Crop Weed Research Articles

Impact of repeated fumigant applications on soil properties, crop yield, and microbial communities in a plastic-mulched tomato production system

Pre-plant soil fumigation is widely applied to control nematodes, soil-borne fungal pathogens, and weeds in vegetable crops. However, most of the research evaluating the effect of fumigants on crop yield and soil microbial communities has been done on single compounds despite growers mainly applying fumigant combinations. We studied the effect of different fumigant combinations (chloropicrin, 1,3-dichloropropene, and metam potassium) on soil properties, crop yield, and the soil bacterial and fungal microbiome for two consecutive years in a plastic-mulched tomato production system in Florida (United States). While combinations of fumigants did not improve plant productivity more than the individual application of these products, application of fumigants with >60 % chloropicrin did significantly increase yield. Fumigant combinations had no significant effect on bacterial diversity, but fumigants with >35 % chloropicrin reduced soil fungal diversity and induced temporary changes in the soil bacterial and fungal community composition. These changes included short-term increases in the relative abundance of Firmicutes and Ascomycota, as well as decreases in other bacterial and fungal taxa. Repeated fumigation reduced network complexity and the relative abundance of several predicted bacterial functions and fungal guilds, particularly after fumigation and at end of harvest (3-months post fumigation). A structural equation model (SEM) showed fumigants not only directly impact crop yield, but they can also indirectly determine variations in plant productivity through effects on the soil microbiome. Overall, this study increases our understanding of the environmental and agricultural impacts of fumigants in a plastic-mulched tomato production system.

Management of Rumex dentatus L. in Vicia faba L. cultivations via Ononis vaginalis Vahl. As a potential bioherbicide

Biological control of undesirable weeds associated with crop cultivation is a sustainable approach that can reduce chemical herbicide dependence. The current study aimed to assess the bio-herbicidal potential of the donor species Ononis vaginalis Vahl. on germination efficiency as well as various growth and physiological parameters of the recipient species Rumex dentatus L., a major broad bean pest (Vicia faba L.). To assess the greatest inhibitory allelopathic effect on the recipient species in mixed (Rumex dentatus L. and Vicia faba L.) and pure cultures (each one separately), two experiments were conducted under laboratory conditions. A Petri dish experiment using O. vaginalis shoot aqueous extract (5%, 10%, 20%, and 40%) and a pot experiment using O. vaginalis shoot crude powder (1%, 2%, 5%, and 10%) were conducted to investigate its biological activity on some growth and physiological parameters of both crop and weed species. O. vaginalis underwent a general phytochemical screening that revealed a high production of allelochemicals, which are secondary metabolites and may have a function like that of natural herbicides. The result showed that the germination of V. faba seeds in both pure and mixed cultures was not significantly affected by low levels of O. vaginalis shoot aqueous extract treatments in pure and mixed cultures, in contrast, those recorded for R. dentatus gradually dropped as levels of O. vaginalis increased in both cultures. Results recorded a significant increase in total phenolics of V. faba shoots and roots under different treatments, except at the high concentrations of crude powder at the donor species level (5 and10%). A reduction in the total phenolic and flavonoid fractions was observed in R. dentatus roots under varying concentration treatments. Conversely, under high concentration treatments, flavonoids decreased in the roots of the mixed culture of R. dentatus but increased in the shoots. In conclusion, allelopathy can be used to suppress weeds in field crops. The study confirmed the use of O. vaginalis into current weed control techniques. O. vaginalis could be explored further for weed suppression in the field.

Sustainable sweetpotato production in the United States: Current status, challenges, and opportunities

AbstractSweetpotato (Ipomoea batatas L.) is an important staple crop cultivated in over 100 countries, and the storage roots and vines provide food for humans and livestock. Sweetpotato consumption and demand for its value‐added products have increased significantly in the last two decades and have led to new cultivar development, expansion in acreage, and increased demand in the United States and its export markets. Despite the known nutritional components and other health benefits, further research is needed to characterize the genetic diversity and chemical composition related to their storage root qualities, essential in developing consumer‐preferred cultivars that offer host plant resistance against pests and pathogens. There is a critical need for research on non‐pesticidal control approaches that can provide safe, effective, economical, sustainable, and environmentally sound pest and disease management techniques, especially for socially disadvantaged small farmers in the United States. Moreover, climate change can significantly impact future production practices and yield and may directly or indirectly affect crop pests, weeds, and diseases. In this review, we discuss the current status, challenges, and future approaches associated with sweetpotato production practices; health‐promoting properties of sweetpotato cultivars; value‐added products; genetic diversity and germplasm; pest and disease management; weed and water management; pollination ecology; and other agronomic and cultural practices that may impact sustainable sweetpotato production by small‐scale, organic, and large‐scale growers.

