Total Weed Research Articles

Fate of Weed Seeds after Impact Mill Processing in Midwestern and Mid-Atlantic United States

Abstract Harvest weed seed control (HWSC) technology such as impact mills that destroy weed seeds in seed-bearing chaff material during grain crop harvest, has been highly effective in Australian cropping systems. However, the impact mill has never been tested in soybeans and weeds common to soybean production systems in the Midwest and Mid-Atlantic US. We conducted stationary testing of Harrington Seed Destructor (HSD) impact mill and winter burial studies during 2015-2016 and 2017-2018 to determine (i) the efficacy of the impact mill to target weed seeds of seven common weeds in Midwestern and five in Mid-Atlantic US, and (ii) the fate of impact mill processed weed seeds after winter burial. The impact mill was highly effective in destroying seeds of all the species tested, with 93.5-99.8% weed seed destruction in 2015 and 85.6-100% in 2017. The weak relationships (positive or negative) between seed size and seed destruction by impact mill, and high percentage of weed seed destruction by impact mill across all seed sizes indicate that the biological or practical effect of seed size is limited. The impact mill-processed weed seeds that retained at least 50% of their original size, labeled as potentially viable seed (PVS), were buried for 90 d over winter to determine the fate of weed seeds after winter burial. At 90 d after burial (DAB), the impact mill processed PVS were significantly less viable than unprocessed control seeds, indicating that impact mill processing physically damaged the PVS and promoted seed mortality over winter. A very small fraction (< 0.4%) of the total weed seed processed by the impact mill remained viable after winter burial. The results presented here demonstrate that the impact mill is highly effective in increasing seed mortality and could potentially be used as a HWSC tactic for weed management in this region.

Role of Allelopathy and Transplanting Space in Reducing Herbicide Use under Transplanted Rice (Oryza sativa L.)

Two field experiments were carried out at the farm of Sakha Agric., Res., Station, Kafrelsheikh, Egypt, through 2018 & 2019 seasons to study the role of allelopathy and transplanting space in reducing herbicide use under transplanted rice (Sakha 106 cv). Rice seedlings were manually transplanted under three spaces included 15x20cm, 20x20cm and 25x20cm. Four weed control treatments included pre-mixed herbicide Pindar 13.6% OD (triclopyr-butotyl 12 % + penoxsulam 1.6%) was used at recommended and ½ recommended dose compared with hand weeding and weedy check. Narrow transplanting space recorded the best in controlling E. crus-galli, C. difformis, Eclipta sp., as well as total weeds. Besides, achieved the highest dry weight of rice; panicles m-2; panicle weight and grain yield during both seasons. The highest dry weights of tested weeds and lowest values of rice characteristics were recorded under wider transplanting space throughout the tested seasons. Recommended rate of herbicide exceeded other weed control treatments in weeds control and produced highest dry matter and yield of Sakha 106 cv through both seasons. Recommended or half herbicide rate were the best in controlling weeds; dry weight of rice; grain yield and its attributes under 15 x 20 cm space without significant differences in the two seasons. It could be concluded that allelopathic rice cultivar Sakha 106 can be helpful in reducing herbicide use up to half dose when rice plants were transplanted on 15 x 20 cm.

Advancing cover cropping in temperate integrated weed management.

The effects of cover crops on weeds and the underlying mechanisms of competition, physical control and allelopathy are not fully understood. Current knowledge reveals great potential for using cover crops as a preventive method in integrated weed management. Cover crops are able to suppress 70-95% of weeds and volunteer crops in the fall-to-spring period between two main crops. In addition, cover crop residues can reduce weed emergence during early development of the following cash crop by presenting a physical barrier and releasing allelopathic compounds into the soil solution. Therefore, cover crops can partly replace the weed suppressive function of stubble-tillage operations and non-selective chemical weed control in the fall-to-spring season. This review describes methods to quantify the competitive and allelopathic effects of cover crops. Insight obtained through such analysis is useful for mixing competitive and allelopathic cover crop species with maximal total weed suppression ability. It seems that cover crops produce and release more allelochemicals when plants are exposed to stress or physical damage. Avena strigose, for example, showed stronger weed suppression under dry conditions than during a moist autumn. These findings raise the question of whether allelopathy can be induced artificially. © 2019 Society of Chemical Industry.

