Cover crops are becoming an increasingly important tool for weed suppression. Biomass production in cover crops is one of the most important predictors of weed suppressive ability. A significant challenge for growers is that cover crop growth can be patchy within fields, making biomass estimation difficult. This study tested ground-based structure-from-motion (SfM) for estimating and mapping cereal rye (Secale cereale L.) biomass. SfM generated 3D point clouds from red, green, and blue (RGB) videos collected by a handheld GoPro camera over five fields in North Carolina during the 2022 to 2023 winter season. A model for predicting biomass was generated by relating measured biomass at termination using a density–height index (DH) from point cloud pixel density multiplied by crop height. Overall biomass ranged from 320 to 9,200 kg ha−1, and crop height ranged from 10 to 120 cm. Measured biomass at termination was linearly related to DH (r2 = 0.813) through levels of 9,000 kg ha−1. Based on independent data validation, predicted biomass and measured biomass were linearly related (r2 = 0.713). In the field maps generated by kriging, measured biomass data were autocorrelated at a range of 5.4 to 42.2 m, and predicted biomass data were autocorrelated at a range of 3.4 to 12.0 m. However, the spatial arrangement of high- and low-performing areas was similar for predicted and measured biomass, particularly in fields with greatest patchiness and spatial correlation in biomass values. This study provides proof-of-concept that ground-based SfM can potentially be used to nondestructively estimate and map cover crop biomass production and identify low-performing areas at higher risk for weed pressure and escapes.

Conservation agriculture (CA) is an approach to farming that is defined by three principles: (1) minimal soil disturbance (no-till), (2) crop diversity in time and space, and (3) soil coverage by crop residues and/or cover crops. These principles provide a roadmap to protect and improve soil. However, the narrow criteria for defining CA may fail to account for tradeoffs between soil health and other ecosystem services. A literature review of meta-analyses dealing with CA and an online survey in France were conducted to explore the implementation and performances of CA. Research on CA systems has focused on crop productivity and soil quality whereas research on other dimensions of cropping system sustainability are lacking. The effects of CA on other aspects of sustainability such as biodiversity and profitability are less prevalent in the literature. The online survey results show that 63% of respondents thought that CA helps reduce pesticide use, 91% that CA improves water use efficiency, and 77% that CA helps to store carbon and achieve the objectives of the 4 per 1000 international initiative. Given the prevalence and widespread support for CA, we advocate for moving CA from its current definition based on the means toward a definition that includes performance-based metrics that address different ecosystem services. CA has potential to help address challenges associated with climate change, biodiversity loss, and water pollution, but opportunities may be missed without developing performance targets that go beyond soil conservation.

Drill-interseeding cover crops into corn (Zea mays L.) is an emerging establishment method in northern U.S. production regions. However, cover crop performance in interseeded systems remains variable, and creating environments that are conducive to cover crop but not weed growth is challenging. Cultural practices that partition resources between corn and interseeded cover crops have potential to improve performance if weeds are adequately managed. This study evaluated interactions among corn hybrids differing in leaf architecture (upright, pendulum), corn row spacing (76 cm, 152 cm), and interseeding timing (V3, V6) on light transmittance, relative fitness of cover crop species (cereal rye [Secale cereale L.], annual ryegrass (Lolium multiflorum Lam), red clover [Trifolium pratense L.]) and weeds, and corn grain yield at three U.S. Northeast locations. Results showed that light transmittance through the corn canopy was greater in 152-cm row spacing compared with 76-cm row spacing at the V6 growth stage, with the magnitude of difference increasing at the V10 corn growth stage. Corn hybrids had a marginal effect on light transmittance. The effect of row spacing and interseeding timing on fall cover crop biomass varied across cover crop species and locations. In 76-cm rows, interseeding earlier (V3) increased cover crop biomass production. The relative fitness of cover crops was greater than that of weeds in each combination of cultural practices that included narrow spacing (76 cm), whereas the relative fitness of weeds was greater than that of cover crops when interseeding in wide rows (152 cm). The effect of row spacing on corn yield varied among locations, with higher yields observed in 76-cm row spacing compared with 152-cm at two of three locations. Our results show that interseeding early (V3) on 76-cm row spacing can balance cover crop and corn production management goals, while placing cover crops at a relative fitness advantage over weeds.

