Increased seeding rate and multiple methods of mechanical weed control reduce weed biomass in a poorly competitive organic crop

Concern over the development of herbicide-resistant weeds has led to interest in integrated weed management systems that reduce selection pressure by utilizing mechanical and cultural weed control practices in addition to herbicides. Increasing crop seeding rate increases crop competitive ability and thus can enhance herbicide efficacy. However, it is unknown how increasing the seeding rate affects an herbicide’s efficacy. The objective of this study was to examine the interaction between increasing seeding rate and herbicide dose to control weeds. To meet this objective, the herbicide fluthiacet-methyl was applied to field-grown lentil, with Indian mustard, a proxy for wild mustard, used as a model weed. The experiment was a factorial design with four lentil seeding rates and seven herbicide rates. Overall the herbicide dose response was altered by changing lentil seeding rate. Increasing lentil seeding rate decreased the weed biomass production when herbicides were not applied. In two of the four site-years, increasing lentil seeding rate lowered the herbicide ED50, the dose required to result in a 50% reduction in weed biomass. Increasing the crop seeding rate altered the dose response to provide greater weed control at lower herbicide rates compared with normal crop seeding rates. Increased seeding rates also resulted in higher and more stable crop seed yields across a wider range of herbicide dosages. These results suggest that dose–response models can be used to evaluate the efficacy of other weed management practices that can interact with herbicide performance.

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Pinto Bean Response to Seeding Rate and Herbicides

Weed Technology ◽

10.1017/wet.2020.137 ◽

2020 ◽

pp. 1-15

Author(s):

Kathrin D. LeQuia ◽

Don W. Morishita ◽

Olga S. Walsh ◽

Albert T. Adjesiwor

Keyword(s):

Weed Control ◽

Field Experiments ◽

Block Design ◽

Cultural Practice ◽

Control Treatment ◽

Seeding Rate ◽

Weed Biomass ◽

Pinto Bean ◽

Bean Yield ◽

Herbicide Programs

Abstract 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 were 5 by 5 factorial randomized complete block design with five replications. The weed control treatments comprised a non-treated 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 247000 to 494000 seeds ha-1 planted in 19-cm rows. Weed biomass was reduced by 6 kg ha-1 with every additional 1000 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 3.08 Mg ha-1 in the nontreated control to 4.74 Mg 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.

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Intercropping organic field peas with barley, oats and mustard improves weed control but has variable effects on grain yield and net returns

Canadian Journal of Plant Science ◽

10.1139/cjps-2021-0182 ◽

2021 ◽

Author(s):

Will Bailey-Elkin ◽

Michelle K. Carkner ◽

Martin Entz

Keyword(s):

Grain Yield ◽

Weed Control ◽

Yield Loss ◽

Weed Suppression ◽

Field Pea ◽

Separate Experiment ◽

Seeding Rate ◽

Weed Biomass ◽

Net Return ◽

Field Peas

Interest in intercropping semi-leafless field peas (Pisum sativum L.) is increasing as a means of weed control in organic production. We evaluated field pea (cv. CDC Amarillo) grown alone or intercropped with three seeding rates of either barley (Hordeum vulgare L.), mustard (Brassica juncea L.), or oats (Avena sativa L.). A full seeding rate of field pea was used in each instance, resulting in an additive intercropping design. Each crop combination was conducted in a separate experiment, three times over two years (2019 and 2020) in Carman, Manitoba. Measurements included crop and weed biomass production, grain yield and quality, and net return. Intercrops reduced weed biomass at maturity from 17 to 44% with barley and oats being more suppressive than mustard. Intercrops also reduced field pea yield from 6 to 26%, but increased field pea seed mass. Barley at the high seeding rate provided the most weed suppression per unit of field pea yield loss (2.62 kg of weed suppression per kg of field pea yield loss) compared with oat (1.29) and mustard (0.87). Barley and mustard intercrops decreased net return compared to monoculture field pea. Under low weed pressure (1150 kg ha-1 weed biomass at maturity) and earlier seeding, oat intercrops reduced net return. However, under weedy conditions (2649 kg ha-1) and later seeding, field pea-oat intercrops significantly increased net return. In conclusion, while all three intercrop mixtures reduced weed biomass, reductions in field pea yields were observed, and net return benefits were observed only in certain circumstances.

