مقایسه فلور و تعیین وضعیت پراکنش علفهایهرز در سطح باغهای میوه شهرستان خرمآباد

The weed survey was carried out in 2012 and 2013 cropping season on eight to ten upland rice farmers’ fields respectively in Bambasi, Ethiopia to determine weed prevalence, species composition and distribution. A quadrant size of 0.25 m2 were used in a systematic sampling technique and a total of 21 weed species belonging to 12 families were identified and counted. The most dominant weed family based on the number of species recorded was poaceae (grasses) which comprized 5 species. during both cropping season survey, most (66.67 %) of the species were broad leaved herbaceous plant. weed species composition was analyzed using quantitative means and most frequent weed species in upland rice field during 2012 cropping season was cyprus rotondus (100%) followed by Ageranthum conizoid, Commelina subulata, Digitaria abisynica, Elusin indica and Leucas martinicensis. The dominance range during this year was 0.09 to 54.59% and Ageranthum conizoid accounted 54.59% of the species which was followed by Cyprus rotondus, Spergula arvensis and Commelina subulata. during 2013 cropping season Ageranthum conizoid and Polygonum nepalense were the most frequently (100%) occurred weed species followed by Cyprus rotondus, Commelina subulata, Digitaria scalarum, Elusina indica, Galensoga parviflora. The dominant weed species during this year (2013) was Polygonum nepalense (20%) followed by Ageranthum conizoid and Cyprus rotondus, Commelina subulata and Leucas martinicensis dominance level range between 16.36% and 4.02% respectively. The prevalence and density of most species on upland rice during 2012 and 2013 cropping season was similar. Moreover, similarity index between the 2012 and 2013 surveys were higher (100%). Thus, the weed control and management research strategy should consider the dominant and frequent weed species of both cropping seasons and weed flora composition.

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.

To study weed species diversity and community structure in pistachio (Pistacia vera L.) orchards in 33 orchards of 12 villages an investigation was conducted in Bardaskan County, Khorasan Razavi Province, Iran during 2008-2009. Weed population sampling was conducted in a w shape method using 1m² quadrate. The results showed that the weeds of pistachio orchards were belonging to 15 families and 44 species. dicotyledons (31 species) were more than monocotyledons (13 species). Such as in this community, weed species of C3, C4, annual and perennial were 26, 18, 28 and 13, respectively. The majority of weed species were belonging to the plant families of chenopodiceae (9 species) and poaceae (12 species) amongst dicotyledons and monocotyledons, respectively. the most important species of monocotyledon annual weeds were including Echinochloa crus-gali, Digitaria sanguinlis, Setaria viridis and perennial weeds were including Cyperus routundus, Cynodon dactylon and convolvulus arvensis. Weed species were grouped in seven clusters for density average, frequency and uniformity (similarity 75 percent) whereas in eight clusters for relative density average, relative frequency and relative uniformity (similarity 75 percent). Amplitude changes of Shannon-winter diversity index were between 2.3 and 0.16 and of Simpson dominant index were between 0.97 and 0.17. The difference among indices of biodiversity and dominant clusters were relative to scale and type of management practices.

