Tank Mix Research Articles

Effect of herbicide mixtures on weeds and yield of summer groundnut

Field experiment was carried during summer 2020 at Agronomy farm, B. A. College of Agriculture, Anand Agricultural University, Anand, Gujarat on loamy sand soil to study the effect of herbicide mixtures on weeds and yield of summer groundnut (Arachis hypogaea L.). The experiment was conducted in randomized block design with twelve treatments, replicated four times. Weed density decreased significantly with pre-emergence application (PE) of pendimethalin + oxyfluorfen (tank mix) 900 + 120 g/ha and intercultivation (IC) followed by (fb) hand weeding (HW) at 20 and 50 days after seeding (DAS), as compared to other treatments, which resulted in significant increase in growth and yield attributes viz., periodical plant height (cm), plant dry biomass (g/plant), nodule dry weight (mg/plant), number of pods/ plant, pod yield (kg/ha), haulm yield (kg/ha), seed index (g), harvest index (%) and shelling percentage (%). Maximum net returns (Rs. 125485/ha) and B:C (4.94) was achieved with pendimethalin + oxyfluorfen 900 + 120 g/ha PE which was closely followed by IC fb HW at 20 and 50 DAS and early post-emergence application of fluazifop-p-butyl (11.1%) + fomesafen (11.1%) SL (pre-mix) 250 g/ha.

FirstAct for Efficacy in ACCase-Tolerant Grain Sorghum

The objective of this study was to compare FirstAct with several tank mix partners for efficacy in herbicide-tolerant grain sorghum. FirstAct (quizalofop) alone or in tank mixtures controlled Johnsongrass 94% or more. However, tank mixing FirstAct with any broadleaf herbicide was generally antagonistic to Palmer amaranth control. Minor sorghum injury was 5% or less by four weeks after postemergence treatment. Sorghum yields increased with all postemergence treatments except with atrazine alone.

ТЕХНІЧНА ЕФЕКТИВНІСТЬ БАКОВИХ СУМІШЕЙ ГЕРБІЦИДІВ У ПОСІВАХ СОНЯШНИКУ В УМОВАХ ПІВНІЧНОГО СТЕПУ УКРАЇНИ

At the current weed infestation level of chernozem, it is almost impossible to grow sunflowers without the regulated use of the most effective herbicides with different action spectrum on weeds. It was established that tank mixtures of ethametsulfuron-methyl herbicides (750 g/kg) – 25 g/ha + aclonifen (600 g/l) – 1.2 l/ha + surfactant Trend 90 – 300 ml/ha and ethametsulfuron-methyl (750 g/kg) – 25 g/ha + aclonifen (600 g/l) – 1.5 l/ha + surfactant Trend 90 – 300 ml/ha provided the highest technical efficiency and the lowest air-dry mass of weeds in the oilseed agrocenosis. Their technical efficiency was 61.2–65.8%. Almost all variants of herbicide tank mixtures showed a high phytotoxic effect on green amaranth (Amarantus retroflexus L.) – 51-61%, common ragweed (Ambrosia artemisiifolia) – 52–76%, field bindweed (Convolvulus arvensis) – 100%, yellow foxtail (Setaria pumila L.) was the less controlled – 21– 31%. The variants with the application of herbicide tank mixtures of ethametsulfuron-methyl (750 g/kg) – 25 g/ha + aclonifen (600 g/l) – 1.2 l/ha + surfactant Trend 90 – 300 ml/ha showed the highest indicators of the yield structure elements, here the 1000 seed weight was 73.1 g at a maximum basket diameter of 31.5 cm. These indicators were less in 1.2–1.7 times for other studied variants with the herbicide tank mixtures. When application of the tank mixtures of ethametsulfuron-methyl (750 g/kg) – 25 g/ha + aclonifen (600 g/l) – 1.2 l/ha + surfactant Trend 90 – 300 ml / ha and ethametsulfuron -methyl (750 g/kg) – 25 g/ha + aclonifen (600 g/l) – 1.5 l/ha + surfactant Trend 90 – 300 ml/ha, it was obtained the maximum yield of sunflower seeds 2.15 and 2.07 t/ha, respectively. Other variants with herbicides and their tank mixtures had significantly lower yield of sunflower seeds – by 23–27 %. Key words: sunflower, weeds, herbicides, tank mixes, yield, technical efficiency

