Weeds In Orchards Research Articles

Allelopathic effects of Borreria latifolia on weed germination and identification of allelochemicals.

Borreria latifolia (Aubl.) K. Schum (Rubiaceae) is an annual weed with a strong allelopathic inhibitory effect on malignant weeds in orchards in southern China. This study was carried out to investigate its allelopathic potential and to identify allelochemicals present in B. latifolia. Aqueous extracts of B. latifolia inhibited the germination and radicle growth of Eleusine indica and the radicle growth of Bidens alba in a dose-dependent manner. However, only the high-concentration treatment at 50 mg mL-1 delayed the germination of B. alba and Digitaria sanguinalis. Among the root, stem, and leaf aqueous extracts of B. latifolia, the leaf extract had the strongest inhibitory effects on the germination and seedling growth of E. indica, followed by stem extract and then root extract. A total of 47 published allelochemicals, including coumarin, 4-hydroxybenzoate, salicylic acid, 4-hydroxycinnamic acid, and vanillic acid, were identified in the leaf extract. Among the five allelochemicals, coumarin was found to be present in the highest concentration in the leaf extract. Furthermore, coumarin exhibited a significantly greater inhibitory effect on E. indica (EC50 = 36.87 mg L-1) than did the other allelochemicals (EC50 = 100.87-156.30 mg L-1). This study indicates that the leaf extracts of B. latifolia and their allelochemicals have excellent potential as bioherbicides and that coumarin is one of the key allelochemicals in B. latifolia. © 2024 Society of Chemical Industry.

Evaluation of Pyroxasulfone Crop Safety and Weed Control for California Tree Nut Orchards

Pyroxasulfone is a very long chain fatty acid (VLCFA) inhibitor (group 15) with potential for preemergence weed control in orchard crops and would be beneficial for reducing selection pressure for resistance to more commonly used herbicides, such as glyphosate. Pyroxasulfone is registered and widely used in corn and soybeans in the United States as a solo product and in several premix formulations. However, there is limited published information on the performance and safety of pyroxasulfone in tree nut orchard systems. To assess the potential fit for pyroxasulfone in this crop sector, a series of crop safety and weed control efficacy experiments were carried out in key California orchard crops and in fallow fields with common orchard weeds. The non-crop studies were conducted near Davis, CA, to evaluate winter annual weed control with pyroxasulfone in comparison with pendimethalin and indaziflam. In addition, an irrigation incorporation experiment was conducted in summer to evaluate the effects of incorporation timing on pyroxasulfone, pendimethalin, and indaziflam efficacy as a measure of relative stability. Orchard weed control experiments were conducted in spring in an almond orchard near Arbuckle, CA, and a walnut orchard near Davis, CA. The orchard experiments included pyroxasulfone, pendimethalin, and indaziflam in various rate combinations with glufosinate. To evaluate crop safety, 2-year experiments were conducted to evaluate repeated applications of above-label rates of pyroxasulfone at 1199 g·ha−1 and S-metolachlor at 14,010 g·ha−1 on 1- to 2-year-old almond, pistachio, and walnut trees near Davis. Pyroxasulfone performed similarly to commercial standards with up to 95% control of broadleaf and grass weeds with pyroxasulfone and indaziflam providing 96% to 100% control of annual bluegrass, and pyroxasulfone (293 g·ha−1) being the only herbicide to suppress (>70%) common lambsquarters at 60 days after treatment (DAT). Other weeds controlled by pyroxasulfone include swinecress, redroot pigweed, yellow nutsedge, and Italian ryegrass. No differences were found among treatments in the incorporation timing study indicating adequate stability on the soil surface under summer conditions. Crop injury was not observed in the established orchards or the young orchard studies and there were no treatment effects on tree trunk diameter of almond, pistachio, and walnut in the 2-year crop safety experiments. These results indicate a potential for pyroxasulfone in California tree nut orchard systems that would be an additional site of action and beneficial for management of herbicide-resistant weeds in these crops.

