Aquatic Pest Control

1. The application of pesticides to ornamental aquatic plants in a greenhouse or nursery is not an aquatic pest control activity regulated under the SCPCA.
2. The installation of aeration systems and similar devices or the use of mechanical harvesters to remove vegetation is not an aquatic pest control activity regulated under the SCPCA.
3. The application of fertilizers not mixed with pesticides or herbicides is not an aquatic pest control activity regulated under the SCPCA, nor is the use of dyes to suppress the growth of aquatic vegetation.
4. The installation of devices to exclude, prevent, destroy, repel or otherwise mitigate aquatic pest animals is not an aquatic pest control activity regulated under the SCPCA.

Q. What is South Carolina's most troublesome aquatic weed?
A. Hydrilla is South Carolina's most troublesome aquatic weed and poses the most serious long-term threat to the state's waterways. First discovered in upper Lake Marion in 1982, the plant has since spread to cover about 40,000 acres of lakes and rivers in the lower SanteeCooper drainage basin.

Q. What are the aquatic plant management responsibilities of the Water Resources Division of the S.C. Department of Natural Resources?
A. The Water Resources Division administers the State Aquatic Plant Management Program which includes developing and implementing the annual State Aquatic Plant Management Plan. The Division also coordinates the receipt and distribution of available public and private funds for aquatic plant management activities and research in public waters.

Q. What is the role of the S.C. Aquatic Plant Management Council?
A. The S.C. Aquatic Plant Management Council is a ten-member board that provides valuable interagency coordination of aquatic plant management activities in public waters and serves as the principal advisory body to the Department of Natural Resources on all aspects of managing nuisance aquatic plants. The Council establishes statewide management policies and approves all aquatic plant management plans for public water bodies.

Q. What resource is available for management of aquatic plants in private waters?
A. Assistance, in the form of advice regarding plant control agents and methods, is available to owners of private waters through the Clemson University Cooperative Extension Service, the Wildlife and Freshwater Fisheries Division of the S.C. Department of Natural Resources and the Soil Conservation Service of the U.S. Department of Agriculture. Owners may choose to implement control methods themselves or arrange for a commercial lake management firm to do so.

Q. Who makes up the membership of the S.C. Aquatic Plant Management Society, a nonprofit organization formed in 1978 to promote the management of noxious aquatic plants?
A. The Society's membership includes individuals from the private, public and academic sectors with interest in all aspects of aquatic plant management. The Society provides members with the most current information in the field of aquatic plant management through newsletters and annual meetings.

Q. How do algae and aquatic macrophytes act as the basis of the food chain?
A. They provide food for small animals which in turn become the food for successively larger animals. Plants also provide shelter and breeding habitat for a wide variety of animals including fish, waterfowl and aquatic mammals.

Q. What is the purpose of the Federal Insecticide, Fungicide and Rodenticide Act (FIFRA)?
A. FIFRA allows the federal government to regulate the registration, manufacture, transportation and use as well as the marketing of pesticides.

Q. What are restricted-use pesticides (RUPs)?
A. Pesticides that are more toxic or hazardous to the environment than others and require special handling and user training. Law requires that they be applied by licensed, certified applicators or persons working under their direct supervision.

Q. What is meant by the triple-rinse method?
A. The triple-rinse method is done by filling the container to at least 10 percent of its volume (preferably 1/4 to 1/3 of volume), shaking the container and draining the container into the mix tank. Repeat this two more times. When not using a mix tank, apply the rinse water from the container in the same manner as the pesticide in the container.

Q. Who should you contact to find out more information on the pesticide container recycling program in South Carolina?
A. Check with your local Cooperative Extension agent for pesticide container recycling dates in your area.

Q. How may new infestations of noxious weeds be quarantined and controlled or eradicated under the Noxious Weed Act?
A. A permit from the USDA is required to import plants or plant products into this country. Another permit is required to move all designated noxious weeds into and throughout the United States, whether by mail, freight, baggage or on the person.

Q. What makes up a herbicide formulation?
A. A herbicide formulation consists of an organic (carbon containing) or inorganic active ingredient, an inert carrier and perhaps adjuvants.