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Optimisation of Weed Control in Organic Processing Spinach (Spinacia oleracea L.): Impacts of Cultivar, Seeding Rate, Plant Spacing and Integrated Weed Management Strategy

Agronomy ◽

10.3390/agronomy11010053 ◽

2020 ◽

Vol 11 (1) ◽

pp. 53

Author(s):

Benny De Cauwer ◽

Lieven Delanote ◽

Michaël Devos ◽

Sander De Ryck ◽

Dirk Reheul

Keyword(s):

Growth Rate ◽

Weed Control ◽

Weed Management ◽

Management Strategy ◽

Growth Habit ◽

Integrated Weed Management ◽

Plant Spacing ◽

Seeding Rate ◽

Weed Biomass ◽

The Impact

Weed control in organic spinach for the processing market is challenging because of the low tolerance of weed contamination in the harvested produce and the limited physical weeding options. Optimisation of weed control systems is therefore urgently needed. Three field experiments with autumn spinach were carried out in organic fields to evaluate the impact of cultivar choice, seeding rate (300 and 400 seeds m−2), plant spacing management (10.5-cm-wide single rows and 21-cm-wide single or twin rows) and integrated weed management strategy (combinations of pre-sowing, pre-emergence and post-emergence tactics) on weed biomass and spinach yield and quality. Spinach cultivars with a planophile growth habit and a high growth rate were more weed suppressive than the cultivar with an erectophile growth habit and a slower growth rate. Spinach density was significantly negatively correlated with weed biomass and weed biomass fraction in the harvested produce, but significantly positively correlated with (marketable) spinach biomass and petiole fraction in the harvested produce. Narrow row spacing systems with post-emergence broadcast harrowing had the lowest weed biomass and weed biomass fraction but also the lowest (marketable) spinach biomass as a result of the thinning action of harrowing. Post-emergence harrowing is of key importance for reducing weed biomass in any integrated weed control strategy. Weediness was lowest in systems comprising flaming on false seedbed or in pre-emergence followed by post-emergence harrowing. To mitigate the risk of crop failure, the field should preferably be cropped with quickly growing spinach plants arranged in narrow spaced rows at high plant density and weeded by pre-sowing or pre-emergence flaming followed by post-emergence harrowing.

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Cultural Practices and Mechanical Weed Control for the Management of a Low-Diversity Weed Community in Spinach

Diversity ◽

10.3390/d13120616 ◽

2021 ◽

Vol 13 (12) ◽

pp. 616

Author(s):

Ioannis Gazoulis ◽

Panagiotis Kanatas ◽

Nikolaos Antonopoulos

Keyword(s):

Weed Control ◽

Weed Management ◽

Cultural Practices ◽

Spinacia Oleracea ◽

Row Spacing ◽

Weed Biomass ◽

Weed Communities ◽

Spinacia Oleracea L ◽

Low Diversity ◽

Mechanical Weed Control

Low-diversity weed communities are dominated by few species that are highly competitive to crops. The management of such weed communities should rely upon sustainable cultural and non-chemical practices, especially in crops such as spinach (Spinacia oleracea L.), where very few herbicides are available. A two-year field trial (2020 and 2021) was conducted to evaluate different fertilization practices (broadcast and banded), intra-row spacings (15 cm, 11 cm, 7 cm), and mechanical weed control treatments (untreated, one treatment, two treatments) for the management of a low-diversity weed community in spinach. Weed competition severely affected spinach commercial biomass (R2 = 0.845). Compared to broadcast fertilization, banded fertilization reduced weed biomass and improved spinach yield and nitrogen use efficiency. Narrow intra-row spacing (7-cm) reduced weed biomass by 28 and 45% compared to intra-row spacings of 11-cm and 15-cm, respectively. Two mechanical weed control treatments resulted in 49% lower weed biomass compared to a single treatment. Commercial biomass increased with decreasing intra-row spacing (R2 = 0.881) and increasing the number of mechanical treatments (R2 = 0.911). More cultural and non-chemical practices should be evaluated for weed management in spinach, especially at sites infested with low-diversity weed communities.