Rapid increase in the hectarage and agricultural systems that use cover cropping for soil conservation and improvement, soil moisture retention, and weed management has highlighted the need to develop formal breeding programs for cover crop species. Cereal rye (Secale cereale L.) is preferred by many growers due to high biomass production and weed-suppression potential, which is believed to be partially due to allelopathy. Rye germplasm exhibits large variability in allelopathic activity, which could be used to breed rye with enhanced weed suppression. Here, we provide an overview of rye history and breeding and describe a strategy to develop rye lines with increased allelopathic activity. The discussion focuses on ways to deal with important challenges to achieving this goal, including obligate cross-pollination and its consequent high segregation levels and the need to quantify allelopathic activity under field conditions. This review seeks to encourage weed scientists to collaborate with plant breeders and promote the development of cover crop cultivars better suited to reduce weed populations.

Delaying cover crop termination until cash crop planting (i.e., planting green) is an emerging no-till practice. Improved management recommendations are needed for optimizing weed suppression benefits while minimizing other pest, fertility, and crop management risks when planting green in corn production systems. In a 2-yr field experiment, we evaluated the interaction between cereal rye residue management tactics (standing residue, roll-crimping, roll-crimping with row cleaners) and herbicide programs (1-pass preemergence [PRE], 2-pass postemergence [POST]) when planting green on weed recruitment spatial patterns and corn performance compared to standard termination (14 d preplant [DPP]) and ryelage harvest (14 DPP) practices. In a 2-yr on-farm experiment, we evaluated corn performance in response to the same residue management tactics. Cereal rye biomass production varied significantly across years in on-station experiments, with average (4.9 Mg ha−1) and anomalous (9.9 Mg ha−1) levels observed in 2020 and 2021, respectively. In 2020, planting green with an integrated roll-crimper/row cleaner system resulted in greater intrarow weed density compared with planting green into standing cereal rye. Interrow weed density was lower when roll-crimping was employed compared to early termination (14 DPP). Planting green into standing cereal rye resulted in greater mean corn height (V5 stage) compared to other treatments, but corn population and yield did not differ. In 2021, few differences in weed recruitment patterns were observed, but corn population and yield were significantly lower in planting green treatments compared to early termination. In both years, late-season weed biomass was lower in two-pass POST programs compared to one-pass PRE programs. On-farm trials showed that planting green into standing residue increases corn height and can reduce corn populations, which may lead to reduce yields. Our results suggest that management recommendations for optimizing herbicide application timing should consider intrarow and interrow weed recruitment dynamics associated with residue management tactics needed to optimize corn performance.

There have been no systematic experiments conducted in Nevada's water-limited environment that examined the simultaneous benefits of soil health and feed value derived from cool-season cover cropping systems. The objective of this study was to determine the influence of different annual cool-season cover crop systems on above and belowground biomass production, plant tissue carbon and nitrogen, forage nutritive value (crude protein, acid, and neutral detergent fiber), relative feed value (RFV), and short-term soil health indicators under irrigation in a semi-arid environment. Treatments (cover crop systems) were a fallow (no cover crop), five monocultures of rye (Secale cereale L.), winter lentil (Lens culinaris Medik.), arrowleaf clover (Trifolium vesiculosum Savi), white sweetclover (Melilotus alba), forage kale (Brassica oleracea L.), and two three-species mixtures in 50-25-25 seeding ratios (CCM 1: rye, winter lentil, arrowleaf clover; CCM 2: rye, white sweetclover, forage kale). Cover crop systems were arranged in an RCBD with three replications. Plots were fall seeded in Reno, NV early October of each year (2020 and 2021) and terminated at the end of July of 2021 and 2022, respectively. Averaged across years, aboveground biomass production was lowest for the monoculture of winter lentil (4104 kg DM ha−1; SE = 1551) compared to all other cover crop systems (average = 7593 kg DM ha−1; SE = 1551). Biomass carbon produced was lowest for winter lentil (1717 kg ha−1; SE = 675) relative to all other cover crop systems (average = 3227 kg ha−1; SE = 675). The CCM 1 system had a greater C/N ratio (36.3) than CCM 2 and the monocultures of winter lentil, arrowleaf clover, and white sweetclover (average = 24.9). Belowground biomass did not differ among cover crop systems (average = 3161 kg DM ha−1; SE = 962). Crude protein concentration was similar among cover crop systems but the RFV was greatest for forage kale (RFV = 165; SE = 4.0) among all cover crop systems. Soil total N and organic carbon concentration did not differ among cover crop systems but soil K concentration was greatest under fallow (428 mg kg−1 soil; SE = 26) relative to all other systems (average = 345.6 mg kg−1 soil; SE = 26). Soil microbial community biomass was not altered by cover crop system or its interaction with year. While the short-term impact of the cover crop systems on soil health indicators was minimal relative to the fallow system, the overall results suggested that there is potential to integrate cover crops in Nevada's semi-arid environment under irrigation.

