Chemical Resistance

The question asked by many people in the pond industry is: Do aquatic plants become resistant to chemicals?  Well, let’s think about this as a process of natural selection.  In the gene sequence of a plant species there are slight variations in some of the plants within a single plant population.  When you apply a certain herbicide/insecticide or other chemical repeatedly onto the same population in smaller doses than the recommended treatment, some of the individual plants don’t die.  So these individuals survive and have a gene that allows them to resist treatment by that chemical (their immune system recognizes the product & immediately starts to fight it off as soon as the chemical’s presence is sensed within the plant).  So, after a while these plants multiply, producing a community of “super” plants that are resistant to treatment (all because you didn’t follow the dosing instructions on the label of the product).

An example of this is the resistance that develops in several plants to the chemical: Fluridone (aka Sonar), because the customers purchasing this product do not want to kill the “native” weeds in their ponds and they use a lower dosage than the recommendation on the label that is necessary to kill the targeted plants completely.  These plants that have become resistant in the past include: water milfoil, hydrilla, and coontail.

To avoid the issue of having a plant become resistant to all sorts of herbicides, and creating a super strain of aquatic weeds that can’t be killed by any substance that has been combined in a laboratory thus far, I have a few suggestions for all of you avid aquatic owners out there.  First of all, create an annual rotation of herbicides that you are going to treat with; this gives you the opportunity to treat effectively every year. Your methods will no longer be predictable to the plants that are depriving your pond of its potential aesthetic values; instead you will have the upper hand and will be much more likely to succeed in your treatments.  Secondly, please, use the dosages that are recommended on the labels (I’ll let you in on a little secret: the people that wrote those labels have tried the chemicals, they know what they’re doing, and trusting the professionals’ advice will be worth it in the long run).  Finally, to help decrease the amount of weeds and algae you actually have to treat with chemical products, use aquatic pond dyes and natural bacteria throughout the year.  And, speaking of professionals, if you have any questions about pond maintenance contact the helpful staff at Sanco.