Weed Management & Sustainable Agriculture

A special issue of Agronomy (ISSN 2073-4395). This special issue belongs to the section "Weed Science and Weed Management".

Deadline for manuscript submissions: closed (31 January 2021) | Viewed by 36261

Special Issue Editors


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Guest Editor
Department of Crop, Soil, and Environmental Sciences, University of Arkansas, Fayetteville, AR, USA
Interests: weed demographics and population dynamics; weed eco-physiological aspects; weed-crop interactions

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Guest Editor
University of Cordoba, Spain
Interests: herbicide resistance; mechanisms of resistance; weed management
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

The sustainability of agriculture can be based on an integrated crop and weed management approach. Consequently, further research is required to improve weed management and evaluate new and more ecologically friendly approaches. For this Special Issue, we invite you to share your studies on weed research. In particular, we are seeking submissions on the following topics: 1) mechanical weed control; 2) non-chemical weed control; 3) ecologically based methods; 4) precision weed control; 5) herbicide-resistant crops and weeds; 6) biological weed control; and 7) integrated weed management. Other aspects of weed research outside these topics are also of interest.

Dr. Ilias Travlos
Dr. Nicholas Korres
Dr. Rafael De Prado
Guest Editors

Manuscript Submission Information

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Keywords

  • weed management
  • ecologically based methods
  • mechanical weed control
  • non-chemical weed control
  • allelopathy
  • precision weed control
  • herbicide-resistant crops and weeds
  • biological weed control
  • integrated weed management

Published Papers (13 papers)