Effect of weed management on weed dynamics, crop growth, fodder yield and economics of fodder maize (Zea mays L.) African tall under Chhattisgarh condition

Fodder maize is palatable and nutritious which can be fed as green or dry and makes excellent silage. But it is heavily infested with weeds which often inflicts huge yield and quality losses. A field experiment was conducted at Indira Gandhi Krishi Vishwavidyalaya, Raipur during Kharif 2017. Results showed that the lowest weed density and dry weight was recorded in tank mix application of atrazine 750 g + pendimethalin 750 g ha-1 as pre emergence followed by hand weeding twice at 20 and 40 days after sowing and topramezone 35 g + atrazine 250 g ha-1 as post emergence. These herbicides also recorded higher weed control efficiency (93-95%) and the lowest weed index (1-2%). Highest green and dry fodder yield were also obtained with the tank mix application of atrazine 750 g + pendimethalin 750 g ha-1 as pre emergence followed by hand weeding twice at 20 and 40 days after sowing and topramezone 35 g + atrazine 250 g ha-1 as post emergence. Similarly, crude protein yield was also highest under these combinations. Among herbicides, the highest net returns (Rs 41768 ha-1) and benefit: cost ratio (2.68) were also highest with tank mix application of atrazine 750 g + pendimethalin 750 g ha-1 as pre emergence followed by hand weeding twice at 20 and 40 days after sowing and topramezone 35 g + atrazine 250 g ha-1 as post emergence. Thus, this study suggests tank-mixed herbicide application for better weed control in fodder maize rather than their sole application. These combinations of herbicides may be the alternative of manual weeding.

Management of Singapore daisy (Sphagneticola trilobata) in plantations

Singapore daisy is an invasive alien weed, now a problem in non-cropped areas as well as in perennial crop based systems. Two different experiments were conducted to find the most effective chemical and cultural method to manage Singapore Daisy. In the herbicidal study, 2,4-D, glyphosate, tank mix of 2,4-D + glyphosate, metsulfuron-methyl and premix of metsulfuron-methyl + chlorimuron-methyl were used. Of these, metsulfuron-methyl + chlorimuron-ethyl @ 10.0 g ha−1 and metsulfuron-methyl alone @ 10.0 g ha−1 were found very effective for controlling of this problem weed, followed by combination sprays of 2,4-D @ 1000 g ha−1 + glyphosate @ 820 g ha−1 and glyphosate alone @ 820 g ha−1 and 1640 g ha−1. The visual symptoms of phytotoxicity appeared around 4–7 days after the application of herbicides. Among the cultural control methods, removing the weed along with top 5 cm of soil followed by sowing cowpea was found to be very effective.

Optimization of the elements of onion production technology in an annual crop in the conditions of central Russia

The object of research is onion, cultivated as an annual crop in the Nonchernozem zone of the Russian Federation. The aim of the research is to develop an improved technology for the production of bulb in an annual crop, providing a yield of 70-80 t/ha on alluvial meadow soils of the Nonchernozem zone. Research method - field test. It has been established that the probability of performing each technological operation should be at least 95%. Sowing the seeds, which are previously cleansed from the rot, must be done at an earlier date. The required yield was achieved at N 200 P 160 K 280 + Humic chemical "Rostok" + 10 l/ha BisolbiSan, Azotovit, Phosphatovit biopreparations in equal proportions. The use of the microbiological preparation BisolbiSan in 1% concentration with chemical two-component fungicides (excluding copper-containing ones) increases the immunity of onion plants. In conditions of warm, humid summer, fungicidal treatments of onions are optimal at intervals of 7-10 days from the third decade of June to the end of July. The maximum weed suppression is provided by the post-sowing application of the Stomp Professional + Dual Gold tank mix (3 + 1 l/ha) in combination with the subsequent pre-emergence treatment with Reglon Forte (2 l/ha) and the post-emergence Goal 2E (0.5 l/ha).

