A field study on the effects of the herbicide Tribenuron methyl on biodiversity of wheat aphids (Homoptera: Aphididae) in Mashhad, NE Iran

During a faunistic survey of wheat aphids and their coccinellid predators in 2006-2008 which was carried out for the first time in Mashhad region, using different sampling methods, 6 aphid species as well as 10 coccinellid species were collected and identified as follows: A) Aphid species: Sitobion avenae (Fabricius), Schizaphis graminum (Rondani), Metopolophium dirhodum (Walker), Diuraphis noxia (Mordvilko), Rhopalosiphum maidis (Fitch), Rhopalosiphum padi (L.); B) Coccinellid species: Hippodamia (=Adonia) variegata (Goeze), Oenopia conglobata contaminata (Montrouzier), Propylea quatuordecimpunctata (L.), Brumus undulatus (Weise), Exochomus nigromaculatus (Goeze), Scymnus apetzi )Mulsant (,Chilocorus bipustulatus (L.), Psyllobora vigintiduopunctata (L.), Coccinella septempunctata (L.), Coccinella magnopunctata )Rybakow). Among the identified aphid species in this study, Sitobion avenae and Schizaphis graminum with 53.1 and 29.5 percentage of population respectively were more abundant than other species. Among the collected coccinellids, the species Coccinella magnopunctata is new for fauna of Iran. The following coccinellid species, Coccinella septempunctata and Hippodamia variegata were more abundant and had higher distribution than the others. The coccinellid, Coccinella magnopunctata which was only collected from Akhengan, Toos and Golmakan was considered as a rare species in this study. Key words: Aphididae, Coccinellidae, Wheat pests, Razavi Khorasan

Behavioural thermoregulation is critical for animals to buffer against thermal extremes. However, many animals have to face a trade-off between heat escape and food acquisition during thermoregulation, but how animals balance overheating vs. starvation risk based on their different resistance to heat and starvation currently remains unclear. Here, we proposed a hypothesis for predicting how animals reduce heat vs. starvation risk during behavioural thermoregulation. Animals with higher starvation risk give priority to reducing starvation by taking a higher heat risk, whereas animals with lower starvation risk give priority to reducing heat stress by taking a lower heat risk. We used three aphid species (Metopolophium dirhodum, Sitobion avenae, Schizaphis graminum) as focal animals. First, by simulating linearly increasing ambient temperatures during the daytime, we measured the heat-avoidance temperatures (HATs) and critical thermal maximum (CTmax) values to understand their thermoregulatory behaviour and heat tolerance. Then, we tested the time spent locating a host plant (TL) and the survival time under starvation (TS) of the aphids to assess their food accessibility and starvation tolerance, respectively. Finally, we combined these results by linking the aphids’ heat risk (CTmax minus HAT) and starvation risk (TS minus TL) with their thermoregulatory behaviour to test our hypothesis. Our results provide evidence to support our hypothesis. The species with higher starvation risk gave priority to reducing starvation by spending more time feeding on the host plant and escaping from heat later and thus taking a higher heat risk. In contrast, the species with lower starvation risk gave priority to limiting heat stress by spending less time on feeding and escaping from heat earlier and thus taking a lower heat risk. Animals may adopt different strategies to reduce the integrative risks of starvation and heat based on their respective food accessibility, starvation resistance and heat tolerance. Our findings highlight the complexity of the interactions among multiple risks in animal decision-making behaviour to increase their fitness. Such different behaviours and their potential consequences matter when taking behavioural thermoregulation into account in predicting the impacts of climate change.