Q. Why are contact herbicides more effective on annual plants?
A. Perennial plants that persist from year to year can be defoliated by contact herbicides, but they quickly resprout from unaffected plant parts.

Q. What is meant by cell division?
A. This process involves increasing the number of cells and replacing old cells. It is how plants grow.

Q. What is meant by preemergence?
A. During early growth or before weed seeds germinate (pre-emergence) is when herbicides are most affective.

Q. What is meant by a plant growth regulator?
A. When a herbicide causes abnormal tissue development, abnormalities such as twisting of stems and leaves may be evident. If enough abnormalities occur, plants can die. Herbicides that act in this manner are often called plant growth regulators.

Q. What is photosynthesis?
A. Photosynthesis is the process by which plants use carbon dioxide, water and sunlight to produce relatively simple molecules that are the building blocks of other complex molecules that make up the plant body.

Q. What is meant by broad spectrum and when is it used?
A. Broad spectrum (sometimes called nonselective) herbicides are those that are used to control all or most vegetation. This type of herbicide is often used for total vegetation control in areas such as equipment yards and substations where bare ground is preferred.

Q. How does lack of rainfall affect herbicide efficacy?
A. Lack of rainfall can affect herbicide efficacy because drought stressed plants are less likely to absorb both foliar and soil applied herbicides.

Q. How does temperature affect herbicide efficacy?
A. Low temperature affects herbicide efficacy indirectly by affecting plant growth. At less than ideal temperatures, plant growth slows down, and this may decrease herbicide absorption and activity. Excessively high temperatures can affect foliar applications of some herbicides by causing them to volatilize (change from liquid to vapor) before they are absorbed into the plant.

Q. What methods might you use when controlling aquatic weeds in flowing water?
A. 1) Use of invert emulsions or polymers and trailing hoses to aid sinking the herbicide and adhering it to the plants. 2) Use of special herbicide formulations for flowing water such as slow release pellets. 3) Use of rapidly absorbed herbicides. 4) Use of sequential applications or injection equipment to increase contact times.

Q. What kind of soil has greater capacities for binding herbicides?
A. In general, soils with more organic matter and clay have greater capacities for binding herbicides and require higher application rates than other soil types, such as sandy soils.

Q. What is the importance of numerical values on the pH scale?
A. The pH scale goes from 0 to 14, where 7 indicates neutrality. Values less than 7 indicate acidic water, and values greater than 7 indicate a basic condition.

Q. What is turbidity?
A. Particles suspended in the water decrease the water's ability to send light and this is called turbidity.

Q. What causes water hardness and how is it expressed?
A. The dissolved metals calcium, magnesium, iron and strontium cause water hardness. Hardness is usually expressed in terms of ppm calcium carbonate and can range between close to zero and over 100 ppm.

Q. What precautions should be taken when obtaining make-up water for tank mixes?

1. Use the cleanest water available. Avoid sediments.
2. When tank mixing herbicides that are known to be inactivated by hard water, use the softest water available. If possible use softened or distilled water; lake water is the next best choice. Avoid using well water.
3. Minimize the amount of time that herbicides remain mixed in tanks.
4. Read the label for special precautions or instructions.

Q. What are the advantages and disadvantages of granules?
A. Granules are convenient for spot treatments, are ready to use and require no mixing, reduce drift hazards and can be applied easily. Disadvantages of granules are their sometimes high cost and their ineffectiveness as a foliar treatment.

Q. What are advantages and disadvantages of using wettable powders?
A. Advantages of a WP are lower cost, ease of handling and ease of measuring. Some disadvantages of WP are the abrasion by suspended particles on spray equipment and the requirement for constant tank agitation.

Q. What is the most common route of exposure for acute toxicity?
A. Dermal exposure through splashes and spills is the most common route of exposure.

Q. What are the most common causes of chronic toxicity?
A. Chronic exposure is most often the result of contaminated clothing, leaky spray equipment, inadequate protective clothing and equipment, improperly cleaned spray equipment and, most importantly, failure to clean yourself.

