Overview of Phragmites australis subsp. altissimus
Phragmites australis subsp. altissimus is a tall perennial grass that is native to Australia, New Zealand, Southeast Asia, and the Pacific Islands. It is commonly known as giant reed, cane, or Norfolk reed.
Appearance of Phragmites australis subsp. altissimus
This plant can reach heights of up to 20 feet and has a dense cluster of long, narrow leaves that can grow up to 2 feet in length. The stem of the plant is thick and can reach a diameter of up to 2 inches. The flowers are borne at the top of the stem in a feathery plume that can reach up to 2 feet long. They turn a golden brown color in the fall.
Uses of Phragmites australis subsp. altissimus
Phragmites australis subsp. altissimus is commonly used as an ornamental plant in landscaping due to its dramatic appearance and height. In addition, it is often used for erosion control, as it has a deep root system that stabilizes soil and prevents erosion. It is also used for thatching, to make mats, baskets, and other woven items.
Light Requirements
Phragmites australis subsp. altissimus grows well in full sunlight and partially shaded environments. The intensity of light significantly affects plant growth, especially in the early stages. Inadequate light may lead to stunted growth, while excessive light may cause sunburn or leaf scorching.
Temperature Requirements
Phragmites australis subsp. altissimus thrives in areas with warm temperatures. The ideal growing temperature for the plant ranges from 18 to 30°C. Temperatures above or below this range may slow down the growth rate or cause the plant to wilt.
Soil Requirements
The plant prefers habitats with wet and swampy soil. Phragmites australis subsp. altissimus thrives in soils with high organic content and a pH range of 6.0 - 8.5. The plant can tolerate salinity levels up to 15 dS/m. Clay and silty soils are ideal for root systems as they provide a stable base for the plant to grow tall.
Cultivation of Phragmites australis subsp. altissimus
Phragmites australis subsp. altissimus is cultivated using its rhizomes, cuttings, or seedlings. The best time to plant the species is during spring or fall when the weather is milder. The plant thrives well in loamy, sandy, or clay soils with a pH ranging from 6.5 - 8.5. It is advisable to plant the species in a location with ample sunlight and good air circulation. The recommended spacing for planting is between 18 - 24 inches apart to maintain healthy growth and prevent overcrowding.
Watering Needs
Phragmites australis subsp. altissimus requires regular watering, especially during hot summers when the soil dries up fast. The species can withstand damp or marshy soils, but water stagnation should be avoided. It is advisable to let the soil dry out before irrigating the plant again to prevent root rot. A good way of retaining moisture in the soil is by adding organic mulch around the base of the plant.
Fertilization
Phragmites australis subsp. altissimus requires nutrients for healthy growth and development. In the first year of planting, a balanced fertilizer with a composition of 10-10-10 should be applied twice, first in early spring and again in mid-summer. In the second year and subsequent years, fertilizer should be applied once per year, either in spring or autumn. It is important to follow the manufacturer's instructions on the application rate to prevent over-fertilization, which can damage the plant.
Pruning
Phragmites australis subsp. altissimus does not require regular pruning. However, it is essential to remove any dead or damaged stems during early spring, mainly if they appear unsightly. To maintain the plant's shape and prevent overgrowth, cut back the stems by one-third to one-half of their length during early spring. This will also encourage the emergence of new growth.
Propagation of Phragmites australis subsp. altissimus
Phragmites australis subsp. altissimus, commonly known as giant reed, is a tall perennial grass that can spread rapidly. It is commonly found in wetlands, riparian areas, and disturbed sites. There are several methods for propagating this plant.
Seed Propagation
One way to propagate Phragmites australis subsp. altissimus is through seed. Seeds can be collected from mature plants in the fall and sown immediately in a greenhouse or indoors. The seeds should be planted in a soil mix with good drainage and kept moist. Germination can occur within a few days, and the seedlings can be transplanted into larger containers or directly into the ground once they are large enough.
Vegetative Propagation
Another method for propagating Phragmites australis subsp. altissimus is through vegetative propagation. This can be done through rhizome cuttings or stem cuttings.
Rhizome cuttings should be taken in the early spring or fall. Rhizomes are underground stems that produce roots and shoots. Select healthy and mature rhizomes that are at least 6 inches long. Cut the rhizomes into sections that have 2-3 buds each. Plant the sections in a container or directly into the ground, covering them with soil so that the buds are just below the surface. Keep the soil moist.
Stem cuttings can be taken in the spring or early summer. Select mature stems that are at least 12 inches long. Cut the stems into pieces that have at least two nodes each. Place the cuttings in a container with moist soil. Keep the soil moist and cover the container with plastic to increase humidity. Once the cuttings have rooted, they can be transplanted into larger containers or directly into the ground.
Regardless of the propagation method used, Phragmites australis subsp. altissimus requires plenty of water and nutrients to establish and grow. It is important to keep the soil moist and provide fertilizer as needed.
Disease Management for Phragmites australis subsp. altissimus
Phragmites australis subsp. altissimus is relatively resistant to most diseases. However, several fungal pathogens like rust, smut, and sooty mold may infect this plant. Rust infections often cause yellow spots on the leaves and can weaken the plant as it affects the leaf area available for photosynthesis. Sooty mold is a type of fungus that grows on the honeydew secreted by insects that infest the plant. Smut infections are another concern, but they are not severe.
To manage these diseases, it is essential to maintain good hygiene by removing infected plant parts since they can serve as a source of infection. Fertilizing the plant to maintain its vigor and immunity can also help. Fungicides can also be effective in managing infections. However, it is essential to use them according to the manufacturer's instructions since overuse can lead to resistance.
Pest Management for Phragmites australis subsp. altissimus
Phragmites australis subsp. altissimus is relatively resistant to most pests. However, certain insects and vertebrates like the stem-boring weevil, Phragmites australis aphid, Japanese beetle, mole crickets, muskrats, and Canada geese can cause harm to the plant and even destroy the stand.
To manage these pests, it is essential to maintain good field hygiene by ensuring that the area is clean from debris, which can harbor insects and their eggs. Early detection and management of any infestation can reduce the spread and damage caused. Insecticides and pesticides can also be effective in managing pest infestations. However, it is essential to use them according to the manufacturer's instructions since overuse can lead to the development of resistance.
The use of barriers or exclusion methods like fences and nettings can also help in preventing vertebrates like muskrats and geese from accessing the field. Additionally, regular mowing can deter geese and other animals that might like tall vegetation for foraging or nesting. It is essential to be cautious around wetland areas since some chemicals can have detrimental effects on the environment.
