نشریه دانش علفهای هرز
سال نوزدهم شماره 2 (پاییز و زمستان 1402)

To evaluate the appropriate herbicide for the control of waxy leaved mustard, an experiment was conducted base of a completely randomized block design with 4 replications in the greenhouse of the Faculty of Agriculture, University of Kurdistan. The experimental treatments included 5 herbicides metsulfuron-methyl+ sulfosulfuron (Total), idosulfuron + mesosulfuron + mefen bayer (Atlantis), diflufenican + mesosulfuron methyl + iodosulfuro (Othello), tribenuron methyl (Granstar) and 2,4-D + MCPA in 5 concentrations (0, 0.50, 1, 1.5 and 2 recommended dose) and measured traits were dry weight, leaf area index and stem length. Data were analyzed by SAS (V. V.9.2) and the figures were drawn using SigmaPlot (V.14). The maximum dry weight was 0.27 gr per plant resulted from 2,4-D + MCPA application, and the zero concentration (control) had the highest rate of dry weight among the concentration treatments. Atlantis (Mesosulfuron + Iodosulfuron + Mefen bayer) application resulred the highest leaf area index (0.77) and tribenuron methyl had the lowest leaf area index (zero), equal to the recommended dose of this herbicide. The highest stem length (7.1 cm) was belonged to Atlantis (Mesosulfuron + Iodosulfuron + Mefen bayer) and the lowest (3.8 cm) was obtained from 2,4-D + MCPA. ED10, ED50 and ED90 index evaluation showed that 2,4-D+MCPA herbicide controlled waxy leaved mustard with a lower dose than other herbicides. The results showed that 2,4-D + MCPA is an efficient herbicide in waxy leaved mustard controll. Tribenuron methyl (Granstar) and mesosulfuron + iodosulfuron + diflufenican (Othello) can also be suitable herbicides to control this weed, but Total (metsulfuron-methyl+ sulfosulfuron) and Atlantis (mesosulfuron + iodosulfuron) did not show enough effect on this weed control.

Keeping and returning plant residues to the soil not only improve the physical and chemical structure of the soil, but the presence of chemical compounds of the residues can also reduce the germination and growth of weeds. In this regard, a factorial experiment based on randomized complete blocks design with three replications was conducted at the experimental greenhouse of agricultural research station of the college of agriculture and natural resources, university of Tehran in 2019-2020. Treatments included three levels of plant residues (no-residues, residues of Brassica napus and Hordeum vulgare), two types of soil (no-sterile and sterile), three levels of soil temperature (25, 35 and 45oC) and two types of weed (Amaranthus retroflexus and Hordeum spontaneum). By increasing the temperature from 25 to 45oc, the final emergence percentage and emergence rate of weed seedling in the no-residues increased and in the treatments with Brassica and Hordeum residues decreased. In both sterile and no-sterile soils, the highest final emergence percentage (76.1 and 66.1%) and emergence rate of weed seedling (0.12 and 0.11 h-1) were observed in the no-residues. In addition, in sterile soil, the mentioned treatment was very different from the treatments of Brassica and Hordeum residues. Although the allelopathic effect of Brassica napus residues for controlling the emergence of the H. spontaneum and A. retroflexus compared to H. vulgare was greater; however, both crops were able to disrupt the emergence of the weeds. Therefore, preserving soil plant residues by strengthening the population of soil microorganisms and the relative control of the weed population can be important in reducing the amount and cost of application herbicides, environmental protection, and maintaining the stability of agricultural systems.

In order to control of purple nutsedge (Cyperus rotundus L.) in transplanted onion, an experiment was conducted as a randomized complete block design with nine treatments and three replications in fields of Agricultural and Natural Resources Research and Education Center of South of Kerman in 2019-2021. The treatments included oxyfluorfen (Goal®, 30% SL) at 450 and 600 g a.i ha-1 (1.5 and 2 L ha-1) after establishment of seedlings in the early growth of purple nutsedge, oxadiazon  (Ronstar®,12% SL) at 300 and 360 g a.i ha-1 (2.5 and 3 L ha-1) at after transplantation in 2-4 leaves of purple nutsedge, pendimethalin (Prowl®,45.5% CS) at 1137 and 1365 g a.i ha-1 (2.5 and 3 L ha-1) after transplantation and before emergence of purple nutsedge, bentazon (Basagran®,48% EC) at 960 and 1440 g a.i ha-1 (2 and 3 L ha-1) in 2-4 leaves of purple nutsedge and weed free. To increase the accuracy of the experiment, each test plot was divided into two equal sections, with the upper half serving as the control without spraying and the lower half being sprayed. The results demonstrated that the best treatment was obtained bentazon at 3 L ha-1 and oxyfluorfen at 2 L ha-1 in purple nudsedge control. So that, bentazon reduced 73, 77 and 90 % aerial biomass of nutsedge at 20, 30 and 40 days after treatment. In addition, it reduced underground biomass 83% and it was desirable treatment after weed free. That increased marketable onion yield (7.9 Kg m-2) 60% in comparison to weedy. Therefore, bentazone at 3 L ha-1 controlled purple nutsedge and increased marketable yield of onion.