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Research

11 pages, 1839 KiB  
Article
First Report of Amaranthus palmeri S. Wats. in Cotton, Maize and Sorghum in Greece and Problems with Its Management
by Panagiotis Kanatas, Alexandros Tataridas, Vyronas Dellaportas and Ilias Travlos
Agronomy 2021, 11(9), 1721; https://doi.org/10.3390/agronomy11091721 - 28 Aug 2021
Cited by 10 | Viewed by 2260
Abstract
Amaranthus palmeri S. Wats., or commonly Palmer amaranth, is an invasive plant species that has invaded many countries worldwide and causes significant yield losses to annual spring crops. Palmer amaranth biotypes were detected in maize and sorghum fields in Western Greece and cotton [...] Read more.
Amaranthus palmeri S. Wats., or commonly Palmer amaranth, is an invasive plant species that has invaded many countries worldwide and causes significant yield losses to annual spring crops. Palmer amaranth biotypes were detected in maize and sorghum fields in Western Greece and cotton fields in Central Greece in 2020. The infestations were recorded both inside the crops and in the margins of the fields, indicating that Palmer amaranth could be characterized as an invasive weed for these regions and, thus, must be urgently managed. Four biotypes were screened for resistance to 2,4-D and nicosulfuron by using NDVI, canopy cover, photochemical efficiency, plant height and fresh weight values. All biotypes showed resistance to nicosulfuron. Resistance cases to important herbicides (i.e., ALS and synthetic auxins) in spring crops, such as maize and cotton, indicate that management could become even more challenging if farmers do not adopt integrated strategies and tools to manage this weed. The eradication of Palmer amaranth plants is imperative, since it has yet to be dispersed in several agricultural areas of Greece. Palmer amaranth is recommended to be enlisted as quarantine pest for regulation in Greece. Full article
(This article belongs to the Special Issue Weed Management & Sustainable Agriculture)
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19 pages, 1867 KiB  
Article
Altered Nitrogen Availability in Pea–Barley Sole- and Intercrops Changes Dominance of Two Nitrophilic Weed Species
by Ortrud Jäck, James Ajal and Martin Weih
Agronomy 2021, 11(4), 679; https://doi.org/10.3390/agronomy11040679 - 2 Apr 2021
Cited by 9 | Viewed by 2990
Abstract
Effective and sustainable weed management in agricultural fields is a prerequisite for increasing crop yield without negatively impacting the environment. The aim of this study was to explore how varying nitrogen (N) availability in cropping arrangements of pea (Pisum sativum) and [...] Read more.
Effective and sustainable weed management in agricultural fields is a prerequisite for increasing crop yield without negatively impacting the environment. The aim of this study was to explore how varying nitrogen (N) availability in cropping arrangements of pea (Pisum sativum) and barley (Hordeum vulgare) grown as sole crops and intercrops at different fertilization levels and considering different N sources (soil mineralization, N fixation, N fertilizer) affects the response of weed species with differential N responsiveness. Crop and weed biomass were sampled at flowering and maturity. The total N content and 15N isotope signatures were analyzed to differentiate between N sources and to estimate the amount of N available to weeds. The highly N-responsive weed (Chenopodium album) accumulated more N and biomass than the weed with reduced N responsiveness (Galeopsis spp.). Fertilizer supply favored Chenopodium album, but not the crops. Altered soil N availability caused a shift in the dominance of the nitrophilic weed species towards the highly N-responsive species. This shift in dominance could affect the long-term weed community composition and thus have implications for sustainable weed management. Full article
(This article belongs to the Special Issue Weed Management & Sustainable Agriculture)
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13 pages, 1441 KiB  
Article
Demographic Processes Allow Echinochloa crus-galli to Compensate Seed Losses by Seed Predation
by Heike Pannwitt, Paula R. Westerman, Friederike De Mol and Bärbel Gerowitt
Agronomy 2021, 11(3), 565; https://doi.org/10.3390/agronomy11030565 - 17 Mar 2021
Cited by 4 | Viewed by 2068
Abstract
The effect of weed management that targets the seed stage on subsequent life stages is largely unknown. Post-dispersal seed predation reduces the number of seeds from the soil surface before the seeds contribute to the seedbank. Density-dependent processes can mitigate the effect of [...] Read more.
