Weeds can take over and ruin a pond if not properly managed. These weeds take up large amounts of nutrients in ponds causing pond death.
The earlier you attack the problem the easier it is to control the weeds.
Identify the weed
Before determining the best control method it isn necessary to identify the weed itself. This will determine the control method.
Naiad or Bushy Pondweed, this has opposite leaves that are small and the plant is mainly found in the pond margins. (Prevalent) in ponds under 6ft in depth)The will form a dense mass that blankets the surface of ponds.
Can be controlled by Grass Carp or other fish that eat weeds and this can be a long term solution. It may take 1 – 2 years for this solution to work.
The other solution is to use a herbicide, usually copper based. Submerged weeds are more difficult to remove and may need professional removal.
Chara is an algae and it has an unpleasant odour. This is usually treaded with a chelated copper.
Algae in ponds is, usually Spirogyra, Cladophora or Oedgonium. All of these algae thrive on warm shallow water rich with nutrients and form a slimy cover that can smother a pond.
Pond weed control can be carried out in a number of ways:
- Removal of pond weed In a small pond weed can regularly be scooped out of the pond.
- Chemical control of pond weed. This is banned in many countries. However chemical controls are available in some areas.
- Non chemical control. The addition of copper is sometimes used, however fish and desired plants can be killed also.
- Increase Pond depth. Deeper ponds that minimise the build up of heat.
- Oxygenating plants. Plants that oxygenate water can help control weed
- Control nutrient levels. Overstocking with fish of allowing fertiliser to run into a pond is a sure way to encourage algae growth. Reduce fish stocks, and prevent nutrients from gardening activities from entering the pond.
- Filtration. Pond filters that remove nutrients can help reduce blanket weed.
- Ultrasound devices. This method is being trialled, we suggest you consult a professional if considering this method.
- Mechanical removal can work, especially in ponds choked with weed, however any small fragments can regrow. Mechanical removal is often followed up with other control methods.