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Plant Identification -- Submerged Weeds -- Hydrilla |
HYDRILLA (Hydrilla verticillata)
Common name: Florida Elodea
Treatment Tips: Care should be taken to remove weed fragments from equipment, boats and trailers since infestation of new areas can occur by human transportation.
Description: Stem is long and branched with oppositely arranged leaves at the bottom and whorls of 3 leaves on the upper portion of the plant. Leaf is oval-shaped with margins toothed. There are pointed spines on the mid-rib of the underside of the leaf. Plant fragments are capable of reproduction.
Distribution: California, Arizona, Gulf states and southeastern states north to Washington, D.C.
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Recommended Control Method: Tank mix 3 1/3 gallons of Cutrine-Plus with 2 gallons of Reward and inject below the surface. For soft water, reduce Cutrine-Plus to 2 gallons. Above recommendations will treat 1 acre.
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Apply Clearigate at the rate of 3.6 to 8.7 gallons per acre-foot for Hydrilla or 5.4 to 8.7 gallons per acre-foot for Brazilian Elodea.
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Apply Cutrine-Plus at the rate of 1.2 to 3.0 gallons per acre-foot in areas where water use restrictions are prohibitive.
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Tank mix 5 parts Aquathol K to 3 parts Cutrine-Plus and apply at the rate of 2 gallons per acre-foot.
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Maintenance Control Method: Add Aquashade at the rate of 1 quart per acre-foot of water to prevent initial growth or to retard regrowth of plants after chemical treatment.
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Alternate Control Methods: Fluridone (various liquid and pelletized formulations): (see label).
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Introduced by the aquarium trade, the spread of Hydrilla has been rapid since the early 1960's. Once thought to be limited to subtropical areas, recent infestations have occurred within temperate areas. Reproduction by turions (winter buds), tubers and fragmentation have made this plant quite competitive. It can thrive under a wide variety of environmental conditions within flowing, stagnant, fresh and tidal water areas. It is tolerant of low light intensities and a wide pH range. Hydrilla has been known to grow to depths of 50 feet (15m) and in bio-mass densities over 130 tons (wet plant material) per acre.
These plants can severely restrict navigation, water flow and fishing. They are of little value to wildlife or fisheries. Dense growths will often cause severe stunting in bass and panfish populations.
Some states have taken the initiative to restrict the importation and transportation of this plant. Arizona and California require that it be eradicated wherever it is found.
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| Descriptions and pictures are from the book "How to Identify and Control Water Weeds and Algae", Edited by James C. Schmidt, 5th edition revised 1998, copyright 1976 Applied Biochemists. |
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