منصور منتظری

Potato is a cool-season vegetable that ranks with wheat and rice as one of the most important staple crops in the human diet around the world. Weed control is important in potato production management, because without doing it potato harvest would not be cost- effective. Metribuzin (4-amino-6-tert butyl-3-methylthio-1, 2, 4-triazin-5-one), a triazine, is used as a selective herbicides for control of annuals grasses and broadleaf weeds inpotato. Its herbicide efficiency and its relatively low toxicity are such that it is widely used around the world. Replacing metribuzin with other herbicide that have the greatest effect on weed control in potato seems unlikely. The persistence of metribuzin in soil is defined as the period or extension of time in which it remains active. Knowing the case of herbicides is particularly important because, on one hand, it determines the period of time in which weeds can be controlled, and on the other, it is related to the later phytotoxic effects which can damage the subsequent crops. In order to understand about affiance of this herbicide in potato fields, researches on metribuzin toxicity in common lamb’squarters in soils with different utilizations are essential.
Material and This experiment was conducted to study the effect of soil characteristics and utilization history of metribuzin on its efficiency to common lamb’squarters control as a factorial on the base of randomized complete blocks design with three replications in green house of Institue of Plant Protection in 2012. First factor was soil type in six levels (Hamedan with 15 years and without utilization history, Jiroft with 15 years and without utilization history, Isfahan with 2 years utilization history and Mashhad with 3 years utilization history) and second factor was concentration of metribuzin in six levels (included 0, 100, 300, 700 and 1000 g ai h-1). Soil samples were collected from 0-15 cm depth. Before cultivating, the pots with mentioned soils were treated with metribuzin. Each sample was thoroughly mixed to allow a homogeneous distribution. Non-sprayed samples were used as controls. Common lamb’squarters seeds were planted in pots and the soil in each pot was watered as mist. After emergence, the seedlings were thinned to two per pot. Harvesting weeds were done four weeks after sowing. Then, dry weight and the length of shoot and root were measured. All data were subjected to analysis of variance and means were compared at the 5% level of significance. The classical bioassay, often used to quantify the amount of herbicide in soil, employs a single “standard” dose-response curve. This standard curve show the plant response to different herbicide concentrations and report information of different concepts related to herbicide efficacy, such as selectivity, tolerance and resistance. A typical dose-response curve is sigmoid in shape. One example of such a curve is the loglogistic curve. The data were expressed as a percentage of the untreated control and dose- response curves were drawn.
According to results, more common lamb’squarters was controlled due to increase of herbicide dose. But the effects of metribuzin residue were decreased by increase of amounts of clay, organic matter and utilization history. The amount of herbicide required to reduce the growth of weed by 50% (GR₅₀) when compared with the control was determined for each soil. In the soils with higher organic matter GR₅₀ were increased. The highest and lowest damage to common lamb’squarters was observed in soils of Jiroft without utilization history and Hamedan with 15 years utilization history, respectively So in the soil with long utilization history of metribuzin, common lamb’squarters control was greatly reduced due to the presence of microorganisms adapted to the herbicide and use of it to supply energy. The breakdown of herbicides by soil organisms known as microbes accounts for a large portion of herbicide degradation in soil. Certain bacteria, fungi, and algae use herbicide as a food source. Microbes are herbicide-specific and their population in the soil is related to the amount of herbicide can lead to increased microbe populations and a shorter duration of effective weed control. Organic matter provides excellent habitat for microbes. The adsorption degree of this herbicide is positively correlated with organic matter content and negatively with their persistence. In these situations for controlling this weed higher concentration of metribuzin must be used.

