Technical Report No. 13

EFFECTIVENESS OF A WIPER APPLICATION OF GLYPHOSATE ON SPARTINA ALTERNIFLORA IN PADILLA BAY, WASHINGTON

Sharon R. Riggs and Douglas A. Bulthuis

August 1995

Bibliographic Citation
Riggs, Sharon R. and Douglas A. Bulthuis. 1995. Effectiveness of a wiper application of glyphosate on Spartina alterniflora in Padilla Bay, Washington. Washington State Department of Ecology (Publication No. 95-69), Padilla Bay National Estuarine Research Reserve, Technical Report No. 13, Mount Vernon, Washington. 20 pp.

Abstract
The herbicide glyphosate (Rodeo®, 33% solution) with adjuvant (LI-700® at 5%) was applied with hand held wipers to Spartina alterniflora Loisel in Padilla Bay, Washington, in September, 1994. Treated plots appeared yellower than control plots one month after treatment. Seven months after treatment (April, 1995) there was no significant difference in density of live S. alterniflora shoots between treatment and control plots at either an exposed site nor at a sheltered site on Dike Island. The lack of effectiveness of hand held wiper applications of glyphosate may have been due to wetness of the leaf surface, sediment on the leaf surface, the time of year relative to flowering of S. alterniflora, or the concentration or type of adjuvant mixed with the glyphosate.