عوامل مؤثر بر تراکم جمعیت علفهایهرز و کاهش عملکرد ناشی از آنها در گندم: مطالعه موردی استان گلستان- بندرگز

In 1988, this survey was carried out to determine weed species, density and widespread in carcel oil fields in Adana. At the same time, it was conducted to determine the most effective chemical control against weeds in carcel oil fields in 1989-1990. According to the results of survey; it was determined that the most abundant weeds were found as wild oat ( Avena sterilis L.), common fumitory species ( Fumaria spp.), shepherd's purse ( Capsella bursa pastoris Medic.), annulal yellow sweet clover ( Melilotus indica L.), wild clover species ( Medicago spp.), vetching species ( Lathyrus spp.), mayweed species ( Anthemis spp.), corn gromvell ( Buglossoides arvensis (L.) John.); and that the most widespread weeds were found as wild oat, common fumitory species, vetching species, charlock ( Sinapis arvensis L.), vetch species ( Vicia spp.) corn poppy ( Papaver rhoeas L.), shepherd's neddle ( Scandix pecten-veneris L.), rye grass species ( Lolium spp.) in Adana. At the chemical control of weeds, trifluralin (96 g/da a.i.), propyzamid (100-125 g/da a.i.) gave effective control against broadleaf weeds; and fluazifop-P-butyl, halloxyfop-ethoxy ester (9.37 g/da a.i.), fenoxoprop-ethyl (18 g-da a.i.), dichlofop- methyl (55 g/da a.i.) gave effective control against grass weeds in carcel oil fields. There was unimportant phytotoxicity to carcel oil.

In 2003, Citrus yellow vein clearing virus (CYVCV, genus Mandarivirus, family Alphaflexiviridae) (Loconsole et al., 2012) symptoms were observed in citrus lemon (Citrus limon), sour orange (C. aurantium), sweet orange (C. sinensis), mandarin (C. reticulata) and grapefruits (C. paradisi) in a collection orchard in the Cukurova region in Turkey (Onelge et al., 2011). Here we report on a two-year survey for CYVCV in the collection orchard in spring and autumn. 200 symptomless weed samples of the families Amaranthaceae, Asteraceae, Brassicaceae, Chenopodiaceae, Compositeae, Graminaceae and Solanaceae were analyzed by RT-PCR with a specific primer pair (sense: 5′-ACCTCACCGA TGGACCACGTT-3′ and antisense: CAGAAAATGGAAACTGAAAGCCTG-3′) designed in the coat protein gene (GenBank accession No. JX040635) (Loconsole et al., 2012) and total RNA extracted using the Axigen kit. A 476-bp long amplicon was obtained for three samples of Malva sylvestris, three samples of Solanum nigrum, two samples of Sinapis arvensis and two samples of Rananculus arvensis. All samples were cloned with TA Cloning kit (Invitrogen) and sequenced. BLAST analysis of all amplicons showed more than 97% identity of CYVCV isolates from weeds (Accession Nos. JX040635 and KP313241) with the corresponding region of CYVCV reference genome (Loconsole et al., 2012; Chen et al., 2014). Mechanical transmission of CYVCV from infected weeds to sour orange showed yellow vein clearing on lateral veins, leaf crinkling and deformation on young leaves of indicator plants. The presence of CYVCV was confirmed in the symptomatic sour orange plants by RT-PCR. To our knowledge this is the first report of Malva sylvestris, Solanum nigrum, Sinapis arvensis and Rananculus arvensis as hosts of CYVCV.

