Core Ideas Cover crops were successfully established in corn with a drill interseeder.Cover crop biomass production varied notably across the mid‐Atlantic region.Spring cover crop biomass was often proportional to fall cover crop performance.Interseeding cover crops at corn growth stages V2–V3 decreased corn grain yields.Interseeding cover crops at or after corn V4 did not affect corn grain yield. Cover crop adoption remains low in the mid‐Atlantic United States despite potential conservation and production benefits. The short growing season window after corn (Zea mays L.) is a primary limiting factor. A high‐clearance grain drill was recently developed to allow for cover crop interseeding into standing cash crops. Experiment 1 tested the viability of drill interseeding cover crops into corn at the V5 growth stage across multiple locations. Experiment 2 tested interseeding timing (V2–V6 corn growth stage) on corn yield in Pennsylvania. At 16 locations throughout Maryland, Pennsylvania, and New York, we evaluated cover crop fall and spring biomass and the effect on corn yield. Cover crop treatments included annual ryegrass [Lolium perenne L. ssp. multiflorum (Lam.) Husnot]), a mixture of legume species, and an annual ryegrass–legume mixture. Each cover crop treatment successfully established across locations yet was highly variable. Across locations, annual ryegrass–legume mixture produced the highest mean aboveground biomass in fall and spring. Spring biomass of interseeded cover crops generally increased compared with fall biomass. Interseeded cover crops did not affect grain yields of the host corn crop during the year of establishment across locations. Experiment 2 indicated that cover crops interseeded before the V3 growth stage reduced corn grain yields. We recommend interseeding at or after V4 to prevent competition with corn. Our results highlight the viability of drill‐interseeding as a strategy for increasing cover crop adoption.

No-till planting crops into rolled-crimped cover crops can improve soil health while reducing labor and fuel requirements compared with traditional tillage-based production. However, little information is available to help farmers optimize the management of organic no-till planted crops. Weed suppression, crop yield, and profitability were assessed across soybean [Glycine max (L.) Merr.] seeding rates and soil nitrogen environments in an experiment conducted at two sites in central New York. Soybeans were no-till planted into rolled-crimped cereal rye (Secale cereale L.) at 0, 185,000, 371,000, 556,000, and 741,000 seeds ha−1. Three rates (0, 63, or 125 kg ha−1) of sodium nitrate (15-0-2) were applied across seeding rates to create different soil nitrogen environments. When pooled over sites, the lowest weed biomass occurred at the highest soybean density in the lowest soil nitrogen environment. An interaction was observed between soybean seeding rate and nitrogen treatments on weed communities. Soybean yield increased asymptotically with crop density and was not affected by nitrogen or site treatments. When pooled over nitrogen treatments and sites, partial returns to the soybean seeding rates were maximized at $2,238 ha−1 with 527,800 seeds ha−1. Results suggest that crop density is an important lever for optimizing weed suppression and crop yield in organic no-till soybean, and that managing for low soil nitrogen conditions may further enhance weed suppression while maintaining high yields.

Hairy vetch (Vicia villosa Roth) is a commonly grown legume cover crop in the United States. Critical breeding goals for the species include increasing early fall vigor and spring biomass production. To ascertain genetic improvement for these traits, we explored the relationship between fall and spring vigor. Moreover, we evaluated the variation in genotypic performance across multiple environments and assessed how weather variables affected germplasm performance. The relationship between fall and spring vigor differed by winter weather conditions. In warmer locations, top‐performing genotypes in the fall were the top performers in the spring, allowing simultaneous selection for both traits of interest. Environments with colder winter conditions, however, did not show linear relationships between fall and spring vigor. At cold sites, the most and least vigorous plants in the fall tended to underperform in the spring. Results suggest that fall vigor is not a linear predictor of spring vigor in cold environments, and consequently, breeding programs should screen and select for both traits in cold climates. Genotype × environment interaction (GE) heavily contributed to spring vigor performance. In our dataset, days below freezing without snow cover, days below freezing, minimum daily temperature, and freezing degree days were related to the signal in GE. As a result, breeding programs would benefit from dividing selection sites according to the severity of winter conditions.

Weed communities can be influenced by nutrient availability, nutrient form (e. g., ammonium vs. nitrate), amendment timing, amendment type (e.g., organic vs. inorganic), and by immigration of seeds during amendment applications. The objective of this research was to compare the long-term effect of different fertility treatments in a corn (Zea mays L.)-alfalfa (Medicago sativa L.) rotation on taxonomic and functional structure and composition of weed communities by analyzing the soil weed seedbank. After 14 years of a long-term experiment in Aurora, NY, United States, soils were sampled in five fertility treatments for corn years in the rotation: liquid dairy manure, semi-composted separated dairy solids; or inorganic nitrogen (N) as starter fertilizer with either no sidedress N, a low rate or a high rate of inorganic N as sidedress fertilizer. Soil was collected in early spring 2015 and a greenhouse weed seed germination bioassay was used to quantify the germinable soil weed seedbank. Total weed seedbank density, species richness, and evenness did not vary by treatment. However, fertility treatments modified the ecological niche represented by 20 environmental descriptors, which filtered the weed community creating distinct functional group assemblages. A trait-based analysis revealed that nitrophilic dicotyledons preferring alkaline soil were associated with high concentrations of inorganic N fertilizer, whereas highly specialist monocotyledons preferring high amounts of light were associated with low concentrations of inorganic N fertilizer. Because fertility treatments affected weed community composition but not seed bank density and richness, results encourage the development of holistic management strategies that adopt coherent weed management and crop fertilization.

A field experiment in central New York evaluated the effect of sunflower (Helianthus annuus L.) density on weed biomass and yield in organic sunflower production. Two varieties of sunflower, Badger DMR and N5LM307, were seeded at 6.1 and 8.6 seeds m−2, and grown using organic management practices at one site in 2016 and two sites in 2017. Sunflower density, weed biomass, and sunflower yield were quantified at crop maturity. Weed biomass was lower (P < .05) in plots with sunflower seeded at 8.6 seeds m−2 compared to 6.1 seeds m−2 in only one variety in one site‐year. However, a negative relationship (P < .05) was observed between sunflower density and weed biomass when data were pooled over site‐years. No difference was observed in sunflower seed yield between varieties or seeding rate treatments. Sunflower seed yield was higher in 2016 (354 g m−2) when conditions were extremely dry, and in one site‐year in 2017 (308 g m−2), when conditions were extremely wet and seeding was delayed by a month. In the other site‐year in 2017, sunflower seed yield was lower (225 g m−2), which was likely due to weed competition as weed biomass was an order of magnitude greater in this site‐year than the other two site‐years. Although more research is needed to refine management recommendations for organic sunflower production, our results suggest that increasing sunflower density can contribute to weed suppression.