This investigation was conducted to evaluate the effect of herbicides trifluralin, ethalfluralin, alachlor and metribuzin on mycellial growth of Rhizoctonia solani anastomosis group 4, the causal agent of cotton and soybean damping off. The experiments were carried out in 2011 at Department of Weed Research, Iranian Research Institute of Plant Protection, Tehran. At first stage, growth reaction of the fungal colonies to the herbicides on PDA was studied. Then, this reaction to discs contaminated with the herbicides, compared with not using herbicide control, in two series of experiments was investigated. The results of high concentration of herbicides in PDA indicated that growth of the fungal colonies on PDA containing trifluralin at 12500 or 25000 ppm, ethalfluralin at 17500 or 35000 ppm, alachlor at 20000 or 40000 ppm was completely inhibited. R. solani growth on PDA containing metribuzin at 2500 or 5000 ppm was not completely inhibited, but this treatments, compared with control, significant reduced mycellial growth of the pathogen. The experiment at lower concentrations of the herbicides showed that alachlor, trifluralin and ethalfluralin, resprctively at 509, 318 and 445 ppm, significantly reduced the colonies growth. Among the recent treatments, the effect of alachlor was significantly more than the others. Paper discs contaminated with herbicides at three different concentration, showed no evidence of their effect on mycellial growth of the pathogen.

This field experiment was conducted at Amol Rice Research Station in 2009 to evaluate the efficacy of rice selective herbicides in control common of barnyardgrass (Echinochloa crus–galli), sea clubrush (Scirpus maritimus) and common water-plantain (Alisma plantago-aquatica) and crop yield. The treatments were consisted of application of penoxsulam at 24, 30, 36 and 42 g ha-1, premixed of anilofos+ethoxysulfuron (Sunrise Plus) at 945 g ha-1, tank mix application of butachlor+cinosulfuron at 900+20 g ha-1, butachlor+bensulfuron-methyl at 100+45 g ha-1, twice hand weeding and weedy check. The herbicides were treated as droplet application seven days after rice transplanting. All treatments significantly reduced the number and dry weight of barnyard grass plants, but the effects of penoxulam at all rates of application, was more than that of butachlor+bensulfuron-methyl or anylofus+ethoxysulfuron. The lowest plant number of sea clubrush, similar to hand weeding, obtained from application of butachlor+bensulfuron which was significantly different from other herbicide treatments. Penoxulam at 24, 30, 36 or 42 g ha-1, in contrast to other treatments, showed no significant effect on dry weight of sea clubrush, compared with weedy check. All treatments completely (100%) controlled common water-plantain. The herbicide treatments, compared with weedy check, significantly increased rice foliage and root dry weight. The crop grain weight in weedy check was significantly lower than all treatments.

This study was conducted in 2010-2011 to evaluate the effects of herbicides trifluralin, ethalfluralin, alachlor and metribuzin on the incidence of damping off disease caused by Rhizoctonia solani on soybean varieties Williams, Mill 82 and Clark in sterile or non-sterile soil. The pathogen was grown on PDA and incorporated into the soil of each pod up to four cm depth. The incidence of the disease in herbicide-treated soil was compared with those of untreated soil which was pre-inoculated with the pathogen as control. In these experiments, Clark showed higher disease incidence than other varieties. Also the disease incidence was higher in sterile soil than in non-sterile soil. Compared with the untreated control, only trifluralin, significantly increased the disease incidence.

This study was conducted during 2010-11 in Karaj and to evaluate the efficacy of wheat selective herbicides for weed control in triticale. Herbicide treatments consisted of sulfosulfuron, mesosulfuron+iodosulfuron (Atlantis), metsulfuron+sulfosulfuron, isoproton+diflufenican, mesosolfuron+ iodosolfuron (Shovalieh), clodinafop-propargil, pinoxaden, diclofop methyl), pinoxaden + clodinafop-propargil, fenoxaprop-p-ethyl, tralkoxidim, difenzoquat) and flamprop-m-isopropyl. The results indicated that mesosolfuron + iodosolfuron (Atlantis) and difenzoquat significantly reduced plant number of cheat grass (Bromus tectorum), but these treat ments were not significantly different from mesosolfuron+iodosolfuron (Atlantis), isoproton+diflufenican or metsulfuron+solfosulfuron. All treatments, except flamprop-m-isopropyl, fenoxaprop-p-ethyl and clodinafop-propargil, compared with weedy chech, significantly reduced the dry weight of cheat grass. The lowest plant number of false barley (Hordeum murinum) was evaluated in treatment mesosolfuron + iodosolfuron (Atlantis), but this treatment had no significant difference from metsulfuron+sulfosulfuron or isoproton+diflufenican. All treatment, except mesosolfuron+ iodosolfuron (Shovalieh), pinoxaden, fenoxaprop-p-ethyl and difenzoquat, significantly reduced the dry weight of false barley. The number and dry weight of winter wild oat (Avena ludoviciana) in treatments sulfosulfuron and flamprop-m-isopropyl were not significantly different from weedy check, but other herbicides significantly controlled this weed. Among herbicides, pinoxaden and pinoxaden + clodinafop-propargil caused phytotoxicity on triticale, and metsulfuron+sulfosulfuron reduced its plant hight; however, these herbicides had no significant effect on crop yield. All treatment, except sulfosulfuron, significantly increased crop biological yield. Application of mesosolfuron+iodosolfuron (Atlantis) and pinoxaden significantly increased triticale grain yield, but they were not significantly different from other herbicides.