In order to study of chemical and mechanical weed management methods and their integration in potato (Solanum tuberosum), a field experiment was done in 2008 at Ferdowsi University of Mashhad Research Field. Experimental design was completely randomize block design with 6 treatments and 3 replications. Treatment included broadcast herbicide application (standard treatment), between row cultivation, banded herbicide application (in-row), between row cultivation+banded herbicide (integrated treatment), and weed free and weed infested (controls). metribuzin (sencor) was applied as pre-emergence at 1.2 kg/ha product in all herbicide treatments. In broadcast and banded herbicide treatments, sencor was applied on entire plot and in row (in a 25 cm band over the row), respectively. Cultivation treatment was done 3 weeks after potato emergence. Results were showed significant effects of treatments on weed control percentage, density, and biomass, potato leaf area index and yield. Highest weed control percentage and so highest potato yield was obtained in weed free control, broadcast herbicide, cultivation+banded herbicide, banded herbicide and cultivation treatments, respectively. Highest potato yield was obtained in weed free control (34.43 t/ha) and after that broadcast herbicide (31.13 t/ha) and banded herbicide+cultivation (27.93 t/ha) resulted in higher yield than other weed control practices. Difference of weed control percentage, density, and biomass in banded herbicide+cultivation and broadcast treatments was not significant, also potato yield in banded herbicide+cultivation reduced no more than 10% relative to broadcast herbicide. Despites lower weed control level and potato yield in integrated treatment, herbicide use decreased 66% relative to broadcast application, which has significant importance from economical and environmental point of view. Keywords: Broadcast herbicide application, Banded herbicide application, Cultivator, Metribuzin, Integrated weed management

Under the existing statutory framework, the U.S. Department of Agriculture’s Animal and Plant Health Inspection Service (“APHIS”) has the authority to regulate certain genetically engineered crops, while the Environmental Protection Agency (“EPA”) regulates all herbicide products sold in the United States. Although the development of a crop engineered to be resistant to a certain herbicide contemplates the future widespread use of that herbicide, EPA and APHIS fail to account for this cumulative impact. Specifically, when performing a National Environmental Policy Act (“NEPA”) analysis for the deregulation of crops designed to be herbicide-resistant, APHIS violates NEPA and its implementing regulations by failing to analyze the environmental effects of the increased herbicide use that the deregulation presupposes. Meanwhile, the courts have determined that EPA need not comply with NEPA when registering herbicides, finding the Federal Insecticide, Fungicide, and Rodenticide Act (“FIFRA”) analysis sufficient even though it does not evaluate the environmental effects of registering the herbicide. Consequently, APHIS, EPA, and the courts have perpetuated a cycle of herbicide registration and herbicide-resistant crop deregulation in which neither EPA nor APHIS fully contemplates the cumulative impact of their respective actions. ... The regulation of the herbicide 2,4-Dichlorophenoxyacetic acid (“2,4-D”); the deregulation of Enlist™ corn and soybean, designed to be resistant to 2,4-D and glyphosate; and the regulation Enlist Duo™, designed for use in controlling weeds in corn and soybeans genetically-engineered to tolerate 2,4-D and glyphosate, is emblematic of the cycle that this regulatory regime continues. ... This article will proceed as follows. Part II will address the cycle of herbicide use that the introduction of herbicide-resistant crops perpetuates, with particular focus on the Enlist™ varieties and 2,4-D. Part III will explain the regulatory system for herbicides and herbicide-resistant crops and will share some common criticisms of that regime. Part IV will outline the parts of NEPA and its implementing regulations pertinent to herbicide registration and the deregulation of herbicide-resistant crops. Part V will establish that APHIS failed to consider the impact of the increased herbicide use contemplated by its decision to deregulate the Enlist™ varieties, thus violating NEPA. Part VI will demonstrate that EPA’s decisions to reregister 2,4-D and register Enlist Duo™ did not account for the effects of registering these herbicides for use with herbicide-resistant crops. Part VII will demonstrate that EPA and APHIS consistently fail to consider the cumulative impact of pairing herbicides with herbicide-resistant crops. Part VIII will recommend that the power to regulate both herbicides and herbicide-resistant crops reside in APHIS.