Assure II Alone and with Tacoma and Classic for Efficacy in Fallow

The objective of this trial was to compare Assure II (quizalofop) at two rates with or without tank mix partners for grass control in fallow. Assure II at either rate alone provided similar control of volunteer corn and barley. Corn control was 90% or more regardless of rating date with all herbicides except Assure II at 8.0 oz/a plus Classic (chlorimuron) at 42 days after treatment (DAT). Tacoma (fenoxaprop) at 3.5 or 5.4 oz/a added to Assure II at 8.0 oz/a improved barley control later in the season.

Efficacy of herbicides against diverse weed flora of wheat (Triticum aestivum L.)

The present experiment was conducted at Barrister Thakur Chhedilal College of Agriculture and research station, Bilaspur, Indira Gandhi Krishi Vishwavidyalaya, Raipur (C.G.) during Rabi season 2021-22. With a view to study the Efficacy of herbicides against diverse weed flora of wheat (Triticum aestivum L.) In wheat. The wheat variety GW322 was used for the research and the treatments were replicated three times in a randomized block design and the treatments was consisted of thirteen treatments. Results revealed that treatment T11 where Weed Free at tillering and jointing stages resulted the highest plant height, number of effective tillers at harvest, number of tillers (m⁻²) length at harvest, grain yield (q ha-1), straw yield (q ha-1). Which was significantly superior over other treatments but was at par with T7 Pyroxasulfone + Metsulfuron (EPOST tank mix) 127.5 + 4 g a.i./ha-1 at tillering and jointing stages with grain yield (qha-1) closely followed by the treatment T5.

Impact of glyphosate formulations and adjuvants: effects on leaf interaction, metabolism, and control of sourgrass

ABSTRACT: The addition of commercial formulations and adjuvants to a tank mix may result in differences in the wettability on the plant surface, foliar uptake and herbicide efficacy. Thus, the objectives of this study were to evaluate the influence of glyphosate formulations and tank-mixture adjuvants on the contact angle (CA), uptake, metabolism and sourgrass control and the damage to the cuticular microstructure of this species caused by herbicide solutions. For this purpose, assays were carried out in a completely randomized design, and treatments distributed in a 2x5+1 factorial scheme with five replications. Two glyphosate formulations isopropylamine salt (SL) and ammonium salt (WG) combined or not with the adjuvant methylated soybean oil (MSO), mineral oil (MO), ethoxylated alkyl ester (EAE) or polyoxyethylenealkylphenol ether (PAE); and one control (water) were evaluated. CA measurements of the droplets deposited on a sourgrass leaf surface and on the standard surface (parafilm) were obtained using a tensiometer. Herbicide uptake and shikimate accumulation were simultaneously determined by chromatography and spectrometry. The control effect was assessed by observing plant survival dry weight reductions. The glyphosate SL and WG formulations had similar effects on the variables analyzed. However, mixing the adjuvants EAE, MO or MSO with either formulation of herbicide led to greater wettability and more severe damage to the cuticular microstructure, favoring glyphosate uptake and shikimate accumulation. Despite evidence regarding the treatments containing oils/surfactants, the control effect on sourgrass was similar. The combination of glyphosate formulations with such adjuvants is potentially more effective and guarantees satisfactory sourgrass control.

Effect Of Seedbed Preparation Methods And Herbicide Application On Yield And Economics Of Dry Direct-Seeded Rice At Parwanipur, Nepal

Field experiments were conducted during the 2016 and 2017 normal season (June-November) dry direct[1]seeded rice (DDSR) at RARS Parwanipur to assess the effect of various combinations of herbicides mixture under seedbed preparation to evaluate different attributes of weed control efficiencies (WCE) coupled with grain yield and economics of DDSR. The experiment was laid out in two factors factorial strip plot design with four replications. Treatments consisted of nine levels of weed management practices that include weed free, weedy check, Pendimethalin, Bispyribac sodium, Ethoxysulfuron, Pendimethalin followed by (fb) Bispyribac sodium, Pendimethalin fb Ethoxysulfuron, Bispyribac sodium tank mix with Ethoxysulfuron and Pendimethalin fb tank mixture of Bispyribac sodium and Ethoxysulfuron as horizontal factor whereas two levels of seedbed preparation methods (stale seedbed and normal seedbed) as the vertical factor. The result of the experiments revealed lower weed intensity (WI) and higher weed control efficiency (WCE), net return and benefit-cost (B:C) ratio with Pendimethalin fb tank mixture of Bispyribac sodium and Ethoxysulfuron in both the years 2016 and 2017. Grain yield was significantly higher with weed free treatment followed by Pendimethalin fb tank mixture of Bispyribac sodium and Ethoxysulfuron in both the years due to higher WCE and lower WI which resulted in better growth and development of DDSR. Therefore, the Pendimethalin fb tank mixture of Bispyribac sodium and Ethoxysulfuron is a better option for DDSR under Parwanipur condition during main season rice DDSR rice production.

