Here are a few pond weeds we looked at last week. Maidencane is standing in the back, southern watergrass and algae are in front of it. Maidenane and southern watergrass are both emergent plants. These are rooted plants that usually grow on the shoreline and stand above the surface of the water. These ponds are very shallow, and the plants can grow in the middle. The stems of emergent plants are somewhat stiff or firm.
Southern watergrass is a perennial that growers in shallow water. It’s leaves can be underwater (to 3 feet), floating or in dense colonies that can rise to 12 inches in height on stems to 3 feet long. Leaves are more long and narrow.
Maidencane is hard to tell apart from other grass weeds. It’s leaves are long, narrow and tapered (up to 12 inches long and 1 inch wide). They have a rough upper surfaces and margins. Flowers form along a narrow spike. Maidencane forms extensive rhizomes.
There is also algae between these two emergent weeds and copper sulfate was used. The copper worked on one pond and not another. UGA Extension Aquatic Scientist Dr. Gary Burtle says the copper spreads out in an open pond but may be prevented from spreading when heavy weeds mats are present.
Glyphosate works good on grassy weeds. It is good to use around pond edges, and certain formulations are used in the pond. However, much of the efficacy of glyphosate is lost when it touches water. The more leaves out of the water, the better it works. Glyphosate will work better on these maidencane than the watergrass, since most of these watergrass are underwater. Since most watergrass is submerged, imazamox would be a better control option here.