پیزور علفهرزی چند ساله و مقاوم به غرقاب از خانواده اویارسلام است که در سالهای اخیر جمعیت آن در مزارع برنج شمال کشور رو به افزایش است. بهمنظور کنترل شیمیایی پیزور در برنج، آزمایش مزرعهای طی دو سال متوالی در مؤسسه تحقیقات برنج کشور واقع در رشت اجرا شد. در سال اول، کارایی علف‌کش‌های رایج مزارع برنج شامل پرتیلاکلر، بوتاکلر، بنسولفورونمتیل، اکسادیارژیل و تیوبنکارب در کنترل پیزور مطالعه شد. بر مبنای نتایج سال اول، کارایی برخی علف‌کش‌های انتخابی و جدید از گروه سولفونیل اوره ها ( ALSها) مزارع برنج از جمله فلوستوسولفورون، پنوکسولام، مت‌سولفورونمتیل و نیز علف‌کش پیرازولیت از خانواده پیرازول‌ها در مقایسه با بنسولفورونمتیل در سال دوم مورد بررسی قرار گرفت. نتایج سال اول نشان داد که حداقل زیست‌توده پیزور در کرت‌های تیمار شده با بنسولفورونمتیل (5/1 گرم بر متر مربع) و پرتیلاکلر (6/10 گرم بر متر مربع) در شش هفته پس از نشاکاری مشاهده شد، درحالی‌که سایر علف‌کش‌ها کارایی مطلوبی در کنترل پیزور نداشتند. نتایج آزمایش سال دوم مشابه نتایج آزمایش اول، یعنی کارایی بسیار خوب بنسولفورونمتیل (97%≤) در کنترل پیزور بود. بعلاوه، نتایج نشان داد که کاربرد فلوستوسولفورون و پیرازولیت سبب کاهش معنی‌دار زیستتوده پیزور (91%≤) در مقایسه با شاهد عدم کنترل گردید، درحالی‌که علف‌کش‌های پنوکسولام و مت‌سولفورون تأثیر بسیار کمی در کاهش زیستتوده پیزور (49%≥) داشتند. با توجه به مکانیزم عمل متفاوت علف‌کش‌های جدید و سازگاری آنها با برنج، کاربرد آنها در تناوب با علف‌کش‌های موجود برای کنترل شیمیایی پیزور و اجتناب از مقاومت در صورت ثبت در کشور توصیه میشود.

In 1984-1986, a survey was carried out to determine weed species, density and widespread in second crop soybean fields in Adana, Antalya, Hatay, Icel, Kahramanmaras provinces. The possibilities of the most effective control measures were also studied with various chemical and mechanical control methods; and then studied on soybean yield and rotation crop wheat. According to the results of survey; in the second crop soybean fields in desity in Adana, nudsedge species ( Cyperus rotundus L.) common purslane ( Portulaca oleracea L), Johnson grass [ Sorghum halepense (L.) Pers.], in Icel common purslane, nudsedge species, tumble pigweed ( Amaranthus albus L.); in Antalya nudsedge species, common purslane, johnson grass; in Kahramanmaras, awnless barnyard grass ( Echinochloa colonum (L.) Link.), common purslane, johnson grass; in Hatay tumble pigweed, nudsedge species, awnless barnyard grass were determined weed species which are the most important, and their density were above 10 plant/m2. In widespread nudsedge species was the most important weed in all provinces; at the same time the other species were also important weeds which are widespread in second crop soybean field. In 1984-1985, control experiments were carried out in Cukurova Agricultural Research Institute, metolachlor, prometryn, terbutrin, linuron, trifluralin, metribuzin, vernolate, fluazifop-butyl, bentazon and mechanical control were tested against all weeds. Metolachlor (500 ml/da prep.) was found effective against purple nudsedge, and fluazifop-butyl (100 ml/da prep.) gave sufficient effect against johnson grass. It was not found different among chemical and mechanical control to effect and yield. For that purpose, mechanical control could be recommended against weeds in soybean fields. I has been found that the herbicides were not phytotoxicity to germination of rotation wheat seeds.

به منظور بررسی تأثیر تراکم‏های مختلف کاشت و مقادیر مختلف کاربرد علف‏کش متری‏بیوزین بر عملکرد، اجزای عملکرد و صفات فیزیولوژیک گندم رقم پیشتاز، آزمایشی در سال زراعی 86-1385 در مزرعه تحقیقاتی بخش علف های هرز مؤسسه تحقیقات گیاه‏پزشکی کشور واقع در مشکین‏دشت کرج به‌صورت فاکتوریل در قالب طرح بلوک‏های کامل تصادفی با 4 تکرار اجرا شد. فاکتورهای آزمایش شامل تراکم گندم در سه سطح (400، 500 و 600 بوته در مترمربع) و دز علف کش متری بیوزین در پنج سطح (صفر، 2/0، 4/0، 6/0 و 8/0 کیلوگرم در هکتار) بودند. نتایج حاصل از بررسی تأثیر تیمارها روی شاخص‏های فیزیولوژیکی رشد نشان داد که شاخص سطح برگ، تجمع کل ماده خشک و سرعت رشد محصول در تراکم-های 500 و 600 بوته در مترمربع و دزهای 6/0 و 8/0 کیلوگرم در هکتار، برتری معنی‌داری را نسبت به سایر تیمارها دارا بودند. بالاتر بودن شاخص‌های رشد گندم در این تراکم‌ها توجیه‌کننده افزایش قدرت رقابتی گندم در مواجهه با علف‌های هرز می باشد. عملکرد نهایی گندم نیز از این روند تبعیت کرد، به‌طوری‌که در تراکم 500 بوته در مترمربع و کاربرد مقادیر 6/0 و 8/0 کیلوگرم در هکتار متری بیوزین نسبت به تراکم‌های 400 و 600 بوته در مترمربع از میزان بیشتری برخوردار بود.