A Static Laser Weeding Device and System Based on Fiber Laser: Development, Experimentation, and Evaluation

To demonstrate the feasibility and improve the implementation of laser weeding, a static movable lift-adjustable closed fiber laser weeding device and system have been developed, followed by experiments and performance evaluations. Physical experiments were conducted on the energy required for laser cutting of weed stems, targeting four common larger weeds (Chenopodium album, Amaranthus spinosus, Setaria viridis, and Eleusine indica) in farmland and orchards. At the same irradiation distances, the energy required to cut the same type of large weed generally increases with increasing distances and stem diameters but decreases with increasing irradiation time. The variance of stems’ power density after irradiation was larger and the values were more dispersed for Chenopodium album and Setaria viridis weeds, and the values were relatively scattered, while the power density values of Amaranthus spinosus and Eleusine indica weeds were more concentrated. When the irradiation time was 10 s, the 3.892 W/mm2 laser was sufficient to eliminate weeds and plants with the irradiation distances of 2 m. The 2.47 W/mm2 laser was more effective, as it killed weeds within a distance of 1 m in less than 1 s. This work demonstrates the feasibility of the laser weeding device and system that can completely cut off the stems of large weeds, and this technology has the potential to promote sustainable agriculture.

Ratiometric emission of Tb(III)-functionalized Cd-based layered MOFs for portable visual detection of trace amounts of diquat in apples, potatoes and corn

Diquat (DQ) is a typical bipyridine herbicide widely used to control weeds in fields and orchards. The severe toxicity of diquat poses a serious threat to the environment and human health. Metal-organic frameworks (MOFs) have received widespread attention due to their unique physical and chemical properties and applications in the detection of toxic and harmful substances. In this work, a two-dimensional (2D) Tb(III) functionalized MOF Tb(III)@1 (1 = [Cd(HTATB)(bimb)]n·H2O (Cd-MOF), H3TATB = 4,4′,4″-triazine-2,4,6-tribenzoicacid, bimb = 1,4-bis((1H-imidazol-1-yl)methyl)benzene) has been prepared and characterized. Tb(III)@1 has excellent optical properties and high water and chemical stability. After the Tb(III) is fixed by the uncoordinated -COO- in the 1 framework, Tb(III)@1 emits the typical green fluorescence of the lanthanide ion Tb(III) through the “antenna effect”. It is worth noting that Tb(III)@1 can be used as a dual emission fluorescence chemical sensor for the ratio fluorescence detection of pesticide DQ, exhibiting a relatively low detection limit of 0.06 nM and a wide detection range of 0–50 nM. After the addition of DQ, a rapid color change of Tb(III)@1 fluorescence from green to blue was observed due to the combined effects of IFE, FRET and dynamic quenching. Therefore, a simple test paper box has been designed for direct on-site determination of pesticide DQ. In addition, the developed sensor has been successfully applied to the detection of DQ in real samples (fruits a Yin-Xia Sun and Bo-Tao Ji contributed equally to this work and should be considered co-first authors.nd vegetables) with satisfactory results. The results indicate that the probe developed in this study has broad application prospects in both real sample detection and actual on-site testing.

Evaluation of weed control efficacy and crop safety of the PPO-inhibiting herbicide tiafenacil in California orchard cropping systems

Abstract Tiafenacil is registered in the United States for use in annual crops such as corn and soybean, but not on orchard crops. Field studies were conducted to determine orchard crop safety and efficacy of tiafenacil on important California orchard weeds. To evaluate crop safety, tiafenacil was applied at 74, 148, and 222 g ai ha−1 alone and with 38 g ai ha−1 of tolpyralate three times per year at the base of almond, pistachio, prune, and walnut trees. The first treatment was applied 2 mo after the trees had been transplanted. In all four tree crop experiments, treatments were applied once in May 2020, then three times again during the winter of 2021 and 2022 at 21-d treatment intervals. There were no visual foliar injury symptoms or treatment-related effects on tree trunk diameter change even at the highest tested rate of tiafenacil applied seven times over three growing seasons. In a separate study of weed control, in most instances, tiafenacil applied at 12 g ai ha−1 performed similarly to that of tiafenacil plus glufosinate. Control of glyphosate-resistant hairy fleabane with tiafenacil applied alone at 25 g ai ha−1 was 65% by 14 d after treatment. Tiafenacil applied at 50 g ai ha−1 to hairy fleabane performed similarly to glufosinate plus glyphosate. In a greenhouse study, tiafenacil applied at 12 g ha−1 provided 95% to 100% control of barnyardgrass and junglerice, and there was no significant difference between tiafenacil applied alone or with glufosinate. Saflufenacil applied alone or in a mixture with glufosinate was not as effective as the tiafenacil treatments for grass weed control. Based on experiments conducted over three growing seasons in four tree fruit and tree nut crops, tiafenacil crop safety appeared to be acceptable even at up to 2- or 3-fold the expected use rate.

First Report of Powdery Mildew Caused by Golovinomyces ambrosiae on Xanthium orientale in Korea.

