|RODGERS, JR, JOHN|
Submitted to: Chemosphere
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/1/1999
Publication Date: N/A
Interpretive Summary: The effects of herbicides on aquatic plants are important because such plants are often accidentally exposed to herbicides by aerial drift or agricultural runoff. The common cattail is a plant commonly found in wetlands, as well as roadside and agricultural drainage ditches. Especially in areas of intensive agriculture, stands of cattails may be exposed to a variety of agricultural pesticides such as atrazine and paraquat dichloride. Currently, little is known about the effects of atrazine and paraquat dichloride on cattail seed germination and root and shoot growth. Algae or duckweed are commonly used as representative of all plant species in toxicity experiments. This type of testing does not take into account plants which are deemed "emergent" (i.e. plants like cattails which are rooted in the soil) which may react differently to pesticides. This research determined how sensitive cattail seedlings are to these two widely used herbicides, and it suggested that cattails should be used for toxicity testing. This research provides valuable information for agri-chemical companies, EPA, NRCS, and other state and federal agencies.
Technical Abstract: Aqueous 7-d germination and growth experiments were performed to compare responses of *Typha latifolia* to exposures of atrazine and paraquat dichloride. *T. latifolia* seed germination was < 50% in concentrations greater than or equal to 1.0 mg/L of paraquat dichloride. No observed effect concentration (NOEC) and lowest observed effect concentration (LOEC) for paraquat and root growth were 0.001 and 0.01 mg/L, respectively, while NOEC and LOEC for paraquat and shoot growth were 0.01 and 0.1 mg/L, respectively following 7-d exposures. Greater than 72% of seeds germinated in each concentration up to 30 mg/L atrazine. After 7-d exposure, NOEC and LOEC for atrazine and root growth were 0.1 and 1.0 mg/L, while atrazine and shoot growth NOEC and LOEC values were 15 and 30 mg/L, respectively. This research provides data concerning relative sensitivity of *T. latifolia* seedlings to the herbicides atrazine and paraquat, as well as the potential use of *T. latifolia* as a representative plant test species.