Weed Suppression in Cover Crop Monocultures and Mixtures

Weed Science ◽  
2017 ◽  
Vol 66 (1) ◽  
pp. 121-133 ◽  
Author(s):  
Barbara Baraibar ◽  
Mitchell C. Hunter ◽  
Meagan E. Schipanski ◽  
Abbe Hamilton ◽  
David A. Mortensen
Keyword(s):  
Ecosystem Services ◽  
Cover Crops ◽  
Cover Crop ◽  
Biomass Accumulation ◽  
Weed Suppression ◽  
Species Selection ◽  
Grass Species ◽  
Weed Seed ◽  
Crop Species ◽  
Cereal Rye

Interest in planting mixtures of cover crop species has grown in recent years as farmers seek to increase the breadth of ecosystem services cover crops provide. As part of a multidisciplinary project, we quantified the degree to which monocultures and mixtures of cover crops suppress weeds during the fall-to-spring cover crop growing period. Weed-suppressive cover crop stands can limit weed seed rain from summer- and winter-annual species, reducing weed population growth and ultimately weed pressure in future cash crop stands. We established monocultures and mixtures of two legumes (medium red clover and Austrian winter pea), two grasses (cereal rye and oats), and two brassicas (forage radish and canola) in a long fall growing window following winter wheat harvest and in a shorter window following silage corn harvest. In fall of the long window, grass cover crops and mixtures were the most weed suppressive, whereas legume cover crops were the least weed suppressive. All mixtures also effectively suppressed weeds. This was likely primarily due to the presence of fast-growing grass species, which were effective even when they were seeded at only 20% of their monoculture rate. In spring, weed biomass was low in all treatments due to winter kill of summer-annual weeds and low germination of winter annuals. In the short window following silage corn, biomass accumulation by cover crops and weeds in the fall was more than an order of magnitude lower than in the longer window. However, there was substantial weed seed production in the spring in all treatments not containing cereal rye (monoculture or mixture). Our results suggest that cover crop mixtures require only low seeding rates of aggressive grass species to provide weed suppression. This creates an opportunity for other species to deliver additional ecosystem services, though careful species selection may be required to maintain mixture diversity and avoid dominance of winter-hardy cover crop grasses in the spring.

scholarly journals Ecosystem Services and Cash Crop Tradeoffs of Summer Cover Crops in Northern Region Organic Vegetable Rotations

2021 ◽  
Vol 5 ◽  
Author(s):  
Vivian M. Wauters ◽  
Julie M. Grossman ◽  
Anne Pfeiffer ◽  
Rodrigo Cala
Keyword(s):  
Ecosystem Services ◽  
Crop Yield ◽  
Cover Crops ◽  
Cover Crop ◽  
Biomass Accumulation ◽  
Weed Suppression ◽  
Soil Protection ◽  
Total Biomass ◽  
Cash Crop ◽  
Vegetable Farming

Intensive production practices characterizing vegetable farming contribute to high productivity, but often at the expense of supporting and regulating ecosystem services. Diversification with cover crops may support increased resilience through soil organic matter (SOM) contributions and physical soil protection. Vegetable farming often includes spring and fall production, limiting establishment and productive potential of over-wintered cover crops that are more widely used in the USA. In northern climate vegetable systems, warm-season cover crops planted during short summer fallows could be a tool to build resilience via ecosystem service enhancement. This project evaluated summer cover crops in the northern USA (MN and WI) for biomass accumulation, weed suppression, and contribution to fall cash crop yield. Our study included four site years, during which we investigated the effects of four cover crop species treatments, grown for 30 (short duration, SD) or 50 days (long duration, LD) alongside bare fertilized and unfertilized control treatments: buckwheat (Fagopyrum esculentum) and sunn hemp (Crotalaria juncea) monocultures, and biculture of chickling vetch (Lathyrus sativus) or cowpea (Vigna unguiculata) with sorghum-sudangrass (sudex) (Sorghum bicolor x S. bicolor var. Sudanese). To quantify cover crop quantity, quality, and weed suppression capacity, we measured cover crop and weed biomass, and biomass C:N. To quantify effects on cash crops, we measured fall broccoli yield and biomass. Mean total biomass (cover crop + weeds) by site year ranged from 1,890 kg ha−1 in MN Y1 to 5,793 kg ha−1 in WI Y2 and varied among species in Y1 for both the SD and LD treatments. Most cover crops did not outcompete weeds, but treatments with less weeds produced more overall biomass. Data from Y1 show that cover crops were unable to replace fertilizer for fall broccoli yield, and led to reduced fall crop yield. Broccoli in Y2 did not reach maturity due to fall freeze. Summer cover crops, because of their biomass accumulation potential, may be used by farmers in northern climates to fit into cropping system niches that have historically been left as bare soil, but care with timing is necessary to optimize weed suppression and mitigate tradeoffs for cash crop production.