Xanthium orientale L. (syn. Xanthium canadense Mill., Asteraceae), known as cocklebur, is an annual weed native to North America, which is now a neophyte distributed throughout the world. This plant was accidentally introduced to Korea in the late 1970s ( So et al. 2008) and is considered a problematic exotic weed in orchards, for which many herbicides are ineffective (Kim et al. 2020). In September 2018, powdery mildew was observed on X. orientale in Jeju, Korea. The disease incidence ranged from 40 to 60%. Voucher specimens were deposited in the Korea University Herbarium (Accession No. KUS-F30795) and Kunsan National University Herbarium (KSNUH1988). Symptoms appeared as round to irregular white patches with abundant hyphal growth on the leaf surface. Hyphal appressoria were nipple-shaped, and 3 to 6 μm diam. Conidiophores (n = 30) were 145 to 206 × 9 to 11.6 µm and produced 2 to 5 immature conidia in chains with a sinuate outline. Foot-cells of the conidiophores were straight, cylindrical, and 43 to 100.9 μm long. Conidia (n = 30) were ellipsoid-ovoid, doliiform to somewhat limoniform, 25.2 to 31.8 × 13.6 to 16.8 μm (l/w 1.6 to 2.1), and devoid of distinct fibrosin bodies. The morphological characteristics corresponded to those of Golovinomyces ambrosiae (Schwein.) U. Braun & R.T.A. Cook (Braun and Cook 2012, under Golovinomyces spadiceus (Beck. & M.A. Curtis) U. Braun; Qiu et al. 2020). To confirm the identity of the causal fungus, the internal transcribed spacer (ITS), large subunit (LSU) (Bradshaw and Tobin 2020), the intergenic spacer (IGS) of rDNA, and the glyceraldehyde-3-phosphate dehydrogenase (GAPDH) gene (Bradshaw et al. 2022) were amplified for a herbarium specimen (KUS-F30795). A BLASTn search of these sequences revealed 100% identity with reference sequences of G. ambrosiae on diverse Asteraceae plants (AB077644 for ITS, AB077643 for LSU, ON361171 for IGS, and ON075648 for GAPDH). However, there was a single nucleotide difference on both the IGS and GAPDH sequences when compared to the closely related species Golovinomyces latisporus. The sequences were deposited in GenBank (Accession No. OQ165157 (ITS), OQ165164 (LSU), OR050524 (IGS), and OR086076 (GAPDH)). Phylogenetic analyses of ITS, LSU, IGS, and GAPDH sequences revealed the Korean sample formed a well-supported group with other G. ambrosiae sequences, confirming its identity. A pathogenicity test was performed through inoculation by gently pressing diseased leaves onto the leaves of five healthy plants. Five non-inoculated plants served as controls. All plants were maintained in a greenhouse at 25±2°C. Powdery mildew colonies developed on the inoculated plants after ten days, whereas the control plants remained symptomless. The fungus present on the inoculated leaves was morphologically identical to that observed on the initially diseased leaves, fulfilling Koch's postulates. Powdery mildew on X. orientale has previously been reported as Golovinomyces cichoracearum (≡ Erysiphe cichoracearum) sensu lato in the USA, G. ambrosiae (= G. spadiceus) throughout all continents, and Podosphaera fusca sensu lato (now P. xanthii) in Korea (Braun and Cook 2012; Farr and Rossman 2023). To date, powdery mildew in Korea has been reported only on Xanthium strumarium as G. cichoracearum s. lat. and Podosphaera xanthii (KSPP 2022). To our knowledge, this is the first report of powdery mildew caused by G. ambrosiae on X. orientale in Korea.

Steam application with paraquat to control goat weed (Scoparia dulcis) in citrus orchards

Reducing herbicide use in horticultural crop production can ameliorate adverse environmental effects but may also impact weed control effectiveness, especially as it pertains to difficult-to-control weeds. This challenge can be addressed by integrating a non-chemical strategy such as steam application with herbicide application. In this study, steam, as a non-chemical approach, was combined with post-emergence herbicide (paraquat) application for goatweed (Scoparia dulcis) management in citrus orchards. Two field trials based on randomized complete block design were conducted in citrus orchards in Immokalee, FL, in 2018 and 2021. Steam was applied to goatweed at a flow rate of 53 L ha−1 for 5–6 s. Twenty-four hours after steam application, low and high paraquat rates (0.3366 and 1.010 kg ai ha−1) were applied. In addition, the same rates of paraquat were applied without steam for comparison. Untreated checks (UTC) of no herbicide or steam applications were also included in the experiment as a control. Based on visual injury ratings, a combination of steam + low dosage of paraquat was as effective as the high dosage of paraquat alone and steam + high dosage of paraquat at 1, 8, and 16 days after treatment application (DAT) in 2018 trial and 1, 8, 16 and 22 DAT in 2021 trial.However, based on one site-year of biomass data, the percentage of dead weed biomass out of total biomass was statistically similar among all the treatments. Results from this study demonstrate that combining a low rate of paraquat applied in tandem with the steam application has the potential to provide effective goatweed control in citrus orchards.

