Crop bromide concentrations following methyl bromide fumigation for pale cyst nematode in southeastern Idaho

Methyl bromide (MeBr) is a sterilizing fumigant used to control quarantine pests that is restricted due to its detrimental atmospheric effects. The degradation of injected MeBr produces crop-available Br^- . Up to five applications of MeBr were used in southeastern Idaho fields to combat the pale cyst nematode (Globodera pallida). Data regarding the uptake and partitioning of Br^- in crops following MeBr application in the region were unavailable. Research determined background concentrations of Br^- in alfalfa (Medicago sativa L.), barley (Hordeum vulgare L.), corn (Zea mays L.), potato (Solanum tuberosum L.), and wheat (Triticum aestivum L.) compared to MeBr-treated fields. Background Br^- concentrations ranged from nondetectable (ND) to 33.0 mg Br^- kg^-1 ; vegetative tissue concentrations were greater than reproductive, except corn where there was no difference. Nearly all crops grown in MeBr-treated fields had greater Br^- concentrations than background. Background-baled-alfalfa tissue Br^- concentration was 33.0 mg kg^-1 compared to 117.8 mg Br^- kg^-1 from a MeBr-treated field. Br^- concentration in green alfalfa decreased from 79.8 to 36.5 mg Br^- kg^-1 at the final cutting in a MeBr-treated field, where time after application decreased crop Br^- concentrations. Small grains had low Br^- concentrations in reproductive tissue (1.7 mg Br^- kg^-1 ) compared to vegetative tissue (106.5 mg Br^- kg^-1 ). Corn stover concentration (12.7 mg Br^- kg^-1 ) was low relative to small-grain straw, but corn ear (5.8 mg Br^- kg^-1 ) was greater than small-grain reproductive tissue in the MeBr-treated field. Crop selection following MeBr applications should consider the likelihood of elevated Br^- concentration for the plant fractions intended end use.