Surveys of weed management on flooded rice yields in southern Brazil

AbstractOne of the main limiting factors for high yields of flooded rice (Oryza sativa L.) is the presence of weeds, especially herbicide-resistant weeds. The aim of this study was to evaluate the association of weed management practices adopted by flooded rice farmers in the state of Rio Grande do Sul (RS), Brazil, with grain yield. For this purpose, 324 interview surveys were administered to farmers who supplied information about the history of weed management and yields. The answers to the survey indicated that weedy rice (Oryza sativa L.) and Echinochloa spp. were the most important weeds that occurred in flooded rice areas in RS. Advanced growth stage of weeds and inadequate environmental conditions such as air temperature and relative humidity were listed as the main reasons for low weed control efficacy. Farmers achieved greater rice yields when they adopted rice–soybean [Glycine max (L.) Merr.] (9,140 kg ha−1 average yield) and herbicide site of action rotations (8,801 kg ha−1 average yield) along with tank mixes (8,580 kg ha−1 average yield) as specific management practices for resistant weed control. The use of glyphosate with residual herbicides in a tank mix in the rice spiking stage is the main factor related to greater yields. The postemergence applications and their relationship to delaying of flooding in rice is a factor that reduces rice yield when no spiking glyphosate application was made. Identification of the most important weeds in terms of occurrence and knowledge of the main agronomic practices adopted by farmers are essential so that recommendations for integrated management practices can be adopted in an increasingly accurate and sustainable manner in flooded rice areas in southern Brazil.

Integrated control of the mealybug Phenacoccus solenopsis (Hemiptera: Pseudococcidae) in Australian cotton with insecticides and naturally occurring beneficial arthropods

AbstractInsecticidal treatment options based on putative integrated pest management (IPM) compatible active ingredients spirotetramat, sulfoxaflor and buprofezin were evaluated for efficacy against first and second instar (small) and large (third instar and adult) cotton mealybugs, Phenacoccus solenopsis. Four field evaluations were conducted at the Department of Agriculture and Fisheries (Queensland) research station facilities at Kingaroy (KRS) and Emerald (ERS) in 2016 and 2017. Two ‘insecticide evaluations’ included treatment options with different rates of active ingredients and adjuvants, aimed at validating efficacy results obtained in previous glasshouse evaluations. The other two ‘IPM evaluations’ were designed to test the compatibility of selected insecticidal active ingredients with naturally occurring beneficial arthropods through differential exclusion by means of large field cages configured to be either partially open or fully closed to regulate access. Spirotetramat gave consistent and commercially acceptable (≥80%) control of large and small mealybugs at the highest rate of 96 g in these insecticide evaluations. The addition of crop oil to spirotetramat as a tank mix partner significantly enhanced efficacy, as documented previously in glasshouse evaluations. Sulfoxaflor provided equivalent control of large and small mealybugs but only at the ERS site. The overall control efficacy of buprofezin was equivalent to spirotetramat and sulfoxaflor at the ERS site but inferior to both at the KRS site. In the IPM evaluations, the abundance of predatory arthropods and their potential contribution to overall mortality was generally low. Parasitism contributed significantly to overall mortality among treatments over time and was independent of cage status (closed or open). Large mealybugs were equitably distributed between the upper (terminal) and lower sections of the cotton plant canopy in both ERS evaluations whereas in the KRS evaluations the distribution was biased towards the lower section. The importance of pest distribution within the crop canopy in the context of insecticide efficacy is discussed. The results of this study confirm the importance of spirotetramat, sulfoxaflor and buprofezin as key insecticidal platforms that will give growers and crop managers the flexibility and confidence to implement sustainable, multi‐pest IPM strategies in Australian cotton.

