| Hand Pulling (physical) | |
|---|---|
| Effectiveness: | Removes a few individual plants at time |
| Specificity to Target: | High |
| Advantages: | Good for localized areas/ few plants. Plants physically removed from waterbody |
| Disadvantages: | Labor intensive Good for small infestations only. Not practical when plant growth is dense |
| Cost*: | Labor Costs vary depending upon contractor costs or staff time |
| Mechanical Harvesting (physical) | |
| Effectiveness: | Removes large amounts of vegetation at a time |
| Specificity to Target: | Not Specific |
| Advantages: | Rapidly removes vegetation from area Plants physically removed from waterbody |
| Disadvantages: | Fragments plants which could cause regrowth Removes beneficial native vegetation. Could increase turbidity, ultimately affecting other aquatic life Does not remove rooting systems |
| Cost*: | Ranges widely depending on plant density, location, disposal, etc. Generally $350-$1500 per acre |
| Hydro-raking (Physical) | |
| Effectiveness: | Removes large amounts of vegetation at a time |
| Specificity to Target: | Not specific |
| Advantages: | Rapidly removes vegetation
Removes rooting systems to prevent rapid regrowth. Plants removed from waterbody |
| Disadvantages: | Fragments plants
Could increase turbidity, ultimately affecting other aquatic life Removes beneficial native vegetation |
| Cost*: | Ranges widely depending on plant density, location, disposal.
Generally $350-$2500 per acre |
| Benthic Barrier permeable non-permeable (Physical) | |
| Effectiveness: | Used for very small infestations |
| Specificity to Target: | Specific to area where barrier is located Impacts all plants under barrier |
| Advantages: | Compresses plants to sediments and prevents likelihood of fragmentation by wind, wave, or anthropogenic means |
| Disadvantages: | Labor intensive
Must frequently be cleaned/re-staked Plants not physically removed from waterbody May cause sediment/water anoxia May impact non-target species such as fish, invertebrates, and others |
| Cost*: | $0.60-$1.22 per square foot or ($25,000-$50,000 per acre) |
| Chemical Treatment | |
| Effectiveness: | Herbicides which are taken up by root systems (systemic herbicides) more effective than contact herbicides |
| Specificity to Target: | Most chemicals have target species for which they are most effective
Varying application rates can increase target specificity |
| Advantages: | Chemical has potential to eliminate exotic plant infestation if done at correct time, and if correct concentration is used
Relatively rapid effect Longer time span of control than other types of control techniques |
| Disadvantages: | Addition of chemical to waterbody
May impact non-target species if not applied according to label restrictions Could be environmentally damaging if not applied per label restrictions |
| Cost*: | Varies with chemical and size of treatment area
Could range from $200-$1000 per acre. |
| Drawdown (Habitat manipulation) | |
| Effectiveness: | Somewhat effective if repeated frequently
More effective if drawdown maintained for long time period |
| Specificity to Target: | Not specific |
| Advantages: | Could control density of vegetation due to plant die off from dessication or freezing
Winter drawdowns favorable |
| Disadvantages: | Impacts non-target plants
Impacts fish, amphibians, insects, and other aquatic organisms Devastating to entire waterbody ecology |
| Cost*: | Low cost if dam or other means of drawing down water is available |
| Dredging (Habitat manipulation) | |
| Effectiveness: | Effective in removing plants from localized area where dredge takes place |
| Specificity to Target: | Not specific |
| Advantages: | Completely removes plant material
Removes nutrient laden sediments Removes seed bank |
| Disadvantages: | Devastating to entire system.
Impacts non-target plants and animals Could cause excessive turbidity Must wait for waterbody to be filled again |
| Cost*: | $16,000-32,000 per acre
Previously used and successful in one lake in New Hampshire (Milville Lake) |
| Biological Controls | |
| Effectiveness: | Effective against target plants |
| Specificity to Target: | Specific |
| Advantages: | Insects, bacteria, or viruses used in this method are typically specific to target plant. Their life cycles revolve around particular plant species
Does not affect other non-target species |
| Disadvantages: | May cause decline in oxygen as plant material decays
Many biological controls are themselves exotic Still experimental |
| Cost*: | Cost of insects
Monitoring cost high |
* Costs are averages determined from data obtained from "Draft Generic Environmental Impact Report" for Massachusetts, and from Aquatic Control Technology, Inc. Fact Sheet.