Vol. 54—2000 - NorthEastern Weed Science Society

WETLAND NURSERIES AND WATER GARDEN TRADE SPREAD A FEDERAL
NOXIOUS AQUATIC WEED, Salvinia motesta
S. H. Kay and S. T. Hoyle'
ABSTRACT
Giant salvinia (Salvinia motesta D. S. Mitchell), a federal noxious weed, was found
in TX in a schoolyardpond in Houstonin May 1998 and in a farm pond in July. In
September,it was collectedin LA fromtheBayouTecheandfoundin the backwatersof
Toledo Bend Reservoir. In October, a technician with NC State University discovered it in
a water garden exhibit at the NC State Fair. By December, it had heen detected in the
lower reaches of the Sabine and Trinity Rivers in TX and had been found in several small
ponds, nurseries,gardencenters,andpersonalwatergardensinNC. Giantsalvinia was
identified in a pond in Auburn, AL, in January 1999, and in a canaIin Naples, FL, in
February. In April, it was seen in a pond and adjacent ditch in MS and in Enchanted Lake,
HI. InJune,the USDA-ARS releasedimportedweevils, Cyrtobagous salviniae, for giant
salvinia control at three locations in eastern TX. By July and August, new infestations had
been reported in TX, AZ, and CA, and the Auburn, AL, pond infestation was no longer
contained. CA reported giant salvinia for sale in 37 towns in 12 counties in July and that a
few plantswere found in a pondedarea of the SanDiego River. Gardencentersin all of
these states as well as OR, WA, VA, PA, and OK have been selling this weed as an
ornamental. Severalwetlandnurserieshave advertisedthis plantin theircatalogsand via
theirwebsites, andtherehavebeeninstanceswhereindividualsadvertisedthe plantson line
eitherforsaleortrade.
The escape andnaturalizationof giant salvinia in the Southand Southwest,its
widespread sale by nurseries and garden centers, and its easyavailability throughcatalogs
andon-linesourcespresenta seriousdilemmaforwater resourcesmanagementin the
southern United States. The presence of natuIa1ized populations in northern TX indicates
that giant salvinia hasthe potential to spread to areas which had heen presumed much too
cold forits survivalduringthe winter. Examinationof the weed's CUITeIltdistributionand
theplanthardinesszones andits successfuloverwinteringin watergardensin NC suggests
that it also could become established in some areas of coastaINew England and the Pacific
coast.
Regulationof salesof federalnoxiousweeds,includinggiantsalviniaandothers,
primarily hasheen left up to the departments of agriculture in each state, once the plants
havebecomeestablishedwithin thebordersof the UnitedStates. Inconsistencyof stateand
federal regulatory statutes and enforcement, combined with the unfamiliarity of regulatory
'Assoc. Prof. and Agric. Res. Tech., respectively, Dept. of Crop Science, NC State
University, Raleigh, NC 27695.
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