EFFICACY TEST OF TWO HERBICIDES IN CONTROL WEEDS IN SIMPLE LAND PROCESSING

Residents of agrarian areas are residents who depend their livelihood to agricultural products, but the production of community plantations is often not as desired. Our research aims to know influence the physiological response of weeds to glyphosate herbicide and paraquat herbicide. This experiment was conducted at the UGL Kutacane Faculty of Agriculture experimental garden, Babussalam Subdistrict, Southeast Aceh Regency, which ran from January to February 2018. This study used a non-factorial Randomized Block Design (RBD) consisting of 4 treatment levels: H1: Glyphosate Herbicide = 300 ml/4 L water; H2: Glyphosate herbicide = 1000 ml/13 L water; H3: Herbicide Paraquat = 300 ml/4 L water; H4: Herbicide Paraquat = 1000 ml/13 L of water. The results of Glyphosate Herbicide 1000 ml / 13 L of water effectively control total weeds up to 14 HSA. Glyphosate herbicide is able to inhibit the 5-enolpiruvil-shikimat-3-phosphate synthase (EPSPS) enzyme which plays a role in the formation of aromatic amino acids. The author concludes that the recommended dose of glyphosate based on the research is 1000 ml/13 L of water, because the dose is herbicide Glyphosate has been able to suppress total weed growth.

Soil bacterial communities of wheat vary across the growing season and among dryland farming systems

Despite knowledge that management practices, seasonality, and plant phenology impact soil microbiota; farming system effects on soil microbiota are not often evaluated across the growing season. We assessed the bacterial diversity in soil around wheat roots through the spring and summer of 2016 in winter wheat (Triticum aestivium L.) in Montana, USA, from three contrasting farming systems: a chemically-managed no-tillage system, and two USDA-certified organic systems in their fourth year, one including tillage and one where sheep grazing partially offsets tillage frequency. Bacterial richness (range 605–1174 OTUs) and evenness (range 0.80–0.92) peaked in early June and dropped by late July (range 92–1190, 0.62–0.92, respectively), but was not different by farming systems. Organic tilled plots contained more putative nitrogen-fixing bacterial genera than the other two systems. Bacterial community similarities were significantly altered by sampling date, minimum and maximum temperature at sampling, bacterial abundance at date of sampling, total weed richness, and coverage of Taraxacum officinale, Lamium ampleuxicaule, and Thlaspi arvense. This study highlights that weed diversity, season, and farming management system all influence soil microbial communities. Local environmental conditions will strongly condition any practical applications aimed at improving soil diversity, especially in semi-arid regions where abiotic stress and seasonal variability in temperature and water availability drive primary production. Thus, it is critical to incorporate or address seasonality in soil sampling for microbial diversity.

Effect of Seedling Age and Weed Management on Growth and Yield of Transplanted Rice (Sakha 106 cv).