برای ارزیابی پاسخ گندم به اختلاط علفکش ها با حشره کش و کود آزمایشی در سال 1386 در گلخانه تحقیقاتی دانشکده کشاورزی دانشگاه فردوسی مشهد انجام گرفت. این آزمایش مرکب از 8 تیمار تری بنورون متیل + کلودینافوپ پروپارژیل، تری بنورون متیل + کلودینافوپ پروپارژیل + فنیتروتیون + لیبرل، تری بنورون متیل + کلودینافوپ پروپارژیل + فنیتروتیون، تری بنورون متیل + کلودینافوپ پروپارژیل + لیبرل، مزوسولفورون + یدوسولفورن، مزوسولفورون + یدوسولفورن + فنیتروتیون + لیبرل، مزوسولفورون + یدوسولفورن + فنیتروتیون، مزوسولفورون + یدوسولفورن + لیبرل بود که در قالب طرح کاملاً تصادفی با 4 تکرار به اجرا درآمد. یک تیمار نیز به عنوان شاهد در نظر گرفته شد و مخلوط ها در زمان پنجه زنی گندم بکار برده شدند. نتایج نشان داد که اختلاط مزوسولفورون + یدوسولفورن با حشره کش فنیتروتیون و اختلاط آنها با کود لیبرل BMX به طور معنی-داری موجب کاهش در ارتفاع بوته‌های گندم به ترتیب با 20 و 15 درصد، سطح برگ 44 و 39 درصد، وزن تر برگ 40 و 38 درصد، وزن تر ساقه 36 و 32 درصد، وزن خشک برگ 30 و 25 درصد و وزن خشک ساقه با 37 و 29 درصد شد. همچنین در اختلاط تری بنورون متیل + کلودینافوپ-پروپارژیل با حشره کش فنیتروتیون و نیز اختلاط آنها با کود لیبرل BMX سطح برگ، وزن تر برگ و ساقه، وزن خشک برگ و ساقه گندم نیز کاهش یافت، ولی این کاهش به اندازه اختلاط مزوسولفورون +یدوسولفورن با آنها نبود. اختلاط هر یک از علفکش ها با کود لیبرل BMX هیچ گونه خسارتی در بوته های گندم ایجاد نکرد.

Association of Acremonium endophytes with enhanced resistance to insects in various turfgrasses was studied using three species of aphids; greenbug, Schizaphis graminum (Rondani); bird cherry-oat aphid, Rhopalosiphum padi (L.); and yellow sugarcane aphid, Sipha flava (Forbes). Choice and no-choice tests were used to test resistance in three to four genotypes each of endophyte-infected and endophyte-free perennial ryegrass, Lolium perenne L.; tall fescue, Festuca arundinacea Schreb.; and three species of fine fescues: hard fescue, F. longifolia Thuill; Chewings fescue, F. rubra L. subsp. commutate Gaud.; and blue fescue, F. glauca Lam. Feeding deterrence and antibiosis were significant in endophyte-infected tall fescue for all turfgrass genotypes and aphids tested, with no aphids surviving after 3 d on infected tall fescue. Feeding deterrence and antibiosis to greenbug and yellow sugarcane aphid were significant in endophyte-infected perennial ryegrass with all genotypes tested. None survived on endophyte-infected perennial ryegrass after 72 h. Resistance to bird cherry-oat aphid was dependent on concentration of endophyte hyphae in the host, with significant resistance observed in genotypes with high concentrations. Resistance in endophyte-infected fine-leaved fescues varied with insect and grass species. Preference was generally not significantly affected, but dramatic differences in survival were found in ‘Ensylva’ strong creeping red fescue, blue fescues, Chewings fescues, and hard fescues. Endophyte-enhanced resistance to insects varies between species of grasses and insects, and within species of grasses, suggesting that each endophyte or endophyte-host genotype complex should be evaluated individually.