scholarly journals 008 Evaluation of Weed Control in a No-tillage Vegetable Production System

HortScience ◽  
1999 ◽  
Vol 34 (3) ◽  
pp. 442B-442
Author(s):  
Christine Crosby ◽  
Hector Valenzuela ◽  
Bernard Kratky ◽  
Carl Evensen
Keyword(s):  
Weed Control ◽  
Cover Crops ◽  
Cover Crop ◽  
Weed Suppression ◽  
Grass Species ◽  
No Tillage ◽  
Vegetable Crops ◽  
Seeding Rate ◽  
Crop Species ◽  
Weed Growth

In the tropics, weed control is a year-round concern. The use of cover crops in a conservation tillage system allows for the production of a crop biomass that can be killed and mowed, and later used as mulching material to help reduce weed growth. This study compared yields of three vegetable species grown in two conventional tillage systems, one weeded and one unweeded control, and in two no-tillage treatments using two different cover crop species, oats (Avena sativa L. `Cauyse') and rye grain (Secale cereale L.). The cover crops were seeded (112 kg/ha) in Spring 1998 in 4 × 23-m plots in a RCB design with six replications per treatment, and mowed down at the flowering stage before transplanting the seedlings. Data collection throughout the experimental period included quadrant weed counts, biomass levels, and crop marketable yields. Weed suppression was compared with the yields of the vegetable crops. The greatest vegetable yields were in the conventionally hand-weeded control and the worst in the un-weeded controls. Weed species composition varied depending on the cover crop species treatment. The rye better suppressed weed growth than the oats, with greater control of grass species. Rye, however, suppressed romaine and bell pepper yields more than the oat treatments. Similarly greater eggplant yields and more fruit per plant were found in the oat treatment than in the rye. Both cover crops suppressed weed growth for the first month; however, by the second month most plots had extensive weed growth. This study showed that at the given cover crop seeding rate, the mulch produced was not enough to reduce weed growth and provide acceptable yields of various vegetable crops.

Integration of residual herbicides with cover crop termination in soybean

2019 ◽  
Vol 34 (1) ◽  
pp. 11-18 ◽  
Author(s):  
Derek M. Whalen ◽  
Lovreet S. Shergill ◽  
Lyle P. Kinne ◽  
Mandy D. Bish ◽  
Kevin W. Bradley
Keyword(s):  
Weed Control ◽  
Cover Crops ◽  
Cover Crop ◽  
Biomass Accumulation ◽  
Field Studies ◽  
Italian Ryegrass ◽  
Cereal Rye ◽  
Herbicide Treatments ◽  
Residual Herbicide ◽  
Herbicide Programs

AbstractCover crops have increased in popularity in midwestern U.S. corn and soybean systems in recent years. However, little research has been conducted to evaluate how cover crops and residual herbicides are effectively integrated together for weed control in a soybean production system. Field studies were conducted in 2016 and 2017 to evaluate summer annual weed control and to determine the effect of cover crop biomass on residual herbicide reaching the soil. The herbicide treatments consisted of preplant (PP) applications of glyphosate plus 2,4-D with or without sulfentrazone plus chlorimuron at two different timings, 21 and 7 d prior to soybean planting (DPP). Cover crops evaluated included winter vetch, cereal rye, Italian ryegrass, oat, Austrian winter pea, winter wheat, and a winter vetch plus cereal rye mixture. Herbicide treatments were applied to tilled and nontilled soil without cover crop for comparison. The tillage treatment resulted in low weed biomass at all collection intervals after both application timings, which corresponded to tilled soil having the highest sulfentrazone concentration (171 ng g−1) compared with all cover crop treatments. When applied PP, herbicide treatments applied 21 DPP with sulfentrazone had greater weed (93%) and waterhemp (89%) control than when applied 7 DPP (60% and 69%, respectively). When applied POST, herbicide treatments with a residual herbicide resulted in greater weed and waterhemp control at 7 DPP (83% and 77%, respectively) than at 21 DPP (74% and 61%, respectively). Herbicide programs that included a residual herbicide had the highest soybean yields (≥3,403 kg ha−1). Results from this study indicate that residual herbicides can be effectively integrated either PP or POST in conjunction with cover crop termination applications, but termination timing and biomass accumulation will affect the amount of sulfentrazone reaching the soil.

