N.C. STATE UNIVERSITY

College of Agriculture and Life Sciences
N.C. Agricultural Research Service
N.C. Cooperative Extension Service


Integrated Management of Aquatic Weeds

Prepared by: Stratford H. Ray


Published by: North Carolina Cooperative Extension Service

Publication Number:

Last Electronic Revision: January 1997 (MSD)


Long-term Objectives

1. To develop more cost-effective and environmentally acceptable methods for weed management in aquatic systems.

2. To reduce the use of herbicides and demonstrate acceptable alternatives to herbicides for weed management in aquatic systems.

3. To reduce the impacts of aquatic herbicides on nontarget organisms.


Short-term Objectives

1. To examine short-term summer drawdown for monoecious hydrilla control.

2. To use the phenology of aquatic weeds to optimize timing of herbicide applications for maximum efficacy and to reduce the application rate.

3. To demonstrate biological control and mechanical removal as viable management options for aquatic weeds in ponds and lakes.


Accomplishments

1. Mesocoam studies indicated that a short-term summer drawdown of 2 weeks or longer may be effective for control of monoecious hydrilla.

2. Phenological studies on monoecious hydrilla at Lake Gaston indicated a window for herbicide application in mid-June through early July.

3. Cutting with a boat-mounted weed mower appeared to be practical on certain weeds, such as American lotus.

Short-term summer drawdown may be a viable alternative for managing monoecioua hydrilla and other submerged weeds in large, multi-user lake systems without large-scale herbicide applications. Research suggests that its impacts are primarily on submersed weeds and should be minimal on emergent and floatingleaf vegetation. Phenological studies on monoecioua hydrilla are being used by state agencies in planning a long-term management program for hydrilla and other aquatic weeds at Lake Gaston. Mowing of American lotus appears to be an effective alternative to herbicide spraying both for weed control and to open boat lanes for fishing access. These projects will reduce herbicide applications while maintaining aquatic vegetation at levels more acceptable to the public.


Future Plans

1. Field test short-term summer drawdown for efficacy on hydrilla in a moderately large impoundment having rapid recharge (may be proposed for implementation at Roanoake Rapids Lake in 1996).

2. Refine mowing studies to determine the best timing and frequency required for maximum efficacy and determine the practicality for its use on other species of noxious aquatic weeds.

3. Continue phenology studies on monoecious hydrilla and expand to include other noxious aquatic weeds.


Published by: North Carolina Cooperative Extension Service

Publication Number:

Last Electronic Revision: January 1997 (MSD)