Effect of Hand Frequency Weeding on Crop Growth Parameters and Yield

An effort made to reveal the literatures review about hand weeding frequency attributed on crop yield and crops growth parameters. This review paper has been literature reviewed necessary material that help assesses effect of hand hoeing on crop growth and weed management. Various weed controls methods practiced by small scale farmers of different agro ecology zones in order to compact the injurious effect of weeds on crop yields and growth parameters. Among available farmers practice I used for controlling weeds is hand-hoeing weed control system. Farmer practice of hand- weeding is very time consuming, physically demanding, and not cost efficient for a farmer especially where labour is scarce than other methods While, an advantage of manual control is that it minimizes soil disturbance, and decreases the likelihood of erosion and seed germination. A few farmers have started using herbicides to control weeds. However, herbicides have been found to be less effective than hand-weeding, as they require specific conditions which may be more limiting than other control method. This paper intended to reflect the current state to investigate the effect hand hoeing weeding frequencies on yield and growth parameters is still by far the most widely practiced cultural weed control technique in field crop production throughout the traditional agricultural sector, because of the prohibitive costs of herbicides and fear of toxic residue coupled with the lack of knowledge about their use.

Effectiveness and Selectivity of Pre- and Post-Emergence Herbicides for Weed Control in Grain Legumes.

Grain legumes represent important crops for livestock feed and contribute to novel uses in the food industry; therefore, the best cultivation practices need to be assessed. This study aimed to identify herbicides to meet the current need for controlling broadleaf weeds without phytotoxicity in the grain legume crop per se. Field experiments were undertaken during the 2019 and 2020 growing seasons and laid out in a randomized complete block design with three replicates as follows: four grain legume crops (vetch, pea, faba bean, and white lupine) and nine pre-emergence (PRE) or post-emergence selective (POST) herbicide treatments (PRE: aclonifen, pendimethalin plus clomazone, metribuzin plus clomazone, benfluralin, terbuthylazine plus pendimethalin, S-metolachlor plus pendimethalin, flumioxazin; POST: pyridate, imazamox) alongside weedy check plots. Plant phytotoxicity, crop dry matter, yield features, weed presence, and weed dry matter were assessed during the experiments. There was differential efficacy among the nine herbicide treatments; the weed control was more effective in the case of Veronica arvensis L. and Sonchus spp. L. compared with Chenopodium album L., Sinapis arvensis L., and Silibum marianum L. regardless of the herbicide treatment. The most effective PRE herbicide was flumioxazin, which had the greatest control over the majority of weeds (>70%) resulting in the lowest total weed biomass. The second-best treatment was benfluralin and the mixture of terbuthylazine plus pendimethalin (both had only limited control in S. arvensis). The best POST herbicide was imazamox, with only limited control in S. arvensis. The tested herbicides caused low to medium and transient levels of phytotoxicity mainly in vetch and secondly in peas but not in faba beans and lupines. Concerning all weed management treatments, benfluralin resulted in the highest grain yields for all four grain legume crops during both growing seasons. Among grain legumes, vetch had the highest competitive ability against weeds, whereas peas were the least tolerant against weed competition.

Vision based crop row navigation under varying field conditions in arable fields

Accurate crop row detection is often challenged by the varying field conditions present in real-world arable fields. Traditional colour based segmentation is unable to cater for all such variations. The lack of comprehensive datasets in agricultural environments limits the researchers from developing robust segmentation models to detect crop rows. We present a dataset for crop row detection with 11 field variations from sugar beet and maize crops. We also present a novel crop row detection algorithm for visual servoing in crop row fields. The proposed method uses deep learning based crop row skeleton segmentation method followed by a crop row scanning algorithm that identifies the central crop row which the robot then follows. The unique dataset we used with skeleton representations for crop row detection enables robust crop row detection in challenging real world field conditions. Our algorithm can detect crop rows against varying field conditions such as curved crop rows, weed presence, discontinuities, growth stages, tramlines, shadows and light levels. Dense weed presence within inter-row space and discontinuities in crop rows were the most challenging field conditions for our crop row detection algorithm. An End-of Row detector algorithm was developed to detect the end of the crop row and navigate the robot towards the headland area when it reaches the end of the crop row.