Introduction: According to the importance of corn in supplying the human food directly and indirectly, it is one of the most important plants among crops. One of the major problems in corn production systems, is competition with weeds that reduce corn yield significantly. Weeds not only reduce crop yields but also decrease the commercial quality and the feeding palatability of main crops. They enhance the soil seed bank of weeds, which may cause continuous weed infestation of field crops as well. Herbicide application is a reliable and highly effective method for weed control. However, demand for safe food products that have been produced with a minimum application of chemical inputs is increasing. Therefore, farmers interested in weed management have to rely on other control approaches. An alternative weed control method is the use of cover crops, which can suppress the growth of weeds by preventing them from light and by producing allelopathic compounds. Cover crops successfully have been integrated into conservational agriculture systems in many areas of the world. Legumes are used as cover crop because of their rapid growth, in addition their potential to provide further nitrogen,along with high ability to compete with weeds. Materials and Methods: In order to study the effect of cover crops (soybean and wheat) and different fertilizers sources on yield of corn and weed control, a filed experiment was conducted in randomized complete block design with three replications in 2012. Treatments included two cover crop (wheat and soybean) and three fertilizer (no fertilizer, chemical fertilizer and compost)..Fertilizer treatments was used according to soil analysis and requirement of corn (as a main plant). Weed-infestation and weed-free plots were used as controls. Study cultivars of corn, wheat and soybean were NS-640, Milan and Sari, respectively. Planting of corn was in June and cover crop was planted with corn simultaneously and between corn rows. The dominant weed species were velvetleaf (Abutilon theophrasti Medic.), johnson grass (Sorghum halepense (L.) Pers.), wild melon (Cucumis melo var. agrestis) and giant foxtail (Setaria glauca L.) in the field. In order to determine the dry weight and density of weeds, three-stage sampling was performed from the middle rows of corn. Corn yield was also measured by mechanical harvesting in middle rows and adjusting to 14% moisture. A week before the final harvest, ten plants of corn were selected randomly from the three middle rows of each plot and yield components including the number of rows in corn, number of kernels per row, weight of 1000 grains was measured. Results and Discussion: The results showed that soybean cover crop reduced weed density compared to control in weed infestated plots, but wheat was not successful in suppressing weeds and reducing their density due to poor biomass and dying at the end of growing season . So, the lowest dry matter of velvetleaf, wild melon and other weeds were related to planted corn with soybean and compost and the maximum was related to monoculture of corn with weed infestation. Results of analysis of variance indicated treatments had significant effect on grain yield. The lowest yield of corn (2733.3 Kg ha-1) was in weed-infestation control while the highest one (12124.0 and 8351.3 Kg ha-1 respectively) was in weed-free control and soybean’ cover crop plus compost. For both cover crops between fertilizer treatments, compost and chemical fertilizer had more corn biological yield than no fertilizer and differences between this two fertilizer treatments wasn’t significant. Reduction of yield under no fertilizer treatments was due to competition for nutrients, light between weed and corn. The maximum and minimum number of rows in corn and number of kernels per row respectively was obtained with monoculture of corn in weed free and weed infestation, while the maximum weight of 1000 grains was observed in soybean with applying compost. Generally, the living mulch as cover crops can reduce competition between weeds and the main crop. Conclusion: As cover crops reduce weeds growth, and there was no significant difference between chemical and organic fertilizer in corn yield, so we can use these two options for producing optimum yield in sustainable agriculture. Results showed application of soybean as cover crop, especially integrated with organic fertilizers, can be an alternative approach for herbicides and are more effective than the others.

در این تحقیق ذرت در سه تراکم (8 ، 12 و16 بوته/متر مربع) و در دو الگوی کاشت تک ردیفه و دو ردیفه و بذر هفت گونه علف هرز تاج خروس وحشی، سلمه تره، تاجریزی سیاه، علف چمن، دم روباهی کشیده، تاتوره و قیاق کشت شدند. دما، کیفیت و شدت نور در سطح خاک اندازه گیری شد و تعداد گیاهچه های سبز شده از هر علف هرز در سه نمونه برداری بررسی شد. نوسان دمایی تحت تأثیر تراکم و الگوی کشت قرار نگرفت و با تشکیل کانوپی ذرت کاهش یافت. سه الگوی سبز شدن در علفهای هرز دیده شد، از گونه های بذر ریز، تاج خروس یک فلاش جوانه زنی داشت و به پوشش کانوپی پاسخی نداد. تعداد گیاهچه سبز شده علف چمن و سلمه تره و دم روباهی کشیده در تیمار بدون پوشش گیاهی نسبت به با پوشش گیاهی و الگوی کاشت تک ردیفه نسبت به دو ردیفه با اختلاف معنی داری بیشتر بود و سه فلاش جوانه زنی داشتند. از گونه های بذر نسبتا درشت، تعداد گیاهچه‌های سبز شده در تیمار با پوشش گیاهی نسبت به بدون پوشش گیاهی در دو گونه داتوره و تاجریزی سیاه تفاوت معنی داری نداشت ولی در گونه قیاق افزایش یافت و در هر سه گونه در الگوی کاشت دو ردیفه بیش از الگوی تک ردیفه بود. داتوره سه ولی تاجریزی و قیاق یک فلاش جوانه زنی داشتند.

