Annual and seasonal differences in pesticide mixtures within channelized agricultural headwater streams in central Ohio.

Highlights: [•] Information on pesticide mixtures within agricultural headwater streams is limited. [•] Pesticide mixtures were documented in channelized agricultural headwater streams in Ohio for 5 years. [•] Pesticide mixtures consisted mostly of herbicide or herbicide–fungicide mixtures. [•] Seasonal trends in pesticide mixtures differed annually. [•] Pesticide mixtures did not differ among watershed sizes ranging from 0.7 to 4.5km2. [Copyright &y& Elsevier]