Weed management is one of the major constraints in the Zimbabwe smallholder farming sector contributing to smallholder poor yields, hence there is need to identify cropping systems that have potential to reduce weed pressure while improving crop yields. Conservation agriculture has been suggested as one of these farming systems. The implementation of CA three key principles reduces weed pressure even when the use of herbicides is minimised. Crops included in crop rotations, intercropping or relay cropping may have faster growth rate than weeds hence, have a comparative advantage over weeds. Maintenance of permanent soil cover through crop residues impedes weed germination thereby reducing weed population. Elimination of ploughing also reduces the chances of bringing buried weed seeds to the surface where their chances for germination are high. Hence, some seeds lose viability thus reducing weed density. Weed seeds accumulate at the surface, when allowed to set seed, increasing their exposure to predation resulting in reduction of weed density over time. The use of herbicides ensures that the fields are weed free as the season’s progress thus ensuring better yields at the end of each growing season. Hence, weeds are reduced in CA systems over time despite the weeding option used.

این آزمایش در سال زراعی 1386 در مزرعه تحقیقاتی بخش تحقیقات علفهای هرز موسسه گیاهپزشکی کشور، واقع در ورامین به صورت کرتهای خرد شده در قالب طرح بلوکهای کامل تصادفی با چهار تکرار به اجرا درآمد. الگوی کاشت ذرت با چهار سطح تکردیفه با تراکم معمول و دو ردیفه زیگزاگ با تراکمهای معمول، 25 درصد و 50 درصد بیشتر از تراکم معمول به عنوان فاکتور اصلی و مصرف علفکش نیز با پنج سطح مخلوط آترازین به میزان 8/0 کیلوگرم ماده موثره در هکتار و ارادیکان به میزانهای به ترتیب 28/3، 10/4 و 92/4 کیلوگرم ماده موثره در هکتار، مخلوط آترازین به میزان 8/0 کیلوگرم ماده موثره در هکتار و آلاکلر به میزان 4/2 کیلوگرم ماده موثره در هکتار و ارادیکان به میزان 92/4 کیلوگرم ماده موثره در هکتار به صورت پیشکاشت و به عنوان فاکتور فرعی اعمال گردید. کرتهای شاهد شامل شاهد بدون علفهرز (وجین کامل) و شاهد با علفهرز (بدون مصرف علفکش) بود. تغییر الگوی کاشت ذرت از تک ردیفه با تراکم معمول به دو ردیفه زیگزاگ با تراکمهای 25 درصد و 50 درصد بیشتر از تراکم معمول موجب افزایش معنیدار عملکرد دانه ذرت شد. تغییر الگوی کاشت ذرت از تک ردیفه به دو ردیفه زیگزاگ همچنین تراکم و وزنخشک علفهایهرز را کاهش داد و الگوی کاشت دو ردیفه زیگزاگ با تراکم 25 درصد بیشتر از تراکم معمول، کمترین تراکم و وزنخشک علفهایهرز را نشان داد. در الگوهای کاشت مختلف، پس از تیمار شاهد بدون علف هرز، تیمارهای 8/0 کیلوگرم ماده موثره در هکتار آترازین + 92/4 کیلوگرم ماده موثره در هکتار ارادیکان و 8/0 کیلوگرم ماده موثره در هکتار آترازین + 10/4 کیلوگرم ماده موثره در هکتار ارادیکان به ترتیب کمترین تراکم و وزنخشک علفهایهرز را نشان دادند. از طرف دیگر به غیر از تیمار شاهد با علف هرز عملکرد دانه سایر تیمارهای علفکشی اختلاف معنیداری با عملکرد دانه تیمار شاهد بدون علف هرز نداشت. در نتیجه میتوان از مقادیر کاهش یافته علفکشها استفاده نمود و در نتیجه میزان مصرف علفکشها را کاهش داد. بر اساس نتایج حاصل شده الگوی کاشت دو ردیفه زیگزاگ با تراکم 25درصد بیشتر از تراکم معمول (92500 بوته در هکتار) و ترکیب علفکشی آترازین به میزان 8/0 کیلوگرم ماده موثره در هکتار + ارادیکان به میزان 10/4 کیلوگرم ماده موثره در هکتار به عنوان بهترین تیمار پیشنهاد میگردد.

