In temperate climates, corn (Zea mays L.) is often harvested too late for sufficient cover crop growth to meet grower objectives. This study was conducted to evaluate intersowing into standing corn in terms of cover crop establishment and growth and the impact on corn yield. Three experiments were conducted from 2009 to 2011 in southwestern Ontario sweet and hybrid seed corn production systems to assess timing of cover crop intersowing, utility of alfalfa (Medicago sativa L.) and 17 other cover crops species or multispecies mixes. In all 22 locations over 3 yr, corn yield was not affected in any of the three cover crop experiments. Sweet corn cover crop treatments exhibited poor stands of limited growth (<1% ground coverage) at corn harvest, attributed to sweet corn canopy closure. At seed corn harvest, early‐sown (corn V4–V6) cover crops accumulated 1116 kg ha−1 dry biomass and 42.4 kg N ha−1, which were 33% greater than the late‐sown (V10–V12) treatments. A lack of a cover crop effect compared with the no‐cover‐crop treatment in soil mineral N and corn yield indicates little N competition. Hairy vetch (Vicia villosa Roth), oilseed radish (OSR, Raphanus sativus L. var. oleoferus Stokes) and three of six cover crop blends were the only treatments to accumulate dry biomass over 1000 kg ha−1 by corn harvest. Of the cover crops evaluated, interseeding into hybrid seed corn production systems appears to be of little risk to yield and can provide ground cover during postharvest fallow periods.

Much of cover crop research to date focuses on key indicators of impact without considering the implications over multiple years, in the absence of a systems-based approach. To evaluate the effect of three years of autumn cover crops on subsequent processing tomato (Solanum lycopersicum L.) production in 2010 and 2011, a field split-split-plot factorial design trial with effects of cover crop type, urea ammonium nitrate fertilizer rate (0 or 140 kg N ha -1 preplant broadcast incorporated) and tomato cultivar (early vs. late) was conducted. The main plot factor, cover crop, included a no cover crop control, oat (Avena sativa L.), winter cereal rye (hereafter referred to as rye) (Secale cereale L.), oilseed radish (OSR) (Raphanus sativus L. var. oleiferus Metzg Stokes), and mix of OSR and rye (OSR + rye) treatments. Cover crop biomass of 0.5 to 2.8 and 1.7 to 3.1 Mg ha -1 was attained in early Oct. and the following early May, respectively. In general, OSR increased soil mineral N during cover crop growth and into the succeeding summer tomato growing season, while the remaining cover crops did not differ from the no cover crop control. The lack of a cover crop by N rate interaction in soil and plant N analyses at harvest suggests that growers may not need to modify N fertilizer rates to tomatoes based on cover crop type. Processing tomato fruit quality at harvest (rots, insect or disease damage, Agtron colour, pH, or natural tomato soluble solids (NTSS)) was not affected by cover crop type. In both years, marketable yield in the no cover crop treatment was lower or not statistically different than all planted cover crops. Partial profit margins over both years were 1320 $ ha -1 higher with OSR and $960 higher with oat compared to the no cover crop control. Thus, results from a systems-based approach suggest that the cover crops tested had no observed negative impact on processing tomato production and have the potential to increase marketable yield and profit margins.

Glyphosate-resistant (GR) giant ragweed has recently been identified in southwestern Ontario and has the potential to be a significant problem for regional corn producers. Eight field trials [four with preplant (PP) and four with postemergence (POST) herbicides] were conducted from 2013 to 2014 on various Ontario farms infested with GR giant ragweed to determine the efficacy of PP and POST tank-mixes in corn. Glyphosate tank-mixed with atrazine, dicamba, dicamba/atrazine, mesotrione plus atrazine, flumetsulam, isoxaflutole plus atrazine, saflufenacil/dimethenamid-P, Smetolachlor/atrazine and rimsulfuron applied PP provided up to 54%, 95%, 93%, 95%, 40%, 89%, 91%, 50% and 93% control of GR giant ragweed and reduced dry weight 69%, 100%, 99%, 100%, 30%, 92%, 98%, 66% and 99%, respectively. POST application of glyphosate alone and tankmixed with 2,4-D ester, atrazine, dicamba, dicamba/diflufenzopyr, dicamba/atrazine, bromoxynil plus atrazine, prosulfuron plus dicamba, mesotrione plus atrazine, topramezone plus atrazine, tembotrione/thiencarbazone-methyl and glufosinate provided up to 31%, 84%, 39%, 94%, 89%, 86%, 83%, 78%, 72%, 43%, 63% and 58% GR giant ragweed and reduced dry weight 55%, 99%, 72%, 99%, 99%, 98%, 96%, 96%, 93%, 89%, 91% and 95%, respectively. In general, PP control of GR giant ragweed was greater than POST applied herbicides evaluated. Based on these results, glyphosate tank-mixes containing dicamba or mesotrione plus atrazine applied PP, and dicamba applied POST will provide the most consistent control of GR giant ragweed in corn.

Proactive aggression (PA) is a planned and unprovoked form of aggression that is most often enacted for personal gain or in anticipation of a reward. Frequently described as “cold-blooded” or goal oriented, PA is thought to be associated with low autonomic arousal. With this view in mind, we performed a scoping review of the biological correlates of PA and identified 74 relevant articles. Physiological findings indicated a robust association between PA and reduced resting heart rate, and to a lesser extent a relationship between PA and decreased heart rate and skin conductance reactivity, perhaps indicating dampened sympathetic function. The twin literature identified PA as a heritable trait, but little evidence implicates specific genes in the pathogenesis of PA. Neuroimaging studies of PA pinpoint impaired amygdala function in the assessment and conditioning of aversive stimuli, which may influence the establishment of behavioral patterns. Nodes of the default mode network were identified as possible neural correlates of PA, suggesting that altered function of this network may be involved in the genesis of PA. Given the overlap of PA with reactive aggression and the overall behavioral complexity of PA, it is clear that multiple endophenotypes of PA exist. This comprehensive review surveys the most salient neurobiologically informed research on PA.

Field experiments were conducted from 2011 to 2013 near Ridgetown and Exeter, Ontario, Canada to evaluate the tolerance of seven identity-preserved (IP) soybean cultivars to protoporphyrinogen oxidase (PPO)-inhibiting herbicides flumioxazin, saflufenacil/dimethenamid-P, and sulfentrazone applied PRE; fomesafen applied POST; as well as PRE followed by (fb) POST application. Ridgetown sites demonstrated excellent tolerance (< 10% injury) to PRE treatments, whereas PRE sulfentrazone caused up to 36% injury at 1 and 2 wk after application (WAA) at Exeter. Of the PRE fb POST treatments evaluated, those containing saflufenacil/dimethenamid-P and sulfentrazone were most injurious to soybean, with cultivar being a further determinant of injury. At Exeter 1 WAA, cultivars ‘S03W4’ and ‘S23T5’ showed 23 to 27 and 45 to 46% injury for saflufenacil/dimethenamid-P and sulfentrazone when followed by POST fomesafen, respectively. Sulfentrazone application (PRE alone or fb fomesafen) consequently reduced S03W4 yield up to 38% and S23T5 up to 25%, whereas saflufenacil/dimethenamid-P fb fomesafen reduced S03W4 by 18%. In general, PRE fb POST caused more injury than PRE treatments; however, injury diminished over time and no significant reduction to soybean yield could be attributed to adding POST fomesafen. On the basis of this study, the injury from PPO herbicides applied PRE is active ingredient, cultivar, and environment specific. Although PPO herbicides have the potential to cause unacceptable crop injury in some IP soybean cultivars, selecting a tolerant cultivar will minimize yield losses.