The first and most important step in weed management planning is to know the weed population. The proper sampling method is necessary to get a real and accurate knowledge of weed contamination in the fields. To investigate the effectiveness of grid sampling methods in estimating the weed population of corn fields under drip, furrow and sprinkler irrigation systems, a research was conducted in 2020 in six corn (Zea mays L.) fields. The fields were gridded with nine methods (three square methods, a rectangle along the field and a rectangle across the field each in three sizes). At the intersection of the lines, using square (100×100 cm) and rectangular (80×125 cm) squares perpendicular to the planting lines, data on the density and diversity of weed seedlings were recorded by species and at the four-leaf stage of corn. The results showed that in weed species such as A. belitoides, which had a wide distribution range, in drip and furrow irrigation systems, the square quadrat showed a more accurate estimate, and in the rain irrigation system, the rectangular quadrat showed a more accurate estimate. This was affected by the different wetting patterns of the soil in different irrigation methods, which somehow affected the emergence of weeds in the field. In other weed species, such as A. retroflexus, which had a more limited distribution range, the square quadrat in all three irrigation systems estimated weed density with less error than the rectangular quadrat. Examining the accuracy of grid sampling methods in weed population estimation showed that rectangular grid methods by increasing the grid dimensions along the length or width of the land had a more accurate estimate of species diversity and population density, as well as the density of single weed species compared to square grid methods with larger dimensions. By using these networking methods, along with the appropriate estimation of species diversity and weed population density, the status of weed species in the field can be investigated by reducing the sampling points with greater ease and less human effort.

In order to investigate the effect of weed control method on yield and yield components of lentil, this study was conducted as a factorial experiment in a randomized complete block design with three replications at Deylaman district of Siahkal county, Guilan province, in 2020. Experimental factors consisted of lentil genotypes (Kimia and landrace cultivars of lentil) and weed control programs (twice handweeding, once handweeding, pendimethalin (900 g ai ha-1) + handweeding, pendimethalin + pyridate (1200 g ai ha-1), pyridate, and weed infested control). Based on the results, the efficacy of control program on weed density and dry weight reduction was 45-63% for pyridate, 68-93% for pendimethalin + pyridate. 64-86% for pendimethalin+ handweeding, and 56-80% for once handweeding. Plant height, number of branches per plant, biological yield, seed yield, number of pods per plant, and 1000-seed weight of Kimia cultivar were more than those of landrace of lentil, while the harvest index was lower. In both genotypes, full-season weedy treatments comparing to twice hand weeding caused an increase in height, but decreased the number of branches per plant, biological yield, and seed yield. In Kimia cultivar and landrace of lentil, the maximum biological yield was associated with twice hand weeding (4648 and 4329 kg ha-1) or application of pendimethalin + pyridate herbicides (4556 and 4092 kg ha-1), and the highest seed yield was observed in twice hand weeding (1771 and 1649 kg ha-1) and then with application of pendimethalin + pyridate (1479 and 1372 kg ha-1, 16% lower). Full-season weed infestation reduced biological and seed yield by 67%. Generally, twice hand weeding for limited cultivation areas, and then applying pendimethalin + pyridate and pendimethalin +hand weeding could be recommended; while appropriate chemical weed control requires more evaluation of available herbicides, and may even involving registeriation of new and effective herbicides.

Understanding the relationship between weeds and lentils is essential for effective weed management. an experiment was conducted in the growing season of 2017 in a field located in the Agriculture and Natural Resources Campus of Razi University, Kermanshah. At the early stages of crop growing, the field was monitored and different infestation levels of weeds were determined and six classes were determined. Class, one exhibited the lowest level of weed infestation, whereas class six showed the highest. Each class was treated as a separate treatment, with five replications conducted for each one. The results of our survey showed that the lentils yield, biomass and harvest index were significantly affected by the weed infestation levels in which up to 81% yield loss was observed with increasing weed infestation intensity. The maximum leaf area index of lentil was achieved at 50 to 60 days after emergence. The maximum lentil leaf area index was observed in the first and second weed infestation classes, and with the increase in the infestation intensity, the lowest amounts of lentil leaf area index was observed in the fifth and sixth classes. In addition, the accumulation of lentil dry matter in the first and second classes of weed infestation were more than the other classes. In general, due to the high vulnerability of lentil to competition with weeds, weed management until the lentil reaching the maximum leaf area index (day 50 days after emergence) is crucial.

