Tioxazafen is a seed-applied nematicide used in row crops. Currently, there are no data on nematode toxicity, nematode recovery, or effects of low concentrations of tioxazafen on nematode infection of a host root for Meloidogyne incognita or Rotylenchulus reniformis. Nematode toxicity and recovery experiments were conducted in water solutions of tioxazafen, while root infection assays were conducted on tomato. Nematode paralysis was observed after 24 hr of exposure at 27.0 µg/ml tioxazafen for both the nematode species. Based on an assay of nematode motility, 24-hr EC50 values of 57.69 µg/ml and 59.64 µg/ml tioxazafen were calculated for M. incognita and R. reniformis, respectively. Tioxazafen rates of 2.7 µg/ml and 27.0 µg/ml reduced the nematode hatch after 3 d of exposure for both the nematode species. There was no recovery in nematode motility after the 24-hr exposure of M. incognita and R. reniformis to their corresponding 48-hr EC50 values of 47.15 µg/ml and 47.25 µg/ml tioxazafen, respectively. Mortality of M. incognita continued to increase after 24 hr exposure, whereas R. reniformis mortality remain unchanged after nematodes were rinsed and removed for 48 hr from the tioxazafen solution. A 24-hr exposure to low concentrations of 0.38 to 47.15 µg/ml for M. incognita and 47.25 µg/ml for R. reniformis reduced the infectivity of each nematode species on tomato roots. The toxicity of tioxazafen was similar between nematode species; however, a greater rate of tioxazafen was needed to suppress R. reniformis infection of tomato than for M. incognita.

The movement of seed-and soil-applied fluopyram was evaluated in soil columns. The nematicide was sampled at three soil depths and used in a nematode motility bioassay. Based on Meloidogyne incognita mortality, the downward movement of soil-applied fluopyram was affected by soil type and application method. No nematode-toxic levels of soil-applied fluopyram were detected past 5 cm depth in sandy loam soil compared to 10 cm depth in sandy soil. A slower rate of water infiltration had little impact on the movement of soilapplied fluopyram in sandy soil, but did affect the movement of soilapplied abamectin. In the seed-applied nematicide experiments, a greater effect on nematode mortality was observed at the 0 to 5 cm depth in sandy soil with fluopyram-than abamectin-treated cotton seed, whereas a similar effect was observed with soybean seed. No effect on nematode motility was observed with other seed-applied nematicides, thiodicarb, and Bacillus firmus. Overall, soil-applied fluopyram had a greater effect on M. incognita mortality at 10 cm depth in sandy soil than seed-applied fluopyram. These data provide a better understanding as to the movement of fluopyram as affected by soil type, water infiltration rates, and application methods.

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The Cambridge Quarterly has a history of presenting multidisciplinary perspectives in bioethics, welcoming a lively dialogue between clinicians, philosophers, theologians, social scientists, lawyers, and others on a range of bioethics concerns. This special issue of the journal focuses explicitly on contributions from anthropologists to the field.

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