This year we have been overwhelmed with calls relating to pond management, specifically weed control. Today I want to provide you with some basic knowledge on what I have seen as the most common aquatic problems we have diagnosed throughout the county.

Duckweed

Duckweed is the most prevalent aquatic species I have seen in over 20 pond visits throughout Adams County. There are three different types of duckweed — little duckweed, large duckweed, and water meal. Small duckweeds are most common and are tiny (1/16 to 1/8 inch) green plants with shoe-shaped leaves. Each type is free floating and forms blankets of green growth that can completely shelter the pond’s surface.

Thankfully, there is one product that has been found to be environmentally friendly and highly successful in controlling duckweed — Sonar AS. In over 20 test ponds throughout Mississippi, Sonar has achieved 100 percent control in 19 out of 20 ponds and no regrowth has occurred 18 months after treatment. (The pond that did not have 100 percent control was due to human calculation error). It can be applied by mixing and pouring directly into the water. The only drawback is Sonar is rather expensive, but if you have been battling this weed for years it may be well worth the cost.

Alligator weed

Alligator weed is a difficult weed to control because it has the ability to grow in a wide range of soil type and water conditions. I have observed it growing free-floating in ponds, rooted on banks, emerging from the water and even on dry land over the past few weeks. However, it generally grows as a mat of interwoven plants near pond edges. The leaves are opposite, glossy, lance shaped, 2 to 5 inches long, and have a distinct midrib.

Alligator weed is easy to control but like most weeds more than one treatment is probably necessary. Chemical 2,4-D is the cheapest option for controlling this along with Rodeo or Renovate which are aquatic weed control formulations.

Water Primrose

Water primrose is commonly usually around the edges of ponds with shallow water. They have oval leaves about 3 inches long that are light green. The stems are hollow and are often have a reddish green color that makes is easier to identify. If it has a flower it will be bright yellow. Like alligator weed 2,4-D and Renovate both do a good job in controlling this but multiple applications will be needed.

Algae

Many ponds during these hot dry months will also begin to have algae appearing. This can be due to several factors and there are several forms of algae. Two of the more common treatments for algae are Copper Sulfate or Cutrine-Plus. A word of caution — Copper Sulfate can be toxic to fish depending on water alkalinity. Cutrine is a very safe effective product. Fish can consume it immediately after application and ponds can be used for livestock or even swimming immediately after application with no harm.

Although grass carp are extremely effective for controlling some aquatic weeds they provide little long term effect on any of the weeds mentioned above. Please remember to read all labels and follow all directions before handling any chemical.

David Carter is the director of the Adams County Extension service.