Peer review of the pesticide risk assessment of the active substance glyphosate.

The conclusions of EFSA following the peer review of the initial risk assessments carried out by the Assessment Group on Glyphosate (AGG), consisting of the competent authorities of France, the Netherlands, Sweden and Hungary, acting jointly as rapporteur Member State for the pesticide active substance glyphosate are reported. The context of the peer review was that required by Commission Implementing Regulation (EU) No 844/2012. The conclusions were reached on the basis of the evaluation of the representative uses of glyphosate as a herbicide as proposed by the applicants, covering uses pre-sowing, pre-planting and pre-emergence plus post-harvest in vegetables and sugar beet; post-emergence of weeds in orchards, vineyards, row vegetables, railway tracks against emerged annual, biennial and perennial weeds. Moreover, uses as spot treatment against invasive species in agricultural and non-agricultural areas, and in vegetables and sugar beet against couch grass are also included. The reliable endpoints, appropriate for use in regulatory risk assessment, are presented. Missing information identified as being required by the regulatory framework is listed. Concerns are reported where identified.

Dominant weed species exert significant impacts on hazelnut orchards and rural livelihoods

Turkey contributes ~76% towards global hazelnut production; thus, it has significant socioeconomic impacts in the country. However, product losses due to weeds and challenges faced during harvesting impair hazelnut production. Therefore, weed management in hazelnut orchards is one of the major challenges faced by hazelnut producers in Turkey. Multiple complaints are received regarding weed spreading in hazelnut orchards of Turkey to different institutes. This study aimed at determining the dominant weed taxa faced by hazelnut producers and providing basic data for the precautionary measures and management strategies that could be opted to manage weed spreading. For this purpose, face-to-face interviews were conducted with the hazelnut producers between 2018 and 2020. Weed species causing significant problems in hazelnut orchards were identified according to their life forms, morphological and biological characteristics and defined as “dominant/robust” species. Considering this definition, the hazelnut producers complained of 32 taxa belonging to 19 families in hazelnut orchards. The identified taxa were compared with the earlier reported taxa from hazelnut orchards in the Black Sea region (the primary growing region of hazelnut production in Turkey) and this comparison revealed 14.81–38.89% similarities. In addition, it has been determined that the most problematic weeds in hazelnut orchards are Calystegia sepium, Coronilla varia, Dioscorea communis, Hedera spp., Rubus spp. The results showed that significant changes occurred in hazelnut fields over time and the main reason for this change was the dominant weeds. For this reason, it is recommended to consider the management strategies according to the dominant weed species in the hazelnut production areas. The results also provide empirical data for the development of effective management strategies in the region.

Molecular determination of root-knot nematode species, Meloidogyne spp. Goeldi, 1892 (Tylenchida: Meloidogynidae) infesting weeds in kiwifruit orchards in Türkiye

In this investigation, the species of root-knot nematodes (RKNs) infesting weeds in kiwifruit orchards were investigated in the Ordu Province, Türkiye. A survey was conducted in 2018 and roots of weeds with RKN infestations were found in kiwifruit orchards. The infested weed samples were collected from 27 kiwifruit fruit orchards located in the Ordu Province. Identification of RKNs was performed using the molecular method based on mitochondrial DNA (mtDNA). The mtDNA region between the cytochrome oxidase II and the large subunit ribosomal RNA was amplified using two pairs of primers TRNAH/MRH106 and MORF/MTHIS. Species-specific primers previously described were used to confirm Meloidogyne species as the last step. Meloidogyne incognita (Kofoid & White, 1919), Meloidogyne arenaria (Neal, 1889) and Meloidogyne hapla (Chitwood, 1949) (Tylenchida: Meloidogynidae) were identified from fifteen weed species (2 unidentified) in eight families. Meloidogyne incognita was the most frequent species with 74.1% of the samples infested, followed by M. hapla at 22.2% and M. arenaria at 3.7%. In this study found Erigeron canadensis L. (Asterales: Asteraceae), Mercurialis annua L. (Malpighiales: Euphorbiaceae), Oxalis pes-caprae L. (Oxalidales: Oxalidaceae), Clinopodium nepeta (L.) Kuntze (Lamiales: Lamiaceae), Fumaria officinalis L. (Ranunculales: Papaveraceae) and Lycopus spp. (Lamiales: Lamiaceae) to be previously unrecorded hosts of M. incognita and Sigesbeckia orientalis L. (Asterales: Asteraceae) and Lythrum spp. (Myrtales: Lythraceae) a host of M. hapla.