Weed management is the most important limiting factor in butternut production by smallholder irrigation farmers in South Africa. Post-emergence chemical weed control options for butternut farms are very limited and often ineffective since most of the registered selective herbicides control annual grasses but not the broadleaf weeds. An on-farm experiment was therefore conducted to investigate the effects of pre-plant weed control (application or non-application of glyphosate to kill the first flush of weeds before planting), nitrogen (N) rate (60, 90, 120, 150 and 180 kg ha-1) and plant density (10, 000, 20, 000 and 30, 000 plants ha-1) on weed biomass and butternut yield. Pre-plant weed control resulted in a six-fold decrease in weed biomass, while increasing plant density from 10,000 to 30,000 plants ha-1decreased weed biomass by 47%. No marketable fruits were obtained when planting was done without prior weed control. Yield increased significantly with increase in plant density and the optimum density was estimated to be 25,000 plants ha-1. Yield increased with N rate and the rate giving the highest marginal rate of return was 120 kg N ha-1, which gave a yield of 26.7 t ha-1. These findings suggest that pre-plant weed control, and use of optimum N rate and plant density are pre-requisites to successful butternut production. Key words: Pre-plant weed control, plant density, N rate, butternut yield.

Ischaemum rugosum Salisb. commonly known as ribbed murainagrass is a problematic herbicide-resistant weed in directseeded rice systems. To evaluate the competitive ability of rice cultivars against I. rugosum, a study was established with two rice cultivars (Mestiso 21, a hybrid and IR 64, an inbred). These cultivars were sown at density of 4 plants per pot with four different densities of I. rugosum (0, 2, 4, and 8 plants pot(-1)). Across weed density levels, IR 64 had 14% lower while Mestiso 21 had 20% higher plant height than I. rugosum. In competition with eight I. rugosum plants per pot, Mestiso 21 had 17% higher plant height (85 cm) than of IR 64 (73 cm). Without competition, IR 64 had higher tiller number, leaf number, leaf area, and root biomass than Mestiso 21 while in competition with eight weed plants per pot, Mestiso 21 had higher leaf biomass (29%), stem biomass (13%), specific stem length (38%), panicle biomass (29%), florets number (41%), and florets biomass (36%) than IR 64. In comparison with control (no weed competition), weed densities of 2, 4, and 8 plants pot(-1) reduced the total rice biomasses and grain yields by 32, 42, and 50%; and 26, 46, and 56% for IR 64 and by 23, 37, and 45%; and 20, 28, and 42% for Mestiso 21, respectively. The Mestiso 21 reduced the I. rugosum plant height, number of tillers, leaf biomass, inflorescence biomass, root biomass, and total aboveground biomass by 16.3, 0.3, 22.1, 31.3, 21.8, and 22.7%, respectively, compared with IR 64. The results of this study suggest that the hybrid rice Mestiso 21 has a better competitive ability to suppress I. rugosum than IR 64 therefore can be used in an integrated weed management of problematic weeds in direct-seeded rice systems.

