I was asked to look at a pond on the Thomas/Brooks line with weed problems. There was quite a bit of torpedograss along the edge. However, we are starting to see algae show up in ponds. Copper complexes are good control options for all algae. Diquat also works well with filamentous algae. This pond has already been treated. UGA Aquatic Specialist Dr. Gary Burtle says one thing to remember is that these herbicides last for about a week, then algae may regrow. For this reason it is recommended to also stock grass carp at 10 per acre to maintain control.
It is still very hot and with fish in ponds, it is best to either treat after we start to cool in the fall or treat very small sections of the pond at each time. Treatment will control the torpedograss for a month or more. Retreatment my not be necessary this late in the summer, but torpedograss treated with glyphosate in early summer will require another application. Use a 2% solution of glyphosate and an adjuvant (surfactant or sticker/spreader).