The search for exudates from Eurasian watermilfoil and hydrilla

Secondary metabolites are produced by aquatic plants, and in some instances, exudation of these metabolites into the surrounding water has been detected. To determine whether infestations of Eurasian watermilfoil or hydrilla produce such exudates, plant tissues and water samples were collected from laboratory cultures and pond populations and were analyzed using solid phase extraction, HPLC, and various methods of mass spectrometry including electrospray ionization, GC/MS, electron impact and chemical ionization. Previously reported compounds such as tellimagrandin II (from Eurasian watermilfoil) and a caffeic acid ester (from hvdrilla), along with a newly discovered flavonoid, cyanidin 3 dimalonyl glucoside (from hydrilla), were readily detected in plant tissues used in this research but were not detected in any of the water samples. If compounds are being released, as suggested by researchers using axenic cultures, we hypothesize that they may be rapidly degraded by bacteria and therefore undetectable

Clearigate ® Treatments for Control of Giant Salvinia

Results of recent field trials using the chelated copper formulation Clearigate® 4 showed that applying a 20% solution by volume was effective for controlling populations of giant salvinia in irrigation canals. 5 Lower rates may be efficacious, thereby reducing chemical use and cost; however, little is known about the dose-response effects of Clearigate® against giant salvinia. The objective of this study was to determine the effective rate range of chelated copper applied as Clearigate® for control of giant salvinia

Plant Manage

ABSTRACT The contact aquatic herbicide, diquat (6,7-dihydrodipyrido[1,2-α :2',1'-c]pyrazinediium ion) was evaluated under simulated flowing water conditions in an outdoor mesocosm facility for efficacy on five submersed aquatic plants: hydrilla ( Hydrilla verticillata (L.f. Royle), Eurasian watermilfoil ( Myriophyllum spicatum L.), sago pondweed ( Stuckenia pectinata (L.) Boerner) , American pondweed ( Potamogeton nodosus Poiret) , and egeria ( Egeria densa Planchon). Diquat was applied at concentrations of 0.37 mg/L ai and 0.185 mg/L ai (cation) under flow-through conditions to provide theoretical 3 and 6 hr herbicide half-lives that produced observed herbicide half-lives of 2.5 and 4.5 hr, respectively. An additional treatment included 0.37 mg/L ai applied under static conditions (no water exchange). Results showed that diquat applications significantly inhibited shoot biomass production from 42 to 100 percent at all application concentrations and exposure times for all species, except hydrilla. Diquat resulted in no measurable control of hydrilla, except under static conditions. Results suggest that Eurasian watermilfoil, egeria, and sago pondweed are highly susceptible to diquat even in areas where herbicide dilution may occur in less than three hours