When it comes to water weeds, one of the worst offenders is Hydrilla. Hydrilla grows and expands quickly, blanketing lakes and ponds with thick weeds that form mats. These weeds make it hard for boaters, navigation, and intakes, and though some weeds have a positive effect on water in small amounts, Hydrilla isn't one of those weeds.
Considered an invasive weed, Hydrilla is a noxious weed and a submersed aquatic plant. This means that it has long stems that grow to the top of the water and form tangles on the surface of the water. No body of water is immune to Hydrilla; it's found in many types of ponds, marshes, rivers, and lakes. To identify Hydrilla, look to the plant's leaves. The leaves of the Hydrilla are small and slightly pointed, and the branches of the plant can extend to 25 feet. It's also the only water weed that includes tubers at its roots, making it easy to distinguish from other weeds that may look similar.
Unlike most water weeds, Hydrilla also produces flowers, which are white and very small. Hydrilla is also difficult to kill and hard to control, and the weed can exist no matter what the temperature is. It's strong and hardy, even in the winter weather. It can also grow when there is low light available, something that not many aquatic plants can do successfully. These factors all contribute to making Hydrilla hard to deal with. Some scientists even go so far as to call Hydrilla the most damaging, destructive lake weed in the country.
It spreads through its root or stem fragments, which means all anyone has to do is catch some Hydrilla in their boat and move it around the water to ensure even more growth. The weeds also harm fish and native wildlife and plants, making it a water weed that requires permanent removal.
Once you find Hydrilla in your water, the war is on. It must be completely removed and eradicated before it does even more harm to your pond or lake. If you only see a small amount of the weed, you can use benthic matting for control. You'll need to use the mats beginning in the springtime and use them throughout the summer for the best results. However, if Hydrilla has already taken over, you may need to resort to chemical methods to kill the weeds. An aquatic herbicide may be what does the trick in cases like this. Complete removal is the ultimate goal.
Whatever you do, avoid harvesting the Hydrilla or allow it to grow to its maturity. This can create an even stronger weed that will be nearly impossible to kill. Keep an eye on waterfowl, as they can carry the seeds and spread them around to other water bodies. The Hydrilla seeds can lie dormant until the time is right for growth.