KEEFEKTIFAN BEBERAPA HERBISIDA CAMPURAN DALAM MENGENDALIKAN GULMA UMUM PERKEBUNAN KELAPA SAWIT

Herbicide mixing technology is an opportunity to improve efficiency and control weeds. This study aimed to develop the effectiveness of a mixed herbicide (tank mix) between the active ingredient formulations of tiafenacil, glyphosate, methyl metsulfuron, and paraquat dichloride in controlling common oil palm weeds. The research was carried out for approximately 3 months, from January to March 2021, in oil palm plantations. The research used was a randomized block design with 9 treatments and 4 replications. Herbicide application using a knapsack sprayer and a red nozzle. Spraying is carried out on weeds in the oil palm weed circle. Vegetation analysis was carried out before the application of herbicides, the percentage of mortality was observed 3,7, 14, 21, and 30 days after spraying and weed regrowth was carried out 30, 45, and 60 days after spraying. The results showed that the paraquat mixture of tiafenacil was able to increase the effectiveness of the herbicide against common weeds compared to the single herbicide tiafenacil at doses of 2 l/ha and 4 l/ha based on mortality. The paraquat mixture in methyl metsulfuron was able to increase the effectiveness of the herbicide against common weeds compared to the single herbicide methyl metsulfuron based on its mortality. The single herbicide tiafenacil dose of 2 l/ha was able to suppress the dry weight of Ottochloa sp better than the single herbicide tiafenacil dose of 4 l/ha. The mixture of methyl metsulfuron in tiafenacil was able to suppress the dry weight of Asystasia sp better than the single herbicide tiafenacil at a dose of 2 l/ha.

Interaction between pesticides applied alone or in mixtures in corn

The objective of this work was to evaluate the selectivity of herbicides applied alone or in tank mix, and also of combinations of different classes of pesticides (fungicides, herbicides and insecticides) on corn. An experiment was installed in the 2017/18 crop to assess herbicide selectivity, and repeated in 2018/19. The second experiment aimed to assess the selectivity of mixtures of different classes of pesticides, and was installed only in 2017/18. The experimental design adopted in the tests was randomized blocks, with four replicates. In each trial, a total of 16 treatments were evaluated, plus a control. At 7, 14 and 21 days after the application of treatments the phytotoxicity to corn was evaluated and the yield components and grain yield were determined. Herbicides caused low levels of injury to the corn plants, with small variations in yield components, and affected crop yield differently. The mixtures of pesticides promoted low phytotoxicity, affected yield components inconsistently and caused changes in corn yield. Although these herbicides and other pesticides are registered for use in corn crops, application alone or in tank mix of certain molecules can cause losses in grain yield.

Is tank mixing site-specific premixes and multi-site fungicides effective and economic for managing soybean rust? a meta-analysis

Soybean rust (SBR), caused by Phakopsora pachyrhizi, is controlled with sequential applications of commercial premixes containing two and, more recently, three site-specific fungicides. However, their efficacy has been reduced due to the development of fungicide resistance in the fungal population; hence the use of multi-site fungicides in tank mixing has been encouraged. In this work we used data from 45 uniform fungicide trials conducted across eight Brazilian states during three crop seasons (2014/15, 2015/16, and 2017/18) to identify scenarios when the practice of adding multi-site fungicides in commercial premixes was both technical- and cost-effective. Premixes of quinone outside inhibitor (QoI) + demethylation inhibitors (DMI) or succinate dehydrogenase inhibitors (SDHI) were applied alone, or tank mixed with multi-site fungicides. Three premixes (PICOxystrobin + CYPRoconazole, PYRAclostrobin + FLUXapyroxad and AZOXystrobin + BENZovindiflupyr) were tank mixed with one of three multi-site fungicides (+MANCozeb, +COPpeR oxychloride, and +ChLORothalonil). The benefits from tank mixing a multi-site tended to be highest for the least effective premix. Improvements in control efficacy (C‾, percent point; p.p.) and yield response (D‾, kg/ha) ranged from 3 to 15 p.p. and 58–240 kg/ha, respectively. The improvements in C‾ and D‾ were affected by severity in the non-treated check; significantly higher improvements in D‾ were determined in trials experiencing high SBR severity levels (>80%). The economic analysis for scenarios of soybean price and multi-site costs showed that the addition of +MANC, given its lower price, was more likely to be profitable compared with +CLOR and +COPR, particularly when tank mixed with the least effective commercial premix.