The effect of weed management that targets the seed stage on subsequent life stages is largely unknown. Post-dispersal seed predation reduces the number of seeds from the soil surface before the seeds contribute to the seedbank. Density-dependent processes can mitigate the effect of seed predation in subsequent life stages. In this study, we tested if (i) targeting the seed stage affects the subsequent seedling stage; (ii) if density-dependent mortality in subsequent life stages partly compensates seedling abundance; and (iii) if the magnitude of final seed production depends on seed predation. We fully parameterized a model for the summer-annual weed Echinochloa crus-galli (L.) P. Beauv. Field data from three maize fields in north-eastern Germany were obtained, in the presence or absence of seed predation and different population levels of the weed species. Seeds of E. crus-galli were applied in autumn and the number of seedlings, adult plants, and seed production per m2 was determined the following season. Seed predation reduced the number of seedlings. Density-dependent mortality during the seedling stage increased fecundity with decreasing seedling density, and, thus, compensated for lower numbers of seedlings. The final level of seed production per m2 did not depend on seed predation and initial population densities, but differed among fields. We conclude, solely targeting the seed stage can scarcely limit the population growth of E. crus-galli. Full article
(This article belongs to the Special Issue Weed Management & Sustainable Agriculture)
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17 pages, 716 KiB  
Article
Weed Diversity, Abundance, and Seedbank in Differently Tilled Faba Bean (Vicia faba L.) Cultivations
by Kęstutis Romaneckas, Rasa Kimbirauskienė, Aušra Sinkevičienė, Iwona Jaskulska, Sidona Buragienė, Aida Adamavičienė and Egidijus Šarauskis
Agronomy 2021, 11(3), 529; https://doi.org/10.3390/agronomy11030529 - 11 Mar 2021
Cited by 8 | Viewed by 1906
Abstract
Differently tilled faba bean cultivations, in particular, require a comprehensive study of weed diversity, abundance, and seedbank due to the lack of experimental data. Therefore, in 2016–2018, field trials were conducted at Vytautas Magnus University on the basis of a long-term tillage experiment. [...] Read more.
Differently tilled faba bean cultivations, in particular, require a comprehensive study of weed diversity, abundance, and seedbank due to the lack of experimental data. Therefore, in 2016–2018, field trials were conducted at Vytautas Magnus University on the basis of a long-term tillage experiment. Conventional deep and shallow plowing, deep chiseling, shallow disking, and no-tillage systems were investigated. According to the results of the investigations, the air temperature and amount of precipitation during the vegetative season had a greater influence on the total number of weeds (r = 0.538 and 0.833 p > 0.05) than the types of tillage systems investigated. However, on average, a reduction in tillage intensity did not change the weed number, especially in disked and not tilled plots. On average, the biomass of weeds varied little between the treatments (from 105.9 to 125.7 g m−2) and mainly depended on the volume of forecrop residues (rannual = −0.982 p ≤ 0.01 and rperennial = 0.890 p ≤ 0.05). Higher total weed seedbanks were found in the disked (+43.0%) and not tilled (+21.6%) soils compared to deeply plowed ones. The weed seedbank was almost similarly distributed between the treatments, irrespective of the tillage depth and method used. Full article
(This article belongs to the Special Issue Weed Management & Sustainable Agriculture)
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19 pages, 1764 KiB  
Article
Efficacy of Post-Emergence Herbicides against Important Weeds of Sugarcane in North-East Thailand
by Phitsanu Aekrathok, Patcharin Songsri, Nuntawoot Jongrungklang and Santimaitree Gonkhamdee
Agronomy 2021, 11(3), 429; https://doi.org/10.3390/agronomy11030429 - 26 Feb 2021
Cited by 8 | Viewed by 3761
Abstract
Weeds represent a significant problem in Thailand’s sugarcane production. The various cycles of sugarcane cultivation result in degrees of weed severity in which each species requires a different weed control method, the most popular of which is the post-emergence herbicide method. However, sugarcane [...] Read more.
Weeds represent a significant problem in Thailand’s sugarcane production. The various cycles of sugarcane cultivation result in degrees of weed severity in which each species requires a different weed control method, the most popular of which is the post-emergence herbicide method. However, sugarcane farmers often use incorrect rates, and operators’ safety is missing or applications are not selective, causing toxicity and interrupted growth of sugarcane. The effects of post-emergence herbicide types, time, and application rates are presented herein, through an experiment in Northeast Thailand, conducted in a randomized complete block design (RCBD) with four replications. The herbicides paraquat and ametryn were evaluated, with paraquat being more effective, yet resulting in higher toxicity and lower yield components. We may conclude through our experiments that ametryn and paraquat can be applied only once for sugarcane at the tillering stage and at rates of 540 and 2400 g ai ha−1, respectively. These rates were lower than the recommended rates, which represented the minimum doses necessary to control Thailand’s dominant weed species like Brachiaria distachya (L.) Stapf., Dactyloctenium aegyptium (L.) P.B., Praxelis clematidea R.M King & H. Rob and Pennisetum polystachion (L.) Schult. Consequently, the adequate control of weeds is a rather case-specific situation and therefore each weed species should be taken into account. Full article
