Generally, the row width is 5 cm, the row spacing is 25 cm, the sowing groove is 1.5-2 cm deep, and the seeds are covered with 1-2 cm of soil and watered thoroughly. A layer of straw is placed over the seedling bed to maintain humidity, and the straw is removed in stages as the seeds germinate.
3. Seedling Cultivation: The period from when the seedlings emerge from the soil after sowing to when they can stand independently and grow is known as the seedling emergence period. The Leshan Amomum can germinate within 20-30 days after sowing, and the seedling emergence period lasts for about 15-20 days. During this period, the seedlings are very tender and weak, with shallow root distribution and low resistance. The key to seedling cultivation is to provide a favorable environment for seed germination and seedling emergence, ensuring the necessary moisture and aeration for seed germination. However, the seedbed should not be overly wet or waterlogged, as excessive moisture can lead to poor aeration, affecting seed development and causing seed rot. At this stage, the tender seedlings cannot produce nutrients on their own, and their nutrient source is primarily the stored nutrients from the seeds, so fertilization is not required.
4. Seedling Stage: The period from when the Lechang Xianxiao seedlings emerge from the soil until they begin to grow vigorously is referred to as the seedling stage, which lasts approximately 20 days. During this phase, the seedlings start to develop true leaves, begin photosynthesis to produce organic matter, and the number of leaves gradually increases, with the root system growing rapidly and lateral roots forming. At this time, the seedlings are still very tender, with weak resistance to adverse environmental conditions and a high mortality rate. Measures should be taken to prevent phenomena such as drought, waterlogging, high temperatures, and low temperatures. Partial shading should be applied, weeding and loosening the soil should be done early, and attention should be paid to the prevention and control of pests and diseases. The need for nutrients during the seedling stage is not substantial, but applying a moderate amount of dilute nitrogen and phosphorus fertilizers can improve the quality of the seedlings.
5. Growth Peak: The growth peak of seedlings is from the point when the height growth increases dramatically to when it decreases dramatically. The growth peak of Leshan Osmanthus starts in mid-May and ends in mid-October, with a growth peak from early May to early July, where the seedling height can reach 20-25 cm. From July to August, during the hot and dry summer season, growth is slow. Another growth peak appears in September and October, with an average height growth of about 30 cm.