The results of the production check of the mock-up sample of the tool with an active drive of rotary working bodies

Rationale. Improvement of the annular working bodies by dividing the solid cutting blade into separate parts (cutting knives) and turning them at an angle to the axis of rotation provides conditions for stable sliding of the soil over the working surface. The lack of knowledge of the process of furrow formation by these working bodies prevents the choice of their parameters that ensure the evenness of the bottom of the furrow in accordance with agrotechnical requirements.
 The purpose of the work is to improve the quality of work of rotary working bodies.
 Materials and methods. The production check of the prototype tool with an active drive of rotary working bodies was carried out in accordance with GOST 209152011 and ST RK 15592006. Qualitative indicators were assessed according to ST RK 1559-2006. The depth of tillage was 56 cm, the angle of attack of the rotary working body was 40, the kinematic parameter =0.880.94, the speed of the unit was 910 km/h. The conditions for conducting were determined according to GOST 209152011. Agrotechnical indicators were determined: soil crumbling, stubble retention and the degree of weed cutting, the rowness of the field surface; the content of erosive particles, the height of the ridges at the bottom of the furrow.
 Results. It has been established by research that a mock-up sample of the tool for pre-sowing tillage and steam treatment at a speed of 910 km/h, a tillage depth of 56 cm provides at least 98% of weed crops, 64.5% of stubble conservation, soil crumbling 84 85%, field surface ridges 1.4 - 1.6 cm, average height of ridges at the bottom of the furrow 1.8 cm. The content of erosion-hazardous particles less than 1 mm in size in the upper soil layer decreased compared to their content before the operation by 4%.
 Conclusion. The results of the production check show that the use of a mock-up sample of a tool with an active drive of rotary working bodies on surface tillage ensures the high-quality implementation of the technological process.

Inventions, innovations and the origins of spelt wheat

What turns an invention into an innovation? How, if at all, might we observe this process archaeologically? Loosely put, new varieties of plants or animals might be considered as inventions (whether from deliberate breeding or by chance), but ones that are only taken up by humans more systematically as innovations when certain social, demographic, economic and environmental factors encourage such take-up. The archaebotanically-observed history of spelt wheat (Triticum spelta) is an interesting case in this respect. Prior to 3000 bce, spelt is occasionally found in very small amounts at sites in eastern Europe and south-west Asia, but is usually considered to be a crop weed in such contexts, rather than a cultivar. However, rather suddenly across Central Europe ~ 3000−2500 bce spelt appears more consistently at multiple Chalcolithic and especially Bell Beaker sites, in quantities which suggest a shift to its use as a deliberate crop. By the full-scale Bronze Age in this region, spelt becomes one of the major crops. This paper discusses this Central European process in greater detail via macro-botanical evidence. It argues that demographic factors during the Neolithic may have inhibited the spread of Asian spelt into central Europe, and that while small amounts of local European spelt were probably present earlier on, it was only at the very end of the Neolithic, in tandem with human population increases and major technological changes such as the introduction of the plough that spelt was taken up as a cultivar. In particular, a shift by some communities in the region ~ 3000−2500 bce to more extensive (and sometimes plough-enabled) agricultural strategies may have favoured deliberate cultivation of spelt on less productive soils, given this variety’s relative robustness to harsher conditions. In other words, a combination of conditions was necessary for this innovation to really take hold.

A new variety of Solanum sisymbriifolium obtained by in vitro polyploidization

Abstract Solanum sisymbriifolium is a shrub native to South America and considered a weed of several important crops. Despite this, this species has proven nematicidal capacity and medicinal properties, due to its ability to produce alkaloids. Thus, the objective of this work was to adjust a reliable protocol to obtain in vitro polyploid plants of S. sisymbriifolium to generate germplasm that serves as the basis for a breeding program of this species aimed to improve the sanitary conditions of horticultural crops with less impact on the environment.

