| Summary: | ABSTRACT. Because concerns have been expressed about the effects of irrigating truck-garden crops with water from a stream treated with the lampricide 3-trifluoromethyl-4-nitrophenol (TFM), I conducted studies on the effects of TFM on young plants of common vegetables and fruits. Plants established in horticultural flats were irrigated for 12 h with water containing 10 mg/L of TFM and later compared with plants irrigated for a similar period with untreated water. Lettuce, radish, sweet corn, and potato plants were virtually unaffected. Green bean and tomato plants developed brown or dead spots on many leaves but growth rates and survival were not affected. Cucumber and cantaloupe plants were severely damaged; some were killed and about 40% of the leaves on surviving plants were dead or dying. Two weeks after treatment, the mean weight of surviving treated cantaloupe plants was significantly less than that of control plants. The parasitic sea lamprey (Petromyzon marinus) is controlled in the Great Lakes by treating more than 400 nursery streams with the lampricide 3-trifluoromethyl-4-nitrophenol (TFM) to kill the larvae. Some of these tributaries flow through agricultural land, where the stream water is used to irrigate truck-garden crops. Farmers have been reluctant to forego irrigation while a stream is being treated, without evidence that TFM would damage their crop. Lack of irrigation for even 1 day reportedly can affect crop growth, delay marketing, and prevent a farmer from getting full market price for a product. To date, sea lamprey control agencies have had no specific information to give to farmers about potential damage to their crops from using TFM-treated irrigation water. It is known that TFM has adverse effects on aquatic plants ranging from reduced production after exposure to 10 mg/L for 1 h to plants becoming limp and cyanotic after exposure to 20 mg/L for 3 h (National Research Council of Canada 1985). No studies of the effects of TFM on terrestrial plants have been published. In response to ...
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