Two field experiments were conducted at the Experimental Farm of Sakha Agricultural Research Station, Kafrelsheikh, Egypt during 2016 and 2017 summer seasons to study the effect of seedling age and weed management on growth and yield of transplanted rice (Sakha 106 cv). A split plot experimental design arranged in randomized complete block with four replications was used in both seasons. Three seedling ages viz., 21, 28 and 35 days were allocated to the main plots, while five weed control treatments i.e., thiobencarb (50% EC) at 2.39 kg ai ha-1, oxadiazon (25% EC) at 0.045 kg ai ha-1, penoxsulam (24% SC) at 0.029 kg.ai ha-1, hand weeding two times (20 and 40 DAT) and untreated (weedy check) were assigned to the sub-plots. The results showed transplanting rice seedlings at 21 days old recorded the lowest dry weight of Eclipta sp C. difformis E crus-galli and total weeds. Also, the increasing in rice dry weight, number of panicles m-2, panicle weight, number of filled grains panicle-1, 1000-grain weight and rice grain yield as compared to rest seedling ages (28 and 35 days). The application of penoxsulam at 0.029 kg ai ha-1 applied at 15 DAT achieved the lowest dry weight of weed species and total weeds as well as the highest rice yield as compared to weedy check. The interaction between seedling ages and weed control treatments had significant effect on dry weights of weed species, total weeds dry, rice yield and its components. Where, transplanting rice seedlings treatment at 21 days old treated with herbicide of penoxsulam at 0.029 kg ai ha-1 at 15 DAT are the best among the studied treatments to achieve the best weed control and the highest rice dry mater, grain yield and its components for Sakha 106 cv. under this study conditions.

The Impact of Weeding Regime, Planting Density, and Growth Habits on Watermelon Yield in an Organic System

The southeastern United States produces 50% of U.S. conventional watermelon (Citrullus lanatus) but only 7% of U.S. organic watermelon. Weeds are a major threat to watermelon yield in the southeastern United States, and organic weed control is estimated to cost 20-times more than conventional herbicide programs. The objectives of this study were to determine the optimal weed control regime to reduce hand-weeding costs while maintaining yield and to compare the weed suppression of two watermelon types with differing growth habits in an organic system. In 2014 and 2015, watermelon plots were randomly assigned to the following treatments in a factorial arrangement: vine or compact growth habit; 1.0- or 0.5-m in-row spacing; and weekly weed control (kept weed-free by hoeing and hand-pulling weeds) for 0, 4, or 8 weeks after transplanting (WAT). At the time of the watermelon harvest, not weeding resulted in average total weed densities of 86.6 and 87.0 weeds/m2, and weeding for 4 WAT resulted in average total weed densities of 26.4 and 7.0 weeds/m2 in 2014 and 2015, respectively. Nonetheless, weeding for 4 WAT resulted in watermelon yields and fruit counts comparable to those of weeding for 8 WAT during both years. This partial-season weeding regime resulted in 67% and 63% weeding cost reductions for vine and compact plants, respectively, in 2014, and a 43% reduction for both growth habit types in 2015. In 2015, a separate experiment that evaluated weeding regimes that lasted 0, 1, 2, 3, 4, and 8 WAT found that yields resulting from weeding for 3 WAT were greater than those resulting from weeding for 2 WAT. However, the yields did not differ when weeding was performed for 4 WAT and 8 WAT.

Field Testing of a Biomass-Fueled Flamer for In-Row Weed Control in the Vineyard

Concern about the adverse effects of chemicals on the environment and on human health, and increasing restrictions of herbicide use, have led to a renewed interest in non-chemical weed control, particularly under the row of vineyards. A new, biomass-fueled (wood pellet), flaming prototype (CS Thermos, San Vendemiano, TV) was tested in the vineyard during Spring–Summer 2018, and compared with tillage (disc cultivator, weeder blade, and finger blade) and mowing (in-row, vine-skipping mower). Efficacy (in % of weed biomass removed or killed) and re-growth between two applications (in g dry biomass/m2) were assessed for each treatment at two sampling locations (between the vines, and around the vines). Flaming resulted in greater efficacy of weed removal in comparison to tillage (blade weeder) and mowing, both between the vines (64%–75% versus 44%–68%, and 40%–68%, respectively) and around the vines (56%–78%, 39%–46%, and 37%–48%, respectively). However, five applications of tillage significantly reduced total weed growth until 27 July (by 26%) between vines in comparison to three applications of flaming, while no significant differences were found around vines. Such findings suggest that more frequent applications of flaming may be needed to give average weed control comparable to that of tillage, while improving it close to the vine trunks. Advantages and disadvantages of the prototype versus tillage and mowing, and versus conventional, LPG-fueled flamers are discussed in the paper.