این تحقیق جهت مقایسه تنوع زیستی علف‌های‌هرز بوم‌نظام‌های برنج (Oryza sativa L) شهرستان‌های بابل و بابلسر انجام گردید. نمونه‌ها از شش مزرعه دو نظام مدیریتی (ارگانیک و پرنهاده)، در سال زراعی 91-1390، جمع‌آوری شد. داده‌ها (شامل تعداد گونه‌های علف‌هرز و فراوانی هر یک) از نُه کوادرات (یک×یک متر) هر مزرعه، طی چهار مرحله (پنجه‌زنی، ساقه‌روی، پرشدن دانه و پس از برداشت) به‌دست آمد. مقایسه میانگین شاخص-های تنوع زیستی دو نظام مدیریتی، نشان داد که علی‌رغم افزایش مقادیر شاخص‌های تنوع در نظام ارگانیک، اختلاف معنی‌داری بین دو نظام قابل مشاهده نبود. مقایسه مراحل مختلف نمونه‌برداری بر اساس میانگین دو نظام، حاکی از کاهش تنوع و یکنواختی علف‌های‌هرز در مرحله چهارم (پس از برداشت) بود. ارزیابی شاخص‌های تنوع زیستی دو نظام پرنهاده و ارگانیک نیز حاکی از کاهش معنی‌دار شاخص‌های تنوع زیستی علف‌های‌هرز در مرحله چهارم نسبت به مراحل قبلی بود. این نتیجه می‌تواند به‌علت تخریب ایجاد شده در بوم‌نظام‌های برنج، ناشی از برداشت محصول و فراهم شدن زمینه برای ظهور گونه‌های مختلف علف‌هرز باشد. علی‌رغم اینکه در این شرایط انتظار افزایش تنوع می‌رود، اما به‌واسطه وجود تنش خشکی در مرحله برداشت، گونه‌های مقاوم به تنش ظاهر شده و مستقر گردیدند. برتری تنوع در نظام ارگانیک، به‌ویژه در مرحله چهارم را می‌توان به ظهور و استقرار علف‌های‌هرز مقاوم به شرایط تخریب و تنش مانند علف انگشتی (Digitaria spp.)، توق (Xanthium strumarium L.) و اکلیپتا (Eclipta prostrata L.) (گونه‌های شرایط غیرغرقاب) علاوه بر علف‌های‌هرز رایج (گونه‌های شرایط غرقاب) بوم‌نظام برنج مانند سوروف (Echinochloa crussgalli P. Beauv) و گونه‌های اویارسلام (Cyperus spp.) نسبت داد. نتیجه این که در مجموع، شاخص‌های تنوع زیستی (تنوع و یکنواختی) علف‌های‌هرز در نظام ارگانیک نسبت به رایج برتری داشت.

Student Square was opened on September 1, 2007 at the intersection of the busy Moscow Avenue and K. Ivanov Street. The total area is 2,5 hectares. The predominant tree species are Tilia cordata Mill., Betula pendula Roth and Acer platanoides L. In 2016, the first inventory of the square flora was carried out, 94 plant species from 79 genera and 37 families were identified. Pinopsida are represented by 4 cultivated introducents. Only 6 species from the Poaceae are monocotyledons. The systematic diversity of the flora is very low. Virtually every genus is represented by only one species. The average level of species wealth in one family is 2,54. The number of families with one species is 21 (56,8%). The top ten in the number of species families are concentrated by 63,8% of the species. The spectrum of the leading families of the flora of the Student Square indicates its thermophilic appearance. The share of synanthropic species in the flora as a whole is 53,2%. The index of synanthropization ( Is ) of the square flora is 1,14 and emphasizes the anthropogenic nature of the landscape. The aboriginal fraction of the flora is strongly altered ( Is = 0,48). In the ecologo-cenotic spectrum, there is a preponderance towards plants of open habitat types, among which weed species predominate (34%), among which 4 are malignant invasive species: Acer negundo L., Conyza canadensis (L.) Cronq., Lepidotheca suaveolens (Pursh) Nutt., Xanthoxalis stricta (L.) Small. On the second place is a group of meadow plants (16%). The distribution of other coenotic groups in general is consistent with the regional spectrum of the flora of Chuvashia. The hygromorph spectrum is dominated by mesophytes (71,3%), followed by xeromesophytes (16%), the share of the remaining groups varies from 1,1 to 6,4%. The trofomorph spectrum is dominated by mesotrofs (62,8%) and megatrofs (36,2%). Aliens fraction is 30,9% of the square flora. 17 species (58,6%) are cultivated introducents, and the rest - weed plants. Kenophytes (75,9%) predominate, ergasiophytes and ergasiofigophytes (24,1% each), epekophytes and agrio-epekophytes (65,5%), North American (31%) and Iranian-Turanian (20,7%) species.