Field studies were conducted in 2021 in Kibler and Augusta, AR, to determine the effect of winter cover crops and cultivar selection on weed suppression and sweetpotato [Ipomoea batatas (L.) Lam.] yield. The split-split-plot studies evaluated three cover crops [cereal rye (Secale cereale L.) + crimson clover (Trifolium incarnatum L.)], [winter wheat (Triticum aestivum L.) + crimson clover], and fallow; weeding (with or without); and four sweetpotato cultivars (‘Heartogold’, ‘Bayou-Belle-6’, ‘Beauregard-14’, and ‘Orleans’). Heartogold had the tallest canopy, while Beauregard-14 and Bayou Belle-6 had the longest vines at 5 and 8 wk after sweetpotato transplanting. Sweetpotato canopy was about 20% taller in weedy plots compared with the hand-weeded treatment, and vines were shorter under weed interference. Canopy height and vine length of sweetpotato cultivars were not related to weed biomass suppression. However, vine length was positively correlated to all yield grades (r > 0.5). Weed biomass decreased 1-fold in plots with cover crops compared with bare soil at Augusta. Cover crop biomass was positively correlated with jumbo (r = 0.29), no. 1 (r = 0.33), and total sweetpotato yield (r = 0.34). Jumbo yield was affected the most by weed pressure. On average, sweetpotato total yield was reduced by 80% and 60% with weed interference in Augusta and Kibler, respectively. Bayou Belle-6 was the high-yielding cultivar without weed interference in both locations. Bayou Belle-6 and Heartogold were less affected by weed interference than Beauregard-14 and Orleans.

Region- and system-specific research is needed to understand the viability of delayed cover-crop termination (i.e., planting green) as an integrated weed management (IWM) tactic in no-till soybean. In a 3-yr field experiment, we evaluated the potential for planting green to facilitate elimination of soil-applied, preemergence residual herbicides within a soybean phase of a 6-yr grain–forage cropping systems experiment in Pennsylvania. This IWM tactic was contrasted with a Standard treatment, which included 14 to 21 d pre-plant termination of cereal rye and a two-pass herbicide program with preemergence herbicides. A 63% increase in cereal rye biomass production was observed within the IWM treatment in 2019, but only a 22% and 33% increase in 2020 and 2021, respectively. In 2020, significantly lower volumetric water content (%VWC) was observed within the IWM treatment in dates closest to planting and greater %VWC at multiple dates in June and July compared to the Standard treatment. No differences occurred in soybean populations, but soybean biomass at the V4 growth stage was reduced in the Standard treatment compared to the IWM treatment, which we attribute to injury from preemergence applications. The Standard treatment resulted in greater soybean yield (2,590 kg ha–1) than the IWM treatment (1,870 kg ha–1) in 2020, but yields were similar in other years. The IWM treatment resulted in 58% fewer herbicide inputs, as measured by the number of active ingredients applied, compared to the Standard over the 3-yr study. Yet, peak weed biomass did not differ between treatments. However, the IWM treatment resulted in greater total horseweed density and the number of horseweed plants that exceeded recommended size-based height thresholds (10 cm) compared to the Standard treatment just prior to postemergence applications (35–42 d after planting) in 2020 and 2021, underscoring the importance of integrating surface mulch residues with effective herbicide sites of action.

