Background: Weed interference is one of the factors that reduces the productivity of citrus orchards, as it limits the availability of resources for plants. Objective: Evaluate the influence of weed control area width on the development, productivity, and quality of the 'Pera Rio' orange tree. Methods: The experiment was conducted in a commercial 'Pera Rio' orange orchard. A randomized block design was used, with 12 treatments and three replications, evaluating different weed control widths: manual crowning in radii of 0.5 m, 1 m, and according to the projection of the canopy; clean and infested strips of 1 m, 2 m, and 3 m; as well as two controls (with and without management). Vegetative development (height, crown diameter, branch length, and chlorophyll content) was assessed at 0, 12, and 18 months, and fruit yield and quality (mass, diameter, juice yield, soluble solids, acidity, and ratio) at two harvests. Weeds were controlled through weeding or the use of glyphosate herbicide and monitored after seven applications. Results: The presence of weeds reduced vegetative growth (except height), productivity, and fruit quality of the 'Pera Rio' orange tree. The highest yields were observed in the control group, in the 1 m radius crowning, and in the 1 and 3 m clean strips. These same conditions also favored fruit with greater mass, diameter, and juice yield. Continuous coexistence with weeds resulted in yield losses of up to 60%. Conclusions: The control area directly influences vegetative growth, productivity, fruit quality, and the industrial yield of 'Pera Rio' orange juice.
Background: Growing public concerns about the health and environmental hazards associated with synthetic herbicides have necessitated the pursuit of sustainable weed management alternatives. Allelopathic plant extracts present a potential solution for environmentally friendly weed control. However, little is known about the bioherbicidal potential of allelopathic plant species native to Ghana. Objective: This study screened aqueous and ethanol extracts from allelopathic plants in Ghana, to examine their potential as bio-herbicides for sustainable weed management, and also identified the allelocompounds present. Method: Laboratory experiments evaluated 27 plant extracts plus a control using a completely randomized design with three replications. Both aqueous and ethanol extraction methods were applied to different plant organs (leaves, roots, bark, stems). Daily emergence of monocot and dicot weeds was monitored over 21 days and analyzed using Generalized Linear Models with control as reference. Using GC-MS analysis, promising extracts were analyzed for bioactive compounds responsible for herbicidal activity. Results: Multiple extracts suppressed (p<0.05) cumulative monocot weed emergence over the 21 days compared to the control. Effective aqueous extracts included Chromolaena odorata leaves (ChLE), Gliricidia sepium bark (GBE), Azadirachta indica leaves (NLE), Moringa oleifera leaves (MLE), among others. Ethanol extracts of Senna siamea bark (CBE), Callophyllum inophyllum leaf (CiLE), and Leucaena leucocephala root (LeRE) demonstrated superior performance with sustained suppression effects. GC-MS analysis identified phenolic compounds, alkaloids, and terpenoids, including I-[-]-4-Hydroxy-1-methylproline, 5-Hydroxypipecolic acid, as major bioactive compounds showing potential for commercial bioherbicide development. Conclusion: The study identified plant extracts with bioherbicidal activities, with specific plant-solvent combinations showing potential for commercial bioherbicide development.
Background: Buttonweed (genera Borreria and Mitracarpus) is an emerging, difficult to control weed increasingly prevalent in agricultural areas of Brazil, particularly in the Cerrado biome. Objective: Identify four buttonweed accessions, common in agricultural areas of the Brazilian Cerrado, in addition to separate and group the species based on molecular analysis. Methods: Seeds were collected, sown in pots, and plants cultivated under greenhouse and field conditions. At the time of field transplantation, part of the plants from each accession was sent to the laboratory for molecular analysis. The species of the four accessions were determined based on vegetative and reproductive morphological characteristics, using identification keys for Borreria and Mitracarpus species. In the laboratory, samples were processed, and DNA was extracted for subsequent PCR amplification, Sanger sequencing, sequence alignment, and phylogenetic analysis. Results: The accessions were identified as Borreria diacrodonta L.M. Miguel & E.L. Cabral, Borreria spinosa Cham. & Schltdl. ex DC, Borreria verticillata (L.) G. Mey., and Mitracarpus hirtus (L.) DC, corresponding to accessions PA-01, PA-02, PA-03, and PA-04, respectively. The phylogenetic analysis showed that the PA-01 accession grouped with B. diacrodonta, the PA-02 accession grouped with B. spinosa, the PA-03 accession grouped with B. verticillata and the PA-04 accession grouped with M. hirtus. Conclusions: Three species of Borreria and Mitracarpus hirtus were identified, and confirmed by molecular analysis. Borreria diacrodonta was reported for the first time as a weed in Brazil. This study provided additional morphological and molecular information to correctly identify the buttonweed species in Brazil.