For effectively controlling weeds in tobacco fields, the seed pools of weeds in main tobacco growing areas in Sichuan was studied in terms of composition and population with germination method in2011-2014. The results showed that there included 24 weed species, belonged to 15 families, spread mainly in 0-15 cm soil layer. The dominant species were of Gramineae, followed by those of Compositae and then of Chenopodiaceae. The species of dicotyledonous weeds exceeded the species of monocotyledonous weeds in number, but the density of seed was obviously lower. The highest density(19 119 seeds/m2) seed pool was found in the sample from Guangyuan, while the lowest(6 177 seeds/m2)was found in the sample from Panzhihua.

Herbicidal effects and crop selectivity of aqueous leaf extracts of sorghum (Sorghum bicolor L.) were evaluated against several weed species for developing sustainable weed management in organic farming. Aqueous sorghum leaf extracts were highly phytotoxic to different weed species. No broadleaf weeds were germinated in the concentration of 5 fold or higher concentrated sorghum leaf extracts and 90% of seed germination was inhibited within that range in grass species. Sorghum leaf extracts strongly inhibited the growth of different weeds by pre-emergence and foliar applications in greenhouse condition. Foliar application of sorghum leaf extracts had a higher inhibitory effect than the pre-emergence application. Broadleaf weed species were more susceptible than grasses to the application of sorghum leaf extract in foliar applications than grasses. Galium spurium, Erigeron candensis, and Rumex japonicus were completely killed at the highest concentrated sorghum leaf extract both in pre-emergence and foliar application. Most broadleaf weed species were inhibited more than 80% at pre-emergence application at 50 fold concentrated sorghum leaf extract. G. spurium, E. candensis, R. japonicus, Eclipta alba, Plantago asiatica and Portulaca oleraeea were most susceptible to sorghum leaf extract in foliar application. Growth of most broad leaf weed species was suppressed by greater than 90% at 50 fold concentrated sorghum leaf extract. Most crop species were tolerant to sorghum leaf extract but shoot growth was slightly reduced by the application of 40~50 fold concentrated extracts, Sorghum leaf extract may used to control weeds in organic fanning without affecting the growth of crop.

A survey was conducted in different field crops of six districts (Chilga, Gondarzuria, Metema, Takussa, Dabat and Dembia) in Northwestern Ethiopia within 2016 and 2017 cropping seasons. The objective of the study was to identify the most important weed species and to determine their frequency, density and uniformity at different altitudes. A quantitative and qualitative method was employed for the enumeration and identification of weed species. Quadrats were laid along transects and individual weed species in each quadrat was identified and counted. Frequency, uniformity, similarity index and relative abundance were used to determine the weed community structure. A total of 76 weed species belonging to 65 genera within 27 families were identified across different field crops. The most dominant families, based on the family dominance index (FDI), were Asteraceae, Poaceae, and Fabaceae with 78.97, 63.76, and 20.72 FDI, respectively. The most frequent, abundant and dominant weed species were Digitaria abyssinica (Hochst. Ex A. Rich), Cyperus rotundus L. and Cynodon dactylon L. The average values for frequency and dominance of weed species in arable fields ranged between 49.34 to 59.87% and 3 to 3.69%, respectively. Results obtained from this study would be useful in creating a weed management programme and making inform decision on choice of herbicides and directing research toward new or improved weed control measures. Key words: Altitude, density, district, dominance, family, frequency, species.

