Owning a rural property with a dam is a point of pride for many Australians, particularly those who dream of creating a picturesque, swimmable oasis perfect for family gatherings and serene moments of relaxation. The tranquil setting of a well-maintained dam can enhance the beauty and enjoyment of any rural property.
However, there’s a plant you might have noticed that can threaten this idyllic vision: cumbungi. In this article, we’ll take a thorough look into what cumbungi is, its distinctive characteristics, and examine whether it poses a significant problem for your dam.
Understanding this plant will help you take the necessary steps to maintain the health and beauty of your waterway.
What is Cumbungi?
Cumbungi, also known as Bullrush, refers to a group of plants from the genus Typha. In Australia, there are two native species, narrow leaf cumbungi (Typha domingensis) and broad leaf cumbungi (Typha orientalis), as well as an introduced species, Typha latifolia. These plants are commonly found in slow-moving or still bodies of water like dams, irrigation channels, and wetlands.
Some parts of the cumbungi plant are edible and can be eaten raw. These aquatic plants have been traditionally used by Indigenous Australians. The young shoots, rhizomes, and roots can be eaten raw or cooked. However, it’s important to properly identify and prepare these parts to ensure they are safe for consumption.
Identifying Cumbungi
Cumbungi is characterised by its tall, reed-like appearance with grass-like leaves. These leaves are thick and spongy, growing up to 2.5 meters high. Each stem produces a distinctive flower head that appears in summer, divided into an upper spike of male flowers and a lower, cylindrical spike of female flowers.
The introduced cumbungi (Typha latifolia) can be identified by its dark brown female flower spike, while the native species have lighter brown spikes. The narrow leaf cumbungi has cinnamon-brown female spikes, whereas the broadleaf cumbungi’s spikes are chestnut-brown.
Cumbungi in Australian Dams
Cumbungi is particularly common in New South Wales, Victoria, and Tasmania, thriving in nutrient-rich waters where it can form dense infestations. These dense growths can reduce the holding capacity of dams, impede water flow in irrigation channels, and obstruct access to water for both people and animals. The spread of cumbungi is facilitated by both seeds and underground stems (rhizomes), making it a resilient and persistent plant.
Native Species
Australia is home to two native species of cumbungi: narrow leaf cumbungi and broadleaf cumbungi. These native species can provide ecological benefits, such as shelter for aquatic organisms and erosion control. However, they can also become problematic if not managed properly.
Irrigation Channels
Cumbungi thrives in irrigation channels, where it can block water flow and reduce efficiency. Regular maintenance is essential to prevent cumbungi from causing significant issues in these channels.
Flower Spikes and Reproduction
Cumbungi reproduces through both seeds and rhizomes. The female flower spikes produce seeds that are dispersed by wind and water, while the male flower spike releases pollen. Each cumbungi plant can produce tens of thousands of seeds, making it highly prolific.
The rhizomes, or underground stems, also play a crucial role in the spread of cumbungi. These rhizomes can create new plants, contributing to the dense infestations that can take over dams and other water bodies.
Control Methods and Treatment
Controlling cumbungi requires a strategic approach to ensure effective management and long-term prevention of regrowth. Different methods can be applied based on the extent of the infestation and the specific conditions of the area.
Physical Removal
For smaller infestations, manual removal using tools such as our Aquatic Weed Hand Cutter can be highly effective. This method involves carefully digging out the plants and ensuring that all parts of the roots and rhizomes are completely removed.
Any leftover root fragments can lead to regrowth, so thoroughness is essential. Physical removal is labor-intensive but provides immediate results without the use of chemicals.
Mechanical Excavation
In cases of larger infestations, mechanical removal might be necessary. This method involves the use of machinery to excavate the cumbungi plants, making it a more intensive approach. Care must be taken to avoid causing damage to the surrounding waterway and habitat during the process.
While mechanical excavation can efficiently clear extensive areas, it may also require follow-up treatments to manage any regrowth from missed root fragments.
Effective control of cumbungi often requires a combination of methods. Here are some additional tips:
- Timing: The best time to control cumbungi is before it seeds. Early intervention can prevent the plant from establishing a dense infestation.
- Herbicides: Use herbicides designed for aquatic plants, but be mindful of their impact on the ecosystem.
- Collaboration: Coordinate control efforts with neighbouring properties to manage cumbungi effectively across larger areas.
In some regions, cumbungi is classified as a weed under the Biosecurity Act, which mandates control measures to prevent its spread. Compliance with these regulations is essential to manage cumbungi effectively and avoid penalties.
Spot Spraying
Another effective control method is spot spraying, which involves the targeted application of herbicides to manage cumbungi. Herbicides can be very effective in killing the plants, but they come with the risk of off-target effects that can harm other vegetation and aquatic life.
Therefore, herbicide use should be carried out cautiously and in accordance with environmental regulations. Proper application techniques and timing are crucial to minimize unintended damage and to achieve optimal results.
Additionally, lowering the water level in the dam can expose cumbungi rhizomes to drying, which can help control its spread.
Is Cumbungi Bad for Your Dam?
The answer depends on your goals for the dam. Here are the pros and cons:
Pros
- Habitat for Wildlife: Cumbungi provides habitat for birds and aquatic animals.
- Erosion Control: The dense root systems can help stabilise the edges of dams and waterways, reducing erosion.
- Water Filtration: Cumbungi can help filter pollutants from the water, improving water quality.
Cons
- Reduced Water Capacity: Dense infestations can reduce the storage capacity of your dam.
- Blocked Water Flow: In irrigation channels and other waterways, cumbungi can impede water flow.
- Aesthetic Impact: For those wanting a clear, swimmable dam, cumbungi can be an eyesore.
- Management Challenges: Controlling cumbungi can be labor-intensive and costly, especially in large infestations.
Female and Male Flower Spikes
Understanding the reproductive parts of cumbungi is essential for effective management. The female flower spikes are cylindrical and contain the seeds, which are dark brown or cinnamon-brown in colour. The male flower spikes are located above the female spikes on the same stem and are responsible for pollen distribution.
Cumbungi Seed and Spread
Cumbungi seeds can be transported by wind, water, animals, and even machinery. This ability to spread easily makes cumbungi a formidable plant to control. The seeds can remain viable for several years, contributing to long-term management challenges.
Underground Stems and Rhizomes
The rhizomes of cumbungi are extensive and can quickly lead to new plant growth. These underground stems are robust and can survive harsh conditions, making physical removal difficult. Cutting the stems below the water surface can help control the plant, but repeated treatments are often necessary.
Final Thoughts On Cumbungi
Cumbungi can be both a beneficial and problematic plant in your dam. While it provides habitat and erosion control, it can also reduce water capacity, block water flow, and require significant management efforts. Understanding the characteristics of cumbungi and implementing effective control methods can help you maintain a beautiful, swimmable dam that your family can enjoy for years to come.
Regular monitoring and early intervention are key to keeping cumbungi in check. By staying proactive and informed, you can strike a balance between the ecological benefits and the aesthetic goals for your rural property.