Common ragweed (Ambrosia artemisiifolia) is the number one weed in Hungary: it covers ca. 5% of the arable land, causing huge losses in row crops, especially in sunflowers. In addition, because of the high allergenicity of its pollen, common ragweed is a heavy burden on the health care system. This minireview discusses the importance of use of herbicide-tolerant sunflower hybrids in eliminating common ragweed from sunflower fields, with special emphasis on the efficacy of common ragweed control of two acetolactate-synthase inhibitor postemergence herbicides (imazamox and tribenuron methyl) in several sunflower hybrids that carry the resistance gene against such herbicides. Common ragweed control by these herbicides was excellent: they suppressed the growth of the weed plant until the canopy closure of the crop (8-leaf stage). Common ragweed plants germinating after this date were unable to compete with the crop: although they survived, they remained small (ca. 70% reduction in height), produced ca. 90% less male inflorescences (source of the allergenic pollen), and caused no significant reduction in the crop yield. In order to stop the seed production by the few late-germinating weed plants we recommend a mechanical common measure (row-cultivator) in late August.

Among cereal crops, wheat (Triticum aestivum L.) is an important staple food for human. Rhopalosiphum maidis, Rhopalosiphum padi, Schizaphis graminum and Sitobian avenae are the major aphid species of wheat in Pakistan, which cause huge yield losses in wheat crop. The study was conducted to check the effect of aphid density on wheat crop and its yield. Our observation was made from heading to early-dough stage. Mean spike length, number of grains per spike, 100 grains weight and yield kg/ha was significantly affected by the population density of an aphids. Aphid density was low correlated with mean spike length but it was significantly correlated with number of grains per spike, 100 grains weight and yield kg per hectare.