ТЕХНИКО-ТЕХНОЛОГИЧЕСКИЕ АСПЕКТЫ ЛАЗЕРНОЙ ПРОПОЛКИ РАСТЕНИЙ

The creation of technologies and autonomous robots for laser weeding of agricultural crops is a promising and relevant direction in the fight against weeds, which will allow for high-precision and targeted processing of crops without the use of herbicides. (Research Purpose) The research purpose is analyzing technologies and technical means for laser weeding of plants. (Materials and methods) Using the aspect approach, the analysis of domestic and foreign scientific publications on the use of laser technologies in agricultural practice was carried out. (Results and discussion) It has been established that laser weeding technology includes several key components: mobile robotic devices, computer vision systems for plant recognition, navigation systems for precise positioning of robotic platforms in field conditions and laser systems for high-precision weed eradication. Artificial intelligence and deep learning methods are preferred for plant recognition. CO2 lasers, fiber and diode lasers are mainly used as laser energy sources. The most effective solution for laser weeding is a ground-based mobile robotic platform with a block-modular design, which is equipped with integrated laser systems for processing plants, weed recognition systems, as well as various navigation systems. (Conclusions) It is determined that carbon dioxide lasers with wavelengths of 9.3, 10.2 and 10.6 micrometers and power up to 100 watts are used for laser weeding. Diode lasers operate in the wavelength range of 450-900 nanometers with pulses lasting up to tenths of a second and a power of 5-25 watts, forming a contact spot measuring 0.5-2.5 millimeters. It has been established that fiber lasers with high peak power of short pulses and compact dimensions with a wavelength in the visible and near infrared ranges of 0.75-1.4 micrometers are promising for laser weeding. To treat weeds, carbon dioxide lasers require the least amount of energy - up to 125 Joules per weed at a wavelength of 10,600 nanometers. When using wavelengths of 1908, 940 and 532 nanometers (fiber, diode and solid-state lasers), 230, 237 and 1400 Joules are spent per weed. It is also determined that the height of treatment of weeds with a laser beam is 0.3-0.6 meters.

Common ragweed (Ambrosia artemisiifolia L.) accessions in the Mid-Atlantic region resistant to ALS-, PPO-, and EPSPS-inhibiting herbicides

Abstract Common ragweed is a troublesome weed in many crops. Farmers and crop advisors in the coastal Mid-Atlantic region have reported inadequate control of common ragweed in soybean fields with glyphosate and other herbicide modes of action. To determine whether herbicide resistance was one of the causes of poor herbicide performance, 29 accessions from four states (Delaware, Maryland, New Jersey, and Virginia) where common ragweed plants survived herbicide applications and produced viable seeds were used for greenhouse screening. Common ragweed seedlings from those accessions were treated with multiple rates of cloransulam, fomesafen, or glyphosate, applied individually postemergence (POST). All accessions except one demonstrated resistance to at least one of the herbicides applied at twice the effective rate (2×), 17 accessions were two-way resistant (to glyphosate and cloransulam, or to glyphosate and fomesafen), and three-way resistance was present in eight accessions collected from three different states. Based on the POST study, five accessions were treated preemergence (PRE) with herbicides that inhibit acetolactate synthase (ALS), and two accessions were treated with herbicides that inhibit protoporphyrinogen oxidase (PPO). All accessions treated PRE with the ALS inhibitors chlorimuron or cloransulam demonstrated resistance at the 2× rates. Both accessions treated PRE with the PPO inhibitor sulfentrazone had survivors at the 2× rate. When the same accessions were treated PRE with fomesafen, one had survivors at the 2× rate, and one had survivors at the 1× rate. Results from these tests confirmed common ragweed with three-way resistance to POST herbicides is widespread in the region. In addition, this is the first confirmation that common ragweed accessions in the region are also resistant to ALS- or PPO-inhibiting herbicides when applied PRE.

Annotated checklist of Indigenous and Alien Dicotyledonous Agrestal Weeds of Rabi in Uttar Pradesh, India

The present study enumerates the diversity of indigenous and alien agrestal weeds of rabi crops in Uttar Pradesh, India. After a detailed survey of 5 years during 2018–2023, a total of 88 species of weeds belonging to 75 genera and 30 families were documented. In accordance to APG IV classification, the documented weeds are distributed across six major clades; the Malvids and Lamiids with 27 and 19 species respectively, followed by Campanulid (19 species), Fabids (18 species), Eudicots (Four species) and Asterid (one species).

