This study quantified the uptake of five antibiotics (chlortetracycline, monensin, sulfamethazine, tylosin, and virginiamycin) by 11 vegetable crops in two different soils that were fertilized with raw versus composted turkey and hog manures or inorganic fertilizer. Almost all vegetables showed some uptake of antibiotics from manure treatments. However, statistical testing showed that except for a few isolated treatments the concentrations of all antibiotics in vegetable tissues were generally less than the limits of quantification. Further testing of the significant treatments showed that antibiotic concentrations in vegetables from many of these treatments were not significantly different than the corresponding concentrations from the fertilizer treatment (matrix effect). All five antibiotic concentrations in the studied vegetables were <10 μg kg(-1). On the basis of the standards for maximum residue levels in animal tissues and suggested maximum daily intake based on body weight, this concentration would not pose any health risk unless one is allergic to that particular antibiotic.

Glucosinolates are a class of nitrogen (N) and sulfur (S) containing compounds shown to have cancer-preventing properties in animal models and widely found in cruciferous plants. The overall objective of this study was to determine whether N and S fertility affects glucosinolate concentrations in cabbage (Brassica oleracea L. Capitata group). Field studies on a sandy soil low in available N and S were conducted over a 2-year period with both green (`Grand Slam') and red (`Vorox') cabbage cultivars. Treatments evaluated each year were the interactive effects of N (125 and 250 kg·ha–1) and S (0, and 110 kg·ha–1) fertilizer application. Yield of both cabbage cultivars increased with increasing N and S in the second year of the study, but not in the first. Tissue N concentrations in heads at harvest increased with N application and tissue S concentrations increased with S application. When S was not applied, tissue S decreased significantly as N rate increased, while N rate had no effect on tissue S concentrations when S was applied. The dominant glucosinolate detected in both cabbage cultivars was glucobrassicin, with indole forms accounting for about 80% of the total glucosinolates regardless of treatment. Tissue N was negatively correlated and tissue S and S to N ratio were positively correlated with total glucosinolate concentration, although all correlations were generally weak (r2 < 0.5). Total glucosinolates and glucobrassicin concentrations were maximized in both cultivars at the low N and high S application rates. Except for sinigrin in one of the 2 years, all glucosinolates detected were higher in Vorox than in `Grand Slam'. Based on these results, glucosinolates in cabbage can be manipulated by cultural management practices as well as genetics.

Field studies were conducted in Michigan, Minnesota, and Wisconsin to explore interactions among DPX-V9360 herbicide applied postemergence, terbufos insecticide applied as an in-furrow treatment, and the environment. Field corn (‘Pioneer 3751’) and sweet corn (‘Jubilee’) were planted with and without an in-furrow application of terbufos. DPX-V9360 was applied postemergence when the corn was in the 4- to 6-leaf stage at 0, 35, 70, 140, and 280 g ai ha-1with nonionic surfactant and 28% N fertilizer solution. Crop response to DPX-V9360 was similar at all three locations, varying only in magnitude of injury. Crop injury was greater with Jubilee sweet corn than with Pioneer 3751 field corn. Injury to both hybrids increased as DPX-V9360 application rate increased. Application of terbufos increased injury from DPX-V9360 to both hybrids. Significant yield reduction did not occur with either hybrid when DPX-V9360 was applied at rates of 140 g ha-1or less and no terbufos was applied.

Lee W. Wattenberg, who spent his entire career at the University of Minnesota, was a true pioneer in the field of chemoprevention. This paper is a tribute to his groundbreaking research which uncovered the cancer prevention properties of many dietary compounds, including those discussed here in some detail-indole-3-carbinol and diindolylmethane. These compounds occur as glucosinolate conjugates in cruciferous vegetables and are released when one chews or otherwise macerates the vegetable. They have numerous beneficial effects including the ability to prevent cancer in laboratory animals treated with carcinogens. We review some of the early work on indole-3-carbinol and diindolylmethane which spurred subsequent studies on their efficacy and molecular mechanisms of prevention. We also present unique data on field conditions that affect levels of their glucosinolate precursors in vegetables and on the release of diindolylmethane in people who consume cruciferous vegetables.