Introduction: There are many reasons for no effectiveness of herbicides on weeds, including the incorrect herbicide, the insufficient use of herbicide, the unprincipled sprayer, spraying at the wrong time especially adverse weather conditions, and a factor that often overlooked is the "water quality in herbicide spray tank". Most of the herbicides are mixed with water and applied as a spray. Obviously water quality is an extremely important issue. Water quality factors in this regard that effect on uptake and translocation of herbicides included as water hardness, pH, bicarbonate ion concentration, turbidity, organic matter and other substances. Hardness is determined by the amount of calcium and magnesium present and is expressed as calcium carbonate (CaCO3) equivalent in parts per million. Petroff (27) classified water based on hardness: water with a hardness 0-75 ppm is considered “soft” water, 75-150 ppm is “medium hard”, 150-300 ppm is considered “hard”, and more than 300 ppm is “very hard”. Hard water is a problem in over 85% of the United States according to the US Geological Survey. The contrast between the herbicides and dissolved ions depend on amount and type of minerals in the spray tank. So that different herbicide may show different responses to the same action. If soft water is not available, surfactant and chemicals additives such as ammonium sulfate (AMS), ammonium nitrate (AMN) and urea- ammonium nitrate can be added to the spray tank to increase herbicide efficacy (7). These compounds prevent from the adverse effects of the ions in water. Glyphosate and nicosulfuron belong to two different chemical families of herbicides and are soluble in water. Therefore, water quality such as the presence of calcium carbonate may have a significant effect on these herbicide performances, while removing the inhibitory effect of water hardness by adding nitrogen compounds such as ammonium sulfate need to experiment. According to the above, basic experiments carried out as the influence of adding ammonium sulphate to spray solution of calcium carbonate-containing glyphosate and nicosulfuron on barnyardgrass and velvetleaf control. Materials and Methods: Four experiments were performed as factorial arrangement of treatments 6×2 based on completely randomized design with six replications (+six control pots for each weed species) at Research Greenhouse of the Ferdowsi University of Mashhad in 2010. Factors were included different concentrations of calcium carbonate (CaCO3; Merck, Germany) of water in spray tank at six levels 0, 100, 200, 300, 400 and 500 ppm in deionized water (w/v) in combination with 0 (-AMS) or 3 kg/ha (+AMS) ammonium sulphate (Merck, Germany) as adjuster the hardness. Glyphosate (Roundup®) and nicosulfuron (Cruse®) herbicides were applied post emergent at 385 and 550 mL ha-1 as commercial products (158 and 22 g ai ha-1; based on ED50 outcome preliminary test (12), recpectively) at the 3-4 leaf stage of the weeds (barnyardgrass and velvetleaf) in a spray volume of 250 L ha-1. Four weeks after treatment, survival, plant height, leaf area, and shoot dry weight of weeds (% control) were calculated. The data of experiment were subjected to ANOVA using MSTATC software. Means of the treatments were separated using Duncan’s Multiple Range Test at α = 0.05. Also, based on the distribution of data, regression analysis was used as linear, two, and third-degree polynomial by EXCEL 2007. Results and Discussion: The results showed a significant reduction (p≤0.01) for survival, plant height, leaf area, and shoot dry weight of weeds (% control) with addition of calcium carbonate in spray tank of glyphosate and nicosulfuron herbicides, but this effect was not similar. So that, 500 ppm Ca2+ to the nicosulfuron spray solution compared with its absence increased barnyardgrass and velvetleaf biomass (% control) 16 and 50%, respectively. The corresponding values for glyphosate were 78 and 51%. Accordingly, Nalewaja et al. (24) reviewed the effect of different calcium compounds such as calcium carbonate (0.02 mol) in water as a solvent nicosulfuron herbicide (15 g ai ha-1; 160 L ha-1) interaction to seven surfactants on finger grass (Digitaria sanguinalis L.) at greenhouse conditions found that CaCO3 across seven surfactants reduced about 8% nicosulfuron performance. In research conducted by Buhler and Burnside (5) concluded that an increase in calcium ion (prepared from CaCl2) to 2 mmol in spray tank was not affected on glyphosate (400 g ai ha-1; 190 L ha-1) performance. With the increasing of Ca++ to 8 mmol, was reduced significantly (P≤0.05) toxicity herbicide on oat (Avena sativa L.) from 80 to less than 20%, 14 days after spray at the greenhouse experiment. Adding ammonium sulphate (+AMS) decreased the antagonistic effects of water hardness, and increased herbicides efficacy on barnyardgrass and velvetleaf. However, the synergistic effect of +AMS on velvetleaf control by glyphosate was higher. Green and Cahill (10) concluded adding 2% AMS to spray tank increased the pH of nicosulfuron solution from 4.6 to 4.7 and finger grass was well controlled by this herbicide because of increasing nicosulfuron solubility from 12 to 16%. In research conducted by Mueller et al. (22), the presence of calcium (Ca++) and magnesium (Mg++) ions concentration of 250 ppm reduced the effectiveness of three types of glyphosate salt, but adding 2% by weight of ammonium sulfate (AMS) to the spray tank overcame to the ions antagonistic effect. Conclusion: Results of current experiment emphasized the role of water hardness (CaCO3) in spray tank of glyphosate and nicosulfuron on barnyardgrass and velvetleaf control.

Over the past 20 years since tribenuron-methyl herbicide registration in Iran, reports of erratic control of broadleaf weeds with it have increased in wheat fields of Aq Qala. In order to evaluate the incidence of resistance in wild mustard (Sinapis arvensis) and turnipweed (Rapistrum rugosum) to tribenuron-methyl herbicide, dose-response assays were conducted during the years 1390 and 1391 at Gorgan University of Agricultural Science and Natural Resources. Wild mustard and turnipweed biotypes with suspected resistance to tribenuron-methyl herbicide were collected from wheat fields by moving on two hypothetical diameter of Aq Qala map. For each weed species, one susceptible biotype also collected from areas which had never been applied by herbicides. In these experiments, responses of sensitive and suspected resistance biotypes of both weeds were assayed by spraying the seedlings with different doses of tribenuron-methyl herbicide. Dose-response assays indicated resistance of wild mustard and turnipweed to tribenuron-methyl herbicide. Resistance factors of SRA2 biotype of wild mustard and SRR1 and SRR2 biotypes of turnipweed to tribenuron-methyl herbicide were 4.05, 26.90 and 24.42, respectively. This is first report of resistance in wild mustard and turnipweed to tribenuron-methyl herbicides in the country. Distribution maps of infected fields to resistant wild mustard and turnipweed biotypes were processed using Geographic Information System. Results of this study could be used for running programs to manage resistant weeds and to prevent the development of resistant biotypes to other parts of the region.