The weevil, Hypolixus pica (F.) (Coleoptera: Curculionidae) as a potential biological control agent of Amaranthus species (Amaranthaceae) in Adana Province, Turkey

Amaranthus species (Family) are among the most important weeds in summer crops and orchards in Turkey. The detrimental effects of pesticides on the environment and human health and the development of high levels of resistance to several herbicide classes by Amaranthus species have generate interest in alternative weed control methods. Since the biological control of weeds has gained great prominence recently, this study was carried out to determine the potential biological control agents of Amaranthus spp. in Adana Province. Turkey. For this aim, ten randomly selected fields randomly were in three districts (Yüreğir-Ceyhan-İmamoğlu). In each field, ten Amaranthus plants were collected randomly and dissected, and the numbers of the weevils and theirdifferent stages were recorded. In this study, three Amaranthus species were identified and A. palmeri was the most common, followed by A. retroflexus and A. spinosus. Fifty-nine larvae, 26 pupae and 10 adults were collected from the Amaranthus plants. All adult individuals were identified as H. pica according to their genital organs. Our results show that H. pica could be considered to be a potential biological control agent of A. palmeri and A. retroflexus. More detailed studies are needed to determine its ecology and role as a biological control agent of the target weed species. In addition, it is crucial to develop mass rearing methods for potential beneficial insects such as H. pica.

The impacts of ecological mowing combined with conventional mechanical or herbicide management on weeds in orange orchards

AbstractIn fruit crops like citrus, weeds coexist throughout their long cycle and can cause several yield losses. Ecological mowing (ECO) is an integrated weed management (IWM) option for citrus, as it produces an in‐situ mulch that suppresses the weeds; however, there is a lack of information on the impacts of tree‐row conventional (CONV) and ECO mechanical weed control when combined with residual or non‐residual herbicides, or standard frequent mechanical (MECH) control. This study aimed to evaluate, for 3 years in a young orange orchard, IWM using ECO and conventional mowing when combined with one of five weed control programmes: pre‐emergent (PRE) herbicides (sulfentrazone [spring], indaziflam [summer]), post‐emergence (POST) herbicides (glyphosate [spring], saflufenacil [summer]), PRE + POST herbicides (sulfentrazone + glyphosate [spring], indaziflam + saflufenacil [summer]) and P/P (pre/post‐emergence duality) herbicides (flumioxazin [spring], diuron [summer]). Impacts on cover crop biomass deposition, weed density, population dynamics, biomass accumulation and seed banks were evaluated. Alternanthera tenella Colla (joyweed), Bidens pilosa L. (hairy beggarticks), Digitaria horizontalis Willd (crabgrass), Galinsoga parviflora Cav. (smallflower galinsoga) and Raphanus raphanistrum L. (wild radish) were the most critical weeds with changes in their population dynamics over time. The ECO treatment promoted greater biomass deposition in the tree‐rows (up to ≈8.0 t ha−1), reducing weed density and biomass accumulation by mulch formation; similarly, MECH resulted in low weed density and a reduction in biomass accumulation. The POST and P/P treatments resulted in low levels of weed control, while ECO + PRE + POST led to almost absolute weed control (>95%). Thus, we suggest ECO + PRE + POST is an efficient IWM option in citrus tree‐row crops with low‐risk herbicide resistance (up to 5 MoA year−1 + mulch).

First report of Curvularia intermedia Boedijn causing leaf blight disease on Microstegium vimineum in China.