Management of cover crops of cold cereal, on total fresh weight, total dry weight weed, yield and yield components peppermint

To study the effect of cover crop and how manage cover crop an experiment was conducted in Agricultural Research Center of University of Mohaghegh Ardabili , the experiment was factorial based on complete randomized block design with three replications. winter cover crops and spring cover crops as the main factor with six levels( winter wheat, spring wheat, winter barley , spring barley, winter rye, winter rye+ winter barley) and how manage cover crop with three levels (living mulch, heading mulch, mulch with herbicide) as a second factor. For comparison, two controls (without cover crop with weeding weeds and without cover crop without weeding weeds) was aside experiments. The results showed that main effect of type cover crop on the number of branches, leaf fresh weight, leaf dry weight of peppermint and also the total dry weight of weeds and at the first stage of sampling, Had a significant impact. The main effect of management was significant for all traits measured. However, the interaction of cover crop in how management cover crop were not significant. Winter wheat highest number of branches, leaf fresh weight, leaf dry weight of peppermint, relative to other levels of cover crops. In the first stage sampling is obtained by winter rye, the lowest total weed weight relative to other levels. Spring barley, winter rye the lowest total weed dry matter to create than other cover crop. All three methods to manage of cover crops the most affected by weeds dry weight compared to control. (no weeding and no cover crop weed)

Herbicidal weed management in dual purpose tall wheat (Triticum aestivum)

The field efficacy of pre- and post-emergence herbicide combinations for control of complex weed flora in dual purpose tall wheat was evaluated in a field study conducted at Research farm of CCS HAU Hisar (Haryana) during rabi of 2015-16 and 2016-17. Phalaris minor Retz., Rumex dentatus L., Convolvulus arvensis L., Medicago denticulata Willd., Cirsium arvense (L). Scape, Cyperus rotundus L. etc. were major weeds in experimental area. Application of herbicides in both growing seasons reduced weed density and increased wheat grain yield as compared with weedy. After cutting of wheat for fodder, total weed density was reduced under application of pendimethalin 1500 g/ha PRE fb pinoxaden + metsulfuron (50+4) 2 WAC (week after cutting at 55 DAS), pendimethalin 1500 g/ha PRE fb sulfosulfuron+ metsulfuron (30+2) 2 WAC and pendimethalin 1500 g/ha PRE fb clodinafop + metsulfuron (60+4) 2 WAC as compared to alone application of post emergence herbicides. During 86-115 DAS period, more crop growth rate was observed under sequential application of herbicides as compared to post-emergence herbicides. Among herbicidal treatments, significantly higher leaf area index, crop dry weight, grain yield and B:C ratio was reported under sequential application of herbicides which were significantly higher than weedy and alone pre- and post-emergence application of herbicides during both the years of study.

Management of Glyphosate-Resistant Weeds in Mexican Citrus Groves: Chemical Alternatives and Economic Viability.

