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A biotype of false cleavers ('Galium spurium' L.) was previously reported to express resistance to the ALS-inhibitor families of herbicides, the sulfonylureas and imidazolinones and the auxinic herbicide quinclorac (Hall et al. 1998). Based on comparisons of mortality and shoot dry weight between the resistant (R) and susceptible (S) biotypes, both R and S false cleavers were susceptible to glyphosate, glufosinate and bentazon, and tolerant to the auxinic herbicides 2,4-D and clopyralid. Only the R biotype was highly resistant to the ALS-inhibitor, thifensulfuron-methyl, and quinolinecarboxylic acids, moderately resistant to MCPA, and slightly resistant to the auxinic herbicides dicamba, picloram, fluroxypyr, and triclopyr. Classical Mendelian inheritance analysis indicates that quinclorac resistance is a single, recessive nuclear trait with a F2 1:3 (R:S) segregation ratio and ALS-inhibitor resistance is due to a single, dominant nuclear allele with a 3:1 segregation ratio (R:S) in the F2 generation. These resistances to quinclorac and ALS-inhibitor herbicides in false cleavers were conferred by two, unlinked genes. The mechanism of quinclorac resistance is not due to altered [ 14C]quinclorac absorption, translocation, root exudation or metabolism. Both biotypes were equally responsive to exogenously applied ethylene at the etiolated seedling and at the 2-whorl stages of development. However, after treatment with quinclorac, the endogenous levels of the phytohormones ethylene and abscisic acid increased in quinclorac-treated S plants, but not in quinclorac-treated R plants and non-treated R and S plants. In quinclorac-treated S plants, ethylene and abscisic acid biosynthesis increased 3-fold and 14-fold, respectively, when compared to non-treated plants. Increases in these phytohormones correlated positively with quinclorac-induced phytotoxicity. Based on these results, it is hypothesized that the mechanism of quinclorac resistance is due to an altered target-site, which reduces herbicide binding and/or an alteration in the auxin signal transducation pathway.

The fate and persistence of ethametsulfuron-methyl (methyl 2-(((((4-ethoxy-6-(methylamino)-1,3,5-triazine-2-yl) amino) carbonyl) amino) sulfonyl) benzoic acid) was investigated to provide data for its Canadian registration for use on rutabaga (Brassica napobrassica Mill.) crops for the control of wild mustard (B. kaber (DC) L. C. Wheeler). Absorption and translocation of ethametsulfuron-methyl in rutabaga did not change for the duration of the study (50 DAT). Less than 4% of recovered ($\sp{14}$C) ethametsulfuron-methyl was present in the rutabaga root. Ethametsulfuron-methyl was metabolized through a proposed -OCH$\sb2$CH$\sb2$-OH unstable intermediate that dissipated after 3 DAT to two major metabolites as determined by mass spectrometry, O-desethyl ethametsulfuron-methyl and N-desmethyl-O-desethyl ethametsulfuron-methyl. It was estimated that at a spray dose of 30 g ai ha$\sp{-1}$ and a harvest weight of 0.5 kg, the edible portion of the rutabaga root would contain no ethametsulfuron-methyl and approximately 1.3 ppb total of both identified metabolites. Based on residue analysis and toxicological data, it is reasonable to expect that the registration of ethametsulfuron-methyl for use on rutabaga crops will be approved. In other experiments, attempts to use known chemical inhibitors of cytochrome P450 as evidence for the involvement of cytochrome P450 in the metabolism of ethametsulfuron-methyl in rutabaga was inconclusive.

The effects of cover crop type, planting date (early-August and early-September) and cereal rye ('Secale cereale' L.) spring biomass removal in a cucumber ('Cucumis sativus' L.)-cover crop-cucumber rotation on N dynamics were investigated from 2008-2010. Relative to no cover crop (NoCC), cover crops of rye, oats ('Avena sativa' L.), oilseed radish (OSR) ('Raphanus raphanistrum' [L.] var. ' oleiferus' Metzg Stokes) and forage peas ('Pisum sativum' L.) consistently increased plant available N (PAN) during the cover crop growing season, while hairy vetch ('Vicia villosa' L.) had no effect. Differences among planting dates during the fall did not translate into differences in PAN during the cucumber season. Higher PAN in the NoCC+84 kg N ha -1 did not result in higher cucumber marketable yield income compared to OSR and pea in 2009 and all treatments in 2010. Leachate samples in lysimeters were sporadic but generally supported cover crop N dynamics observed over the rotation.

The effect of cover crops on N and weed dynamics was assessed within a pea ('Pisum sativum' L.) - cover crop - sweet corn (' Zea mays' L.) rotation. Cover crops of oat ('Avena sativa' L.), perennial rye (rye) ('Secale cereale' L.), oilseed radish (OSR) ('Raphanus sativus' L. var. oleoferus Metzg Stokes), and OSR plus perennial rye (OSR+rye) increased plant available N (PAN) over the cover crop growing season compared to the no cover control at the Bothwell site only. However, at neither site did cover crops result in increased PAN for the sweet corn, indicating that these cover crops will not reduce required N fertilizer applications. Also, cover crops posed neither an increased or decreased need for weed management during sweet corn production. However, OSR may be useful in pesticide reduced programs due to its potential ability to reduce fall herbicide applications, provided it does not set viable seed.