An audit was made for weed science in Iran by Iranian Society of Weed Science for the years 2009 and 2010. All the information was collected by filling special forms. Other information was collected by media search. All collected data was processed and analyzed according to the requirements of this report. Results indicated that the number of MSc candidates accepted for weed science in six state universities was 86 and ten Islamic Azad university branches، 443، during the two years of this survey. At the same period، 18 PhD candidates were accepted in the two state universities (Tehran and Mashhad). The number of scientific body of weed science specialists at the above mentioned universities was 18 in state and 10 in Islamic Azad university branches. In the research sector، there were 97 researchers active in weed research at the Ministry of Agriculture research units of whom 41 were members of the scientific body. A total of 356 scientific articles were published during this study period، of which 30 were ISI grade and 9 extension category. Amongst the 30 ISI articles، 21 were from state universities، 6 Islamic Azad university branches and 3 from agricultural research units. It was also shown that 62. 02% of all the published articles were of basic nature and 37. 92%، applied. The above data also revealed that، on the average، for every member of the scientific body of universities and research units، 2. 56 articles have been published (3. 81 for state universities، 1. 67 for Islamic Azad university branches and 1. 76 for agricultural research units). As for articles presented at Iranian and foreign conferences، a total of 620 articles were recorded. The subject of 194 were chemical، 168 non-chemical، 180 basic and 78 biological studies. During This period، 15 weed science books (12 authored، 3 translations) were published، four of which belonged to state universities، one from Islamic Azad university branches and 10 from agricultural research units. During the period of this survey، 240 theses were presented، of which 71 belonged to state universities and 169 came from Islamic Azad university branches.

A constrain for basic research on broomrape is unsatisfactory seed germination of this parasitic weed, particularly in the absent of host plant. In this research, the effect of few factors on seed germination of Egyptian broomrape (Orobanche aegyptiaca) was studied in vitro and in the absence of host plant as a factorial experiment. Immersing the seeds in sulfuric acid at 100 or 50 percent concentration for 30 or 60 seconds, exposing them to gibberellic acid at 0 (control) 100, 250 or 500 ppm and incubation at 15, 20 or 25 oC were the treatments. The results indicated that gibberellic acid at all concentrations significantly reduced the seed germination. Immersing the seeds in sulfuric acid at 50% concentration for 60 seconds and incubation at 15 oC, with 44% germination, significantly enhanced the germination more than the other treatments. On seed germination, the effect of temperature was more pronounced than two other factors.

To evaluate the effect of herbicides and biofarm (Pseudomonas spp.) as biological fertilizer on weeds and yield components of canola, a factorial experiment based on randomized complete block design with three replications was conducted at Agricultural Research Center of East Azarbaijan in 2009. The treatment factors consisted of herbicide (factor A) at 4 levels (application of trifloralin, Treflan, at 2.5 l/ha as pre-planting, chlopyralid, Lontrel, at 0.8 l/ha when canola plants were at 2-4 leaf stage, metazachlorꫨꞙ, Butizan star, at 2.5 l/ha at cotyledonous stage of canola, and not controlling the weeds as check. Biological fertilizer (factor B) at 2 levels, using or not using the biofarm. Wild mustard (Sinapis arvvensis) and tansy mustard (Descurainia sophia), being in same family with canola, were the dominant weeds in the field. Traits like number of species and biomass of weeds, biomass and yield of the crop were recorded to evaluate the effects of the treatments. The statistical analysis indicated that Botizan star and Treflan, compared with control, significantly reduced the number and biomass of wild mustard. In spite of non significant effect of the herbicide on number of tansy mustard and total weed, Botizan star and Treflan significantly reduced their biomasses. Application of biofarm and its interaction with herbicides did not influence the evaluated traits significantly. The herbicides, also, did not have significant effect on biomass and yield of the crop.