Glyphosate is a cheap herbicide that has been used to control a wide range of weeds (4–6 times/year) in citrus groves of the Gulf of Mexico; however, its excessive use has selected for glyphosate-resistant weeds. We evaluated the efficacy and economic viability of 13 herbicide treatments (glyphosate combined with PRE- and/or POST-emergence herbicides and other alternative treatments), applied in tank-mixture or sequence, to control glyphosate-resistant weeds in two Persian lime groves (referred to as SM-I and SM-II) of the municipality of Acateno, Puebla, during two years (2014 and 2015). The SM-I and SM-II fields had 243 and 346 weeds/m2, respectively, composed mainly of Bidens pilosa and Leptochloa virgata. Echinochloa colona was also frequent in SM-II. The glyphosate alone treatments (1080, 1440, or 1800 g ae ha−1) presented control levels of the total weed population ranging from 64% to 85% at 15, 30, and 45 d after treatment (DAT) in both fields. Mixtures of glyphosate with grass herbicides such as fluazifop-p-butyl, sethoxydim, and clethodim efficiently controlled E. colona and L. virgata, but favored the regrowth of B. pilosa. The sequential applications of glyphosate + (bromacil + diuron) and glufosinate + oxyfluorfen controlled more than 85% the total weed community for more than 75 days. However, these treatments were between 360% and 390% more expensive (1.79 and 1.89 $/day ha−1 of satisfactory weed control, respectively), compared to the representative treatment (glyphosate 1080 g ae ha−1 = USD $29.0 ha−1). In practical and economic terms, glufosinate alone was the best treatment controlling glyphosate resistant weeds maintaining control levels >80% for at least 60 DAT ($1.35/day ha−1). The rest of the treatments, applied in tank-mix or in sequence with glyphosate, had similar or lower control levels (~70%) than glyphosate at 1080 g ae ha−1. The adoption of glufosiante alone, glufosinate + oxyfluorfen or glyphosate + (bromacil + diuron) must consider the cost of satisfactory weed control per day, the period of weed control, as well as other factors associated with production costs to obtain an integrated weed management in the short and long term.

Maize Yield and the Associated Weeds as Affected by Plant Population Density and Weed Control Treatments

Two field experiments were carried out in the Farm of Agricultural Research and the Experimental Center of Faculty of Agriculture at Moshtohor, (Toukh Directorate, Qalyubia Governorate) Benha Univ. Egypt, during 2017 and 2018 seasons to investigate the effect of five plant population densities, i.e. 18, 21, 24, 27 and 30 thousand maize plants/feddan (fed) {one fed = 4200 m2} and five weed control treatments, i.e.pendimethalin 682.5 g a.i./fed (stomp extra 45.5 % CS),acetochlor840 g a.i./fed (harness 84 % EC), nicosulfuron24 g a.i./fed (active 6 % SC), hand hoeingtwice and the unweeded check (the control) on yield, some of its components and associated weeds in maize (single cross hybrid 2036 for MisrHytech Seed Int.). Increasing plant population density from 18 to 30 thousand maize plants/fed reduced weed biomass at 50 days after sowing as well as significantly increased mean values of silking date, leaf area index at 80 days after sowing, plant height, ear height, No. of barren plants/fed, No. of ears/fed and stover yield/fed in both seasons. On the other hand, mean values of area of topmost ear leaf at 80 days after sowing, leaf area/plant at 80 days after sowing, stem diameter, No. of plants carried two ears/fed, ear length, No. of kernels/ear, weight of kernels/ear, shelling %, 100-kernel weight and harvest index were significantly decreased in the two seasons.Maize planted at 24000 plants/fed produced the highest mean values of grain and biological yields/fed in both seasons. Weed control by hand hoeing twice or using nicosulfuron herbicide surpassed the other weed control treatments in depressing mean values of fresh and dry weights of broad-leaved, grassy and total annual weeds at 50 days after sowing maize, as well as gave the best mean values of all maize traits without significant difference between them. Maize planted at 30000 plants/fed under mechanical weed control (hand hoeing twice) or using nicosulfuron herbicide gave the lowest mean values of all weed measurements at 50 days after sowing as well as gave the greatest mean values of leaf area index, plant height, ear height, No. of ears/fed and stover yield/fed in both seasons. The greatest mean values of area of topmost ear leaf, leaf area/plant, No. of kernels/ear, weight of kernels/ear and 100-kernel weight were obtained from planting 18000 maize plants/fed with hand hoeing twice. Maize planted at 24000 plants/fed and hand hoeing twice produced the greatest mean values of biological yield/fed in both seasons. The maximummean values of grain yield/fed were obtained by maize planted at 24000 and 21000 plants/fed and hand hoeing twice the first and second seasons, respectively.Planting maize by 21000 plants/fed with hand hoeing twice gave the highest mean values of nitrogen uptake/fed and protein yield/fed in both seasons.