In order to study the effectiveness of the new herbicide metazosulfuron in controlling weeds and its selective performance on rice, pot and field experiments were carried out at Rice Research Institute of Iran in 2018. In the pot test, the recommended dose of metazosulfuron (83 g ai ha-1) in comparison with the herbicides flucetosulfuron, triafamone + ethoxysulfuron, pyrazosulfuron ethyl+pretilachlor, pretilachlor and thiobencarb in the control of weeds, Bolboschoenusplaniculmis, Paspalum distichum, Monochoria vaginalis, Alisma plantago aquatica, Echinochloa oryzoides and Potamogeton nodosuswere investigated. The results showed that metazosulfuron had ≥98% efficiency in controlling all of the above weeds and provided similar or higher efficiency compared to other registered herbicides. In the field experiment, the efficacy of 0, 41, 83, 124 and 165 (g ai ha-1) metazosulfuron in comparison with pretilachlor+bensulfuron methyl, thiobencarb+bensulfuron methyl, triafamone + ethoxysulfuron, bensulfuron methyl, thiobencarb and hand weeded control was investigated. Different doses of metazosulfuron, except of 41 g ai ha-1, had similar effectiveness in controlling field weeds.Also, the highest paddy yield per hectare (4236 kg) was observed in pertilachlor + benzosulfuron-methyl treatment, which did not show any significant difference with thiobencarb + benzenesulfuron-methyl (4121 kg), the dose of 165 g ai ha-1 metazosulfuron (4103 kg) and manual weeding control (4291 kg). Since no significant difference was observed between the doses of 83, 124 and 165 g ai ha-1 metazosulfuron in terms of paddy yield, the dose of 83 g ai ha-1can be introduced as the best dosage of this herbicide in controlling of weeds.

In order to investigate the effectiveness of random, zigzag and diagonal sampling methods in seven sampling levels in estimating the weed population of corn fields under drip, furrow and sprinkler irrigation systems, a research was conducted in 2020 year in six corn fields. In order to estimate the accuracy of the sampling methods, first, the studied area was gridded with the standard grid sampling method of 5 m × 5 m and at the intersection of the lines using a square quadrat an area equal to one meter. The data related to the species number and density of weed seedlings by species were recorded in one stage. The results showed that increasing the sampling levels increased the accuracy in estimating the number of weed species in different sampling methods. At low sampling levels, the random sampling method estimated weed density with less error, but with increasing sampling levels, the accuracy of diagonal and zigzag systematic sampling methods increased and with 20 and 21 sampling units, respectively, they estimated the density of seedlings of the weed population with acceptable accuracy. With the increase of sampling levels, the amount of error in estimating the density of C. album species decreased so that the lowest error was in levels IV , VI (with 24 samples in random and diagonal methods and 25 sample in zigzag method) and VII (with 28 samples in random and diagonal methods and 29 samples in zigzag method) were observed with 0.04, 0.02 and -0.06 respectively.

Purple nutsedge (Cyperus rotundus L.) is one of the most problematic weeds in onion (Allium cepa L.) fields in southern Kerman, and so far is no registered herbicide to control purple nutsedge not reported in onion. The experimental design was a randomized complete block design with nine treatments and three replications in Jiroft Agro-Industrial Farms in onion. The treatments were included allyl isothiocyanate (dominus) and Dimethyl tetrachloroterephthalate (Dacthal) as pre planting herbicides, Bentazone + MCPA (Basagran M60), Penoxsulam (Rezlan), Ioxynil (Totril), Oxadiazon (Ronstar), Glyphosate + 2,4-D + MCPA (Roundup + U, 46 Combi fluid) as post emergence herbicides as well as Weed free control and weed infested control by transplanting method was evaluated. The results showed that there was a significant difference between the treatments on traits of stem density, tuber density, dry weight of above and below ground organs, neck diameter, average onion weight and yield of onion. Among the tested treatments, allyl isothiocyanate herbicide with 70.661- 70.542 tons ha-1 was selected as the best experimental treatment in during experment two years. weed infested treatment with 8.333 tons ha-1 and 7.261 tons ha-1 caused 89.53% and 89.73% reduction in onion yield compared to weed free condition during the first and second year, respectively. Therefore, the density and dry weight of purple nutsedge reduced 100% with application allyl isothiocyanate (280 L. ha-1 dominus).

Grapevine production encounters significant challenges due to competition from Cynodon dactylon. We conducted a three-year study in a Red Yaghuti vineyard using a randomized complete block design. Our experiment included treatments with Clethodim, Sethoxydim, Fluazifop-p-butyl, and Haloxyfop R-methyl ester, as well as the application of polyethylene mulch (PM) for one, two, or three consecutive years. A control group with no weed control measures was also included, resulting in a total of eight experimental treatments. Even the least effective herbicide, Sethoxydim, reduced the dry weight of both above-ground and underground parts of C. dactylon by at least 60%, underscoring the efficacy of the herbicides for controlling C. dactylon. However, among the herbicides tested, Clethodim was the most effective in reducing the dry weight of both above-ground and underground parts of C. dactylon. Keeping C. dactylon plants under PM for two consecutive seasons virtually eliminated measurable dry weight in both above-ground and underground parts. The treatment of three consecutive years of soil under PM produced similar results to two consecutive years, resulting in zero dry weight for both above-ground and underground parts of C. dactylon. In comparison, the control and one-year PM treatments consistently yielded less than the herbicide treatments. The highest yield was achieved with consecutive years of PM use, producing approximately 13,000 kilograms per hectare. The economic and environmental costs of Clethodim use versus PM in vineyards differ significantly. While herbicides like Clethodim involve recurring costs and potential.