(This article belongs to the Special Issue Weed Management & Sustainable Agriculture)
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11 pages, 1027 KiB  
Article
Can Hydromulch Reduce the Emergence of Perennial Weeds?
by Maria Teresa Mas, Gabriel Pardo, Jorge Pueyo, Antoni M. C. Verdú and Alicia Cirujeda
Agronomy 2021, 11(2), 393; https://doi.org/10.3390/agronomy11020393 - 23 Feb 2021
Cited by 4 | Viewed by 2212
Abstract
Herbicide weed control is difficult in the first years of perennial crop establishment or in minor crops, and plastic sheet mulches can leave persistent residues. Liquid spray-on mulch (hydromulch) might be a solution in these cases. To test three hydromulch formulations on perennial [...] Read more.
Herbicide weed control is difficult in the first years of perennial crop establishment or in minor crops, and plastic sheet mulches can leave persistent residues. Liquid spray-on mulch (hydromulch) might be a solution in these cases. To test three hydromulch formulations on perennial weed emergence, greenhouse assays were conducted for two years in two localities to evaluate their rhizome sprouting and shoot emergence. Data, obtained from a completely randomized block design, were analyzed by means of generalized linear mixed models with binomial distribution and logit link function; the effects of hydromulch, species, and their interaction were considered fixed, while the other sources of variation (i.e., locality, year, block and rhizome length) were considered random. All three hydromulches, based on wheat straw, rice husk, and used substrate for mushroom cultivation, were capable of reducing rhizome sprouting of all four species tested when compared to the non-mulched treatment. Many rhizomes sprouted but were trapped under the mulch layer, especially those of Paspalum dilatatum (87%), Cynodon dactylon, and Sorghum halepense (around 50%), while Cyperus rotundus was least affected by the hydromulch treatments (16%). All three blends showed promising results in the reduction of perennial weed emergence, warranting field trials to test combined weed management strategies. Full article
(This article belongs to the Special Issue Weed Management & Sustainable Agriculture)
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14 pages, 2602 KiB  
Article
Effect of Repeated Application of Sulfonylurea Herbicides on Sulfosulfuron Dissipation Rate in Soil
by Amit Paporisch, Yael Laor, Baruch Rubin and Hanan Eizenberg
Agronomy 2020, 10(11), 1724; https://doi.org/10.3390/agronomy10111724 - 6 Nov 2020
Cited by 14 | Viewed by 2718
Abstract
Accelerated microbial degradation following previous repeated applications of the same pesticide, or another pesticide of a similar chemical structure, is a known phenomenon. Currently there is limited information regarding accelerated degradation of sulfonylurea (SU) herbicides. This study is aimed to evaluate the effect [...] Read more.
Accelerated microbial degradation following previous repeated applications of the same pesticide, or another pesticide of a similar chemical structure, is a known phenomenon. Currently there is limited information regarding accelerated degradation of sulfonylurea (SU) herbicides. This study is aimed to evaluate the effect of repeated SU applications on the degradation rate of the SU herbicide sulfosulfuron in soil. The effect of repeated applications of sulfosulfuron on its degradation was assessed in two soils, using a sorghum root elongation bioassay. The effect of consecutive applications of sulfonylurea herbicides over the course of three to four seasons was further examined in controlled environment and a field study. Degradation of sulfosulfuron was determined following its application to soil samples from the field or a controlled environment, by measuring sulfosulfuron residues using liquid chromatography-tandem mass spectrometry. Following the repeated application of sulfosulfuron in the bioassay, the time to reduce sorghum root growth by 50% was shortened by up to 31.6%. However, consecutive application of SUs in the controlled environment had no effect on sulfosulfuron degradation rate constant. Yet, sulfosulfuron degradation rate was enhanced by a factor of 1.35 following consecutive application of SUs in the field, compared to untreated control soil. The data confirm that sulfosulfuron degradation could be enhanced due to repeated sulfosulfuron applications, thus potentially reducing its herbicidal efficacy. Full article
(This article belongs to the Special Issue Weed Management & Sustainable Agriculture)
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12 pages, 1529 KiB  
Article
Can Control of Glyphosate Susceptible and Resistant Conyza sumatrensis Populations Be Dependent on the Herbicide Formulation or Adjuvants?