Field experiments were conducted over 2 yr (2019 to 2020) at two locations in Iowa to evaluate multi-tactic strategies for managing multiple herbicide–resistant (MHR) waterhemp [Amaranthus tuberculatus (Moq.) Sauer] in a corn (Zea mays L.)–soybean [Glycine max (L.) Merr.] rotation. The effect of three herbicide programs on A. tuberculatus control was tested in corn (2019). The effects of the prior year’s corn weed control, a cereal rye (Secale cereale L.) cover crop, and soybean row spacing (38-cm vs. 76-cm wide) on A. tuberculatus density, biomass, and seed production were tested in soybean (2020). A herbicide program used in corn with two sites of action provided only 35% control of MHR A. tuberculatus compared with ≥97% control by a herbicide program with three sites of action. In soybean, adequate control of A. tuberculatus (≥90%) in the prior year’s corn crop and use of a cover crop or narrow rows reduced A. tuberculatus density by more than 60% at 3 and 9 wk after planting (WAP) compared with inadequate control (30%) in the prior year’s corn and no cover crop. Cover crop and narrow-row soybean reduced A. tuberculatus density by 44% at 3 WAP compared with no cover crop and wide-row soybean. Inclusion of a single control tactic, adequate control (≥90%) with multiple herbicides in the prior year’s corn, use of a cover crop, or narrow-row soybean reduced A. tuberculatus biomass and seed production at soybean harvest by at least 24% compared with inadequate control (30%) in the prior year’s corn, no cover crop, and wide-row soybean. The combination of all three control tactics reduced A. tuberculatus biomass and seed production at soybean harvest by at least 80%. In conclusion, diverse control tactics targeting A. tuberculatus at multiple life-cycle stages can make substantial contributions to the management of MHR populations.

While conservation practices promote soil health and reduce the negative environmental effects from agricultural production, their adoption rates are generally low. To facilitate farmer adoption, we carried out a survey to identify potential challenges faced by farmers regarding conservation tillage and cover crop adoption in the western margin of the US Corn Belt. We found farmers' top two concerns regarding conservation tillage were delayed planting, caused by slow soil warming in spring, and increased dependence on herbicide and fungicides. Narrow planting window and lack of time/labor were perceived by farmers as the two primary challenges for cover crop adoption. Some sense of place factors, including the commonly included dimensions of attachment, identity and dependence, played a role in farmers' perceived challenges. For example, respondents more economically dependent on farming perceived greater challenges. We found that farmers' challenge perceptions regarding reduced yield and lack of time/labor significantly decreased as years of usage increased, implying that time and experience could dilute some challenges faced by farmers. Our findings indicate that social network use, technical guidance and economic subsidies are likely to address the concerns of farmers and facilitate their adoption of conservation practices.

Soybean is the world’s most widely grown leguminous crop and is an important source of oil and protein for food and feed in addition to other industrial uses. However, herbicide-resistant and troublesome weed control challenges limit yield potential and threaten conservation tillage (CT) systems. Cover crops have been widely adopted as an integrated pest management component in CT systems to suppress weeds and maintain soybean yield potential. A 3-yr field experiment was conducted to estimate the influence of a cereal rye cover crop following CT on the critical period for weed control (CPWC) in soybean. The experiment was implemented in a split-plot design in which main plots as CT following cover crop (CT + CC), CT following winter fallow (CT + WF), and conventional tillage (CVT), and subplots were multiple durations of weed-free and weed interference. Results showed that the estimated CPWC of CT + CC and CT + WF treatments was 0 wk and >7 wk, respectively, in 2018. In 2019, the estimated CPWC was 0 wk, 5.0 wk, and 1.3 wk under CT + CC, CT + WF, and CVT treatments, respectively. In 2020, the estimated CPWC was 3.5 wk, >6.2 wk, and 0 wk under CT + CC, CT + WF, and CVT treatments, respectively. The presence of a cover crop delayed the CTWR and caused an early beginning of the CWFP compared with CT + WF treatment, and hence shortened the CPWC in 2018 and 2019. In conclusion, the CT + WF system did not reduce the weed competition and subsequent yield loss in soybean compared to the CT + CC system.

