Question two in the Q+A Series from some recent correspondence between myself and a customer that would like to get rid of Water Willow and Algae. They also have a problem with dead vegetation and "muck" at the bottom, which they will be using a form of beneficial pond bacteria to get rid of.
Question #2- Can we spray those aquatic weeds now or wait until we get our coldest weather and hope that they die down, then spray as they begin to come back?
It is best to apply aquatic herbicides and liquid algaecides during the spring and summer months of the season when you start to see early season growth. Water temperatures around 50 to 55 degrees Fahrenheit is about the time you can get started. If you see early season growth prior to that, you can apply aquatic herbicides, but be sure to confirm visual growth of the weeds if you are closer to the 50 degree end. This will ensure that you get the best return from your investment in terms of overall results. The early season growth is when the weeds are most susceptible to chemical treatment and also the time of year that you can get by on the smallest quantity in terms of product used for treatment. This will also give you the longest amount of time for enjoyment of a weed free recreational area.
Please feel free to email me or post questions you may have and I will respond accordingly.