Water is the most common carier used to dilute herbicides and their application. Researches had shown that water quality is an important factor in some herbicide efficacy. In order to study the effect of water hardness on 2,4-D efficacy, an experiment was carried out under controlled conditions in 2010 at the College of Agriculture, Ferdowsi University of Mashhad. Experimental treatments included herbicides doses at 6 levels (0, 1000, 1250, 1500, 1750 and 2000 ml ha-1 ), calcium carbonate concentration in water as index of water hardness at 6 levels( 0, 100, 300, 600, 1000 and 1500 ppm) and weeds at 2 levels ( redroot pigweed and common lamsquarter), were evaluated as a completely randomized design in a factorial arrangement with three replications. Spray was done at 6-8 weeds leaf stage and two weeks after spray weeds survival and shoot dry matter was measured. For results analysis, data analysis of variance was done and plants response to 2,4-D doses in deferent water hardness levels was fitted with 4 parametric sigmoidal equation to the shoot biomass data as a function of the herbicide doses and was used to calculate the herbicide dose for 50 % inhibition of plants shoot growth inhibition (ID50). Results showed herbicide rate and water hardness had significantly effect(P<0.01) on growth and survival of two weeds. Increasing herbicide doses, decreased the survival and growth of both weeds in pure water spraying. Increasing water hardness decreased 2,4-D efficacy in both weeds. Maximum (79.4 % , 91.7 %) and minimum (35.5 % , 74.3 %) shoot biomass lose were indicated at the highest and lowest levels of 2,4-D and calcium carbonate levels in common lambsquart and redroot pigweed respectively. Redroot pigweed was more susceptible to 2,4-D application in each level of water hardness . Increasing of water hardness, increased ID50 parameter in both weeds. Minimum (1057 ml ha-1) and maximum(2783 ml ha-1) 2,4-D ID50 for common lambquart indicated in distilled water and 1000 ppm of calcium carbonate concentration. Minimum (559 ml ha-1) and maximum(1270 ml ha-1) 2,4-D ID50 for redroot pigweed was observed in 100 and 1500 ppm of water hardness. Keywords: Calcium carbonate, Dry mater, Water quality

