Iowa Commercial Pesticide Applicators Aquatic Pest Control (Category 5) Solved 100%

C1: Describe the value of plants in aquatic ecosystems - Answer They are primary producers in the aquatic food chain, produce oxygen, provide shelter & sites for spawning, can dampen the force of waves, use nutrients & improve water clarity, stabilize the bottom material C1:Identify specific problems caused by aquatic weeds - Answer 1)Restriction of recreational activities, 2)foul taste & odor, 3)hinder fish growth & survival, 4)water flow restrictions, 5)accelerate water loss, 6)accelerate fill, 7)interfere with navigation, 8)offer a home for noxious insects, 9)water becomes toxic, 10)loss of aesthetic appeal, and increase maintenance costs. C1:Recognize two instances when aquatic weeds should be eliminated from a body of water - Answer 1) Retention ponds used for fire control or irrigation systems; 2) exotic, invasive species C2:Describe how sunlight and nutrients affect plant growth - Answer Light: photic zone; water hardness- dissolved calcium & magnesium, low hardness, soft, prevents good light penetration, high hardness (60-75 ppm) increased light penetration. Nutrients: runoff; eutrophication. C2:List the three nutrients regulating aquatic plant growth - Answer 1) carbon (in the form of bicarbonates), 2) nitrogen, and 3) phosphorus C2:Describe how water temperature affects aquatic plant growth - Answer Most plants grow best in warming water in spring & early summer, most die back in fall as water cools, some grow best in late winter & spring (curlyleaf); a few later in summer (naiads) C2:Explain why sand is a good substrate in small bodies of water, but bad in rivers - Answer Rivers sand shifts, ponds it doesn't matter C2:Explain why rock and gravel substrates are not conducive to growth of rooted plants - Answer They provide little in the way of fertile sediments for nutrient uptake C3:Identify three major types of algae - Answer 1) microscopic, 2) filamentous, 3) stonewarts (Nitella & Chara) C3:Differentiate between the four types of flowering plants based on the habitat they occupy in the aquatic environment - Answer 1) submersed plants- water depths of less than 1 foot to 20 feet, 2) free-floating plants- water surface (duckweed), 3) rooted floating plants- water depths of 1 to 5 feet (water lotus, pondweed), 4) emergent plants- water depths less than 3 feet C3:List four types of leaf arrangement that aid in the identification of submersed plants - Answer 1) alternate leaf arrangement- one leaf per node (pondweed), 2) opposite leaf arrangement- two leaves per node (naiads), 3) whorled leaf arrangement- three or more leaves per node (coontail & elodea), & 4) basal leaf arrangement- does not have an erect stem (eelgrass) C3:Discuss why duckweed can be especially problematic in a water body - Answer Can completely cover the surface and cause the bottom layer of water to become anaerobic & unsuitable for fish C3:Identify the location of leaf emergence for rooted floating plants - Answer Underground or in sediment (rhizomes)- American lotus, spatterdock, water lily, water shield; From stems- pondweeds C3:Distinguish the two types of emergent plants and give an example of each - Answer 1) herbaceous- grass-like plants (cattail, bulrush), plants with broad leaves (arrowhead, smartweed); 2) woody plants- (willow, buttonbush) C4:Identify three major objectives in preventive aquatic plant control - Answer 1) prevention of weed spread, 2) elimination of nutrient sources that support growth, and 3) reduction of shallow areas where plants can root C4:List the seven steps to reducing nutrient input through a watershed management plan - Answer 1) install sod or native grasses/vegetation along drainage areas & buffers, 2) stop fertilizing grass in a 10 to 20 foot strip along a body of water, 3) prevent livestock from entering water, 4) practice conservation tillage in watershed areas that are subject to erosion, 5) construct a settling or retention basin to receive nutrients before they reach the main body of water, 6) avoid the addition of fertilizer directly to a pond, and 7) check for hidden sources of nutrients such as septic fields & drainage tiles C4:Discuss how to eliminate shallow areas of ponds and lakes for existing and new construction sites - Answer New ponds should be constructed so that shoreline edges have a 3 to 1 bank slope to reduce areas for rapid plant establishment, not in swimming areas; existing ponds or lakes- dredges or draglines, also maintenance- which may involve rehabilitation and draining & then excavate and shape C4:Describe two types of equipment used for mechanical aquatic weed control and their advantages and disadvantages - Answer 1) dragline- effective, expensive & must be repeated every few years, 2) weed harvesters- Advantages: removes all types of aquatic vegetation, no restrictions, can cut fishing & boating lanes, plant material not left in water to decompose & possibly cause fish kills, removing plant materials aids in removing nutrients, Disadvantages: high equipment & maintenance cost, like mowing a lawn have to repeat several times a season, not effective in water less than 3 to 4 feet deep, many bodies of water too small for large commercial equipment, dumping area away from lake, continued harvesting may lower nutrient level in pond or lake, aquatic plants are quite heavy to move off site (85% water) C4:Describe six types of aquatic weed habitat alteration - Answer 1) fabric liner & riprap on the shoreline, 2) winter drawdowns, 3) cover bottom sediments with bottom barriers or other sediment liners, 4) nontoxic dyes acting as light screens, 5) aeration, 6) aluminum sulfate (alum) to address problem of phosphorus C4:Discuss potential biological control agents for weed control in lakes and ponds - Answer Grass carp; beetle & weevils; swans, ducks, & geese (greatly increased fertility C5:Identify the important considerations in using an aquatic pesticide - Answer 1) proper identification of plants, 2) uses of the water to be treated, 3) potential nontarget & environmental problems, 4) timing of the applications, 5) water temperature, 6) method of application, 7) retreatment within the same year, 8) cost