Critical Time for Weed Removal in Corn as Influenced by Planting Pattern and PRE Herbicides

Determining the critical time for weed removal (CTWR) is essential for the development of an integrated weed management plan. Therefore, field experiments were conducted to evaluate the effects of two planting patterns (standard and twin-row) with and without PRE-applied herbicides on CTWR in corn. Experiments were laid out in a split-plot arrangement with two main plots: (i) standard row planting (SRP) that is 70 cm wide, and (ii) twin-row planting (TRP) with 50 cm distance between each set of double rows. Each main plot was divided into two sub-plots (with and without PRE herbicides). The sub-sub-plots consisted of seven weed removal timings for PRE herbicides, and tank mixes were utilized (S-metolachlor (1.44 kg a.i. ha−1) + terbutylazine (0.75 kg a.i. ha−1)). The CTWR without PRE herbicides was similar in both the SRP and TRP systems, where it was around the V1 to V2 (16 to 19 d after emergence (DAE)) growth stages. The use of PRE-applied herbicides delayed CTWR in SRP to the V4 to V10 (25 to 58 DAE) stages and up to the V11 (60 DAE) stage in TRP. These results clearly indicate that PRE herbicides are important for protecting corn yields regardless of the planting pattern. In more meteorologically favorable seasons (sufficient heat and precipitation) in both sowing systems, corn plants produce their biological maximum with the fact that over the number of plants per unit area (SRP = 80,000 plants ha−1, TRP = 93,900 plants ha−1) provide higher yields in variants with PRE herbicides, and thus the advantage of the TRP system can be justified.

Tolerance of ‘Camarosa’ Strawberry (Fragaria ×ananassa Duch.) to Extra-label Use of Single and Tank Mix Preemergence Herbicides in Annual Hill Plasticulture

Relatively few herbicides are registered in Alabama or in the southeastern United States for use in annual hill plasticulture production of strawberries. Acquisition of 24(c) special local needs status for certain herbicides could make more of these chemistries available to the strawberry industry. These herbicides, especially when applied as tank mixes pose potential risks to strawberry plant growth and fruit yield. Special local needs status for these herbicides has been granted for other states, but more evaluation of these products in Alabama soils under plastic mulch is needed. The objective of this study was to assess tank mix applications of preemergence herbicides with different modes of action on plant growth, crop yield, and fruit size of ‘Camarosa’ strawberry. A study was conducted at the Chilton Research and Extension Center in Clanton, AL, in 2018 and 2019. Pendimethalin (3.5 L·ha–1) and S-metolachlor (1.6 L·ha–1) were evaluated for potential phytotoxicity in ‘Camarosa’ strawberry when applied alone or in tank mixes with napropamide (8.6 kg·ha–1), sulfentrazone (0.3 L·ha–1), or terbacil (0.42 L·ha–1) by comparing them to a nontreated control. At 18 weeks after planting, pendimethalin tank mixed with napropamide reduced plant dry weight by 33% compared with the control, but this reduction was not significant. Additionally, tank mixes of pendimethalin with sulfentrazone, napropamide, and terbacil reduced shoot dry weight by 43%, 52%, and 43%, respectively, compared with pendimethalin alone. Pendimethalin + napropamide tank mix reduced relative growth rate by 95% compared with the control between 6 and 18 weeks after planting. All treatments were similar to the control in marketable yield. Differences in plant growth parameters did not appear to affect yield by the end of the experiment. All single applied treatments along with S-metolachlor tank mixed with napropamide and sulfentrazone; pendimethalin tank mixed with sulfentrazone and terbacil appeared to be safe for direct application to strawberry planting beds covered in polyethylene mulch.

