I. SUMMARY:  Aquatic weed control can be a difficult goal if the pond manager is not fully aware of the variables which affect the outcome of a control scenario.

II. PROBLEM:  It is often frustrating for pond managers to control weeds in their ponds due to unreasonable expectations or improper control methods. 

III. OBJECTIVES:  This demonstration was intended to demonstrate the effectiveness of an integrated approach to pond weed control.

IV. MATERIALS AND METHODS:  A variety of weeds were positively identified in this test pond.  Weed species in the pond consisted of some very common aquatic weeds.  Among the weed species noted were the following:  Filamentous algae, Chara (Muskgrass), Duckweed, Waterfern, Watermeal, Watermilfoil, Pondweed, Coontail, Waterprimrose, Watershield, & Cattail.

These weed species varied from Algae, floating weeds, submersed weeds and emersed weeds.  Each species will require a control specific to itself.  Some control options overlap (chemical, biological or mechanical) between species.  Improper control selection will not result in the desired weed control.

Category             Weed                                        Suggested Chemical Control Option (s)
Algae (s) -                Filamentous algae                    Copper Sulfate
                                   Chara                                        Copper Sulfate
Floating Weeds-      Duckweed                                Diquat or Glyphosate or Fluridone
                                   Waterfern                                 Diquat or Glyphosate
                                   Watermeal                                Diquat or Glyphosate
Submersed Weeds-  Coontail                                   Endothall or Fluridone
                                    Pondweed                                Endothall or Fluridone
                                    Watermilfoil                             Endothall or Fluridone
Emersed Weeds-      Cattails                                     Diquat or Glyphosate
                                   Waterprimrose                          Diquat or Glyphosate
                                   Watersheild                              Diquat or Glyphosate

Category   Weed   Suggested Biological Control Option (s)

Algae (s) -                 Filamentous algae                  Tilapia or Triploid Grass Carp   
                                    Chara                                       Tilapia or Triploid Grass Carp 
Floating Weeds-      Duckweed                                Triploid Grass Carp
                                   Waterfern                                 Triploid Grass Carp   
                                   Watermeal                                Triploid Grass Carp
Submersed Weeds-  Coontail                                   Triploid Grass Carp
                                    Pondweed                                Triploid Grass Carp       
                                    Watermilfoil                            Triploid Grass Carp
Emersed Weeds-      Cattails                                     (plants near the bank can be removed by goats 15 head per acre)
                                    Waterprimrose                         none
                                    Watersheild                              none

In addition to the chemical and biological controls, other options include mechanical control for some weed species.  These may include management methods such as deepening the edges of the pond, increasing the drop-off at the waters edge, fertilization management or physically removing the undesirable plants.   

V. RESULTS:   The chemical control options were not initiated due to the weather conditions experienced in 1998.  Extended dry weather and hot temperatures created a potential serious condition.  The potential for oxygen depletion problems prevented the application of these controls.  Late summer 1999 conditions were unsuitable for chemical treatment options on the size and scale required.

Triploid Grass Carp were stocked in late 1997.  30 Carp (10 - 14 inches) were stocked in the 10 acre pond.  They have been observed actively eating submerged weeds.  The overall effectiveness of the carp has been slight to date.  This is due to the large volume of weeds in the pond.

VI.   CONCLUSIONS:  Pond weed control is an ongoing management necessity.  Few potential  solutions provide one time only applications and quick results.  Shading the water with an approved aquacultural dye may provide additional relief from submersed plants.  The ongoing persistence of submersed weeds in this lake is due to the clarity of the water.  When selecting control options, the total needs and goals of the pond manager must be taken into account and set as the final objective. 

VII. ECONOMICS:  The economics of this demonstration have not been calculated at this time.

VIII. ACKNOWLEDGMENTS:   We would like to thank the Cooperator,  Mr. Ken Fletcher for allowing us to begin this demonstration at his pond.

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