by Candelario Palma-Bautista, Alexandros Tataridas, Panagiotis Kanatas, Ilias S. Travlos, Fernando Bastida, José A. Domínguez-Valenzuela and Rafael De Prado
Agronomy 2020, 10(10), 1599; https://doi.org/10.3390/agronomy10101599 - 19 Oct 2020
Cited by 10 | Viewed by 2464
Abstract
In this work, we studied the effect of three glyphosate formulations (isopropylamine, ammonium and potassium salts) and two non-ionic adjuvants on the resistance response of two resistant (R1, R2) and one susceptible population of the highly invasive Asteraceae, Conyza sumatrensis, from Southern [...] Read more.
In this work, we studied the effect of three glyphosate formulations (isopropylamine, ammonium and potassium salts) and two non-ionic adjuvants on the resistance response of two resistant (R1, R2) and one susceptible population of the highly invasive Asteraceae, Conyza sumatrensis, from Southern France vineyards. Only in R1, an amino acid substitution (Pro106Thr) was found in the enzyme 5-enolpyruvylshikimate-3-phosphate synthase (EPSPS). The two adjuvants, in a similar fashion, significantly reduced GR50 values for every population and glyphosate formulation. Without adjuvants, glyphosate as potassium salt was the only formulation able to significantly reduce the GR50 values of every population. For every population, the two adjuvants improved, indistinguishably, leaf retention of the herbicidal solution and the potassium salt formulation led to the highest retention, both with and without the adjuvant added. Uptake responses paralleled those of retention and adjuvant addition was more effective in increasing foliar uptake of the lower performing formulations (isopropylamine and ammonium salts). The allocation pattern of glyphosate among plant compartments was only dependent on population, with R2 retaining most glyphosate in the treated leaf, clearly suggesting the occurrence of a Non-Target Site Resistance (NTSR) mechanism. Results indicate that control of weed populations possessing NTSR mechanisms of resistance to glyphosate may be improved through adequate selection of formulation and adjuvant use. Full article
(This article belongs to the Special Issue Weed Management & Sustainable Agriculture)
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18 pages, 228 KiB  
Article
Evaluation of Preemergence and Postemergence Herbicide Programs on Weed Control and Weed Seed Suppression in Mississippi Peanut (Arachis hypogea)
by John W. Seale, Taghi Bararpour, Jason A. Bond, Jeffrey Gore and Bobby R. Golden
Agronomy 2020, 10(8), 1058; https://doi.org/10.3390/agronomy10081058 - 22 Jul 2020
Cited by 4 | Viewed by 1953
Abstract
Weed control and reducing weed seed deposition to the soil seedbank is a challenging issues for Mississippi peanut producers. Research was established during 2017 and 2018 at the Delta Research and Extension Center in Stoneville, Mississippi, to evaluate herbicide programs for weed control [...] Read more.
Weed control and reducing weed seed deposition to the soil seedbank is a challenging issues for Mississippi peanut producers. Research was established during 2017 and 2018 at the Delta Research and Extension Center in Stoneville, Mississippi, to evaluate herbicide programs for weed control and reducing weed seed production in Mississippi peanut production. Treatments were combinations of acetochlor, clethodim, flumioxazin, lactofen, paraquat, and S-metolachlor with their respective adjuvants if needed. Treatments were applied PRE, two to three weeks after emergence (EPOST), and/or four to five weeks after emergence (MPOST). All treatments included a PRE application followed by (fb) application of EPOST and/or MPOST application. Flumioxazin PRE fb lactofen plus clethodim MPOST provided greater than or equal to (≥) 88% control of barnyardgrass, hemp sesbania, Palmer amaranth, pitted morningglory, and prickly sida. Additionally, this treatment reduced total weed seed production 88% compared to the nontreated control. Flumioxazin PRE fb lactofen plus clethodim EPOST fb acetochlor MPOST provided similar weed control and peanut yield as flumioxazin PRE fb lactofen plus clethodim MPOST. This treatment reduced total weed seed production 93%. Treatments containing PRE, EPOST, and MPOST herbicide applications provided the best season-long control of weeds and weed seed suppression in Mississippi peanut. Full article
(This article belongs to the Special Issue Weed Management & Sustainable Agriculture)
22 pages, 1748 KiB  
Article
Evaluation of Commercial Wheat Cultivars for Canopy Architecture, Early Vigour, Weed Suppression, and Yield
by James M. Mwendwa, William B. Brown, Jeffrey D. Weidenhamer, Paul A. Weston, Jane C. Quinn, Hanwen Wu and Leslie A. Weston
Agronomy 2020, 10(7), 983; https://doi.org/10.3390/agronomy10070983 - 9 Jul 2020
Cited by 23 | Viewed by 3356
Abstract
Herbicide resistance in weeds restricts control options, thereby escalating economic loss and threatening agricultural sustainability in cereal production. Field evaluation of the crop performance, competitive traits, and consequent weed suppressive potential of 13 commercial winter wheat (Triticum aestivum L.) cultivars was performed [...] Read more.
