A: That all depends! Because you're applying chemicals to water, you'd think that rain would have no affect on the herbicide—but it actually might. How long it rains, how heavily it rains and how soon it rained after you applied the treatment could impact its quality and effectiveness.
If wet stuff from the sky is a threat and you're thinking about spraying algaecides or herbicides to control nuisance plants in your pond or lake, here are four general guidelines to follow:
- Check the Weather: Is steady rain forecast for the day? If so, postpone any treatment of emergent weeds. Many treatments need to be absorbed by the plant's leaves to be effective. A day-long stint of rain will rinse the chemical off the weed before it can be fully absorbed.
- Check the Weather, Part II: If you're expecting heavy precipitation, definitely put off treatment to another day. The applied chemical could rinse off the plants and overflow from the pond before being taken up by the target weed.
- Reapply If Necessary: A light sprinkle will generally not affect the chemical's potency in a pond that's already been treated. If a downpour occurs within a few hours of application, however, plan to reapply the herbicide in a few days to fully control that target plant.
- Make Your Treatment Count: Use a pond sprayer to apply the chemical as close to target weeds as possible, and use a sticky surfactant to help the chemical absorb into the plant like Treatment Booster Plus. Treatment Booster Plus breaks down the surface of the weed or algae and allows the active ingredient to penetrate.
Even though you're treating aquatic weeds, wet weather can still impact the chemical's effectiveness. Check the short- and long-term forecast and plan accordingly – because you don't want all that hard work (and costly treatments) to be for nothing!