Control of aquatic weeds in area ponds and lakes should occur as soon as possible to reduce problems later in the summer, according to Mike Roegge, University of Illinois Extension crop systems educator. Some aquatic weed species can experience tremendous increases in populations if left unchecked, which can lead to unsightly and poorly utilized water uses. But conversely, since they are plants, they are necessary to water bodies in that they provide oxygen for fish survival. So, pond weeds are necessary for aquatic life, but can also be over abundant in some cases, causing reduced usage of the water body.

There are a few weeds that are common to most area ponds. This list would include: algae, duckweed, watermeal and the pondweed species. Identification of these weeds is necessary before control is considered. Algae is a floating weed, with mat-like growth; some refer to it as moss. Duckweed is another floating weed, very small, with 1 to 5 leaflets and a short root attached. The entire plant is only 1/4 inch or so in size. The last floating weed would be watermeal. It is even smaller, at only 1/8 inch or less in size. It resembles floating green seeds, almost like grains of sand

Another weed is the vine type weeds. There are several that are common, and most are known simply as pondweeds.

Control of aquatic weeds is warranted if they overtake a pond. Again, since they are green plant material, they do contribute oxygen to water, which is necessary. However, often times, the weeds increase in number to the point where they inhibit pond use. In this case, control should be considered

Grass carp should be a species in every pond. They will consume a variety of aquatic weeds; however, they will not feed upon algae. Mechanical control can be useful when aquatic weed populations are slight. Pulling, dredging or cutting can work for small areas, but is very time consuming.

Chemical control is an option for many. Control should be initiated before the problem becomes severe. Also, time the control to avoid fish kill. Dying aquatic weeds during the hot summer time period can lead to reduced oxygen availability in the pond, which can lead to fish kill. It's not uncommon for this to occur. Therefore, now is the time to consider control of aquatic weeds.

Copper sulfate is a very cheap and effective control for algae. Mixing the crystals in a jug of hot water overnight, and then using that to fill a 2 to 3 gallon hand sprayer, allows for much better control than simply placing the crystals in a gunny sack and towing behind a boat.

Other products, such as Diquat/Reward, SonarAS, Avast, Rodeo and others provide control of the remaining aquatic weed species. Consult your local Extension office.