Here's a look at what's coming up in the July 2015 issue of JoVE: The Journal of Visualized Experiments. In JoVE Medicine, we feature an approach for diagnosing halitosis, commonly known as bad breath, in man's best friend: the dog. The approach is much more advanced than simply smelling the dog's breath-it involves taking breath samples and using a gas chromatograph to quantify stinky compounds found in bad breath, such as hydrogen sulfide, methyl mercaptan, and dimethyl sulfide. Di Cerbo et al. use this assay in a randomized, placebo-controlled trial of dog food specially formulated to fight halitosis. The results of their study suggest that certain dietary supplements might reduce embarrassing bad breath in our beloved canine companions. In JoVE Behavior, we know all too well that working in a chronically stressful environment can have deleterious effects-so we feature a stress reduction intervention that might retrain the brain to change its usual responses to stressful situations. Klatt et al. present a structured group program that incorporates mindful meditation, yoga, and relaxing music. This intervention can be delivered onsite, at the workplace, so it's a potentially viable method of stress reduction for busy working adults. In JoVE Environment, we have two articles that explore how plants interact with certain environmental factors. Like animals, plants can transmit electrical signals over long distances, which is an advantageous trait because it allows quick responses to external stimuli. But plants have no nerves, so Salvador-Recatala and Tjallingii examine the plant vasculature, namely the sieve elements of the phloem, as a possible conduit of stimulus-induced electrical signals. They wire up aphids to record signals transmitted from another part of the plant that is sustaining damage, such as a leaf getting cut by scissors or eaten by a caterpillar. The resulting data may reveal how phloem sieve elements integrate information from different environmental stimuli. Another article in JoVE Environment demonstrates methods for testing herbicide resistance in weeds. Overuse of herbicides, combined with natural genetic variability in plants, has selected for resistance in hundreds of weed species reported to date. This is a major concern for ecosystem management and for agriculture. Panozzo et al. present protocols for testing herbicide resistance, inferring the tolerance level by using multiple herbicide doses in the experiments. Besides being highly robust and reliable, these protocols can easily be adapted to a wide range of weeds. The data obtained from these experiments can inform further research and optimize the management of herbicide use. You've just had a sneak peek of the July 2015 issue of JoVE. Visit the website to see the full-length articles, plus many more, in JoVE: The Journal of Visualized Experiments.

به منظور مطالعه تأثیر دزهای مختلف علف‌کش ترفلان و دو گونه قارچ‌ میکوریزایی بر اجزاء سبز شدن (سرعت سبز شدن، یکنواختی سبز شدن و زمان تا 10، 50 و 90 درصد سبز شدن)، برخی صفات رشدی و کلونیزاسیون میکوریزا در گیاه شبدر سفید (Trifolium repens L.)، آزمایشی به-صورت فاکتوریل در قالب طرح بلوک های کامل تصادفی در سه تکرار در دانشکده کشاورزی دانشگاه شاهرود در سال 1391 انجام شد. عوامل مورد بررسی در این آزمایش شامل کاربرد میکوریزا در سه سطح M1: عدم تلقیح، M2: Glommus intraradices و :M3 Glommus mosseae و دزهای مختلف علف‌کش ترفلان در چهار سطح T1: شاهد عدم کاربرد علف‌کش، T2: 1000،:T3 1500 و T4 : 2000 میلی‌لیتر علف‌کش ترفلان از نوع تجاری در هکتار انجام شد. نتایج نشان داد با افزایش دز علف‌کش ترفلان، یکنواختی سبز شدن (EU) کاهش و زمان تا رسیدن به 10(D10) و 90(D90) درصد سبز شدن افزایش یافت. در غلظت های مختلف علف‌کش، تلقیح با میکوریزا حداکثر جوانه زنی (Emax) و وزن خشک اندام هوایی را بطور معنی داری نسبت به عدم تلقیح افزایش داد. همچنین، درصد کلونیزاسیون ریشه در دز پایین علف‌کش تحت تاثیر تلقیح میکوریزا نسبت به عدم تلقیح بطور معنی داری افزایش یافت. تلقیح با قارچ G. intraradices طول ریشه را در دزهای 1000 و 1500 میلی لیتر علف‌کش نسبت به عدم تلقیح در همین تیمارها به ترتیب 34 و 57 درصد افزایش داد. بر اساس نتایج این پژوهش، قارچ های میکوریزا از طریق بهبود رشد گیاه سبب کاهش اثرات تنش دزهای پایین علف کش ترفلان بر گیاه شبدر می شوند.

