Aquatic Weed Management Charlotte Glen Sam Groce Horticulture Agent, County Extension Director, NC Cooperative Extension, Chatham County Center Tonight’s Class: • What makes a plant a weed • Identifying aquatic weeds • Aquatic weed control techniques • Using aquatic herbicides Aquatic Plants • Adapted to grow in standing water or saturated soils • Good because they: – Stabilize shorelines – Absorb nutrients – improve water quality – Food source and habitat for pollinators & wildlife, especially ducks, fish – Plantings on banks deter Canadian Pickerelweed, geese Pontederia – Can be attractive cordata Can Be Bad When Out of Balance • Reduce habitat value, fish kills when out of balance • Increase rate of sedimentation • Impede water flow • Impede recreational activities • Aesthetics, appearance When Does a Plant Become a Weed? Weed Definitions: • Weed Science Society: – “Any plant that is objectionable or interferes with the activities or welfare of people” • A plant out of place Water Hyacinth, Eichhornia crassipes Water Hyacinth, Cape Carteret This Started With 1 Plant!!! Why Do Some Aquatic Plants Become Aquatic Weeds? • Reproduce and spread rapidly – Seed, fragments, roots • Large bodies of clear, shallow water – High nutrient levels, esp. Giant Salvinia – In nitrogen and phosphorus summer, can double its coverage every day! What About Native Plants? • Native Plants – occur naturally in a region without human interference • Can they be weeds? Yes – particularly in non-native conditions – Man-made ponds, Variable Leaf Watermilfoil, drainage canals Myriophyllum heterophyllum Most Aquatic Weeds That Cause Serious Problems Are Non-Native • Introduced from other regions or countries – No natural enemies to limit spread – Have a competitive advantage • Non-native plants that invade Both native and natural areas and displace non-native species of water primrose, native species are termed Ludwidgia, occur in invasive NC How Do Aquatic Plants Spread? • Human activities – Wildlife plantings, boating, fishing enhancement, aquarium dumping, water gardens, dredging • Animals – Wading birds, aquatic mammals • Water movement Hydrilla • Transport by wind and rain