Q. What are causes of oral exposure?
A. Oral exposure can be caused by accidental swallowing, usually from carelessness. Eating, drinking and smoking while applying pesticides or before properly cleaning hands can also contribute to oral ingestion of pesticides.

Q. What is the minimum requirement of protective clothing?
A. When working with pesticides, wear, at the least, a long-sleeved shirt, long pants, shoes and socks. When handling pesticide concentrates or mixing and loading the sprayer, a liquid-proof apron and rubber gloves is suggested.

Q. What kind of gloves should be worn when handling concentrates?
A. Gloves should be unlined and made of a waterproof material that does not contain any cotton, leather or other fabric that will absorb chemicals. Sleeves should be worn on the outside of the gloves.

Q. What type of hats and boots should be avoided when applying pesticides?
A. Hats should be easy to clean, or they should be disposable. Avoid hat fabrics that absorb liquids. Unlined rubber boots are a good investment for pesticide applicators because they are waterproof and easy to clean. Work shoes made of canvas or leather absorb pesticides and cannot be decontaminated easily.

Q. What kind of face protection should be worn anytime concentrate is handled?
A. Wear goggles or a face shield anytime concentrate is handled.

Q. What is the difference between adjuvants and surfactants?
A. Generally the term adjuvant should be used to group all spray tank additives. The term surfactant describes those additives that modify the distribution of spray on plant foliage.

Q. What are some examples of activator adjuvants and what is their purpose?
A. Adjuvants can be grouped into three classes, activator adjuvants, spray-modifier adjuvants and utility-modifier adjuvants. Activator adjuvants increase the activity of the herbicide. Surfactants are associated with the enhancement of penetration of the spray solution through the leaf tissues. Wetting agents are spray additives that increase the ability of water to displace air or liquids from a plant surface.

Q. What is the purpose of spray-modifier adjuvants and what are some examples?
A. This group of adjuvants has its greatest influence on the delivery and placement of the spray solution. Additives which alter or change the spray, such as polymers, inverts and foams, are included in this group.

Q. What is the purpose of utility-modifier adjuvants and what are some examples of each?
A. Utility modifiers are materials that when added to the spray solution improve the conditions in which the formulated mixture is useful. Types of modifiers include emulsifiers, dispersants, stabilizing agents, coupling agents, cosolvents, compatibility agents, buffering agents and antifoam agents.

Q. When is the spray-tank method of application practical for treating aquatic weeds?
A. The spray-tank method is suitable for treating relatively small areas or when mixing several herbicides. When treating large areas, it may be more efficient to use the direct-metering method to reduce the time spent refilling the tank.

Q. What is the importance of maintaining good agitation during a spray-tank application?
A. Good agitation is important for maintaining a uniform spray mixture and for mixing of adjuvants such as inverting oil or polymers.

Q. When is a hydraulic agitation system inadequate?
A. A well designed hydraulic agitation system that uses a venturi device for stirring is adequate for keeping wettable powders in suspension. However, this type of agitator will not stir the mixture enough to form invert emulsions or mix polymers.

Q. When is hose size important?
A. Hose size is important because the pressure loss in the hose depends on the hose inside diameter (ID), length and flow rate. For example, a 1/2-in. hose loses 1 psi per foot at a flow rate of 10 gal per min.

Q. What are the benefits of using diaphragm pumps?
A. Diaphragm pumps are now used in many applications instead of piston pumps. Benefits of diaphragm pumps include relatively low cost, low maintenance and small size compared with other pumps with similar flow and pressure ratings.

Q. What is the importance of the spray nozzle during chemical applications?
A. The spray nozzle forms the spray pattern, determines the droplet size and meters the flow rate. Base nozzle selection on a balance of these three functions.

Q. What is the difference between an invert emulsion and a normal emulsion?
A. An invert emulsion contains water droplets dispersed in a continuous oil phase. This is contrasted to a normal emulsion which is oil droplets dispersed in a continuous water phase.