Stiltgrass [Microstegium vimineum (Trin.) A. Camus], is an annual C4 grass of Asiatic origin whose native range includes India, Pakistan, Nepal, China, Korea, and Japan (Cole et al 2004). In China, it is mainly distributed south of the Yangtze River, and is one of the most important weeds in autumn-maturing dryland crops, orchards, tea gardens, and plantations. With its high shade tolerance, M. vimineum also invades forest understories and crowds out the local vegetation (Warren et al. 2011). From June to August 2019, a leaf disease was observed causing severe defoliation of stiltgrass on the roadside of Sun Yat-sen Mausoleumin Nanjing City, Jiangsu Province, China (32.045964°N, 118.840064°E). Yellow or yellow-brown necrotic spots were observed on leaf tips and margins of the lower canopy, which later expanded to the entire leaf and progressed up the plant. Disease incidence was approximately 75-85% in August. Thirty symptomatic leaves were collected, and tissue samples (5 × 5 mm) were surface disinfected with 75% ethanol for 30 s, 0.02% NaClO for 30 s, 75% ethanol for 30 s, and washed twice with sterile water. Disinfected tissues were placed on potato dextrose agar (PDA) and incubated at 28°C for 5 days. Twenty-seven morphologically similar isolates were obtained from the leaves and purified by single-spore culturing for further study. Colonies on PDA were 70 to 85 mm in diameter after 4 to 5 days, initially white becoming gray-green with flocculent aerial mycelia. Conidiophores were solitary or clustered, 85 to 139 µm long × 5 to 8 µm wide (n = 50), and conidia were obclavate to ellipsoid or spindle shaped, brown, and measured 28 to 37 µm long × 13 to 18 µm wide (n = 50) with three false dissepiments. All characteristics were consistent with the morphology of Curvularia intermedia Boedijn (Sivanesan 1987). The rDNA internal transcribed spacer (ITS), glyceraldehyde-3-phosphate dehydrogenase (GPDH) and translation elongation factor (TEF) of a representative isolate (JSNJ-2019) were amplified using primers ITS1/ITS4, GPD1/GPD2 and EF1-983F/EF1-2218R (Manamgoda et al. 2014). The ITS sequence of JSNJ-2019 (GenBank: MZ613310) showed 99.83% (582/583bp) identity with C. intermedia (GenBank: MF370184 and GU073102); the GPDH sequence (GenBank: MZ701795) showed 99.66% (581/583bp) identity with C. intermedia (GenBank: LT715828) and the TEF sequence (Genbank: OM282974) showed 99.77% (864/866bp) identity with C. intermedia (GenBank: MF370186). Phylogenetic analysis based on the TEF sequences using Maximum-Likelihood and Bayesian methods placed JSNJ-2019 in the same clade with reference strain C. intermedia B19. The isolate was deposited in China Centre for Type Culture Collection (CCTCC) (Isolate code: CCTCC AF 2022041). For the pathogenicity assay, ten healthy M. vimineum plants grown in plastic pots (five to six leaf stage) were sprayed with 20ml conidial suspension (5×104 spores /ml); another ten healthy plants sprayed with sterile water served as controls. All inoculated and control plants were covered with transparent polyethylene bags immediately and were maintained in a greenhouse at 28±1℃. The transparent polyethylene bags were removed after 24 hours. The pathogenicity test was repeated three times. Five days post-inoculation, inoculated plants showed leaf blight symptoms as observed in the field, whereas no disease symptoms was observed on control plants. Reisolations were performed from inoculated plants, and the reisolated pathogen was confirmed as C. intermedia inter based on morphological and PCR assay (Konstantinova et al. 2002). No pathogens were isolated from control plants. Host range tests showed, C. intermedia JSNJ-2019 was pathogenic on corn, wheat, sorghum, barnyardgrass, crabgrass, green foxtail, Chinese sprangletop, cynodon, cogongrass, goosegrass, purslane and bedstraw and non-pathogenic on barley, rice, oat, cotton, bean, peanuts, rapeseed, tobacco and tea. These findings suggest C. intermedia could be used as a biocontrol agent against invasive M. vimineum and farmland weeds. However, application of C. intermedia as a bioherbicide should be limited to insensitive crop growing areas.

Composition and environmental interpretation of the weed communities in the main planting base of jujube (Ziziphus jujuba Mill. cv. 'LingwuChangzao'), Ningxia province of China.

BackgroundZiziphus jujuba Mill. cv. ‘LingwuChangzao’ is a traditional jujube cultivar in northwest China. It is of great significance to explore the weed community composition and environmental characterization for the ecological control and comprehensive management of weeds in jujube orchards. In this article, a total of 37 species were recorded in 40 sample plots (1 m × 1 m). Moreover, fourteen environmental indicators to characterize the spatial locations, climate and soil nutrient characteristics of the plant communities were adopted.MethodologyThrough the two-way indicator species analysis (TWINSPAN) quantity classification and canonical correspondence analysis (CCA) ranking methods, the types of weed communities in the main planting base of jujube ‘LingwuChangzao’ and the main environmental factors affecting the change and distribution of weed types were analyzed.ResultsThe weed communities within the study area were divided into 15 types by the TWINSPAN classification. There were significant differences in soil factors to the species diversity indices of the weed communities, the diversity of weed communities was negatively correlated with available potassium, whereas positively correlated with soil water content. The CCA results showed that community structure and spatial distribution of weed communities were affected by soil water content, total potassium, soil organic carbon, total phosphorus, total nitrogen. Our results can be used as a reference for orchard weed management and provide a theoretical basis for weed invasion control and creating a higher biodiversity in arable land under the background of environmental change.