Field experiments were carried out on the reduction of weed infestation in maize grown in the rotation system on podsolic soil. As a result the following weed species were found to be dominant: barnyardgrass [Echinochloa crus-galli (L.) P. Beav.] and lambsquarters (Chenopodium album L.). A higher weed species composition and a lower soil coverage value (24%) per 1 m area were stated in the maize conventional cultivation system with plowing as compared to reduced maize tillage. Besides the dominant weeds barnyardgrass and lambsquarters the were less numerous field violet (Viola arvensis Murray), creeping speedwell (Veronica pesica L.), shepherds purse [Capsela bursa-pastoris (L.) Medik], corn chamomille (Anthemis arvensis L.), cornflower (Centaurea cyanus L). Taking into consideration the simplified system it was found that the weed species composition was dominated by barnyardgrass and lambsquarters and the coverage of 1 m soil surface amounded to 66%. There was a higher intensity of annual grass weed species barnyardgrass and green bristle grass [Setaria viridis (L.) P. Beav.] as well as perennial species in particularly quackgrass [Elymus repens (L.) Gould] and single weed plants of mugwort (Artemisia vulgaris L.) and Canada thistle [Cirsium arvense (L.) Scop.] were also recorded. The number of annual broad leaved weeds was reduced as compared to the plow cultivation system. The application of herbicides mixture rimsulfuron + dicamba with adjuvant Trend 90 EC controlled the majority of the weed species and gave the best results for this type of soil. Only quackgrass occurring numerously in the experiment as well as winter forms of mugwort and creeping speedwell were less sensitive to the applied mixture of herbicides.

In order to study the weed damage and to determinate the influence of weed species and multiple weed species competition in corn (Zea mays L.), a field experiment was conducted based on interval mapping at the Agronomy Research Field of Ferdowsi University of Mashhad during 2009-2010. Treatments consisted of four density level of crop (5, 6, 7 and 9 plant.m-2) and four type of weed management (completely removed weed, broadleaf control, non control, and grass weeds control). Weed samples were taken at harvest time. Dry matters of corn samples were measured. The Density and dry matter of weed samples were recorded separately for each species. Equations were fitted single plant weight ln of each weed species or crop as dependent variable to compare and evaluate the competition coefficient of inter and intra species. Results indicated that single plant weight ln and plant density per m-2 had high correlation to evaluate competition coefficient. Considering the coefficients of equation the function of single plant weight ln showed that crab grass and prostrate pigweed had the most stimulation effect on corn. While redroot pigweed prostate common purslane field bindweed black night shade common lambsquars barnyardgrass purple grown nutsedge and Green foxtail had inhibition effect on corn. The positive of the former group on corn were resulted from the inhabitation effect on the latter group of weeds.

Allelopathic activity of rotation crop residues to common weeds and selectivity of crops were studied for developing an alternative weed control strategy in upland organic farming. All rotation crop residues with various ratios suppressed weed growth, but the growth of crop species stimulated a little when those were grown with the mixture of rotation crop residues except a few crop species. Among the rotation crop residues used in this study hairy vetch was the most effective, followed by Chinese milkvetch, barley and rye in suppression of weed growth. The 90:10 (crop:soil, v/v) treatments incorporation rate of crop residues such as hairy vetch and Chinese milkvetch suppressed completely the growth of all weed species tested in this study. The effect of crop residues on suppression of weed growth reduced to 90% when the incorporation rates decreased to 60% [60:40 (crop:soil, v/v). It was noticed that broadleaf weed species were more susceptible to rotation crop residues than grass weed species. In the influence of crop residues on the crop growth, no growth inhibition was found in red pepper, lettuce and perllia at any incorporation rates, but tomato, cucumber and corn were slightly inhibited in a few cases at their highest incorporation levels. This study demonstrated that rotation crop residues especially hairy vetch and Chinese milkvetch have high herbicidal effects against weeds without inhibiting the growth of crop species.