Revolutionizing Agriculture: Machine and Deep Learning Solutions for Enhanced Crop Quality and Weed Control

Revolutionizing Agriculture: Machine and Deep Learning Solutions for Enhanced Crop Quality and Weed Control

Unanswered questions and unquestioned answers: the challenges of crop residue retention and weed control in Conservation Agriculture systems of southern Africa

Abstract Production and utilization of crop residues as mulch and effective weed management are two central elements in the successful implementation of Conservation Agriculture (CA) systems in southern Africa. Yet, the challenges of crop residue availability for mulch or the difficulties in managing weed proliferation in CA systems are bigger than a micro-level focus on weeds and crop residues themselves. The bottlenecks are symptoms of broader systemic complications that cannot be resolved without appreciating the interactions between the current scientific understanding of CA and its application in smallholder systems, private incentives, social norms, institutions, and government policy. In this paper, we elucidate a series of areas that represent some unquestioned answers about chemical weed control and unanswered questions about how to maintain groundcover demanding more research along the natural and social sciences continuum. In some communities, traditional rules that allow free-range grazing of livestock after harvesting present a barrier in surface crop residue management. On the other hand, many of the communities either burn, remove, or incorporate the residues into the soil thus hindering the near-permanent soil cover required in CA systems. The lack of soil cover also means that weed management through soil mulch is unachievable. Herbicides are often a successful stopgap solution to weed control, but they are costly, and most farmers do not use them as recommended, which reduces efficacy. Besides, the use of herbicides can cause environmental hazards and may affect human health. Here, we suggest further assessment of the manipulation of crop competition, the use of vigorously growing cover crops, exploration of allelopathy, and use of microorganisms in managing weeds and reducing seed production to deplete the soil weed seed bank. We also suggest in situ production of plant biomass, use of unpalatable species for mulch generation and change of grazing by-laws towards a holistic management of pastures to reduce the competition for crop residues. However, these depend on the socio-economic status dynamics at farmer and community level.

Rhizoctonia solani AG1-IB, AG1-IC, and AG4-HGII cause bottom rot of field lettuce in Vermont.

Members of Rhizoctonia solani (teleomorph: Thanatephorus cucumeris) species complex cause bottom rot on lettuce (Latuca sativa) and yield losses up to 70% (Subbarao et al. 2017). Severe symptoms include necrosis, stem rot, and/or discoloration especially on the leaf midrib. In Vermont, vegetable farms are small (0.5-30 acres) and grow lettuce concurrently with other vegetable crops in the same field but the AG(s) that causes the disease in Vermont has not been determined. Isolates (n = 157) were collected from 31 fields with reported history of bottom rot between July 10 and October 8, 2019, across Addison, Caledonia, Chittenden, Franklin, Lamoille, and Orleans counties. Isolates were collected from lettuce tissue or potato (Solanum tuberosum), a common rotation crop, or uncropped soil baited using radish (Raphanus sativus). Pieces of tissue (5-10 mm) were cut from the leading margin of lesions, surface disinfested with 0.1% NaClO for 1 min followed by 2 rinses with sterile water, blotted dry, and plated onto acidified 2% water agar (0.085% lactic acid, pH 4.8). After incubation for 48 to 72 h, mycelia resembling Rhizoctonia were examined for morphological characteristics including hyphal branching at ca. 90o angles, a septum near the branching point, multiple nuclei per cell, and lack of both clamp connections and conidia (Sneh et al. 1991). Colonies were white to dark brown, and some produced small sclerotia. Koch's postulates were performed by inoculating nine 8-week-old (9 leaf pairs) romaine lettuce plants (Johnny's Seeds, Winslow, ME, cv. Monte Carlo) per isolate. Isolates were grown on 2% potato dextrose agar for 1 week, from which a 5-mm agar plug was placed on the adaxial leaf surface at the base of a petiole. Plants were enclosed in a plastic bag to maintain high humidity and grown under a 16-hour photoperiod at 24 °C. Disease severity was rated 4 days after inoculation (0: healthy, 1: isolated lesions, 2: lesions across multiple petioles, and 3: systemic disease). Putative AG were determined by Sanger sequencing of the internal transcribed spacer (ITS) region using the ITS1F and ITS4B primer pair (758 bp) (Gardes and Bruns 1993). Contigs were assembled using CAP3 software (Huang and Madan 1999). Taxonomy was assigned to each OTU via the NCBI BLASTn database with criteria as 0.0 E and nucleotide match of at least 97%. Of the 10 isolates sequenced with sufficient coverage (735 to 784 bp alignment length) and definitive resolution (96.7 to 99.9% identity), 5 were putative AG 1-IB (Genbank Accession HG934430.1), 2 AG 1-IC (Genbank Accession AF354058.1), 2 AG 3 (Genbank Accession AF354064.1), and 1 AG 4-HGII (Genbank Accession AF354074.1). Fasta files and metadata are archived at 10.6084/m9.figshare.20301324, 10.6084/m9.figshare.20301375. Putative AG 1-IB was highly virulent on lettuce plants whether it originated from potato (mean 2.6) or lettuce (mean 1.3 to 3). AG 4-HGII and AG 1-IC isolated from lettuce and radish, respectively, were moderately severe (mean 1.4 to 2.2) on lettuce with identical symptoms. The two potato isolates (AG3) were not pathogenic on lettuce. Similarly, higher incidence of AG 1-IB is reported on lettuce in Quebec (Wallon et al. 2021), Ohio (Herr 1993), and Germany (Grosch et al. 2004). Because AG vary in their host range (Sneh et al. 1991), knowing the AG will inform management decisions such as crop rotation and weed control. This is the first report of the causal agent of bottom rot of lettuce or any AG of R. solani in Vermont.

