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2832072 
Journal Article 
Influence of water temperature on the efficacy of diquat and endothall versus curlyleaf pondweed 
Netherland, MD; Skogerboe, JD; Owens, CS; Madsen, JD 
2000 
Yes 
Journal of Aquatic Plant Management
ISSN: 0146-6623 
38 
25-32 
WOS:000166874300004 
Studies were conducted in a greenhouse facility and a pond to determine the impact of water temperature on the efficacy of the contact herbicides diquat (6,7-dihydrodipyrido [1,2-alpha :2',1'-c] pyrazinediium ion) and endothall (7-oxabicyclo [2.2.1] heptane-2,3-dicarboxylic acid) for control of the exotic nuisance species curlyleaf pondweed (Potamogeton crispus L.) across a range of water temperatures. Although P. crispus is reported to be highly susceptible to contact herbicides, treatments are usually conducted late in the growing season after turion formation has occurred. These turions are the major source of reinfestation the following spring, and treatment strategies to prevent their production would require applications at water temperatures which are generally thought to inhibit herbicide efficacy. Herbicide treatments were applied to 50-L aquaria containing curlyleaf pondweed growing at water temperatures of 10, 12.5, 15, 20, and 25C. Both diquat and endothall efficacy was inhibited as water temperature decreased; however, treatments at all temperatures significantly reduced biomass and turion formation. Although treatments conducted at 25C were the most efficacious, waiting until the water warms to this temperature limits the potential for reducing turion production. Endothall treatment of small plots in a pond infested with curlyleaf pondweed demonstrated that a late March treatment (18C water) reduced turion densities by 86%, whereas a mid-May treatment (25C water) reduced turions by 40% compared to untreated plots. Based on results of this study, it is recommended that early spring and fall treatment strategies are rested to determine if curlyleaf pondweed can be more effectively managed on a long-term basis by reducing turion populations. 
Potamogeton crispus; herbicide; chemical control; Aquathol K (TM); Reward (TM)