In the Mid-Atlantic United States, there is increasing interest in delaying cereal rye termination until after soybean planting (i.e., planting green). Improved understanding of cereal rye seeding rate effects is needed to balance weed and agronomic management goals. We investigated the effects of cereal rye seeding rates on weed control and crop performance when planting green in complementary experiments in two Mid-Atlantic regions. The Pennsylvania experiment was replicated at three site-years and the Delaware experiment at two site-years. In both experiments, population-level weed responses were evaluated across four cereal rye seeding rates: 0, 51, 101, and 135 kg ha−1. The Delaware experiment also implemented a nitrogen treatment factor (0 and 34 kg N ha−1; spring applied). Both experiments showed that integrating cereal rye in the fall significantly improved winter- and summer-annual weed suppression compared with the fallow control, but no differences in total cereal rye biomass production or weed suppression were found among alternative cereal rye seeding rates (51 to 135 kg ha−1). Soybean yield did not differ among treatments in any of the studies. These results show there is no reason to increase cereal rye seeding rates for weed suppression services or to decrease seeding rates for agronomic reasons (i.e., soybean population and yield) when employing planting-green tactics in no-till soybean production within the Mid-Atlantic region of the United States.

Living mulches are cover crops grown simultaneously with and in close proximity to cash crops. Advantages of living mulches over dead cover crops may include increased weed suppression, reduced erosion and leaching, better soil health, and greater resource-use efficiency. Advantages of living mulches over synthetic mulches may include enhanced agroecosystem biodiversity and suitability for a wider range of cropping systems. A major disadvantage of this practice is the potential for competition between living mulches and cash crops. The intensity and outcome of mulch-crop competition depend on agroecosystem management as well as climate and other factors. In this review, we consider the management of living mulches for weed control in field and vegetable cropping systems of temperate environments. More than 50 yr of research have demonstrated that mechanical or chemical suppression of a living mulch can limit mulch-crop competition without killing the mulch and thereby losing its benefits. Such tactics can also contribute to weed suppression. Mechanical and chemical regulation should be combined with cultural practices that give the main crop a competitive advantage over the living mulch, which, in turn, outcompetes the weeds. Promising approaches include crop and mulch cultivar selection; changes to planting time, density, and planting pattern; and changes to fertilization or irrigation regimes. A systems approach to living mulch management, including an increased emphasis on the interactions between management methods, may increase the benefits and lower the risks associated with this practice.

Introducing cover crops (CC) in annual cropping systems can promote nutrient cycling and improve soil health. However, impacts of CC on soil health indicators vary and depend on the duration of CC, cropping systems, and other environmental conditions. We performed an on-farm assessment of cover cropping impacts on soil health indicators including C and N pools, enzyme activities, and microbial community structure under different no-till maize-based cropping systems (maize (Zea mays L.)–soybean (Glycine max L.) [CS], CS-winter wheat (Triticum aestivum L.) [CSWw], and maize-oats (Avena sativa L.) [CO]). At five farms, fields with different durations of CC were compared to adjacent no CC (NCC) fields. In general, long-term CC enhanced the soil health parameters compared to NCC. Long-term (20-year) winter rye CC had higher water-extractable C and N content, enzyme activities (β-glucosidase (1.2 times greater), urease (5.5 times greater), acid (1.5 times greater) and alkaline (4 times greater) phosphatase, arylsulfatase (0.8 times greater) and fluorescein diacetate (FDA) (0.7 times greater)) and soil bacterial community abundance (1.2 times greater). Short-term (3–6 years) legume and grass CC mixtures increased β-glucosidase (0.9 times), acid (0.7 times) and alkaline (1.5 times) phosphatase, arylsulfatase (3 times), FDA (0.8 times) activities and total phospholipid fatty acid (1.6 times) concentration. However, short-term (3–6 years) winter rye, legume and brassica mixtures did not significantly alter soil microbial community structure. This study showed that implementation of CC for >6 years promoted C, N, S, and P cycling that are beneficial to soil health in maize-based cropping systems.

