POST-TREATMENT
Questions & Answers
When will I see results?
Usually, plants begin to show signs of weakness or die within 2 weeks. Signs include
discoloration, elongation or wilting. Filamentous algae often turns pale yellow or
whitish within 3 to 4 days. Planktonic algae disappears in 24 to 48 hours. Dead plants
with tough stems and sturdy root systems may remain standing until wind or waves break
them up.
What happens to the dead plant material?
Decaying plants and algae usually sink to the bottom after they die. Occasionally,
however, plants with weak stems may break loose and float temporarily. Microscopic
organisms in the water break down (decompose) plant materials leaving a fine residue
of silt that settles to the bottom.
Will my water quality change?
When large masses of vegetation decay, recycling of the plant materials occur. Some
nutrients end up in sediment while others enter the water column. Some temporary
decrease in dissolved oxygen levels may occur.
How long will control last?
Many weed species can be controlled for an entire season with a properly timed,
single treatment. Herbicides do not kill seeds, and some do not get into root systems.
This can result in a re-growth of plants requiring touch-up later in the season. Algae
will generally require treatments 3 to 6 weeks apart during the season because of their
ability to reproduce rapidly.
Will I have fewer plants next year?
Once well established, nuisance aquatic plants will typically continue to be a problem
each year. Some reduction in weed beds may occur the following year if treatments were
made before seed production. Changes in dominant species or plant abundance is more
likely to occur due to environmental factors such as water clarity, nutrient
concentrations and weather factors. Different herbicides may be required.
Do resistant plants establish themselves?
There is some evidence that treating too often, year after year with the same chemicals,
may result in the establishment of an unaffected species. This may require changing
chemicals, dosage rates, using a combination of chemicals, or employing a combination of
techniques (aeration, nutrient deactivation, dilution, etc.).
What happens to the chemical that is put into the water?
Products recommended in this book do not remain in the water in their original state
for extended periods of time. Chemical and biological actions break down (biodegrade)
these compounds into simpler, natural basic compounds. These are recycled within the
environment. They do not build-up as residues in fish nor in the fish food chain.
What are common reasons for failure?
Occasional control failures can occur, usually due to one or more of the following reasons:
- Not reading the product label and following directions.
- Misidentification of the plant resulting in use of the wrong chemical.
- Miscalculation of the treatment area resulting in the wrong dosage.
- Adverse weather conditions (high winds, rain storms, etc.) during or immediately following treatment.
- Water conditions (high turbidity, low temperatures, etc.) physically or chemically interfering with the herbicidal action.
- Weed re-growth or appearance of new vegetation.
- Improper timing of treatment - too early or too late.
- Rapid water exchange causing chemical dilution.
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