به منظور مطالعه تأثیر سختی آب بر کارایی علف‌کش‌ سینوسولفورون، آزمایشی در شرایط کنترل شده به صورت فاکتوریل در قالب طرح آماری کاملأ تصادفی در سه تکرار در سال 1388 در دانشکده کشاورزی دانشگاه فردوسی مشهد انجام شد. عوامل مورد بررسی در این آزمایش، شامل مقادیر مختلف کاربرد علف‌کش سینوسولفورون در 6 سطح (0، 200، 250، 300، 350 و 400 گرم ماده موثره در هکتار )، غلظت کربنات کلسیم در آب به عنوان شاخصی از سختی آب در 6 سطح (0،100، 300، 600، 1000 و 1500 قسمت در میلیون) و علف های هرز در 2 سطح (تاج خروس ریشه قرمز و سلمه تره) بودند. سمپاشی در مرحله 6 تا 8 برگی انجام شد. دو هفته پس از سمپاشی، بقاء و زیست توده اندام‌های هوایی علف‌های‌هرز اندازه‌گیری شدند. برای تحلیل نتایج آزمایش پس از تجزیه واریانس داده‌های حاصل جهت ارزیابی پاسخ علف‌های هرز مذکور به تیمارهای آزمایش از برازش ماده خشک تولید شده به معادله های3 و 4 پارامتری سیگموئیدی استفاده و مقدار علف‌کش لازم برای 50 درصد بازدارندگی رشد علف‌های هرز مذکور در سطوح مختلف سختی آب تعیین شدند. بر اساس نتایج آزمایش، مقدار کاربرد علف‌کش و درجه سختی آب تأثیر معنی داری (0.01≥P) بر رشد و بقای هر دو علف‌هرز داشتند، بطوریکه با افزایش مقدار کاربرد علف‌کش، بقا و رشد هر دو علف هرز در کاربرد سینوسولفورون با آب خالص کاهش معنی‌داری (0.01≥P) یافت و افزایش سختی آب اگرچه تأثیری بر کارایی علف‌کش سینوسولفورون در کنترل تاج خروس نداشت، اما موجب کاهش معنی داری در کنترل سلمه‎تره شد. بیشترین و کمترین زیست توده تولید شده در هر دو غلظت بترتیب در1500 و صفر قسمت در میلیون کربنات کلسیم مشاهده شد. بر اساس نتایج آزمایش سلمه تره و تاج خروس در پاسخ به افزایش مقدار کاربرد علف‌کش پاسخ مشابهی داشتند. اما با افزایش درجه سختی آب (غلظت کربنات کلسیم ) تحمل سلمه‌تره به سینوسولفورون بیشتر از تاج خروس بود. نتایج نشان دادند که افزایش درجه سختی آب شاخص ED50 را در هر دو علف هرز تغییر داد. به ترتیب بیشترین (5/1485، 75/917) و کمترین (6/989، 8/786) مقدار ED50 سینوسولفورون در سلمه تره و تاج خروس در سطوح 1500 و صفر قسمت در میلیون کربنات کلسیم حاصل شد.

The purpose of the present study was to investigate the efficacy of the experimental formulations of the metribuzin (MET) and tribenuron-methyl (TBM) herbicides embedded in the matrix of degradable poly-3-hydroxybutyrate blended with wood flour in field-grown tomato and beet crops infested by weeds. There is a necessity to develop environmentally friendly and effective means to protect plants because of the shortcomings of the free herbicide forms such as the environmentally unsafe spray application of solutions and suspensions of the widespread metribuzin and tribenuron-methyl herbicides, removal from soil during watering events and rains, and transport to natural aquatic environments, where the herbicides accumulate in the trophic chains of biota. Free TBM is also rapidly inactivated in soil and metabolized to nontoxic products in plants. The efficacy of experimental formulations of metribuzin and tribenuron-methyl embedded in the matrix of degradable poly-3-hydroxybutyrate blended with wood flour was tested in field-grown tomato and beet crops infested with weeds. Application of metribuzin resulted in the highest productivity of tomatoes (2.3kg/m2) and table beet (3.4kg/m2), improved biometric parameters of tomato fruits and beet roots, and caused reduction in nitrate nitrogen concentrations in them. The mode of herbicide delivery did not affect sugar contents, but application of both metribuzin and tribenuron-methyl induced a 1.7-fold and 1.4-fold, respectively, increase in vitamin C concentrations in tomato fruits and beet roots relative to the vegetables grown on the subplots treated with free herbicides and the intact plants. Embedded herbicides can be used as preemergence herbicides in the field. Fig. a Graphical abstract.

Population fluctuations of cereal aphids, Rhopalosiphum padi (L.) and Sitobion avenae (F.), (Homoptera: Aphididae) and their impact on crop loss parameters of wheat were revealed in Antakya during the years of 1998–2002. The aphid populations were recorded in infested and aphid-free plots in Reyhanli by seven day intervals from 22 February to 22 April, 1999 on two wheat varieties, “Genc-99” and “Ege-88”. Twenty plants were examined at each sampling date and alive induviduals (adult+nymph) were counted.