This investigation was conducted to evaluate the effect of herbicides trifluralin, ethalfluralin and alachlor on expression of damping off caused by Rhizoctonia solani on three varieties of cotton in sterile or non-sterile soil. The experiments were carried out in 2011 at greenhouse of Department of Weed Research, Iranian Research Institute of Plant Protection. The severity of the disease was compared with control including not using herbicide/with pathogen. The results in non-sterile soil indicated that herbicides had no significant effect on the severity of disease occurrence on variety named Avangard. Ethalfluralin significant decreased the disease incidence on Sepid variety. But on variety Varamin, just alachlor significantly enhanced the expresion of the disease. The results in sterile soil, showed no significant difference between herbicide treatments with control on varieties named Varamin and Sepid, but on variety Avangard using trifluralin significantly enhanced the occurrence of disease. These results indicated that the influence of herbicides on severity of damping off caused by R. solani depends on kind of herbicide used in soil, cotton variety and soil micro-organisms.

In this research، the seed viability and growing status of Swallow-wort (Cynanchum acutum Willd.)، as an alien weed، which has been invasive in pistachio orchards of Aran and Bidgol، north of Esfehan province، was studied. The viability of seeds of this plant which were collected from previous year was tested using tetrazolium solution. The periods of growth stages of the weed in pistachio orchards from seedling emergence up to seed repining were recorded. Further more، seed and rhizome germination of this plant from soil depth was studied. Results indicated that 80-96 percent of the seeds collected from previous year were alive. In nature، emerging the first rhizome-originated seedlings were observed in initiation of March، maximized in mid March and stopped in the first days of June. Emerging of the seed-originated seedlings started from mid April، maximized in initiation of May and stopped at the end of this month. Most rhizome- and seed-originated seedlings were grown respectively in 10-19 and 1-9 cm soil depths. The plants originated from seeds didn''t attach to the pistachio trees.

In this research, the efficacy of a few sugar beet selective herbicides in conventional and minimum tillage systems was evaluated in Shahre-kord area, Iran, in 2008. For conventional tillage, at the end of April, a deep tillage up to 35 Cm was carried out using marl bow plow, but for minimum tillage, no soil disturbance was done. Then, sawing bed was prepared by a cyclotiller with a shallow tilling. The herbicides were applied using a knapsack sprayer equipped with a t-jet nozzle when sugar beet was at 4-leaf stage. The results indicated that, apart from herbicide applications, the number and dry weight of barnyard grass and Anchusa sp. in minimum tillage was significantly less than that of conventional tillage. Tillage systems were not significantly different in the number and dry weight of redroot pigweed. For controlling redroot pigweed and Anchusa sp., application of mixed of metametron and phenmedipham + desmedipham + ethofumesate, respectively at 2800 and 720 g ha-1, were significantly more efficient than tank mixed application of triflusulfuron and phenmedifam respectively at 15 and 314 g ha-1, and clopyralid at 2400 g ha-1. These differences were more pronounced in protective tillage system. But, for reducing the number of barnyard grass plants, the efficacy of tank mixed application of triflusulfuron and phenmedipham in conventional tillage was significantly higher than the other herbicide treatments. But, in protective tillage, due to low population of barnyard grass no significant differences were recognized among the treatments, compared to the weedy check. In both tillage systems, all treatments, compared with weedy check, increased the crop root yield. The highest root yield was obtained in minimum tillage using phenmedipham + desmedipham + ethofumesate or metametron. The treatments had no significant effect on sugar purity of the crop.

This research was carried out in 2009 at greenhouse of Iranian Research Institute of Plant Protection to determine the effect of water quality on weak acidic herbicides in control of Picnomon acarna (L.) Cass, as indicator plant, in wheat and canola. Clopyralid, glyphosate and 2,4-D+MCPA were applied, respectively, at 0.24, 2.64 and 0.72 kg ae ha-1. Each herbicide dissolved in water contained ammonium sulfate (AS) at concentration of 2, 4 or 8 percent, sprayed on the target plants at initial growth stage. AS, parallel to increasing the concentration, enhanced electric conductivity and reduced the pH of herbicide solutions. Adding AS into glyphosate or clopyralid, significantly reduced the percentage of the weed plants. Based on dry weight evaluation, AS had no significant effect on the efficacy of 2,4-D+MCPA or clopyralid. For reducing the number of plant of the weeds, 2,4-D+MCPA without AS was more effective than its solution solute in water contained AS. Adding AS into the solution of clopyralid had to effect on wheat and canola. Similar result obtained with 2,4-D+MCPA on wheat.