In organic farming the control of perennial weed species, in particular Cirsium arvense, can be a major concern for farmers, especially if there is no regulation through perennial forage production. To test whether the stubble cleaner (SC), an enhanced skim plow (PL), is as effective in the control of C. arvense and other weeds as conventional ploughing and perennial forage production, an organic field experiment was established. Three different tillage/crop rotation systems were compared: an SC system and a PL system, both in a cereal-based crop rotation and an additional PL system in a crop rotation that included a perennial alfalfa–grass mixture (PLALF). In the SC system, tillage was carried out solely with the SC, while in the PL and PLALF systems, ploughing was alternated with chiseling. In the fifth year, each main plot was divided into subplots, and seven different cover crop treatments were integrated into each of the three systems. The effects of the three systems and the cover crop treatments on weed cover and density, weed biomass, and weed diversity in the sixth and seventh year of the experiment are the subjects of this paper. The choice of cover crop species was of minor importance for weed control. The PLALF system was generally more effective in controlling C. arvense than the PL and SC systems. No significant differences between the PL and SC systems regarding the control of C. arvense could be identified in four of five assessments. The SC system had significantly higher total weed density than the PLALF and PL systems in both years. However, the differences in weed emergence between the PL and SC systems diminished until the assessment of weed cover and biomass in the main crops, when no significant differences between these two systems (2012) or no differences at all (2013) could be identified. Species richness was not significantly influenced by the tillage/crop rotation system in both years. Evenness and Shannon–Wiener index were significantly higher in the PLALF and PL systems than in the SC system on most assessment dates in 2012. In 2013 there was no clear trend regarding evenness and Shannon-Wiener index probably due to a hoeing operation.. In conclusion, for weed control, the choice of crop rotation was more important than the choice of tillage method, while for the diversity of the weed community, the choice of tillage method was more important than the crop rotation.

As herbicide-resistant weeds become more problematic, producers will consider the use of cover crops to suppress weeds. Weed suppression from cover crops may occur especially in the label-mandated buffer areas of dicamba-resistant soybean where dicamba use is not allowed. Three cover crops terminated at three timings with three herbicide strategies were evaluated for their effect on weed suppression in dicamba-resistant soybean. Delaying termination until soybean planting or after and using cereal rye or cereal rye + crimson clover increased cover-crop biomass by at least 40% compared to terminating early or using a crimson clover–only cover crop. Densities of problematic weed species were evaluated in early summer before a blanket POST application. Plots with cereal rye had 75% less horseweed compared to crimson clover at two of four site-years. Cereal rye or the mixed cover crop terminated at or after soybean planting reduced waterhemp densities by 87% compared to early termination timings of crimson clover and the earliest termination timing of the mix at one of two site-years. Cover crops were not as effective in reducing waterhemp densities as they were in reducing horseweed densities. This difference was due to a divergence in emergence patterns; waterhemp emergence generally peaks after termination of the cover crop, whereas horseweed emergence coincides with establishment and rapid vegetative growth of cereal rye. Cover crops alone were generally not as effective as was using a high-biomass cover crop combined with an herbicide strategy that contained dicamba and residual herbicides. However, within label-mandated buffer areas where dicamba cannot be used, a cover crop containing cereal rye with delayed termination until soybean planting combined with residual herbicides could be used to improve suppression of horseweed and waterhemp.

Organic grain producers are interested in interseeding cover crops into corn (Zea mays L.) in regions that have a narrow growing season window for post-harvest establishment of cover crops. A field experiment was replicated across 2 years on three commercial organic farms in Pennsylvania to compare the effects of drill- and broadcast-interseeding to standard grower practices, which included post-harvest seeding cereal rye (Secale cereale L.) at the more southern location and winter fallow at the more northern locations. Drill- and broadcast-interseeding treatments occurred just after last cultivation and used a cover crop mixture of annual ryegrass [Lolium perenne L. ssp. multiflorum (Lam.) Husnot] + orchardgrass (Dactylis glomerata L.) + forage radish (Raphanus sativus L. ssp. longipinnatus). Higher mean fall cover crop biomass and forage radish abundance (% of total) was observed in drill-interseeding treatments compared with broadcast-interseeding. However, corn grain yield and weed suppression and N retention in late-fall and spring were similar among interseeding treatments, which suggests that broadcast-interseeding at last cultivation has the potential to produce similar production and conservation benefits at lower labor and equipment costs in organic systems. Post-harvest seeding cereal rye resulted in greater spring biomass production and N retention compared with interseeded cover crops at the southern location, whereas variable interseeding establishment success and dominance of winter-killed forage radish produced conditions that increased the likelihood of N loss at more northern locations. Additional research is needed to contrast conservation benefits and management tradeoffs between interseeding and post-harvest establishment methods.

