While lake weeds and algae have many benefits, extreme breeding can cause a lot of problems. If weeds cover more than 25% of the lake surface, this condition is considered quite dense. Weed-covered lakes will interfere with recreational water activities such as boating and swimming. It can also interfere with fishing activities because the lake water smells foul and unpleasant. Moreover, the growth of lake algae can result in the death of many fish because the weeds deplete the oxygen in the water at night. Make sure you take proper control measures in your lake or pond to keep the aquatic environment safe and thriving. Remember, aquatic vegetation is an important part of the ecosystem. If algae and underwater vegetation have taken over a pond or lake, just control them to restore balance without removing all vegetation.
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Method 1 of 4: Taking Preventive Action
Step 1. Design the lake well
Many species of lake weed thrive when plant roots touch the soil at the bottom of the lake. You can prevent this by making steep slopes at the edge of a lake or pond instead of a gentle slope.
Make a steep lake slope to a depth of 1.5 m. This strategy will prevent submerged plants from rooting to the bottom of the lake, but is not useful for preventing the proliferation of algae or plants floating freely on the surface of the water
Step 2. Keep the lake deep
Make sure the depth of the lake is maintained at around 0.6 – 1 meter at its shallowest point. Deep lakes will prevent weeds from rooting to the bottom if plants continue to breed in the lake or pond. Remember, this method only applies to rooted weeds, not algae or plants floating freely on the surface of the water.
Step 3. Create a buffer zone around the lake
The rapid growth of lake weeds is usually due to the abundance of nutrients in the surrounding soil. Fertilizer runoff in the soil will provide nutrients for the lake weeds and make them grow a lot. To prevent fertilizers from running into the lake, create a lakeside buffer zone by planting natural plants or trees 30 meters between the fertilized land and the lake. Choose plants that can prevent erosion and do not require the use of chemicals.
If you have livestock, nutrients from fodder and animal waste can also run off into the lake and cause weeds to thrive. Consider building a fence around the cattle or keeping them at least 30 meters away from the lake shore
Step 4. Be proactive
If the lake weed problem is significant enough, address it as soon as possible. Continued rapid growth will lead to more serious weed problems. The longer you leave it, the more expensive and time-consuming it will be to deal with weed problems later.
If you notice that there are too many ducks or fish food around the lake, reduce the number. Duck droppings can contribute to weed growth
Method 2 of 4: Performing Control Manually
Step 1. Use the shank divider
Betik barrier is a piece of cloth that is placed at the bottom of the lake to prevent the sun from reaching the bottom of the lake, so that weeds die. This is a non-chemical product that can be reused.
- Some vegetative growth has an important role for lake health. If you are using a shingles, leave some open space to allow natural vegetation to grow.
- Do not cover fish spawning grounds or areas where birds nest.
Step 2. Remove weeds by hand
You can easily cut weeds from the roots, collect weeds that have been cut, and remove them from a lake or pond. Weeds can be cut with a sickle or pulled by hand, then removed from the water using a rake or hoe.
Most weeds are perennial plants. This means that this plant will continue to germinate throughout the season because it has roots below the surface of the water. To properly control lake weed growth, you must remove the plant from its root base
Step 3. Use a weed removal machine
You may need a weed control machine or an underwater machine, depending on the size of the lake or pond and the amount of weeds to be removed. Controlling weed growth by hand can be a tedious and difficult job as these plants usually grow back very quickly.
- An underwater weed control machine can help cut weeds from below the water surface, such as lotus and water milfoil (Myriophyllum). There are also weed killers that collect weeds for later disposal. Motorized tools often leave bits of weed in the water. New plants can grow from these cuttings. So, clean it thoroughly if you get rid of weeds this way.
- For algae that live above the water's surface in smaller ponds, the water pump can rotate the top layer of water to prevent the algae scum from settling.
- A lake weed mower is just as functional as a lawn mower. This tool will trim the weeds, but this is only a temporary solution.
