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Controlling Invasive Plants – Weed Control 101

Plant life is an important part of any pond environment. Plants provide essential oxygenation, food and shelter for a myriad of creatures that inhabit the ecosystem in and around a pond. Invasive, non-native plant species, however, place your pond at risk and may become more than a nuisance. Here are a three of the most problematic invasive plants—and some measures for weed control.

Top Wetland Emergent Pests

1. Purple Loosestrife

Purple Loosestrife was introduced because it an attractive flower and is now common in many areas. Loosestrife grows very densely and crowds out native vegetation, making poor habitat for ducks, geese, muskrats, amphibians and other wildlife. About a decade ago, ecologists introduced loosestrife beetles to help regulate the spread of this plant and this effort has seen significant success.  Infestations of purple loosestrife still occur in many areas and control measures such as pulling up the plants by hand and proper herbicide applications are encouraged.

2. Exotic Phragmites

Exotic Phragmites is a tall species of grass and is a very significant invader in the Great Lakes area and surrounding states. This exotic invader forms very dense stands and crowds out all native species. Some stands in shoreline areas extend for miles and disrupt waterfront views and human uses of waterways as well.  When these massive stands ripen off and dry in the fall it can even raise fire danger in some shoreline communities. Phragmites is difficult to control and requires consistent management and application of appropriate herbicides coupled with removal of dead plant material in the winter.

It should be noted that there is a variety of phragmites that is native to North America and care should be taken in properly identifying the exotic variety.

3. Japanese Knotweed

Japanese Knotweed is a tall perennial shrub, sometimes stretching up to 10 feet tall.  This Asian plant has hollow stalks that can resemble bamboo in the winter when foliage has fallen. This aggressive plant displaces other native species that are more beneficial to wildlife. A fully established stand has deep, dense roots that are difficult to eradicate. Attacking the rootstalks with appropriate herbicides is key to controlling this stubborn plant.

Appropriate herbicide applications can be used to deal with these three pests, but there may be other control techniques that make these treatments more effective.  This post touches only the tip of the iceberg, check with state agencies or talk with an experienced aquatic plant control specialist for more information.  Remember:  if you are working around water, check to determine if you require an Aquatic Nuisance Species Control permit, or other permit from the appropriate environmental agency in your state.

Top Aquatic Pests

1. Eurasian Watermilfoil

Eurasian Watermilfoil interferes with swimming and fishing and can even entangle boat propellers. When densities reach high levels, it can also interfere with fish populations and the aquatic food web. Watermilfoil can easily transfer from one pond to another as plant fragments hitch rides on boats, fishing gear and trailers and then take hold in their new home. Once established, it is difficult to wipe out, but there are some effective aquatic herbicides that can maintain control when administered correctly.

2. Curlyleaf Pondweed

Curlyleaf Pondweed can be an aquatic pest at high densities, but is not always bad.  Curlyleaf produces food and provides refuge for some pond life. However, when Pondweed is allowed to expand unrestrained it can crowd out native species, forming high density thickets that can be a nuisance for swimming and fishing and can disrupt the food web. This plant can also hitch a ride from pond to pond on boats and gear.

Aquatic herbicides designed for submerged plants can be useful in controlling these plants when properly applied.

Questions about invasive plant control? We have the answers—and the solutions—you require to handle these pests.

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