Aims: The study aimed to evaluate the influence of different weed management approaches on weed density and weed control efficiency in apple nurseries.
 Study Design: The experimental method used in this study was a Randomized Complete Block Design with seven treatments, each replicated three times.
 Place and Duration of Study: The experiment was set up at the Experimental Farm, Division of Fruit Science, Faculty of Horticulture, Sher-e-Kashmir University of Agricultural Sciences and Technology of Kashmir, Shalimar Campus, Srinagar, Jammu and Kashmir, India during the year 2020.
 Methodology: Seven weed management treatments i.e. manual weeding, pendimethalin @ 1 kg a.i. ha-1, pendimethalin @ 1 kg a.i. ha-1 + manual weeding, paddy straw mulch – 6 cm thick, black polyethylene mulch - 200 micron, weed-free and weedy check were tested in apple nursery (Apple cv. Silver) Spur grafted on M-9 T337 was used as plant material for the study. Weed flora, density, dry weight, and weed control efficiency were all observed and recorded.
 Results: Among different weed management approaches tested, black polyethylene mulch (200 micron) resulted in the lowest weed density and weed dry weight, and the highest weed control efficiency followed by paddy straw mulch (6 cm thick) and pendimethalin @ 1 kg a.i. ha-1 + manual weeding.
 Conclusion: In apple nurseries on clonal rootstock M9-T337, black polyethylene (200 micron) was determined to be the most effective weed control strategy for reducing weed density while increasing overall control efficiency.

Summary In 2008–2010 at the qualification of influence was the aim of investigations tillage systems and weed control methods on effectiveness of destruction of the weed air‐dry mass as well as the influence of damage herbicides applied in the blue lupine tillage. In 2008–2010 a field experiment was carried out at the Agricultural Experimental Farm Zawady of the University of Natural Sciences and Hummanities in Siedlce. The experiment was set up in split‐plot design with four replications. The aim of the study was to evaluate the efficacy of weed regulation in blue lupin crops with the use of: I – different tillage systems (conventional and simplified) and II – five weed control methods. Phytotoxicity of applied herbicides to the plants of blue lupin was also taken into consideration. The best results in weed controlling were obtained after the use of the herbicide mixture: Afalon Dyspersyjny 450 SC + Metron 700 SL + Fusilade Forte 150 EC at both dates of observations, and its efficacy amounted to 81.7 and 53.3% respectively. The results the studies revealed that the efficacy of weed regulation in blue lupin crops depended on such factors as tillage systems, applied herbicides and their mixtures and weather conditions.

CITATION: Langenhoven, S., et al. 2018. Detection and quantification of black foot and crown and root rot pathogens in grapevine nursery soils in the Western Cape of South Africa. Phytopathologia Mediterranea, 57(3):519-537, doi:10.14601/Phytopathol_Mediterr-23921.

Information on integrated weed management systems is needed so that producers can develop systems that minimize the environmental impacts of weed control without sacrificing profitability of crop production. Reduced rates of broadcast‐ or band‐applied alachlor [2‐chloro‐N‐(2,6‐diethylphenyl)‐N‐(methoxymethyl)acetamide] plus metribuzin [4‐amino‐6‐(1,1‐dimethylethyl)‐3‐(methylthio)‐1,2,4‐triazin‐5(4H)‐one] and rotary hoeing, each in combination with between‐row cultivation, were evaluated for weed control in soybean [Glycine max (L.) Merr.]. One or two between‐row cultivations allowed for a 50 to 75% reduction in the amount of herbicide used without reducing weed control or soybean yield. Reducing herbicide rates also decreased soybean injury. Two passes of a rotary hoe reduced weed densities up to 75% and increased the effectiveness of subsequent cultivations. However, two passes of the rotary hoe reduced soybean density as compared to other treatments. In 1989, under low weed densities, several mechanical weed control systems resulted in soybean yields similar to the weed‐free control. In 1990, under greater weed densities, mechanical weed control systems resulted in reduced soybean yields compared to weed control systems that included herbicides. Based on the results of this research, switching from chemical‐intensive systems to mechanical weed management systems under high weed pressure is not advisable. Under high weed pressure, reduced rates of herbicide, broadcasted or banded over the soybean row, in combination with cultivation provided excellent weed control. Mechanical weed control as a part of an integrated weed management system should maximize weed control while minimizing herbicide use.