Wild radish (Raphanus raphanistrum L.) is a highly competitive annual broadleaf weed that significantly constrains wheat (Triticum aestivum L.) production, particularly under increasing herbicide resistance and limited chemical control options. Optimizing sowing geometry offers a practical, nonchemical approach to enhance crop competitiveness and suppress weed growth. A field study was conducted during 2022 and 2023 to evaluate the impact of different sowing geometries on R. raphanistrum suppression and wheat productivity. The experiment was arranged in a randomized complete block design with seven treatments, including broadcast sowing; line sowing at 11, 22, and 33 cm; ridge sowing (30 cm); bed sowing (60 cm); and cross sowing (22 cm). Sowing geometry significantly influenced R. raphanistrum density and biomass at all growth stages (15 to 45 d after sowing). Narrow spacing (11 cm) consistently resulted in the lowest weed density and biomass, while the wider 33-cm spacing resulted in the highest weed pressure. Crop growth and yield responses were consistent across years, with 11-cm line sowing producing the highest number of productive tillers (393.7 m−2), grains per spike (42.9), biological yield (15.4 Mg ha−1) and grain yield (6.0 Mg ha−1) averaged across 2 yr. This treatment was closely followed by cross sowing (22 cm). In contrast, wider spacing (33 cm) reduced grain yield by approximately 25% to 30% due to increased weed competition and reduced crop competitiveness. Correlation and principal component analyses revealed a strong negative association between late-season weed biomass and wheat productivity, emphasizing the importance of sustained weed suppression during critical growth stages. Overall, narrow row spacing, particularly 11-cm line sowing, enhanced crop competitiveness, effectively suppressed R. raphanistrum, and maximized wheat yield, demonstrating its potential as an eco-friendly strategy for integrated weed management.

Field experiments were conducted in 2016 and 2017 to evaluate the effects of seeding rate and herbicide programs on weed control and pinto bean yield under irrigation. The experiments comprised a 5 × 5 factorial randomized complete block design with five replications. The weed control treatments comprised a nontreated control, hand-weeded control, EPTC + ethalfluralin PRE, EPTC + ethalfluralin PRE followed by (fb) dimethenamid-P POST at V1, and EPTC + ethalfluralin PRE fb bentazon/imazamox POST. There were five seeding rates ranging from 247,000 to 494,000 seeds ha–1 planted in 19-cm rows. Weed biomass was reduced by 6 kg ha–1 with every additional 1,000 seeds ha–1. EPTC plus ethalfluralin fb either dimethenamid-P or bentazon plus imazamox reduced weed biomass by at least 29% compared to the nontreated control. There was a significant effect of weed control treatment on pinto bean yield (P = 0.0004). However, there was no significant seeding rate (P = 0.42) or seeding rate–by–weed control interaction effect on pinto bean yield (P = 0.38). Pinto bean yield ranged from 3,080 kg ha–1 in the nontreated control to 4,740 kg ha–1 hand-weeded treatment. Increased seeding rate in narrow rows is a cultural practice that can improve weed control in pinto bean but may not necessarily increase yield.

Successful pigweed management requires an integrated strategy to delay the development of resistance to any single control tactic. Field trials were implemented during 2017 and 2018 in three counties in Kansas on dryland (limited rainfall, nonirrigated), glufosinate-resistant soybean. The objective was to assess pigweed control with combinations of a winter wheat cover crop (CC), three soybean row widths (76, 38, and 19 cm), row-crop cultivation 2.5 weeks after planting (WAP), and an herbicide program to develop integrated pigweed management recommendations. All combinations of the four components were assessed by 16 treatments. All treatments with the herbicide program resulted in excellent (>97%) pigweed control and were analyzed separately from the other components. Treatments containing row-crop cultivation reduced pigweed density and biomass 3 and 8 WAP in all locations compared with the 76-cm row width plus no CC treatment. CC impacts were mixed. In Riley County, Palmer amaranth density and biomass were reduced; in Reno County, no additional Palmer amaranth control was observed; in Franklin County, the CC had greater waterhemp density and biomass compared with the treatments containing no CC. Narrow row widths achieved the most consistent results of all cultural components when data were pooled across locations: Decreasing row widths from 76 to 38 cm resulted in a 23% reduction in pigweed biomass 8 WAP and decreasing row width from 38 to 19 cm achieved a 15% reduction. Row-crop cultivation should be incorporated where possible as a mechanical option to manage pigweed, and narrow row widths should be used to suppress late-season pigweed growth when feasible. Inconsistent pigweed control from CC was achieved and should be given special consideration before implementation. The integral use of these components with an herbicide program as a system should be recommended to achieve the best pigweed control and reduce the risk of developing herbicide resistance.