The allelochemicals or secondary plant metabolites when are released to environment, influence the germination and seedling growth of neighbor's weeds. The aim of this study was to investigate the effect of the extract of worm¬wood (Artemisia annua) on the number and mass of weed seedlings and their seed germination under laboratory conditions. The Worm¬wood extracts were considered with different concentrations (1.25 to 20%) on the germination and seedlings growth of Zea maize, Johnsongrass (Sorghum halepense), common lambsquarter (Chenopodium ¬album) and redroot pigweed (Amaranthus retroflexus) for 5 days. Results showed that with increasing concentration of worm¬wood extracts, their effects on reducing seed germination and seedling growth of the above mentioned plants was more severe. Comparison of extract effects with polyethylene glycol, revealed that reduction of Johnsongrass and common lambsquarter seed germination were attributed to the osmotic pressure of the extract, where as, inhibition of seed germination of redroot pigweed and corn was due to allelochemicals. Results showed the worm¬wood extract was more related to the allelopathic effect.

This research was conducted in 2007 to evaluate the efficacy of penoxsulan SC 240 as a new rice selective herbicide. Penoxsulam at 24, 30, 36 and 42 g ha-1 was compared with mixture of anylofus and ethoxysulfuron (Sunrise) at 945 g ha-1, tank mix application of butachlor plus cinosulfuron at 900+20 g ha-1, and butachlor plus bensulfuron at 100+45 g ha-1 for controlling barnyard grass (Echinochloa crus-galli), Cyperus difformis and rice broadleaf weeds. Efficacy of penoxsulam at 36 and 42 g ha-1 in control of E. crus-galli was the same as that of the other herbicide treatments and better than its application at 24 or 30 g ha-1. Penoxsulam at 36 or 42 g ha-1 and Sunrise were more efficient in control of C. difformis than the other treatments. In control of Alisma plantago-aquatica, penoxsulam at 36 and 42 g ha-1 had no significant difference with the other herbicides, but was significantly more efficient than its application at 24 or 30 g ha-1. Penoxsulam at 42 g ha-1 controlled Sagitaria trifolia same as Sunrise and significantly better than the other treatments. All herbicides greatly reduced the dry weight of the target weeds. The herbicides showed no any evidence of phytotoxicity on rice and had no effect on rice plant height and dry weight, compared with weedy check.

Morphophysiological variations of field bindweed populations in Tehran province was studied during 2006 and 2007 growing seasons using multivariate analysis methods. To determine the variations, 43 morphological and physiological characters were considered biometrically. The main characters at principal component analysis (PCA) consisted of leaf dry weight, shoot dry weight, and leaf area to identify the biotypes. But, the populations were identified based on allometric variables, particularly root weight ratio. The results suggested that field bindweed ecotypes have been formed while the species adapted to specific geographic locations. Factor analysis based on PCA revealed that twelve factors comprise almost 85% of total variations for field bindweed populations in three locations of Tehran province. Phenological and morphological variabilities among biotypes may explain the survival and adaptability of a population of this weed as a result of environmental and field management changes

An isolate of Fusarium moniliforme, a pathogen of winter wild oat (Avena ludoviciana), was obtained from Tehran Province, Iran, in 1994. A host range test performed on wheat, barley, maize, rye, millet, crested wheatgrass, faba bean, red bean, green bean, sunflower, soybean, oilseed rape, cotton, safflower, cucumber,water melon, berseem clover, and sainfoin, resulted in no symptom induction by the pathogen. However, winter wild oat, crested wheatgrass, johnsongrass and tomato showed susceptibility to the pathogen with 78, 24, 19 and 17% mortality, respectively. The results indicate that this pathogen could be considered as a potential biological agent for the control of winter wild oat.