Sustainable Management Strategies and Biological Control in Apple Orchards

Sustainable horticultural practices address the global issues of food security, pest and disease management, soil health, water pollution, depletion of biodiversity, etc. with environment–friendly approaches. Increasingly, the adoption of such strategies is benefitting agricultural production including that in orchards. Even though several Integrated Pest Management (IPM), disease, and weed management strategies have been in use for the control of pests, diseases, and weeds in apple orchards, they are still not the most favored methods of control. There are various economic and acceptance concerns regarding their use, particularly in developing nations. A more sustainable system for apple orchards management, thus, should be adopted. 
 Here, we review various management methodologies, including the sustainable biocontrol methods, employed in the apple orchards. Reviewing these methods, we draw attention towards integrating sustainable IPM methodologies with biocontrol strategies like the use of pest-resistant cultivars, employing natural parasites and enemies of apple pests, use of agro-based pesticides, integration of technological advances that can provide real-time data to farmers and orchard scouting leading to the development of sustainable management of apple orchards. Such systems will not only reduce dependence on chemical control methods but will also minimize ecotoxicity. We also draw parallels from the biocontrol methods adopted in sustainable agri-production in other fruit orchards to suggest strategies that can be employed for sustainable apple production.

Korovi zasada jabuke i njihovo suzbijanje

Floristic composition of the weed community in apple orchards differs, depending on the type of management - extensive or intensive. In extensive orchards, weedy-ruderal-grassland species are dominant. On the other hands, in intensive orchards the inter-row can be dominated by annual (therophyte) weed species, if mechanically cultivated, or grass species, if grasses are used as cover crops, while the rows are dominated by perennial weed species (geophytes, hemicryptophytes). The floristic composition of the weed communities is also dependent on the age of the orchard. In younger orchards row crop weeds are dominant, while as the orchard ages, the community gets a more weedy-ruderal-grassland character. The most common weed species in apple orchards in Serbia are: Amaranthus retroflexus, Ambrosia artemisiifolia, Chenopodium album, Convolvulus arvensis, Carduus acanthoides, Cynodon dactylon, Erigeron canadensis, Hordeum murinum, Lamium purpureum, L. amplexicaule, Medicago lupulina, Setaria spp., Stellaria media, Stenactis annua, Sonchus arvensis, Taraxacum officinale, Veronica spp. and Vicia spp. Weed control in apple orchards can be done using agrotechnical (soil cultivation), physical (mowing, mulching), thermic, chemical, biological measures, and by growing cover crops. In practice, weed control in apple orchards is dominantly done by herbicides, based on the following active substances: napropamide, glyphosate, 2.4D, flazasulfuron, flurochloridone, cycloxydim, fluazifop-p-butyl, clethodim, diquat, fluroxypyr-meptyl, and pyraflufen-ethyl. Given that nowadays the production of healthy and safe food is an imperative, also demanded by the international market, it is expected that bioproducts will be prioritized over classical synthetic herbicides. Moreover, non-chemical measures are also becoming more important as part of integral weed control measures of weeds in apple orchards.

POST control of Italian ryegrass in hazelnut orchards

AbstractItalian ryegrass has become a problematic weed in hazelnut orchards of Oregon because of the presence of herbicide-resistant populations. Resistant and multiple-resistant Italian ryegrass populations are now the predominant biotypes in Oregon; there is no information on which herbicides effectively control Italian ryegrass in hazelnut orchards. Six field studies were conducted in commercial orchards to evaluate Italian ryegrass control with POST herbicides. Treatments included flazasulfuron, glufosinate, glyphosate, paraquat, rimsulfuron, and sethoxydim applied alone or in selected mixtures during early spring when plants were in the vegetative stage. Treatment efficacy was dependent on the experimental site. The observed range of weed control 28 d after treatment was 13% to 76% for glyphosate, 1% to 72% for paraquat, 58% to 88% for glufosinate, 16% to 97% for flazasulfuron, 8% to 94% for rimsulfuron, and 25% to 91% for sethoxydim. Herbicides in mixtures improved control of Italian ryegrass compared to single active ingredients based on contrast analysis. Herbicides in mixture increased control by 27% compared to glyphosate, 18% to rimsulfuron, 15% to flazasulfuron, 19% to sethoxydim, and 12% compared to glufosinate when averaged across all sites, but mixture did not always improve reduction of ground coverage or of biomass. This complex site-specific response highlights the importance of record-keeping for efficient herbicide use. Glufosinate is an effective option to manage Italian ryegrass. However, the glufosinate-resistant biotypes documented in Oregon may jeopardize this practice. Nonchemical weed control options are needed for sustainable weed management in hazelnuts.