Performance of some Sugar Beet (Beta vulgaris L.) Cultivars under Annual Weed Control Condition

Two field experiments were conducted in El-Serw Agricultural Research Station, ARC, during 2015/16 and 2016/17 seasons to study the possible integration between three sugar beet cultivars varied in its growth habitat: Glorius, Lilly and Cleopatra and six weed control treatments which are being: Goltix plus at 1.5 L/fad., Goltix at 2 L/fad., Cross at 2.5 kg/fad. as post emergence herbicides and Harness at 0.75 L/fad. as pre emergence herbicide in addition to hand hoeing twice and unweeded check on weeds associated with sugar beet productivity and its economic feasibility. The main findings showed that both Glorius cultivar suppressed weed growth at 120 DAS by 62.2 and 39.9%, accompanied with increasing sugar beet root yield by 28.4 and 32.6% and with Lilly cultivar by 19.1 and 14.0% reduction on weed growth and increased root yield by 34.5 and 17.0% in both seasons, respectively, compared than Cleopatra cultivar. On other hand, Cross herbicide as ready-made exceeded other herbicides and hand hoeing twice on controlling total weeds until 120 DAS by 85.5 and 71.6% and increasing sugar beet yield by 151.6 and 217.0 % than unweeded check in both seasons. The best integration between Glorius and Lilly cultivars both with application Cross herbicide from view point of weed control by 90.5 and 87.2%, respectively, in 2015/16 season and 88.7 and 71.4%, respectively, in 2016/17 season, respectively and increasing sugar beet root yield by 215.6 and 264.6%, respectively, in 2015/16 season and by 323.9% and 308.6, respectively, in 2016/17 season accompanied with increasing farmer incomes

Broadleaf weed control in rain-fed chickpea

AbstractWeeds are among the main limitations on chickpea production in Iran. The efficacy of herbicide treatments including linuron PPI, imazethapyr PPI, PRE, and POST, pendimethalin PPI and POST, bentazon POST, pyridate POST, and oxadiazon POST along with one or two hand weedings were evaluated for weed control and yield response in rain-fed chickpea in Aleshtar, Lorestan, Iran in 2015 and 2016. Wild safflower, threehorn bedstraw, wild mustard, and hoary cress were the predominant weed species in both experimental years. Total weed dry biomass in weedy check plots averaged 187 and 238 g m−2 in 2015 and 2016, respectively, and weed density and biomass were reduced in all treatments compared to the weedy check in both years. Treatments composed of pyridate followed by one hand weeding or imazethapyr POST followed by two hand weedings resulted in the lowest weed biomass. The presence of weeds reduced yield by 74% and 66% in the weedy check plots compared to the weed-free control plots in 2015 and 2016, respectively. Application of oxadiazon, bentazon, and imazethapyr PPI, PRE, and POST resulted in lower chickpea yields. All herbicides tested injured chickpea slightly, with pyridate causing the least injury.

Exploiting Olive Mill Byproducts and Other Waste for Organic Weed Management

Weed management represents one of the most serious and costly challenges in organic crop production systems. Agricultural waste/byproducts might present phytotoxicity that can be exploited to control weeds. Two experiments were designed to study the effects of four concentrations of olive vegetation water (OVW) and a control water treatment (with no OVW) on cheeseweed (Malva parviflora L.) seed germination in petri dishes and pots. In a third experiment, two rates of four composts (crop residue mix (CR), olive pomace (OP), dairy/horse manure (DM), and an OP/DM mix) were mixed into a clay‒loam soil at 0.10 or 0.20 L L−1, to assess their effects on weed number and biomass, in addition to bell pepper (Capsicum annuum L.) growth. In the petri dish experiment, the three highest OVW concentrations completely prohibited germination during the five-week duration of the study. For the pot experiment, 25 mL application of OVW significantly delayed and reduced cheeseweed germination, with the reduction being proportional to the concentration of OVW. In the third experiment, composts reduced weed dry matter (composed mostly of purslane (Portulaca oleracea L.)), with the CR compost being the most effective, reducing total weed biomass by 67% compared to the control. CR10 and DM10 tended to increase bell pepper yields, although none of the plant parameters was significantly affected by the compost treatments.