هدف از انجام این تحقیق تعیین ارزش غذایی هفت گونه از علف‌های هرز موجود در مزارع یونجه شامل: تلخه، بومادران و ریش قوش از خانواده کاسنی، یونجه و شبدرشیرین از خانواده بقولات و دم روباهی، علف پشمکی و علف باغ از خانواده گندمیان بود. نمونه‌برداری از گونه‌های مورد مطالعه در مرحله برداشت یونجه از مزرعه (10% گلدهی مزرعه) صورت گرفت. نمونه‌های برداشت شده در مزرعه به مدت 72 ساعت هوا خشک شده و برای انجام آزمایشات مورد استفاده قرار گرفت. ترکیبات شیمیایی، تخمیرپذیری و تجزیه‌پذیری نمونه‌ها با روش آزمایشگاهی تعیین شد. نتایج نشان داد که در بین گونه‌های مورد مطالعه از نظر ترکیبات شیمیایی تفاوت‌های معنی‌داری وجود داشت. یونجه با 3/14و دم‌روباهی با 4/8 درصد بیشترین و کمترین مقدار پروتئین خام را در بین علوفه‌های مورد آزمایش داشتند. بیشترین و کمترین میزان دیواره سلولی مربوط به دم روباهی و شبدرشیرین به ترتیب با 7/58 و 8/33 درصد بود. ریش قوش و تلخه به ترتیب با 8/28 و 5/19 درصد بیشترین و کمترین میزان دیواره سلولی منهای همی سلولز را در بین گونه‌های مورد مطالعه داشتند. با مقایسه میزان گاز تولیدی حاصل از تخمیر علف‌های هرز و یونجه در 96 ساعت پس از انکوباسیون، یونجه و علف پشمکی به ترتیب با 7/249 و 4/166 میلی‌لیتر به ازای هر گرم ماده خشک، بیشترین و کمترین میزان گاز تولیدی را به خود اختصاص دادند. در بین علوفه‌های مورد آزمایش بیشترین مقدار قابلیت هضم ماده آلی و اسیدهای چرب کوتاه زنجیر مربوط به یونجه و شبدرشیرین بود. ناپدید شدن ماده خشک برای شبدر شیرین در ساعات مختلف انکوباسیون بیشتر از بقیه گونه‌ها بود. علف پشمکی کمترین میزان ناپدید شدن را در بین گونه‌های مورد مطالعه داشت. شبدر شیرین و علف پشمکی با 6/32 و 2/23 درصد به ترتیب بیشترین و کمترین مقدار بخش سریع تجزیه‌پذیر ماده خشک را در بین علوفه‌ها داشتند. بخش با پتانسیل تجزیه‌پذیری کم و نرخ ناپدید شدن ماده خشک برای شبدر شیرین بیشتر از بقیه علوفه‌ها به جز یونجه بود. نتیجه کلی اینکه تفاوت بین ترکیبات شیمیایی، پتانسیل تولید گاز و تجزیه‌پذیری یونجه در مقایسه با علف‌های هرز بایستی در تنظیم جیره‌های غذایی نشخوارکنندگان مدنظر قرار گیرد اما آنچه مسلم است ارزش غذایی یونجه با توجه به نتایج به‌دست آمده قابل مقایسه با علف‌های هرز نمی‌باشد

Herbicide-resistant weed populations have become problematic throughout the Eastern Corn Belt, with 18 unique herbicide-resistant weed biotypes confirmed in Indiana alone. In response to these resistant populations, the agricultural chemical industry has responded by developing glyphosate-resistant crops paired with resistance to synthetic auxin herbicides such as dicamba and 2,4-D.This research evaluates weed population shifts in cropping systems using row crops that are resistant to synthetic auxin herbicides. Identifying weed population shifts will allow future research to be targeted to weed species that would become more prevalent in cropping systems using synthetic auxin-resistant crops. The use of multiple sites of action will be needed in order to prevent weed shifts in both conventional and no-till corn-soybean production systems. Weed densities and species richness were reduced within field evaluations when six or more herbicide sites of action were implemented with residual herbicides in both corn and soybean years over a seven-year period. Additionally, soil seedbank weed densities and species richness were reduced within 2,4-D-resistant soybean production systems. Additional strategies other than the application of herbicides may be needed to manage weed populations in the future due to the high levels of herbicide-resistant weed populations in the Midwest.Off-target movement of these synthetic auxin herbicides, has been a concern, and label-mandated buffer areas are required near sensitive areas. Investigation of whether cover crops can be an effective tactic in managing weeds in these label-mandated buffer areas was conducted. Cover crop utilization in buffer areas has not been investigated in Indiana. Additionally, termination timing is becoming more prominent as farm operators are increasingly terminating cover crops after planting. Our results demonstrate that using cover crops that utilize cereal rye and that are terminated at, or after the time of soybean planting will be beneficial in suppressing waterhemp, grasses, and sometimes horseweed within label-mandated buffer areas, but not for suppression of giant ragweed. However, delaying termination of cover crops can result in soybean yield reductions and caution should be used. Terminating cover crops with glyphosate and auxin and a residual herbicide was more effective than glyphosate alone, but would not be permitted within label-mandated buffer areas.L