Background: Soybean cultivars show a positive response to low doses of glyphosate, called glyphosate hormesis, though the genetic and biochemical mechanisms are not fully understood. Objective: This study aimed to identify the pathways and differentially expressed genes (DEGs) related to glyphosate hormesis, along with their association with lignin and P content, and the shikimic acid pathway in glyphosate-resistant cultivars (RR and RR2) compared to a non-resistant cultivar (NR). It also evaluated how glyphosate hormesis impacted the electron transport rate (ETR) and biomass accumulation. Results: With 90% of reads matching the soybean reference genome, 31,515 genes were identified, including 587 DEGs. The DEGs enriched by glyphosate application in the NR cultivar were associated with flavone metabolism and auxin signaling, indicating impacts on phenylalaninederived metabolites and developmental processes. In contrast, the RR cultivar showed enrichment in pathways related to stress response and fatty acid metabolism, while the RR2 cultivar exhibited enrichment in various metabolic pathways, notably lignin catabolism and auxin activity. Glyphosate treatments influenced electron transport rate (ETR), lignin, and P content, as well as components of the shikimic acid pathway and amino acid contents in soybean plants, with differential responses observed among cultivars and glyphosate doses. Overall, glyphosate hormesis led to increased dry biomass production across all cultivars. Conclusion: These findings provide insights into the molecular and physiological responses of soybean cultivars to glyphosate hormesis, highlighting the complex regulatory mechanisms that enable unique adaptations in each cultivar to the stress imposed by low herbicide doses.
Background: Phalaris minor Retz. is a major weed of rice-wheat cropping systems in South Asia, where its variable dormancy and germination behavior hinder effective control and often lead to heavy reliance on herbicides. Population-based threshold models offer a useful approach for predicting weed emergence, allowing for better management interventions and potentially reducing dependence on chemical control. Objective: The study aims to predict the germination and emergence behavior of Phalaris minor seeds in rice-wheat cropping systems by predicting key ecological drivers, particularly temperature and soil moisture regimes. Methods: Seeds were tested across a wide range of environmental factors, including temperature, soil moisture levels, light availability, and different sowing depths. Results:P. minor germination is highly temperature-dependent, with a base temperature of approximately 3.5 degrees C and a ceiling temperature of 35.3 degrees C, and a base water potential of-0.6 MPa. The highest germination occurred at temperatures between 20-25 degrees C and at water potentials ranging from 0 to-0.3 MPa. Seeds kept in continuous darkness showed reduced germination compared to those exposed to a 12-hour light cycle. Seedling emergence was highest when seeds were sown on the soil surface, gradually decreased as sowing depth increased, and was completely inhibited at a depth of 6 cm. Conclusion: Understanding these patterns can help optimize weed management strategies by aligning control measures with key germination windows, reducing weed pressure in wheat fields. Further research should focus on validating the model in diverse agro-ecological conditions to improve its applicability in sustainable weed control.
Weeds are a problem for the development of agricultural crops, mainly due to the acquired resistance to herbicides. One approach to weed control is based on the chemical method, using herbicides in a mixture. However, herbicide combinations are complex and may lead to synergistic, antagonistic, or additive effects. One way of evaluating this effect is by means of isobolograms, the doses of which have previously been defined using dose response curve studies. The determination of doses for isobologram construction can be based on the relative potency of the ED50 values, defined as the ratio between the doses of the two herbicides that produce a 50% effect. Nevertheless, calculating these doses manually or using spreadsheets carries a risk of operational errors, potentially leading to incorrect decisions. The aim of this study was to present a computational routine in the R software to help define doses for isobologram studies. To do this, data from four dose-response curve experiments conducted in a completely randomized design under greenhouse conditions were used to obtain the necessary doses. In the same time, doses obtained using Microsoft Excel to validate the proposed methodology. The same results were obtained using the spreadsheet and the proposed routine, but in R it was with more agility, practicality and with the work centralized in the same software.
Background: Triticum monococcum subsp. aegilopoides (wild einkorn wheat) is a problematic weed in the Mediterranean and Middle Eastern winter cereal crops. Objective: A process-based niche model for this species was developed using CLIMEX to evaluate its potentialglobal distribution. Methods: Records from Iran were utilized in the model, and the prediction was applied under the current climate and two climate change scenarios (A1B, A2). Both scenarios represent contrasting temporal patterns of economic development and carbon dioxide (CO2) emissions. Results: The results showed that Europe and Africa continent were the most and least vulnerable regions, respectively, to wild einkorn wheat infestation. Under climate change scenarios A1B and A2, the average Climate Matching Index (CMI) showed significant increases of 4.7% and 5.6% in Europe and North America, respectively, compared to the current conditions. In contrast, Oceania, Asia, and Africa experienced notable decreases of 6.9%, 5.7%, and 4.7%, respectively. In the Northern Hemisphere, 97% of the areas with a CMI's greater than 0.75 were located within the 30 degrees to 48 degrees latitude range. Conclusions: These findings can serve as a foundation for ongoing monitoring efforts to prevent the further spread of this species, as well as to develop effective quarantine regulations and preventive measures aimed at minimizing its negative impact on wheat yields and appropriate management options.
