Abstract
Abstract 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.
Core Ideas Mean Br − concentrations were less in nearly all crop materials from untreated compared to MeBr‐treated fields. There were greater Br − concentrations in vegetative compared to reproductive tissue in untreated and MeBr‐treated fields. Br − concentration in green alfalfa tissue decreased over the duration of the study. Third and fourth cutting green alfalfa tissue Br − concentration was less than baled alfalfa. Whole‐corn (vegetative + reproductive) Br − concentration was less than other whole plants in a MeBr‐treated field.