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Economic evaluation of different strategy for weed management in garlic production

Zbornik Veleučilišta u Rijeci ◽

10.31784/zvr.8.1.5 ◽

2020 ◽

Vol 8 (1) ◽

pp. 445-454

Author(s):

Edita Štefanić ◽

Đorđe Maletić ◽

Dinko Zima ◽

Ivan Štefanić

Keyword(s):

Weed Control ◽

Weed Management ◽

Block Design ◽

Ambrosia Artemisiifolia ◽

Management Options ◽

Chemical Application ◽

Weed Biomass ◽

Weed Density ◽

Density And Biomass ◽

Mechanical Weed Control

A field experiment was conducted to evaluate various weed management options on garlic (Alium sativum L.) production in Northeastern Croatia. This study focus on how different strategies of weed control affects weed community composition and economic benefit of weed management. An experiment was arranged as a complete block design with three different weed management strategies: chemical control (PRE EM and POST EM), mechanical control (three times during the season), and combination of chemical and mechanical treatments, together with weeded checks. Data on weed density, fresh above weed biomass and garlic yield per m2 were collected at the end of the growing season, and were subjected to statistical and economic analysis. The mayor weeds found in the experimental plots were: Sorghum halepense, Ambrosia artemisiifolia, Cirsium arvense and Chenopodium album. The various weed growth (density and biomass) and yield varied with application of weed management practices. Significantly lower values of weed density and fresh above weed biomass were recorded on plots with mechanical and combination of chemical and mechanical treatments compared to weeded check. Chemical application gave in this study insufficient weed control and resulted in lower yields compared to the mechanical treatments and combination of mechanical and mechanical weed control. The best cost: benefit ratio was observed on treatment with combination of chemical and mechanical weed control and can be successfully applied to boost up the bulb yield in garlic and to harvest the maximum profit for farmers.

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Effects of mechanical weed control in organic soybean cultivation on weed biomass and diversity in Luxembourg

10.5194/egusphere-egu2020-7564 ◽

2020 ◽

Author(s):

David Richard ◽

Laura Leimbrock ◽

Gilles Rock ◽

René Diederich ◽

Guy Reiland ◽

...

Keyword(s):