Chitosan/glyphosate formulation as a potential, environmental friendly herbicide with prolonged activity

Although there are many reports on the dangers posed by glyphosate, this herbicide is still one of the most popular and widely used total weed killers. Therefore, great effort should be made to minimize exposure to this herbicide and limit its losses into the environment. The aim of this study was to prepare a new formulation consisted of various molecular weight chitosans with glyphosate and their evaluation toward active substance release, phytotoxicity, and preliminary herbicidal efficiency. The phytotoxicity study of the obtained chitosan/glyphosate formulations was determined based on the Organisation for Economic Co-operation and Development 208 guideline. Among all tested formulations evaluated for phytotoxicity, that containing the highest molecular weight of chitosan was found to be the least toxic, showing simultaneously the most effective herbicidal activity against selected weeds. The release rate of glyphosate from the obtained formulations was dependent on the molecular weight and viscosity of chitosan.

The critical weed-free period in glyphosate-resistant soybean in Ontario is similar to previous estimates using glyphosate-susceptible soybean

A study consisting of 13 field experiments was conducted during 2014–2016 in southwestern Ontario and southcentral Nebraska (Clay Center) to determine the effect of late-emerging weeds on the yield of glyphosate-resistant soybean. Soybean was maintained weed-free with glyphosate (900 g ae ha−1) up to the VC (cotyledon), V1 (first trifoliate), V2 (second trifoliate), V3 (third trifoliate), V4 (fourth trifoliate), and R1 (beginning of flowering) growth stages, after which weeds were allowed to naturally infest the soybean plots. The total weed density was reduced to 24%, 63%, 67%, 72%, 76%, and 92% in Environment 1 (Exeter, Harrow, and Ridgetown) when soybean was maintained weed-free up to the VC, V1, V2, V3, V4, and R1 soybean growth stages, respectively. The total weed biomass was reduced by 33%, 82%, 95%, 97%, 97%, and 100% in Environment 1 (Exeter, Harrow, and Ridgetown) and 28%, 100%, 100%, 100%, 100%, and 100% in Environment 2 (Clay Center) when soybean was maintained weed-free up to the VC, V1, V2, V3, V4, and R1 stages, respectively. The critical weed-free periods for a 2.5%, 5%, and 10% yield loss in soybean were the V1–V2, VC–V1, and VC–V1 soybean stages in Environment 1 (Exeter, Harrow, and Ridgetown) and V2–V3, V2–V3, and V1–V2 soybean stages in Environment 2 (Clay Center), respectively. For the weed species evaluated, there was a minimal reduction in weed biomass (5% or less) when soybean was maintained weed-free beyond the V3 soybean growth stage. These results shows that soybean must be maintained weed-free up to the V3 growth stage to minimize yield loss due to weed interference.

Pengaruh Aplikasi Glifosat terhadap Efikasi dan Komposisi Gulma Pertanaman Kelapa Sawit Tanaman Menghasilkan Muda

This study aimed to obtain the effective dose of isopropylamine glyphosate herbicide for controlling weeds in oil palm plantation andto study the change of weed composition after glyphosate application in early producing oil palm plantation. The research was conducted in smallholder oil palm plantation located in Srimulyo Kenanga Sari Village, Seputih Surabaya Sub-district, Central Lampung Regency and Weed Science Laboratory of Agriculture Faculty, Lampung University from November 2017 to January 2018. This research used randomized block design (RBD) with 4 replications and 7 treatments of 5 isopropylamine glyphosate herbicide doses (1 . 080, 1 . 440, 1 . 800, 2 . 160, and 2 . 520 g . ha -1 ), mechanical weeding, and control. The data homogeneity tested by Bartlett test, the data additivity tested by Tukey test, and the difference of median value tested by the Least Significant Difference (LSD) at 5% level. The results showed that all of isopropylamine glyphosate herbicide doses were effective in controlling total weeds, grassy weeds (Axonopus compressus , Ottochloa nodosa , Imperata cylindrica) and nutsedges (Cyperus rotundus) for 4— 1 2 weeks after application (WAA) and broadleaf weeds (Praxelis clematidea) for 4 WAA. Glyphosate application changed weed composition at 4, 8, and 12 WAA of observations from grassy weeds to broadleaf weeds .