scholarly journals Systemic Colonization by Metarhizium robertsii Enhances Cover Crop Growth

2020 ◽  
Vol 6 (2) ◽  
pp. 64
Author(s):  
Imtiaz Ahmad ◽  
María del Mar Jiménez-Gasco ◽  
Dawn S. Luthe ◽  
Mary E. Barbercheck
Keyword(s):  
Cover Crops ◽  
Cover Crop ◽  
Field Experiments ◽  
Negative Relationship ◽  
Crop Growth ◽  
Above Ground Biomass ◽  
Crop Species ◽  
Metarhizium Robertsii ◽  
Cereal Rye ◽  
Ground Biomass

Fungi in the genus Metarhizium (Hypocreales: Clavicipitaceae) are insect pathogens that can establish as endophytes and can benefit their host plant. In field experiments, we observed a positive correlation between the prevalence of M. robertsii and legume cover crops, and a negative relationship with brassicaceous cover crops and with increasing proportion of cereal rye in mixtures. Here, we report the effects of endophytic M. robertsii on three cover crop species under greenhouse conditions. We inoculated seeds of Austrian winter pea (Pisum sativum L., AWP), cereal rye (Secale cereale L.), and winter canola (Brassica napus L.) with conidia of M. robertsii to assess the effects of endophytic colonization on cover crop growth. We recovered M. robertsii from 59%, 46%, and 39% of seed-inoculated AWP, cereal rye, and canola plants, respectively. Endophytic M. robertsii significantly increased height and above-ground biomass of AWP and cereal rye but did not affect chlorophyll content of any of the cover crop species. Among inoculated plants from which we recovered M. robertsii, above-ground biomass of AWP was positively correlated with the proportion of colonized root but not leaf tissue sections. Our results suggest that winter cover crops may help to conserve Metarhizium spp. in annual cropping systems.

scholarly journals Cover Crop Effectiveness Varies in Cover Crop-Based Rotational Tillage Organic Soybean Systems Depending on Species and Environment

Agronomy ◽  
2019 ◽  
Vol 9 (6) ◽  
pp. 319 ◽  
Author(s):  
Laura Vincent-Caboud ◽  
Léa Vereecke ◽  
Erin Silva ◽  
Joséphine Peigné
Keyword(s):  
Cover Crops ◽  
Weed Management ◽  
Cover Crop ◽  
Crop Yields ◽  
Weed Suppression ◽  
Future Research ◽  
Weed Biomass ◽  
Cereal Rye ◽  
Cereal Grain ◽  
Crop Biomass

Organic farming relies heavily on tillage for weed management, however, intensive soil disturbance can have detrimental impacts on soil quality. Cover crop-based rotational tillage (CCBRT), a practice that reduces the need for tillage and cultivation through the creation of cover crop mulches, has emerged as an alternative weed management practice in organic cropping systems. In this study, CCBRT systems using cereal rye and triticale grain species are evaluated with organic soybean directly seeded into a rolled cover crop. Cover crop biomass, weed biomass, and soybean yields were evaluated to assess the effects of cereal rye and winter triticale cover crops on weed suppression and yields. From 2016 to 2018, trials were conducted at six locations in Wisconsin, USA, and Southern France. While cover crop biomass did not differ among the cereal grain species tested, the use of cereal rye as the cover crop resulted in higher soybean yields (2.7 t ha−1 vs. 2.2 t ha−1) and greater weed suppression, both at soybean emergence (231 vs. 577 kg ha−1 of weed biomass) and just prior to soybean harvest (1178 vs. 1545 kg ha−1). On four out of six sites, cover crop biomass was lower than the reported optimal (<8000 kg ha−1) needed to suppress weeds throughout soybean season. Environmental conditions, in tandem with agronomic decisions (e.g., seeding dates, cultivar, planters, etc.), influenced the ability of the cover crop to suppress weeds regardless of the species used. In a changing climate, future research should focus on establishing flexible decision support tools based on multi-tactic cover crop management to ensure more consistent results with respect to cover crop growth, weed suppression, and crop yields.