Herbicide resistance in weeds restricts control options, thereby escalating economic loss and threatening agricultural sustainability in cereal production. Field evaluation of the crop performance, competitive traits, and consequent weed suppressive potential of 13 commercial winter wheat (Triticum aestivum L.) cultivars was performed in central NSW Australia with a focus on the evaluation and modelling of above-ground interactions. In 2015 and 2016, replicated field trials were established with genetically diverse commercial wheat genotypes under moderate to low rainfall conditions in Wagga Wagga (572 mm) and Condobolin (437 mm) New South Wales, respectively. The heritage cultivar Federation and a commercial cultivar of winter cereal rye (Secale cereale L.) were included as known weed-suppressive controls. Crop and weed growth, as well as early vigour, leaf area index, and photosynthetically active radiation, were monitored at various crop phenological stages including early growth, vegetative, flowering, grain fill, and harvest. Significant differences between wheat cultivar and location were observed for crop biomass, early vigour, leaf area index, weed number, weed biomass, canopy architecture, and yield in both 2015 and 2016. Differences in weed establishment were largely impacted first by rainfall and season and secondly by crop architecture (i.e., height, size, canopy) and phenology (i.e., growth stages). Early vigour and early canopy closure were instrumental in suppressing weed establishment and growth. Cultivar performance and competition with weeds were also clearly influenced by both environmental factors and genotype, as evidenced by differences in early cultivar performance, yield, and weed suppression by season and location. Specifically, Federation, Condo, and Janz wheat cultivars were superior performers in terms of weed suppression in both locations and years; however, Federation produced up to 55% lower yield than recently introduced cultivars. Partial least squares (PLS) regression was performed to develop a predictive linear model for weed competition in commercial wheat cultivars based on weed dry biomass as the response variable and selected aboveground crop canopy traits as predictors. In 2015, the model differed in accordance with crop growth stage, but the impact of predictors on weed biomass at both locations was not significant. In 2016, under local above average rainfall conditions, the model showed a significant negative correlation (p < 0.001) of most predictors on weed biomass (r2 = 0.51 at Condobolin, r2 = 0.62 at Wagga Wagga), suggesting the most influential factors in reducing weed numbers and establishment as crop vigour, biomass, and height. Our results indicate the establishment of competitive wheat cultivars in the absence of post-emergent herbicides resulted in a two to five-fold increased weed suppression over less suppressive genotypes, without significant yield penalties. Therefore, cultivar choice constitutes a cost-effective and sustainable weed management tool, particularly when weed pressure is significant. Full article
(This article belongs to the Special Issue Weed Management & Sustainable Agriculture)
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15 pages, 1520 KiB  
Article
Different Ground Vegetation Cover Management Systems to Manage Cynodon dactylon in an Irrigated Vineyard
by Francisco Valencia-Gredilla, Aritz Royo-Esnal, Alejandro Juárez-Escario and Jordi Recasens
Agronomy 2020, 10(6), 908; https://doi.org/10.3390/agronomy10060908 - 25 Jun 2020
Cited by 12 | Viewed by 2538
Abstract
Ground cover management in vineyards in Spain is focused on minimizing soil erosion and compaction. Such practices have influenced the weed community structure in the inter-rows, contributing to the spread of the high noxious weed Cynodon dactylon (L.) Pers. This fact highlights the [...] Read more.
Ground cover management in vineyards in Spain is focused on minimizing soil erosion and compaction. Such practices have influenced the weed community structure in the inter-rows, contributing to the spread of the high noxious weed Cynodon dactylon (L.) Pers. This fact highlights the need for further investigation of the interaction between ground cover practices and weed control techniques. In this study, the effect of four different ground cover managements (M) in the inter-rows on C. dactylon population dynamics (changes in coverage and frequency) was assessed over three seasons (2015–2017): (M1) a no-till spontaneous vegetation ground cover managed by shredding; (M2) a no-till spontaneous vegetation ground cover managed by shredding plus herbicide application, (M3) tilled soil and spontaneous vegetation growing; and (M4) tilled soil and a barley cover crop seeded (Hordeum vulgare L.). Cynodon dactylon and the other weeds responded differently to the various weed control methods. After three seasons, the barley cover crop was the most efficient management system to control C. dactylon and other weeds. Final soil cover in barley cover crop and tilled soil with spontaneous vegetation were 0.5% and 1.1%, respectively, compared to 3.7% and 7.7% obtained by spontaneous vegetation shredded with and without herbicide application, respectively. In addition, total weed frequency varied from 9.7% for barley cover crop to 45.8% for spontaneous vegetation only shredded. Weed community composition changed due to the pressure exerted by each management and the adaptive strategy of the different species. This study highlights the importance of knowledge of how vegetation management influences weed flora to improve the sustainability of wine grape production systems. Full article