Cover crop management strategies affect weeds and profitability of organic no-till soybean

Abstract Cover crop residue retention on the soil surface can suppress weeds and improve organic no-till soybean (Glycine max) yield and profitability compared to a tilled system. Appropriate cereal rye (Secale cereale) fall planting date and termination methods in the spring are critical to achieve these benefits. A plot-scale agronomic experiment was carried out from September 2018 to October 2021 in Kutztown, PA, USA to demonstrate the influence of cereal rye planting date (September or October) and mechanical termination method [no-till (I & J roller-crimper, Dawn ZRX roller, and mow-ted) and tilled (plow-cultivate)] on cover crop regrowth density, weed biomass, soybean yield, and economic returns. In one out of three years, the September rye planting accumulated more cover crop biomass than the October planting, but the regrowth of the rye after roller-crimping was greater with this planting date. Cover crop planting date had no effect on total weed biomass and demonstrated varying effects on soybean grain yield and economic returns. The Dawn ZRX roller outperformed the I & J roller-crimper in effectively terminating cover crops, while the I & J roller-crimper demonstrated more uniform weed suppression and led to greater soybean yields over a span of three years. Organic no-till strategies eliminated the need for tillage and reduced variable costs by 14% over plow-cultivated plots, and generated ~19% greater net revenue across the study period (no-till vs tillage = US $845 vs US $711 ha−1). Terminating cereal rye with roller-crimping technology can be a positive investment in an organic soybean production system.

Does weed diversity mitigate yield losses?

While intensive control of weed populations plays a central role in current agriculture, numerous studies highlight the multifaceted contribution of weeds to the functionality and resilience of agroecosystems. Recent research indicates that increased evenness within weed communities may mitigate yield losses in contrast to communities characterized by lower diversity, since weed species that strongly affect crop yields, also dominate weed communities, with a concurrent reduction of evenness. If confirmed, this observation would suggest a paradigm shift in weed management towards promoting higher community diversity. To validate whether the evenness of weed communities is indeed linked to higher crop productivity, we conducted two field experiments: one analyzing the effects of a natural weed community in an intercrop of faba bean and oat, and the other analyzing the effects of artificially created weed communities, together with the individual sown weed species, in faba bean, oats and an intercrop of both crops. The evenness of the weed communities ranged from 0.2 to 0.9 in the natural weed community, from 0.2 to 0.7 in faba bean, from 0 to 0.8 in the intercrop and from 0.3 to 0.9 in oats. Neither the natural nor the artificial weed community showed significant effects of evenness on crop grain yield or crop biomass. The results of this study do not validate a positive relationship of crop productivity and weed evenness, possibly due to low weed pressure and the absence of competitive effects but suggest that also less diverse weed communities may be maintained without suffering yield losses. This is expected to have far reaching implications, since not only diverse weed communities, but also higher abundances of few weed species may contribute to ecosystem functions and may support faunal diversity associated with weeds.