scholarly journals Carryover of Common Corn and Soybean Herbicides to Various Cover Crop Species

2017 ◽  
Vol 31 (1) ◽  
pp. 21-31 ◽  
Author(s):  
Cody D. Cornelius ◽  
Kevin W. Bradley
Keyword(s):  
Cover Crops ◽  
Cover Crop ◽  
Production Systems ◽  
Italian Ryegrass ◽  
Hairy Vetch ◽  
Crop Species ◽  
Cereal Rye ◽  
Crimson Clover ◽  
Crop Establishment ◽  
Biomass Reduction

The recent interest in cover crops as component of Midwest corn and soybean production systems has led to the need for additional research, including the effects of residual corn and soybean herbicide treatments on fall cover crop establishment. Field studies were conducted in 2013, 2014, and 2015 in Columbia, Missouri to investigate the effects of common residual herbicides applied in corn and soybean on establishment of winter wheat, tillage radish, cereal rye, crimson clover, winter oat, Austrian winter pea, Italian ryegrass, and hairy vetch. Cover crops were evaluated for stand and biomass reduction 28 d after emergence (DAE). Rainfall from herbicide application to cover crop seeding date was much greater in 2014 and 2015, which resulted in less carryover in these years compared to 2013. When averaged across all herbicides evaluated in these experiments, the general order of sensitivity of cover crops to herbicide carryover, from greatest to least was Austrian winter pea=crimson clover>oilseed radish>Italian ryegrass>hairy vetch>wheat >winter oat>cereal rye. Cereal rye had the fewest instances of biomass or stand reduction with only four out of the 27 herbicides adversely effecting establishment. Pyroxasulfone consistently reduced Italian ryegrass and winter oat biomass at least 67% in both the corn and soybean experiments. In the soybean experiment, imazethapyr- and fomesafen-containing products resulted in severe stand and biomass reduction in both years while flumetsulam-containing products resulted in the greatest carryover symptoms in the corn experiment. Results from these experiments suggest that several commonly used corn and soybean herbicides have the potential to hinder cover crop establishment, but the severity of damage will depend on weather, cover crop species, and the specific herbicide combination.

Drill and broadcast establishment methods influence interseeded cover crop performance in organic corn

2020 ◽  
pp. 1-9 ◽  
Author(s):  
John M. Wallace ◽  
Sarah Isbell ◽  
Ron Hoover ◽  
Mary Barbercheck ◽  
Jason Kaye ◽  
...  
Keyword(s):  
Cover Crops ◽  
Cover Crop ◽  
Weed Suppression ◽  
Organic Farms ◽  
N Retention ◽  
Cereal Rye ◽  
Post Harvest ◽  
Organic Systems ◽  
Winter Fallow ◽  
Corn Grain

Abstract 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.

Herbicide selection to terminate grass, legume, and brassica cover crop species

2019 ◽  
Vol 34 (1) ◽  
pp. 48-54
Author(s):  
Kara B. Pittman ◽  
Charles W. Cahoon ◽  
Kevin W. Bamber ◽  
Lucas S. Rector ◽  
Michael L. Flessner
Keyword(s):  
Active Ingredient ◽  
Cover Crops ◽  
Cover Crop ◽  
Field Studies ◽  
Weed Suppression ◽  
Hairy Vetch ◽  
Crop Species ◽  
Rating Data ◽  
Crimson Clover ◽  
And Control

AbstractCover crops provide a number of agronomic benefits, including weed suppression, which is important as cases of herbicide resistance continue to rise. To effectively suppress weeds, high cover crop biomass is needed, which necessitates later termination timing. Cover crop termination is important to mitigate potential planting issues and prevent surviving cover crop competition with cash crops. Field studies were conducted in Virginia to determine the most effective herbicide options alone or combined with glyphosate or paraquat to terminate a range of cover crop species. Results revealed that grass cover crop species were controlled (94% to 98%) by glyphosate alone 4 wk after application (WAA). Overall, legume species varied in response to the single active-ingredient treatments, and control increased with the addition of glyphosate or paraquat. Mixes with glyphosate provided better control of crimson clover and hairy vetch by 7% to 8% compared with mixes containing paraquat 4 WAA. Mix partner did not influence control of Austrian winter pea. No treatment adequately controlled rapeseed in this study, with a maximum of 58% control observed with single active-ingredient treatments and 62% control with mixes. Height reduction for all cover crop species supports visible rating data. Rapeseed should be terminated when smaller, which could negate weed suppressive benefits from this cover crop species. Growers should consider herbicide selection and termination timing in their cover crop plan to ensure effective termination.