Q. On water, how would you go about measuring applications based on area?
A. Measure distances on water by:

1. dragging a floating rope of known length behind a boat and dropping buoys every time the end of the rope passes a buoy (so that the distance equivalent to the length of the rope can be measured again)
2. using a rangefinder
3. by using a map and some type of planimeter if a map with an adequate legend is available.

Q. What is meant by the term calibration and why is it so important?
A. Adjusting application equipment so that it delivers the correct amount of pesticide is called calibration. Calibration of equipment for application of herbicides to agricultural crops must be precise because there is often a thin line between the rate at which a herbicide will damage the crop or carry over to a following crop.

Q. Why is maintaining constant application rate when applying aquatic herbicides difficult?
A. Maintaining constant application rate is difficult when applying aquatic herbicides because the equipment is mounted in a boat. Also, it is difficult to maintain a constant speed and perfect course due to environmental factors such as wind velocity and speed, water flow and vegetation density.

Q. Why must separate calibration tables must be made for different sized pellets and granules?
A. Spreader output will be different at given settings for different-sized particles.

Q. What types of natural controls keep native plant communities in balance?
A. Natural controls may include environmental restraints, competing species, herbivores (plant eating organisms) and pathogens.

Q. What is the difference between the introduction approach and the augmentation-manipulation approach to biological control?
A. In the introduction approach, small numbers of biocontrol agents are released, where they previously did not exist, so that they can increase to a point where they are in balance with the target pest (weed) and can establish a self-perpetuating population. The augmentation-manipulation approach involves releases of biological control agents at strategic times and at levels capable of providing control.

Q. Why should carp be at least 12 inches long at stocking?
A. Predators such as largemouth bass, snakes, fish-eating birds and alligators can adversely effect grass carp survival, especially if small fish are stocked.

Q. Why is annual restocking of tilapia necessary in South Carolina?
A. Tilapia will not overwinter in water below 55 °F.

Q. What three insects have been successfully released for the control of alligatorweed?
A. Three alligatorweed bioagents include the alligatorweed flea beetle, the alligatorweed thrips and the alligatorweed stem borer.

Q. What three species of insects have been released for control of waterhyacinth and which was the most effective?
A. The three species of insects that have been released for control of waterhyacinth are the mottled waterhyacinth weevil, the chevroned waterhyacinth weevil and the waterhyacinth borer. The weevils (especially the chevroned) have been the most effective of the waterhyacinth insects.

Q. What is a disadvantage to using plant pathogens for biological control of aquatic weeds?
A. Pathogens tend to be environmentally sensitive and can be rendered ineffective by extremes of temperature or humidity.

Q. Why is mechanical removal not practical for large bodies of water?
A. Because of its high cost, mechanical control is generally practical only for small areas such as marinas, swimming areas, boating trails or where other methods are not feasible or are undesirable.

Q. What are some of the disadvantages associated with mechanical harvesting?
A. Mechanical harvesting is usually higher in cost and much slower than other methods, and there are high maintenance and repair costs. Some water bodies are not suitable for mechanical harvesting because of water depth and presence of obstructions. A suitable area for disposal of harvested plants must be available. Wildlife and desirable vegetation is removed along with the harvested weeds. Plant fragments drift to infest new areas. Increased turbidity may result from disturbance of sediments.

Q. How is water level manipulation used for aquatic plant management?
A. Water level manipulation refers to the raising of water levels to control aquatic vegetation by drowning or lowering to control aquatic vegetation by exposing them to freezing, drying or heat.

Q. In what season and to what extent of time should drawdown be conducted for best results?
A. Drawdown is usually conducted during winter months so that plants are exposed to both drying and freezing. For best results, a drawdown should last 60 to 90 consecutive days.

Q. What are methods of reducing light penetration to control submersed aquatic plants?
A. Light penetration can be reduced by the use of special pond dyes, special fabric bottom covers or fertilization.

Q. What kind of personal safety precautions should an applicator take when applying rotenone?
A. Rotenone in powder form may cause respiratory irritation if inhaled. A proper respirator mask should be used during mixing of rotenone powder. Liquid rotenone spray should not be allowed to drift onto personnel.