Use of the imazapic herbicide applied alone or tank mix with imazapyr as growth regulator of lawns

Successive mowing are the major maintenance costs of lawns. Thus, both the expenditure with mowing and the visual and physiological aspect of the lawn have led to the search for alternatives to mechanical management. Thus, this work aimed to study the effects of different rates of imazapic herbicide applied alone or combined with imazapyr as a growth regulator of Bahiagrass (Paspalum notatum) and St. Augustine grass (Stenotaphrum secundatum). The experimental design was a randomized block with four replicates, and the treatments consisted of six rates of imazapic herbicide (35; 70; 105; 140; 175 and 210 g a.i. ha-1) for both species, three rates of imazapic + imazapyr in tank mix (15.57 + 5.25; 23.625 + 7.875; 32.5 + 10.5 g a.i. ha-1) for Bahiagrass and four rates of imazapic + imazapyr mixture (7.875 + 2.625; 15.57 + 5.25; 23.625 + 7.875; 32.5 + 10.5 g a.i. ha-1) for St. Augustine grass. The effect of the treatments was evaluated by observing visible injury symptoms, canopy height, height and number of inflorescences and total dry matter of clippings. Applications of imazapic alone or combined with imazapyr were effective in reducing plant height, number and height of inflorescences and total amount of dry matter of clippings produced by Bahiagrass plants. Imazapic provided satisfactory control of St. Augustine growth, but its utilization caused an increase in the number of inflorescences present in the lawns.

Comparison of premix glyphosate and 2,4-D formulation and direct tank mixture for control of Conyza canadensis and Epilobium ciliatum

Premix or tank mix of glyphosate and 2,4-D are a good alternative to control glyphosate-resistant and -tolerant weeds; however, the combination of herbicides may increase the environmental impacts, since mixtures often have higher toxicity than a single herbicide. In addition, antagonism between these herbicides has also been reported. We compared the efficacy of a premix glyphosate+2,4-D formulation with respect to the tank mix of both herbicides on glyphosate-resistant Conyza canadensis and -tolerant Epilobium ciliatum populations in laboratory and field experiments. 2,4-D suppressed the glyphosate-resistance/tolerance of both species, whose populations presented similar responses to their susceptible counterparts (LD50 ≥ 480+320 g ha−1 glyphosate + 2,4-D, respectively). Plants of both species treated with the premix formulations retained ∼100-μL more herbicide solution, accumulated 20–25% and 28–38% more shikimate and ethylene, respectively, and presented greater 14C-glyphosate absorption and translocation, depending on the species, compared to plants treated with the tank mix treatment. Although doubling the field dose (720 + 480 g ha−1) improved (5–22%) the control of these weeds in the field, split applications of both premix and tank mix provided the best control levels (≤70%), but premix treatments maintained control levels above 85% for longer (120-d). No antagonism between glyphosate and 2,4-D was found. The addition of 2,4-D controlled both broadleaf species. For all parameters evaluated on the C. canadensis and E. ciliatum populations in the laboratory and in the field, the premix treatments showed better performance than the tank mix treatments. Premix formulations could reduce the environmental impact of herbicides used to control glyphosate resistant/tolerant weeds by decreasing the herbicide amount needed to achieve an acceptable weed control level.

Glyphosate Resistance Confirmation and Field Management of Red Brome (Bromus rubens L.) in Perennial Crops Grown in Southern Spain

The excessive use of the herbicide glyphosate on annual and perennial crops grown in Southern Spain has caused an increase in resistant weed populations. Bromus rubens has begun to spread through olive and almond cultivars due to low glyphosate control over these species, whereas previously it had been well controlled with field dose (1080 g ae ha−1). Characterization using Simple Sequence Repeat (SSR) markers confirmed the presence of B. rubens collected in Andalusia. A rapid shikimic acid accumulation screening showed 17 resistant (R) populations with values between 300 and 700 µg shikimate g−1 fresh weight and three susceptible (S) populations with values between 1200 and 1700 µg shikimate g−1 fresh weight. In dose–response experiments the GR50 values agreed with previous results and the resistance factors (RFs: GR50 R/GR50 S (Br1)) were between 4.35 (Br9) and 7.61 (Br19). Foliar retention assays shown no differences in glyphosate retention in both R and S populations. The tests carried out in a resistant field (Br10) demonstrated the control efficacy of pre-emergence herbicides since flazasulfuron in the tank mix with glyphosate had up to 80% control 15 to 120 days after application (DAA) and grass weed postemergence herbicides, such as propaquizafop + glyphosate and quizalofop + glyphosate, had up to 90% control 15 to 90 DAA. Results confirm the first scientific report of glyphosate-resistant B. rubens worldwide; however, the use of herbicides with another mode of action (MOA) is the best tool for integrated weed management.