Weed Control ◽

Protein Production ◽

Field Trials ◽

Negative Control ◽

Shannon Index ◽

Grain Legume ◽

Weed Biomass ◽

Mechanical Methods ◽

Weed Diversity ◽

Mechanical Weed Control

With a high protein content (&#177; 40 %) and an optimal amino acid composition, soybean (Glycine max (L.) Merr.), a member of the family Leguminosae, is one of the most important feed protein sources in animal nutrition. By signing the European Soy Declaration in 2017, Luxembourg aims to promote the regional cultivation of protein crops, e.g. soybean. Organic soybean cultivation in Luxembourg is still in its initial stage, with knowledge gaps mainly in mechanical weed control. The aim of the project &#8220;Sustainable and resource-efficient protein production using various mechanical weed control methods in grain legume cultivation, using soybean as an example&#8221; (LeguTec) is to investigate the efficiency of the selected mechanical systems under consideration of, inter alia, weed biomass.In 2018 and 2019, field trials took place on two organic farms in Luxembourg (in Manternach and Hostert). Five mechanical methods were tested in soybean cultivation (variety Merlin), including A) harrow, B) interrow cultivator with duck-foot shares, C) interrow cultivator with duck-foot shares and finger-weeder, D) a combination of treatments A and C, and E) mixed cropping of soybean and camelina in combination with harrow. A positive control F) weeded by hand and a negative control G) not weeded are also implemented. Field trials were set as one-factorial-exact-trial with four replicates. Weeds were counted and identified and biomass cut before and after each weed control run as well as at flowering. Weed diversity was estimated by means of the Shannon index.&#160; Data were analysed using ANOVA (p<0.05) and appropriated pairwise comparison Tuckey tests.In 2018, significant less weed biomass is observed in Hostert for D in comparison to A and E, and for B, C and D in comparison to A and E, in 2019. Biomass in Manternach in 2019 is significantly lower in treatment D. Globally, weed biomass at flowering tends to be lower in the hoeing treatments (B, C and D) than in the harrowing treatments. High weed pressure from the beginning on in all treatments in Hostert has limited the efficiency of weeding but with a tendency in favour of the interrow cultivator. &#160;At the Manternach site, weed pressure was low in 2018, allowing good regulation resulting in low diversity in all treatments. Values of the Shannon index tend to be negatively affected by mechanical weeding across all field trials. In 2019, significant lower Shannon index is observed in Hostert for treatments C and D, as well as for treatment C in Manternach. Hoeing generally tends to lower the most weed diversity in addition to weed biomass. Low abundant species were more likely to disappear, while 1 to 4 species became over-dominant in each treatment.The increased interest in regional soybean cultivation in Luxembourg due to the LeguTec project shows the need of further research on soybean cultivation to reach the long-term goal of overcoming cultivation barriers and promoting a sustainable, resource-efficient protein production in Luxembourg.

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Spring-planted cover crops for weed control in soybean

Renewable Agriculture and Food Systems ◽

10.1017/s1742170521000107 ◽

2021 ◽

pp. 1-8

Author(s):

Katja Koehler-Cole ◽

Christopher A. Proctor ◽

Roger W. Elmore ◽

David A. Wedin

Keyword(s):

Weed Control ◽

Biomass Production ◽

Cover Crops ◽

Weed Management ◽

Block Design ◽

Weed Suppression ◽

Crop Species ◽

Cold Temperatures ◽

Weed Biomass ◽

Small Grains

Abstract Replacing tillage with cover crops (CC) for weed management in corn (Zea mays L.)-soybean [Glycine max (L.) Merr.] systems with mechanical weed control has many soil health benefits but in the western Corn Belt, CC establishment after harvest is hampered by cold temperatures, limited labor and few compatible CC species. Spring-planted CC may be an alternative, but information is lacking on suitable CC species. Our objective was to evaluate four spring-planted CC with respect to biomass production and weed suppression, concurrent with CC growth and post-termination. Cover crop species tested were oat (Avena sativa L.), barley (Hordeum vulgare L.), brown mustard [Brassica juncea (L.) Czern.] and yellow mustard (Brassica hirta Moench). They were compared to no-CC treatments that were either tilled pre- and post-planting of soybean (no-CC tilled) or not tilled at all (no-CC weedy). CC were planted in late March to early April, terminated 52–59 days later using an undercutter, and soybean was planted within a week. The experiment had a randomized complete block design with four replications and was repeated for 3 years. Mustards and small grains produced similar amounts of biomass (1.54 Mg ha−1) but mustard biomass production was more consistent (0.85–2.72 Mg ha−1) than that of the small grains (0.35–3.81 Mg ha−1). Relative to the no-CC weedy treatment, mustards suppressed concurrent weed biomass in two out of 3 years, by 31–97%, and small grains suppressed concurrent weed biomass in only 1 year, by 98%. Six weeks after soybean planting, small grains suppressed weed biomass in one out of 3 years, by 79% relative to the no-CC weedy treatment, but mustards did not provide significant weed suppression. The no-CC tilled treatment suppressed weeds each year relative to the no-CC weedy treatment, on average 87%. The ineffective weed control by CC reduced soybean biomass by about 50% six weeks after planting. While spring-planted CC have the potential for pre-plant weed control, they do not provide adequate early season weed suppression for soybean.

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