Effects of weed mowing height on the occurrence of phytoseiid mites (Acari: Phytoseiidae) on weeds in apple orchards

Effects of weed mowing height on the occurrence of phytoseiid mites (Acari: Phytoseiidae) on weeds in apple orchards

Accumulation of Target Gene Mutations Confers Multiple Resistance to ALS, ACCase, and EPSPS Inhibitors in Lolium Species in Chile.

Different Lolium species, common weeds in cereal fields and fruit orchards in Chile, were reported showing isolated resistance to the acetyl CoA carboxylase (ACCase), acetolactate synthase (ALS) and 5-enolpyruvylshikimate-3-phosphate synthase (EPSPS) inhibiting herbicides in the late 1990s. The first case of multiple resistance to these herbicides was Lolium multiflorum found in spring barley in 2007. We hypothesized that other Lolium species may have evolved multiple resistance. In this study, we characterized the multiple resistance to glyphosate, diclofop-methyl and iodosulfuron-methyl-sodium in Lolium rigidum, Lolium perenne and Lolium multiflorum resistant (R) populations from Chile collected in cereal fields. Lolium spp. populations were confirmed by AFLP analysis to be L. rigidum, L. perenne and L. multiflorum. Dose-response assays confirmed multiple resistance to glyphosate, diclofop-methyl and iodosulfuron methyl-sodium in the three species. Enzyme activity assays (ACCase, ALS and EPSPS) suggested that the multiple resistance of the three Lolium spp. was caused by target site mechanisms, except the resistance to iodosulfuron in the R L. perenne population. The target site genes sequencing revealed that the R L. multiflorum population presented the Pro-106-Ser/Ala (EPSPS), Ile-2041-Asn++Asp-2078-Gly (ACCase), and Trp-574-Leu (ALS) mutations; and the R L. rigidum population had the Pro-106-Ser (EPSPS), Ile-1781-Leu+Asp-2078-Gly (ACCase) and Pro-197-Ser/Gln+Trp-574-Leu (ALS) mutations. Alternatively, the R L. perenne population showed only the Asp-2078-Gly (ACCase) mutation, while glyphosate resistance could be due to EPSPS gene amplification (no mutations but high basal enzyme activity), whereas iodosulfuron resistance presumably could involve non-target site resistance (NTSR) mechanisms. These results support that the accumulation of target site mutations confers multiple resistance to the ACCase, ALS and EPSPS inhibitors in L. multiflorum and L. rigidum from Chile, while in L. perenne, both target and NTSR could be present. Multiple resistance to three herbicide groups in three different species of the genus Lolium in South America represents a significant management challenge.

Soil phosphorus fractions in an apple orchard with different weed managements

The presence of weeds in apple orchards affects the dynamics of nutrients in the soil, including phosphorus (P). The objective of this study was to evaluate changes in distribution of P fractions in the soil of an apple orchard under different weed managements. The experiment was conducted in an apple orchard in the municipality of Urubici, Santa Catarina, Brazil. The following treatments were implemented in 2011: no weed management (NWM), desiccation of weeds in the apple-tree row (DR), and hoeing of weeds in the apple-tree row (HR). Soil samples of the 0-2.5, 2.5-5, 5-10, 10-15 and 15-20 cm layers were collected in the apple-tree rows at 24 months after the implementation of the experiment. The samples were subjected to chemical fractionation of P, obtaining the following fractions: PiAER, PiNaHCO3, PoNaHCO3, PiNaOH, PoNaOH, PiHCl, PiNaOH05, PoNaOH05, and Presidual. The presence of weeds increased the contents of the following soil P fractions in the surface layers: PiAER, PiNaHCO3, and PoNaHCO3, which are bioavailable to plants. A higher proportion of organic forms of P in the soil was found when the weeds were hoed; these fractions can be mineralized and used for nutrition of apple trees when labile P forms are exhausted.