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Smyth County, Virginia

Information provided for informational purposes only

Note: This information is provided for reference purposes only. Although the information provided here was accurate and current when first created, it is now outdated.

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Pesticide Table for Freshwater Mollusks | About Freshwater Mollusks
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Pesticide Table for Freshwater Mollusks

AZINPHOS-METHYL2
BENOMYL1
CAPTAN1
CARBARYL2
CARBOPHENOTHION2
CHLORPYRIFOS
Alfalfa, Peanuts
43
Apples
41
All Other Uses
2
DIAZINON2
DICOFOL2
DIMETHOATE2
ENDOSULFAN2
ETHION2
FENAMIPHOS2
FENSULFOTHION2
FENTHION
FLURIDONE20
FONOFOS2
MALATHION2
METHIDATHION2
MEVINPHOS2
NALED1
NITRAPYRIN1
PARATHION (ethyl)2
PENDIMETHALIN2
PHOSMET1
PYRETHRINS2
TERBUFOS2
TRICHLORFON2

*TAR = Threshold Application Rate (Pounds of Active Ingredient per acre per application )

CodeLimitations
1Do not apply this pesticide within 20 yards of the water's edge within the the shaded area for ground applications, nor within 100 yards for aerial applications.
20Do not apply directly to water within the shaded area.
41Do not apply this pesticide within 1/4 mile of the edge of water within the shaded area for ground applications , nor within 1/2 mile for aerial applications.
43Do not apply this pesticide within 100 yards of the edge of water within the shaded area for ground applications , nor within 1/4 mile for aerial applications.
199Do not apply this pesticide above the threshold application rate (TAR) indicated within 20 yards of the water's edge within the shaded area for ground applications nor within 100 yards for aerial applications.
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Freshwater mussel [Unionidae]

Freshwater mollusks found in this area include the Fine-rayed pigtoe, the Little-wing pearly mussel, and the Tan riffle shell. These mussels are in the family Unionidae, a family restricted to North America. A far larger percentage of this family are imperiled than any other taxonomic (species) group.

Freshwater mussels can live up to 50 years. In the parasitic larval stage of the mollusk lifecycle it is dependant on fish within its habitat for nutrients and mobility. However, only a few host fish are known. Mature mussels bury themselves in the riffles and shoals and feed by siphoning phytoplankton and other plant matter from the water. Reverse siphoning is used to expell undigestible particles from the shell. Silt in the water can kill mussels by clogging their feeding siphons.

Major factors affecting mussel populations are alterations in temperature, waterflow, and siltation caused by stream damming and channeling. Agricultural runoffs and industrial practices have also affected the mussel habitat by degrading water quality and causing siltation. Because mussels are filter feeders, the effects of pollution are intensified due to the large quantities of water drawn through their siphons in the feeding process. Another significant threat to this species is the widespread and rapid population growth of the introduced zebra mussel. The zebra mussel not only competes with native species, but also attatches to them, adding so much weight that the native species cannot open to feed. In the past, commerial harvests contributed to the decline of freshwater mussels but this industry has since been reduced.

Matthews, J.R. (ed.), The Official World Wildlife Fund Guide to Endangered Species, Beacham Publishing Inc, Washington, DC. Vol II, pp. 955-956.


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