Fall-sown cereal rye has gained popularity as a cover crop in vegetable production due to its weed-suppressive capabilities. However, previous research has shown that replacing preemergence and/or postemergence herbicide applications with roller-crimped rye has variable success at controlling weeds and maintaining vegetable cash crop yields. The objective of this research was to determine whether roller-crimped rye can provide season-long weed control and maintain sweet corn yield. Two rye cultivars (early vs. standard maturity) were compared at three seeding rates (150, 300, and 600 seeds m−2) for their effect on weed control and sweet corn yield. The trial was conducted at three locations: Harrow, ON, and St. Jean-sur-Richelieu, QC, from 2019 to 2021; and Agassiz, BC, in 2019 and 2021. Results suggest that although the early-maturing cultivar allowed for earlier roller crimping in some locations, it was inferior at weed control and resulted in lower sweet corn yield than local standard cultivars. The average rye biomass was lower than the current literature recommendations, and the resulting level of weed control was not high enough to prevent sweet corn yield loss in cover crop treatments. Weed control provided by roller-crimped rye peaked between crimping and 8 wk after crimping and was highest in the standard cultivars sown at 300 and 600 seeds m−2. Preliminary testing of supplemental postemergence weed control showed evidence for sweet corn yields comparable to the weed-free no-cover crop check. However, more research is needed. Overall, with the cultivars and seeding rates tested, roller-crimped rye is not a suitable stand-alone weed control option in sweet corn production. Given the benefits of cover crops, further research should evaluate its potential as a component of an integrated weed management program.

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.

Agro-ecological service crops (ASC) can increase the vegetation complexity of agroecosystems leading to a positive impact on natural enemies of arthropod pests and on weed control. In this study, two ASC terminations (green manure and roller crimper) and a Mater-Bi-mulched control (MB) were compared in order to describe the effects on pests and beneficial dynamics in an organic vegetable system. The trials were conducted over two consecutive growing seasons in 2014 and 2015. Zucchini were grown as cash crop and barley as ASC. Pests and natural enemies were monitored fortnightly by visual samplings along the whole zucchini-growing season. Zucchini plants showed a faster vegetative growth in MB treatment than in ASC terminations. In both years, MB plots were characterized by higher soil temperature and higher leaf nitrogen concentration resulting in plants more susceptible to Aphis gossypii infestations. In all the experimental plots, natural enemies controlled aphid infestations and no insecticide and sprays were necessary. In conclusion, the tested ASC techniques have been suggested as a tool to mitigate aphid infestation.

Organic grain growers rely on cultural practices and biological control to regulate pests, and the implementation and timing of cultural practices can affect many characteristics of the cropping system as a habitat for natural enemies of arthropod pests. Ground beetles (Coleoptera: Carabidae) in particular are important insect and weed-seed predators, and are sensitive to crop rotations, tillage and environmental complexity. In a reduced tillage system in transition to organic management, we evaluated the effect of cover crop species and termination date, crop rotation and high residue cultivation on ground and tiger beetle (Coleoptera: Carabidae) activity-density, community composition and size and trophic groups. The 3-year experiment included a sequence of corn (Zea mays L.), soybean (Glycine max (L.) Merr.) and winter wheat (Triticum aestivum L.). A mixture of hairy vetch (Vicia villosa Roth) and triticale (x Triticosecale Wittmack) preceded corn, and cereal rye (Secale cereale L.) preceded soybean, and each crop sequence was present in each year (full-entry). We compared three cover crop termination (and cash crop planting) dates by terminating the overwintered cover crops with a roller-crimper, and immediately or soon after, we no-till planted corn and soybean through the mat created by the rolled cover crops. In the corn and soybean phases of the rotation, we also compared inter-row cultivation as a pest management strategy to a control treatment (no inter-row cultivation in corn, and an alternative row-spacing in soybean). Wheat was planted on a single date in each year into tilled soil. Carabids were sampled using pitfall traps 2 weeks after termination of the two cover crop treatments, and in mid-June in wheat. Carabid activity-density and species richness increased across the experimental site during the 3-year transition, and community evenness across the experimental site increased by the third year. Crop species influenced carabid community composition, and by the third year, the carabid community was comparable between wheat and hairy vetch-triticale cover crop. The late cover crop termination date was positively associated with higher activity-densities of large carabids in rolled hairy vetch-triticale and rolled cereal rye; carnivorous beetles in rolled hairy vetch-triticale; and granivorous beetles in rolled cereal rye. Inter-row cultivation occurring in corn and soybean resulted in a significantly higher proportion of small beetles in the wheat phase of the rotation, with a significantly higher proportion of large beetles in wheat treatments, which had not received inter-row cultivation in corn and soybean. Results have strong implications for management during the transition to organic, including the importance of plant residue, reduced tillage and timing of cover crop termination dates for augmenting carabid populations.