Organic grain producers are interested in reducing tillage to conserve soil and decrease labor and fuel costs. We examined agronomic and economic tradeoffs associated with alternative strategies for reducing tillage frequency and intensity in a cover crop–soybean (Glycine max L. Merr.) sequence within a corn (Zea mays L.)–soybean–spelt (Triticum spelta L.) organic cropping system experiment in Pennsylvania. Tillage-based soybean production preceded by a cover crop mixture of annual ryegrass (Lolium perenne L. ssp. multiflorum), orchardgrass (Dactylis glomerata L.) and forage radish (Raphanus sativus L.) interseeded into corn grain (Z. mays L.) was compared with reduced-tillage soybean production preceded by roller-crimped cereal rye (Secale cereale L.) that was sown after corn silage. Total aboveground weed biomass did not differ between soybean production strategies. Each strategy, however, was characterized by high inter-annual variability in weed abundance. Tillage-based soybean production marginally increased grain yield by 0.28 Mg ha−1 compared with reduced-tillage soybean. A path model of soybean yield indicated that soybean stand establishment and weed biomass were primary drivers of yield, but soybean production strategy had a measurable effect on yields due to factors other than within-season weed–crop competition. Cumulative tillage frequency and intensity were quantified for each cover crop—sequence using the Soil Tillage Intensity Rating (STIR) index. The reduced-tillage soybean sequence resulted in 50% less soil disturbance compared to tillage-based soybean sequence across study years. Finally, enterprise budget comparisons showed that the reduced-tillage soybean sequence resulted in lower input costs than the tillage-based soybean sequence but was approximately $114 ha−1 less profitable because of lower average yields.

Pigweed is difficult to manage in grain sorghum because of widespread herbicide resistance, a limited number of registered effective herbicides, and the synchronous emergence of pigweed with grain sorghum in Kansas. The combination of cultural and mechanical control tactics with an herbicide program are commonly recognized as best management strategies; however, limited information is available to adapt these strategies to dryland systems. Our objective for this research was to assess the influence of four components, including a winter wheat cover crop (CC), row-crop cultivation, three row widths, with and without a herbicide program, on pigweed control in a dryland system. Field trials were implemented during 2017 and 2018 at three locations for a total of 6 site-years. The herbicide program component resulted in excellent control (>97%) in all treatments at 3 and 8 weeks after planting (WAP). CC provided approximately 50% reductions in pigweed density and biomass for both timings in half of the site-years; however, mixed results were observed in the remaining site-years, ranging from no attributable difference to a 170% increase in weed density at 8 WAP in 1 site-year. Treatments including row-crop cultivation reduced pigweed biomass and density in most site-years 3 and 8 WAP. An herbicide program is required to achieve pigweed control and should be integrated with row-crop cultivation or narrow row widths to reduce the risk of herbicide resistance. Additional research is required to optimize the use of CC as an integrated pigweed management strategy in dryland grain sorghum.

White mold caused by the fungus, Sclerotinia sclerotiorum is a devastating disease of soybean (Glycine max) and other leguminous crops, including dry bean (Phaseolus vulgaris). Previous research has demonstrated that no-till planting soybean into rolled–crimped cereal rye residue can enhance weed management, improve soil health and reduce labor requirements in organic production. However, there are limited data on the effects of cereal rye residue on white mold suppression in no-till planted soybean and dry bean. Two field trials were conducted in 2016–2017 (Year 1) and repeated in 2017–2018 (Year 2) to evaluate the potential of cereal rye cover crop residue to suppress white mold in these crops. In each trial (soybean and dry bean), the experimental design was a randomized complete block with two treatments: (1) rolled–crimped cereal rye residue and (2) no cover crop control. Treatment effects on plant population, biomass and yield components varied between the main crops. Compared with the control treatment, cereal rye residue reduced the incidence of white mold in soybean in both years and in dry bean in Year 2. The reduction in white mold in cereal rye residue plots was due to a combination of (1) decreased sclerotial germination (no stipes formed) and (2) increased nonfunctional sclerotial germination defined here as sclerotia that germinated but produced stipes without the expanded cup where asci containing ascospores are formed. Weed density and biomass were lower in cereal rye residue plots in soybean and dry bean, except in Year 1 in soybean when weed biomass was low in both treatments. Our findings indicate that cereal rye residue could help organic and conventional farmers manage white mold in no-till planted soybean and dry bean. Germination of sclerotia resulting in nonfunctional apothecia could potentially exhaust soilborne inoculum in the upper soil profile and reduce infections in subsequent crops.