Herbicide Programs for the Termination of Various Cover Crop Species

2017 ◽  
Vol 31 (4) ◽  
pp. 514-522 ◽  
Author(s):  
Cody D. Cornelius ◽  
Kevin W. Bradley
Keyword(s):  
Cover Crops ◽  
Cover Crop ◽  
Field Experiments ◽  
Crop Yields ◽  
Production Systems ◽  
Annual Ryegrass ◽  
Crop Species ◽  
Cereal Rye ◽  
Crimson Clover ◽  
Herbicide Treatments

The recent interest in cover crops as a component of Midwest corn and soybean production systems has led to a greater need to understand the most effective herbicide treatments for cover crop termination prior to planting corn or soybean. Previous research has shown that certain cover crop species can significantly reduce subsequent cash crop yields if not completely terminated. Two field experiments were conducted in 2013, 2014, and 2015 to determine the most effective herbicide program for the termination of winter wheat, cereal rye, crimson clover, Austrian winter pea, annual ryegrass, and hairy vetch; and cover crops were terminated in early April or early May. Visual control and above ground biomass reduction was determined 28 d after application (DAA). Control of grass cover crop species was often best with glyphosate alone or combined with 2,4-D, dicamba, or saflufenacil. The most consistent control of broadleaf cover crops occurred following treatment with glyphosate +2,4-D, dicamba, or saflufenacil. In general, control of cover crops was higher with early April applications compared to early May. In a separate study, control of 15-, 25-, and 75-cm tall annual ryegrass was highest with glyphosate at 2.8 kg ha−1or glyphosate at 1.4 kg ha−1plus clethodim at 0.136 kgha−1. Paraquat- or glufosinate-containing treatments did not provide adequate annual ryegrass control. For practitioners who desire higher levels of cover crop biomass, these results indicate that adequate levels of cover crop control can still be achieved in the late spring with certain herbicide treatments. But it is important to consider cover crop termination well in advance to ensure the most effective herbicide or herbicide combinations are used and the products are applied at the appropriate stage.

Timing of Cover-Crop Management Effects on Weed Suppression in No-Till Planted Soybean using a Roller-Crimper

Weed Science ◽  
2011 ◽  
Vol 59 (3) ◽  
pp. 380-389 ◽  
Author(s):  
S. B. Mirsky ◽  
W. S. Curran ◽  
D. M. Mortenseny ◽  
M. R. Ryany ◽  
D. L. Shumway
Keyword(s):  
Weed Management ◽  
Cover Crop ◽  
Crop Management ◽  
Biomass Accumulation ◽  
Weed Suppression ◽  
Hairy Vetch ◽  
Cereal Rye ◽  
No Till ◽  
Termination Date ◽  
Crop Biomass

Integrated weed management tactics are necessary to develop cropping systems that enhance soil quality using conservation tillage and reduced herbicide or organic weed management. In this study, we varied planting and termination date of two cereal rye cultivars (‘Aroostook’ and ‘Wheeler’) and a rye/hairy vetch mixture to evaluate cover-crop biomass production and subsequent weed suppression in no-till planted soybean. Cover crops were killed with a burn-down herbicide and roller-crimper and the weed-suppressive effects of the remaining mulch were studied. Cover-crop biomass increased approximately 2,000 kg ha−1from latest to earliest fall planting dates (August 25–October 15) and for each 10-d incremental delay in spring termination date (May 1–June 1). Biomass accumulation for cereal rye was best estimated using a thermal-based model that separated the effects of fall and spring heat units. Cultivars differed in their total biomass accumulation; however, once established, their growth rates were similar, suggesting the difference was mainly due to the earlier emergence of Aroostook rye. The earlier emergence of Aroostook rye may have explained its greater weed suppression than Wheeler, whereas the rye/hairy vetch mixture was intermediate between the two rye cultivars. Delaying cover-crop termination reduced weed density, especially for early- and late-emerging summer annual weeds in 2006. Yellow nutsedge was not influenced by cover-crop type or the timing of cover-crop management. We found that the degree of synchrony between weed species emergence and accumulated cover-crop biomass played an important role in defining the extent of weed suppression.

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