Background: Sagittaria montevidensis is one of the main weeds in paddy rice, especially in the water-seeded system. The incorrect use of herbicides allowed the selection of populations resistant to the main herbicides labeled for rice. Objective: The objective of the experiment was to evaluate the mechanisms involved in resistance to ALS-and PSII-inhibiting (i.ALS and i.PSII) herbicides in SAGMO 32 and SAGMO 10. Methods: The accessions SAGMO 35 (susceptible), SAGMO 32 (resistant i.ALS and PSII), and SAGMO 10 (resistant i.ALS) were used in the greenhouse experiments. The first study evaluated the effect of CYP450 inhibitors on the activity of the herbicides penoxsulam, bispyribac-sodium, and bentazon. The second study was an in vitro analysis of ALS enzyme activity with imazethapyr and metsulfuron-methyl herbicides. The third study was sequencing the ALS and psbA genes to detect resistance-conferring mutations. Results: CYP450 inhibitors did not alter the efficiency of any of the herbicides tested. SAGMO 32 and SAGMO 10 showed RF (enzyme inhibition) of >600 and >13 for metsulfuron-methyl and imazethapyr. The ALS mutation Trp574Leu was detected in SAGMO, which confers resistance to imazethapyr and metsulfuron-methyl. The psbA sequence did not reveal any resistance-conferring mutations. Conclusions: The resistance mechanism of Sagittaria montevidensis (SAGMO 32 and SAGMO 10) to the ALS-inhibiting herbicides is due to target-site mutation, Trp574Leu. The mechanism of resistance to the herbicide bentazon remains unidentified.
Background: Rice is one of the most important crops due to its importance in human nutrition and its multiple socio-economic contributions. Weeds are one of the main factors limiting rice production and have serious impacts. Objective: We aimed to identify the weed control practices of rice farmers, their problems with weeds and possible solutions to these problems. Methods: A survey (consisting of 41 questions) was conducted among 100 farmers in the Southern Marmara region of Turkiye. Chi-square test was used to test the relationship between the variables. In addition, information on the native and non-native status of weeds in the study area was compiled. Results: Almost all producers (92%) recognised the weeds they encountered. The most important were Echinochloa crus-galli and Echinochloa oryzoides (44%), Cyperus difformis (33%), Diplachne fusca (21%) and Paspalum distichum (2%). Integrated weed management (IWM) is generally not practiced (82%). Knowledge of IWM and the respondents' education and experience are significantly correlated. All producers use herbicides and few practice herbicide rotation (17%). Cyhalofop butyl, oxadiazon,quinclorac, bentazon andimazamoxwere the most commonly used herbicides in the last three years. However, the perceived efficacy of some herbicides has decreased by 65% in the last three years. Conclusions: Farmers lack awareness of IWM practices and herbicide application procedures, but are aware of the possibility of herbicide resistance in weeds. Therefore, we present recommendations to contribute to filling the existing knowledge gap on weed precautions and management.
Background: Cuscuta species are generalist parasites of agricultural, ornamental, and wild species. For Mexico, there is a lack of comprehensive information about the host diversity of Cuscuta, models predicting the distribution of the species, and the use of molecular methods for detecting cryptic species. Objective: This study aimed to test if Cuscuta species have a high host diversity and broad potential distribution areas and show the utility of molecular methods for species identification. Methods: We reviewed herbarium specimens (recording species name, the Mexican state, coordinates, altitude, hosts, and vegetation). We estimated the distribution area for six Cuscuta species with > 30 independent georeferenced reports. Finally, we collected three Cuscuta aff. corymbosa specimens and identified them molecularly. Results: We found 2,533 records (56 species) of which Cuscuta corymbosa, C. tinctoria, and C. umbellata were the most frequent. Most of the 204 host species belong to Asteraceae, Euphorbiaceae, and Fabaceae. Of the six species modeled, those with the largest potential distribution areas were C. tinctoria and C. corymbosa. Molecular identification revealed that the specimens belong to three species, one unknown to the collection site (C. tolteca). Conclusions: Cuscuta species appeared in all Mexican states, but it is necessary to increase the collection because several neotropical states have an unexpectedly low diversity. Their potential distributions are broad, showing well-defined biogeographical affinities. Molecular methods reveal underestimation in Cuscuta diversity.