Organic farming has been historically dependent on conventional tillage operations to convert perennial pasture leys to annual crop rotations, incorporate crop residues, compost and cover crops, as well as to mechanically kill existing vegetation. Conventional tillage, however, has long been known to lead to soil degradation and erosion. A recently developed no-till organic production system that uses a roller–crimper technology to mechanically kill cover crops was evaluated in two states in the western United States. In Washington, pumpkins (Cucurbita spp.) grown in a no-till roller–crimper (NT-RC) system produced yields 80% of conventional tillage, but with fewer weeds. However, in California on-farm research trials in organic cotton (Gossypium barbadense L.), tomato (Lycopersicon esculentum Mill.), eggplant (Solanum melongena L.) and cowpea (Vigna unguiculata (L.) Walp.), the no-till system produced virtual crop failure, or yields less than 20% of the standard production method. The major problems associated with rolled cover crops in California included reduced crop seedling emergence, planter impediment with excessive residue, lack of moisture and delay in transplanting of vegetable crops due to continued growth of cover crops, in-season crop competition from cover crop regrowth and impracticability of using cultivators. Further, excessive dry residue during summer in California can present the risk of fire. In both California and Oregon, considerable success has been demonstrated with zone tillage (strip tillage) in conventionally produced field and vegetable crops. In a replicated Oregon trial, the organic strip tillage treatment produced 85% of the broccoli (Brassica oleracea L.) yield compared to a conventional tillage treatment. Our studies suggest that the zone tillage concept may offer opportunities to overcome many of the agronomic challenges facing no-till.

Organic farmers in western Canada rely on tillage to control weeds and incorporate crop residues that could plug mechanical weed-control implements. However, tillage significantly increases the risk of soil erosion. For farmers seeking to reduce or eliminate tillage, potential alternatives include mowing or using a roller crimper for terminating green manure crops (cover crops) or using a minimum tillage (min-till) rotary hoe for mechanically controlling weeds. Although many researchers have studied organic crop production in western Canada, few have studied no-till organic production practices. Two studies were recently conducted in Saskatchewan to determine the efficacy of the following alternatives to tillage: mowing and roller crimping for weed control, and min-till rotary hoeing weed control in field pea (Pisum sativum L.). The first study compared mowing and roller crimping with tillage when terminating faba bean (Vicia faba L.) and field pea green manure crops. Early termination of annual green manure crops with roller crimping or mowing resulted in less weed regrowth compared with tillage. When compared with faba bean, field pea produced greater crop biomass, suppressed weeds better and had less regrowth. Wheat yields following pea were not affected by the method of termination. Thus, this first study indicated that roller crimping and mowing are viable alternatives to tillage to terminate field pea green manure crops. The second study evaluated the tolerance and efficacy of a min-till rotary harrow in no-till field pea production. The min-till rotary hoe was able to operate in no-till cereal residues and multiple passes did not affect the level of residue cover. Field pea exhibited excellent tolerance to the min-till rotary hoe. Good weed control occurred with multiple rotary hoe passes, and pea seed yield was 87% of the yield obtained in the herbicide-treated check. Therefore, this second study demonstrated that min-till rotary hoeing effectively controls many small seeded annual weeds in the presence of crop residue and thus can reduce the need for tillage in organic-cropping systems.

Rollers crimpers have been used in conservation agriculture to terminate cover crops; however, excessive vibration generated by the original straight-bar roller design has delayed adoption of this technology in the United States. To avoid excessive vibration, producers generally reduce operating speeds that increase the time needed to perform the field operation. The objectives of this research were to identify roller crimper designs that terminated rye cover crops consistently, resulted in soil moisture conservation after use, and minimized vibrations when operated in the field. Six different roller types were developed and tested at 3.2 and 6.4 km h−1 in Alabama field experiments during the 2006, 2007 and 2008 growing seasons. All roller types were used alone and one also in combination with glyphosate. Rye mortalities were evaluated 1, 2 and 3 weeks after rolling and compared with the check (non-rolled standing rye). Soil volumetric moisture content (VMC) was measured at the day of rolling, and then at 1, 2 and 3 weeks after rolling. Vibration was measured on the rollers' and tractor's frames during operation. Mortality for rolled rye 2 weeks after rolling was at least 98% compared with 96% for the check in 2006, 93% for rolling compared with 75% for the check in 2007, and 94% for rolling compared with 60% for the check in 2008 (P<0.10). There were no consistent differences in rye mortality across roller types (without glyphosate) and speeds. VMC for soil in non-rolled rye plots was consistently lower than in rolled rye plots, averaging 3% compared with 7% 2 weeks after rolling in 2006, and 4% compared with 8% in 2008. During 2007, VMC was affected by severe drought conditions, and differences between roller treatments were detected but minor. The straight-bar roller generated the highest vibration on the tractor's frame at 6.4 km h−1 (0.71 m s−2, RMS), which exceeded International Standards (International Standard Office (ISO)). At 6.4 km h−1, new roller designs generated significantly lower acceleration levels from 0.12 to 0.32 m s−2 on the tractor's frame and were below detrimental effects on health ‘health limits’ classified by ISO. Overall, 2 weeks after rolling, all roller designs effectively terminated rye above 90%, which is the recommended termination level of rye to plant a cash crop into residue mat, while protecting soil surface from water loss. New roller designs generate less vibration than the original design and can be used safely at higher operating speeds.