To find out the effect of crop residue management and weed management practices on growth parameters of wheat (Triticum aestivum L)

To find out the effect of crop residue management and weed management practices on growth parameters of wheat (Triticum aestivum L)

Morphological and Molecular Detection of Spongospora subterranea on Plant Harvest in Infected Powder Scab Plots in Antioquia

Potato powdery scab is a disease that negatively affects both roots, causing gall formation, and tubers, resulting in brown pustules. Additionally, it leads to the development of resistance structures that can persist in the soil for several years. Globally, it is one of the most limiting diseases for potato cultivation. This study aimed to identify the species present in areas with a historical occurrence of powdery scab and to evaluate their role as alternative hosts for the pathogen. Samples were collected in the municipalities of Santa Rosa de Osos and La Unión (Ant- Col). The presence of structures (plasmodia and cystosori) associated with the pathogen in the roots was determined using trypan blue staining followed by optical microscopy analysis. Morphological identification revealed twenty-six families with pathogen structures, including Acmella mutisii, Amaranthus dubius, Bidens pilosa, Galinsoga quadriradiata, Holcus lanatus, Hypochaeris radicata, Juncus microcephalus, Oxalis corniculata, Pennisetum clandestinum, Phytolacca bogotensis, Poa annua, Polygonum nepalense, Raphanus raphanistrum, Rumex crispus, Sonchus oleraceus, Trifolium repens, Verbena litoralis, along with Fragaria x ananassa, Solanum tuberosum, and Zea mays. Molecular analysis using RT-PCR for the detection of Plasmodiophoromycetes revealed the presence of Spongospora subterranea in Solanum tuberosum; Polymyxa betae in S. tuberosum, O. corniculata, and T. repens; and Polymyxa graminis in Z. mays. This comprehensive study highlights the importance of crop rotation and weed control to disrupt the pathogen’s lifecycle as effective strategies to mitigate the impact of the disease. It emphasizes the role of alternative hosts and their substantial contribution to elevated inoculum levels.

Response of stevia to reduced-risk synthetic and nonsynthetic herbicides applied post-transplant

Abstract Greenhouse trials were conducted to determine the response of stevia to reduced-risk synthetic and nonsynthetic herbicides applied over-the-top post-transplant. In addition, field trials were conducted with stevia grown in a polyethylene mulch production system to determine crop response and weed control in planting holes to reduced-risk synthetic and nonsynthetic herbicides applied post-transplant directed. Treatments included caprylic acid plus capric acid, clove oil plus cinnamon oil, d-limonene, acetic acid (200 grain), citric acid, pelargonic acid, eugenol, ammonium nonanoate, and ammoniated soap of fatty acids. Stevia yield (dry aboveground biomass) in the greenhouse was reduced by all herbicide treatments. Citric acid and clove oil plus cinnamon oil were the least injurious, reducing yield by 16% to 20%, respectively. In field studies, d-limonene, pelargonic acid, ammonium nonanoate, and ammoniated soap of fatty acids controlled Palmer amaranth (>90% 1 wk after treatment (WAT). In field studies caprylic acid plus capric acid, pelargonic acid, and ammonium nonanoate caused >30% injury to stevia plants at 2 WAT, and d-limonene, citric acid, acetic acid, and ammoniated soap of fatty acids caused 18% to 25% injury 2 WAT. Clove oil plus cinnamon oil and eugenol caused <10% injury. Despite being injurious, herbicides applied in the field did not reduce yield compared to the nontreated check. Based upon yield data, these herbicides have potential for use in stevia; however, these products could delay harvest if applied to established stevia. In particular, clove oil plus cinnamon oil has potential for use for early-season weed management for organic production systems. The application of clove oil plus cinnamon oil over-the-top resulted in <10% injury 28 d after treatment (DAT) in the greenhouse and 3% injury 6 WAT postemergence-directed in the field. In addition, this treatment provided 95% control of Palmer amaranth 4 WAT.