July 1, 1997
WET WEATHER YIELDS ABUNDANCE OF AQUATIC WEEDS
Writer: Kathleen Davis (409) 845-2872, [email protected]
Contact: Dr. Jim Davis, (409) 845-7473, [email protected]
COLLEGE STATION -- A cool, wet spring. A drenching summer thus far. It's a match made for aquatic plants that thrive in water.
"We're talking about a number of different aquatic plants," said Dr. Jim Davis, Texas Agricultural Extension Service fish specialist. "We have everything from algae to willow trees and water lilies."
Seed that may have laid dormant for years, and certainly through last year's drought, is exploding into a tangled mess of aquatic weeds over much of the state, Davis said. That could impact the usefulness of ponds for livestock and fish.
One such nuisance this year is the fresh water jellyfish which hasn't been seen much in Texas for a decade, the specialist said. It comes up on sticks and grows as big as basketballs, Davis said.
"They don't hurt anything, but people are not used to seeing them so they get alarmed," he said. "It doesn't hurt people or fish, so it's no problem really. But you pick them out of the water and it just looks like a big mass of jelly."
The freshwater jellyfish is similar to those found in oceans but it does not move and does not have stinging tenacles.
Almost anywhere there is a pond, unwanted plants are cropping up. Too many weeds in a pond can compete with fishing, use by livestock and aesthetic value and can start problems that continue for years unless managed.
Getting aquatic plants identified is the first step in management, Davis said.
"When you know exactly what the weed is, then you decide on how you're going to control it," he said. "And that doesn't mean it has to be chemical control."
Submersed plants, often called moss, can be controlled by triploid grass carp (which require a permit), for example, he noted. Algae can be controlled with permitted tilapia.
"That way a person doesn't have to worry about chemicals and whether or not it's right or safe to use," he said.
But control may also depend on the pond's usage and speed with which the weeds need to be controlled.
"I always tell people that if you want a quick cure, don't depend on an animal or fish to eat it quickly," Davis noted. "If you have to have it out by next week or the week after, chemical control is probably the only way it's going to happen."
Mechanical removal is not that easy either, he said, because that means raking weeds out of a pond manually and having to repeat that process -- especially as the weather stays wet -- numerous times in the season.
For removing plants that grow along the edges of ponds, Davis' recommendation is "40 goats to the acre.
"If you keep goats down there and that's all they have to eat, they'll clean it up," he said.
Davis said the best aquatic weed control method is prevention, and one of the best measures is to not let sunlight reach the bottom of the pond where seed lies in wait of the rays for germination.
Two ways to keep the bottom dark include keeping the pond well- fertilized to encourage phytoplantkon and making sure water levels don't drop below three feet.
"When a pond is originally constructed or if it has to be reworked, the owner should make sure to get the water three feet deep as quickly as possible," Davis said.
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