Aquatic Plant Management

1. Aquatic Plant Management Louis Helfrich, Ph.D. Department of Fisheries & Wildlife Sciences Virginia Tech

2. Photosynthesis by aquatic plants, both algae and rooted water plants, represents the major source - contributing from 70 to 90% of the dissolved oxygen. Aquatic plants can trap excessive nutrients and detoxify chemicals. Aquatic wildflowers such as the water lily are sold and planted to provide floral beauty in water gardens. Plants: Problem or Benefit?

3. Plants serve as nursery habitat and the foundation of the aquatic food chain. They provide food, dissolved oxygen, and spawning and nesting habitat for fish and waterfowl. • Wildlife • Food • Nursery • Shelter • Critical habitat

4. Too many plants! A weed is simply a very successful competitor for space, light, and nutrients. • Restricted recreation • Fish kills • Fish flavor problems • Pond water odor problems • Drinking water taste problem • Stunted fish growth

5. Why weeds? Nutrients, Light

6. Why weeds? • Shallow water • Clear water • Excess fertility (nutrients) • Invasion of exotic weeds American Lotus, Nelumbo lutrea

7. FertilizationCan you fertilize weeds away? No

8. Aquatic Weed Prevention • Prevent fertilizer runoff • Prevent soil erosion • Do not feed grass clippings • Do not feed fish and ducks • Fence livestock • Steep banks

9. Aquatic plants can be divided into: (1) algae (2) rooted water plants.

10. Algae or Turbidity?

11. Rooted aquatic plants are distinguished from the algae by the presence of true leaves, stems, roots, and flowers.

12. Common Floating Plants Watershield Spatterdock, Nuphar advena

13. Submerged Plants:Exotics

14. Emerged and Shoreline Plants Arrowhead Cattail

15. Algae Turbid water Fertile, P Planktivourous, carp Small zooplankton Ducks & geese Macrophytes Clear water Fertile, less P Predators Large zooplankton No waterfowl Plant Dominance

16. Weed Control Methods • Watershed management • Physical • Biological • Chemical

17. Weed Control: Physical Removal • Drain • Dredge • Dragging • Raking • Cutting • Skimming • Harvesting • Aeration

18. Herbivorous animals • Fish, geese, and swans • Nutrient pumps • Permits for exotic animals

19. Herbicides? • Expensive • Short-term • Toxic • Registered • Liability • Dosage • Timing • Fish Kills • Water-use restrictions

20. Chemical Control • Algae • Copper Sulfate, • Copper Complex (Cutrine) • Submerged Weeds • Diquat (Reward), • Fluridone (Sonar / Avast), • 2, 4-D, (Aqua-Kleen) • Endothal (Aquathol K) • Floating (Duckweed and Watermeal) • Diquat, • Fluridone • Emergent and floating Plants • Endothal, Fluridone, 2,4-D • Glyphosate (Rodeo)

21. Application Timing • Early spring • Actively growing • Cool water • Slow decay Pickerel weed, Pontederia

22. Application Variables • Area treated • Water depth • Water temperature • pH • Hardness • Flow Exchange rates • Weed density • Weather conditions • Suspended particles Arrow Arum, Peltandra virginica

23. Chemical Control • 1/3 of pond at a time • Follow label • Observe waiting periods

24. Aquatic Problems • Water weeds • Water quality • Muddy water • Leaking ponds • Nuisance animals • Poor fishing • Fish kills

26. http://aquat1.ifas.ufl.edu/welcome.html Control Methods For Aquatic Plants in Ponds and Lakes Authors: L. A. Helfrich, R.J. Neves, G. Libey, and T. Newcomb, Extension Specialists, Fisheries and Wildlife Sciences, Virginia Tech Publication Number 420-251, posted March 2000 http://www.ext.vt.edu/pubs/fisheries/420-251/420-251.html

27. The density of aquatic plants (both algae and rooted macrophytes) is largely a function of (1) nutrient concentrations (phosphorous and nitrogen) and, (2) light. In general, nutrient-rich, shallow lakes experience greater nuisance water weed problems than nutrient-poor, deep lakes.

29. Herbicide Irrigation Fishing Livestock Swimming Drinking Fluridone (Sonar) 30 0 0 0 0 Glyphosate (Rodeo) 0 0 0 0 2 Chelated Copper 0 0 0 0 0 Diquat (Reward) 5 0 1 1 3 Endothal Aquathal K 14 3 14 1 <25 Aquathal G 7 3 14 0 <25 Table 2. Waiting period (days) before using water after application of aquatic herbicides (Helfrich et al. 1996). Giant Salvia, Salvinia molesta, exotic

30. Watershed ManagementWhy weeds? excess fertility • Livestock waste • Fertilizer runoff • Waterfowl

31. Water Plant Controlhttp://www.ext.vt.edu/pubs/fisheries/420-251/420-251.html • Watershed management • Physical • Biological • Chemical • Water dyes • Barley straw

32. Aquatic plants can be divided into (1) algae and, (2) rooted water plants. Algae are primitive, simple plants which lack true roots, leaves, or flowers and reproduce by spores, cell division, and fragmentation. They range in form from unicellular (single cells), through colonial and filamentous types, to advanced forms which resemble the higher aquatic plants. Some are microscopic, but impart green color to the water, others are visible as surface films or bottom dwelling forms which are often confused with higher aquatic plants.

33. High Diversity of Aquatic Plant Species Pondweeds, Potamogeton spp.

35. Algae or Vascular Plant? Chara Algae

36. Why water weeds?Excess fertility! • Livestock waste • Crop fertilizer • Ducks & geese • Shallow water • Clear water • Bank slope • Exotic weeds

37. Physical controls • Water diversion • Dilution • Dredging • Deepening • Water level manipulation • Bottom sediment covering • Light elimination • Harvesting

38. Barley Straw? • The rate is 2-50 grams/square meter • 1 acre pond = 4046 m2 of water • Therefore, treatment of 1 acre pond at the lowest recommended dose, 2 grams would require 8092 grams or 17.8 pounds of straw. • Source: Aquatic Ecosystems 1-877-347-4788. They charge $55.00 for 11 pounds of barley straw. • Minimum treatment for 1-acre pond costs $110/acre.

39. Herbicide Selection • Copper compounds • algae • Flouridone (sonar) • Submersed & floating • Glyphosate (rodeo) • emergent • 2-4D • submersed • Diquat • algae & submersed