Step 4. Dredge and deepen the lake
If the weed problem is severe and has covered more than 25% of the lake surface, dredge and deepen the lake. This will kill any existing weeds, the sediment in the bottom layer, and the nutrients underneath that allow the weeds to thrive. Dredging and deepening the lake will expose the nutrient-poor soil layer, reduce exposure to sunlight that can hit weeds, and make it harder for weeds to get their roots to the bottom of the lake.
Method 3 of 4: Using the Right Chemicals
Step 1. Choose the right type of herbicide
Identify the type of weed before you buy a herbicide. Different species and types require different herbicides. If you're not sure what type, contact your local agriculture agency or herbicide dealer to make sure you choose the right herbicide.
- Make sure you understand the effects and implications of using herbicides before using them. Before applying a herbicide, read the packaging first to find out the restrictions and waiting periods for returning to boating, swimming, and lake fishing. This is an important factor when you choose to use herbicides.
- Herbicides are available in liquid and solid form, in spray or granular form.
- To control algae weeds, try copper sulfate or copper chelates, such as Cutrine Plus. This type of herbicide can be applied directly to the area covered with algae according to the instructions for use on the packaging. For certain underwater plants such as pond weed (Potamogetonaceae), and free-floating plants such as water lens plants (duckweed/Lemnoideae), use dist or fluridon. Floating plants with roots such as lotuses and plants growing from the bottom of the lake such as cattails (typha), are best killed with glyphosate.
- Check local regulations or local regulations before using herbicides in waters. Some herbicide uses require a permit.
Step 2. Apply the herbicide at the right time
The best time to apply herbicides is in late spring when the plants are young and still weak. If you wait until the end of summer when the vegetation is thick, applying the herbicide will risk killing a lot of fish because it will deplete the oxygen all at once.
Apply the herbicide when the water temperature is above 15.5°C. Herbicides will not be effective if the water temperature is too cold
Step 3. Use the right dose
Measure the right dose when applying the herbicide. On the herbicide package, it is usually stated how to calculate the dose. This usage dose is measured in square meters (m2), which can be determined by multiplying the surface area by the average depth. On the herbicide package it is stated how many doses should be applied based on this calculation.
Never apply a dose that is larger than the one suggested on the package
Step 4. Repeat if necessary
Herbicides need to be applied periodically in the following years. Weed seeds will not be affected by the herbicide and will therefore grow the following year even if you have applied the herbicide beforehand. Continue using herbicides in the spring to kill dormant weeds during the winter.
Method 4 of 4: Using Biological Control
Step 1. Find out about local regulations
You may need to get permission from the relevant agriculture or wildlife service when using certain types of biological controllers. Some species that can control lake weeds are considered invasive in some areas, and you may not be allowed to use them. Be aware of local regulations before introducing new animals or fish into the lake.
Step 2. Release the swans into the lake
White swans can be released into a small lake. White swans can eat underwater plants and algae. So, these animals are ideal for controlling lake vegetation. Keep in mind, geese need extra care, breeding, and protection from predators.
Step 3. Release the grass carp (grass carp/koan) into the lake
Grass carp are underwater plant eaters. These fish are usually released into lakes to control vegetation. Keep in mind that grass carp will eat almost any type of underwater vegetation, not just invasive species and weeds.
- Grass carp cannot be used to eradicate water lens plants and wolffia (watermeal).
- It is recommended that you include 15 to 30 grass carp per 4m2. Choose fish that are at least 25-30 cm long.
- This grass carp is invasive. Check local regulations to ensure that you are allowed to use these fish as biological controllers before releasing them into the lake.
Step 4. Do some research on which insects might be helpful
To target specific weeds, you can use insects as a form of biological control. You have to find an insect that feeds specifically on the weed; this means that you should choose an insect species that will only eat the weeds you are trying to eradicate. You can look up information about weeds to see if there are any insect species that can help get rid of them. You can also contact your local wildlife or agriculture service or ecologist to find out about this.