Introduction: Seed germination is an important stage in the life history of plant affecting seedling development, survival, and population dynamics. Germination begins with seed, water uptake and terminates with the elongation of the embryonic axis from the seed coat. Germination and seedling emergence are the most important phonological development stages in pigweed and have a vital role in its establishment. Accordingly, predicting the phenological stages would be resulted in improvement of crop management as the number and time of pigweed emergence could be quantified. Sigmoidal curves, also known as growth models, have wide application in agricultural research and can be evaluated by means of nonlinear models, which operates through data modelling by a nonlinear combination of parameters depending on one or more independent variables. This study was conducted to evaluate various regression models to describe the response of germination rate to temperature range in two pigweed ecotypes (Alborz and Fars). Materials and Methods: A glasshouse experiment was carried out as a completely randomized design with four replicates. The seeds were sterilized by soaking in a 3% solution of hypochlorite sodium for 30 seconds. After the treatment, the seeds were washed several times with distilled water. 25 seeds were put in each Petri dish (with 9 cm diameter). The petri dish is monitored on a daily basis and afterwards germinated seeds (according to exit of radicles to the size of 2 mm) were measured and recorded daily in each Petri dish. Six regression models were applied to quantify the germination patterns of two pigweed ecotypes (Alborz and Fars) under a range of temperature between 5 to 35 °C. For both regions, during spring and summer, the range of temperatures was selected in order to simulate the temperature changes. The models were included Weibull, Lognormal, Logistic, Gompertz, Sigmoidal and Chapman. Some criteria were used to describe the goodness of fits of the models, including coefficient of determination (R2), root mean square of error (RMSE) and Akaike index (AIC). Moreover, a simple program called Germin was used to calculate D10, D50 and D90 (the time interval to maximum 10, 50 and 90% of germination, respectively). Results and Discussion: Results showed that Weibull four-parameter and logistic models were the best for describing the germination rate in Alborz and Fars ecotypes, respectively compared to the other models. The difference between ecotypes could be attributed to their base temperatures and thermal time requirements at each developmental stage. Therefore, it can be concluded weed germination during different seasons is not a random phenomenon. However, the germination and emergence of a clear pattern over time follows the pattern of different environmental conditions is subject to change. Results also indicated that the time to D90 was only 4 and 5 days in Alborz and Fars ecotypes, respectively meaning that with increasing temperature during early spring, this weed would germinate much sooner than spring crops and consequently resulted in crop damage. The results showed that the in Alborz population, with increases temperature from 10 to 30 °C, germination percentage linearly increased and with increasing temperature to the desired temperature, it decreased. However, germination in Fars ecotype showed that, in temperatures 10, 15 and 20 °C respectively, the germination was 36, 56 and 84 percent, while, with an increase in temperature from 25 to 35 °C, this component was always a constant process. Germination rate increased with increasing temperature from 10 to 35 °C which was higher in Alborz ecotype compared to Fars. At lower temperatures, the main reason for less germination rate could be decrement of water imbibition and enzyme activity in biochemical processes of germination. Conclusion: Increasing public awareness and concern about the impacts of herbicides on the environment, development of herbicide-resistant weeds, and the high economic cost of herbicides have increased the need to reduce the amount of herbicides used in agriculture. Prediction of weed emergence timing would help reduce herbicide use through the optimization of the timing of weed control. It was concluded that Weibull four-parameter and logistic models could be used as decision making tools in Alborz and Fars, respectively, to predict seed emergence of pigweed which in turn resulted in efficient management as well as reduction of herbicides usage. Future research should be addressed to determine a wider validation of the models, which could be valuable tools for farmers and practitioners for adequate timing of control in pigweed weed.