Q. What kind of environmental precautions should be taken when using rotenone?
A. Fish killed by rotenone may not be eaten according to regulations of the U.S. Food and Drug Administration. Treated water is not harmful to animals which may drink from the pond if the rotenone is applied in accordance with instructions on the label. Swine may in some instances be sensitive to rotenone, and caution should be exercised before allowing swine to drink from treated ponds. Rotenone may not be applied to flowing or public waters except by authorized personnel.

Q. Why is lowering the water level when treating with rotenone recommended and who is responsible for non-target fish kills downstream?
A. Lowering the water level of the pond by draining or pumping is recommended because it will reduce the volume of water to be treated and the amount of rotenone that must be purchased. Drain outlets in the pond must be closed prior to the application rotenone. Any rotenone that escapes downstream is toxic to fish, and the applicator and/or pond owner is responsible for any fish mortalities.

Q. How many years of research is required before an aquatic herbicide is labeled by EPA?
A. Before an aquatic herbicide is labeled by EPA, research that requires about 10 years to complete must be conducted.

Q. When making partial applications of herbicides that can be toxic to fish at use rates, why should you begin applications near shore and proceed toward open water?
A. This allows fish to escape to untreated water. All precautions should be taken to avoid conditions that can lead to potential fish kills when applying aquatic herbicides.

Q. What is the average time for complete decomposition of 2,4-D?
A. Complete decomposition of 2,4-D usually takes about three weeks in water and can be as short as one week.

Q. What are the naturally occurring compounds which occur when endothall is broken down?
A. The by-products of endothall dissipation are carbon dioxide and water.

Q. What are some advantages of maintenance control of plants at low levels before they reach a problem level?
A. Detrimental impacts of aquatic weeds on native plant population are reduced. Detrimental impacts of aquatic weeds on water quality are reduced. The amount of organic matter deposited on the lake bottom from natural processes is reduced, as well as a reduction following control of the plants. Less herbicide is used in the long run.

Q. What is one reason why public education is an important part of a successful maintenance control program?
A. When conducting a maintenance control program, the public may not perceive a weed problem and may question the need to spray.

Q. What are the purposes of plant taxonomy?
A. The science of plant identification is called plant taxonomy. The purposes of plant taxonomy are to name all plants and to classify plants according to their relationships with each other.

Q. Why is correct identification of aquatic plants so vital to aquatic herbicide applicators?
A. Correct identification is necessary to select the proper herbicide for control of a particular weed. Nontarget aquatic plants are important to identify so that herbicide damage can be minimized. There are many aquatic plants, which may become problems, that herbicide activity has not been determined for and knowledge of the taxonomic relationships between plants can aid in predicting herbicide sensitivity.

Q. In South Carolina, how can positive identification of aquatic plant species be obtained?
A. Positive identification of aquatic plant species may be obtained by submitting a sample to the Clemson University Plant Problem Clinic through local Clemson Cooperative Extension Service county offices (listed in the telephone directory under Clemson University Extension Service). There is a Clemson Extension office located in each county in the state.

Q. Why is it helpful to use the official common name that is accepted by the Weed Science Society of America or other standardized listing?
A. Common names can be confusing because several common names may be used for the same plant and the same common name is sometimes used incorrectly for unrelated plants.

Q. What is the difference between submersed, emersed, floating and floating leaf plants?
A. Submersed plants grow completely below the water surface and depend on surrounding water for support of the plant body. Emersed plants are rooted in the bottom, extend above the water surface and are self-supporting. Floating plants are not attached to the bottom and float on the water surface. Floating leaf plants are attached to the bottom and have leaves that float on the water surface. These plants may or may not be self-supporting and can also be emersed.

Q. What are the three separate growth forms of algae?
A. Planktonic algae are single-celled or small colonies of algal cells that are attached to each other and free-floating or suspended in the water column. Filamentous algae are multi-cellular algae composed of cells attached end to end so that they form long threads. Macrophytic algae are large, multi-cellular, branching algae.