(This article belongs to the Special Issue Weed Management & Sustainable Agriculture)
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10 pages, 3326 KiB  
Article
Witchweed’s Suicidal Germination: Can Slenderleaf Help?
by Fridah A. Mwakha, Nancy L.M. Budambula, Johnstone O. Neondo, Bernard M. Gichimu, Eddy O. Odari, Peter K. Kamau, Calvins Odero, Willy Kibet and Steven Runo
Agronomy 2020, 10(6), 873; https://doi.org/10.3390/agronomy10060873 - 18 Jun 2020
Cited by 6 | Viewed by 3518
Abstract
The parasitic plant Striga hermonthica (Delile) Benth. is stimulated to germinate by biomolecules (strigolactones) produced in the roots of host and some non-host plants. Non-hosts induce Striga’s suicidal germination and are therefore used as trap crops. Among trap crops, the Slenderleaf legume [...] Read more.
The parasitic plant Striga hermonthica (Delile) Benth. is stimulated to germinate by biomolecules (strigolactones) produced in the roots of host and some non-host plants. Non-hosts induce Striga’s suicidal germination and are therefore used as trap crops. Among trap crops, the Slenderleaf legume in the genus Crotalaria (Crotalaria brevidens (L.) Benth.) and (Crotalaria orchroleuca (G.) Don.) has been popularized in African smallholder farms. However, the Striga germination efficiency of these locally grown Crotalaria varieties (landraces) is unknown. Also unclear is Crotolaria’s extent to inhibiting Striga growth, post germination. Extensive parasite penetration can expose the trap crop to secondary infections and possible phytotoxicity from Striga. We used in vitro germination assays to determine the Striga germination efficiency of 29 Crotalaria landraces. Furthermore, we determined Crotalaria’s ability to inhibit Striga attachment and growth using histological analysis. We found that: i) Crotalaria stimulated germination of Striga seeds at frequencies ranging between 15.5% and 54.5% compared to 74.2% stimulation by the synthetic strigolactone (GR24) used a positive control; ii) Crotalaria blocked Striga entry at multiple levels and did not allow growth beyond the pericycle, effectively blocking vascular connection with the non-host. Hence, Crotalaria is suitable as a trap crop in integrated Striga management. Full article
(This article belongs to the Special Issue Weed Management & Sustainable Agriculture)
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12 pages, 1845 KiB  
Article
Is There a Possibility to Involve the Hormesis Effect on the Soybean with Glyphosate Sub-Lethal Amounts Used to Control Weed Species Amaranthus retroflexus L.?
by Maja Meseldžija, Sanja Lazić, Milica Dudić, Dragana Šunjka, Miloš Rajković, Todor Marković, Jelena Vukotić, Branka Ljevnaić-Mašić, Aleksandar Jurišić and Ivana Ivanović
Agronomy 2020, 10(6), 850; https://doi.org/10.3390/agronomy10060850 - 14 Jun 2020
Cited by 9 | Viewed by 2802
Abstract
Sub-lethal doses of herbicides can promote plant growth and have a positive effect on an organism this is called hormesis. The purpose of this study was to test the effects of sub-lethal doses of glyphosate on soybean (Glycine max (L.) Merr.) (1.8, [...] Read more.
Sub-lethal doses of herbicides can promote plant growth and have a positive effect on an organism this is called hormesis. The purpose of this study was to test the effects of sub-lethal doses of glyphosate on soybean (Glycine max (L.) Merr.) (1.8, 3.6, 7.2, 36, 180, and 720 g ha−1) and Amaranthus retroflexus L. (7.2, 36, 180, 720, 1440, and 2880 g ha−1). Different biological parameters, such as phytotoxicity, fresh weight, root length, content of photosynthetic pigments, and shikimate concentration, were measured. Glyphosate in doses of 1440 and 2880 g ha−1 destroyed A. retroflexus plants. A fresh weight of A. retroflexus at a dose of 36 g ha−1 was reduced by 76.31%, while for the soybean it was reduced by 19.26%. At the highest dose, the shikimate concentration was 145% in the soybean, while in A. retroflexus, the concentration increased by 58.80% compared to the control plants. All doses of glyphosate were statistically significantly different in terms of chlorophyll a content, while higher doses in A. retroflexus caused chlorophyll b to decrease. The change in the production of carotenoids was not statistically significant. The results showed that sub-lethal amounts of glyphosate did not lead to stimulation of measured parameters of soybean. Full article
(This article belongs to the Special Issue Weed Management & Sustainable Agriculture)
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