EFFECT OF NITROGEN FERTILIZER RATES AND WEED CONTROL TREATMENTS ON WEEDS GROWTH AND PRODUCTIVITY, QUALITY AND ECONOMIC FEASIBILITY OF TARO CROP

Two field experiments for taro vegetable crop were carried out in ElKanater El-Khiria, Horticulture Research Station, Kalubia Governorate, Egypt, in a split plot design during the two successive 2015 and 2016 seasons. This study aimed to investigate the effects of two nitrogen fertilizer rates at 90 or 120 kg/ fed. in main plots and nine weed control treatments in sub plots i.e. Harness at one liter/ fed., Sencor at 300 g/ fed. and Stomp extra at 1.7 liter/ fed. each individual and/ or plus Roundup at one liter/ fed., Roundup individual, hand hoeing twice after 25 and 40 days from sowing and untreated check (control) on weeds growth and vegetative growth, yield, quality and economic feasibility of taro. The main findings of this research revealed that nitrogen fertilizer rate at 90 kg/ fed. gave the highest decrease in dry weight of weed categories i.e. , broadleaf weeds, grassy weeds and total weeds in both seasons and increased diameter and weight of taro corm in the second season. Whereas, taro plant height, taro number of leaves/ plant and uptake of nitrogen by weeds were increased by application of nitrogen rate at 120 than 90 kg/ fed. during the two seasons without any significant differences in the yield of taro, its components, chlorophyll content and chemical analysis characterized. The use of Stomp extra at 1.7 liter/ fed. applied as post-sowing plus Roundup at one liter/ fed. after 25 days from sowing applied as taro pre-emergence above soil surface exhibited significantly decreased in dry weight of total weeds by 96.9 and 95.1 % in first and second seasons, respectively. Application of Seconr at 300g /fed. plus Roundup at rate of one liter/ fed. reduced the previous total weeds by 93.3 and 94.5% and increased taro yield (43.6 and 43.5%) in the first and second seasons, respectively. Thus, these herbicides can broaden weed control weed spectrum with long weed control season, which minimize taro yield by weed competition, consequently eliminated N uptake from soil and improved protein and starch accumulation in favor taro crop yield. Also, it can be advised as alternative hand hoeing to weed control in this crop with economic feasibility and delectable herbicides residues and under permissible levels which accompanied with high quality for taro growth characteristics i.e. plant height, number of leaves/ plant and chlorophyll reading in leaves, corm length, corm diameter, corm weight, corm fresh yield, dry matter % and chemical of taro corms (protein percentage, starch percentage and total nitrogen of corm yield).

Physiological role of thiamine and weed control treatments on faba bean and associated weeds grown under salt affected soil

Background and objectiveSalinity stress is an important abiotic stress that affect adversely on crop production, so using of natural compounds to improve plant tolerance to stress is very important.Materials and methodsTwo field experiments were conducted during two winter seasons of 2014/2015 and 2015/2016 at Tag El-Ezz Research Station of Agricultural Research Centre, Dakahliea Egypt. Field evaluation of the efficiency of weed-control treatments (unweeded, oxadiargyl, and two hand hoeing) and thiamine levels (0, 50, 75, and 100 mg/l) and their interactive effects on weeds, faba bean growth, yield, yield attributes, and some biochemical constitutes of seeds under salinity levels (1.37, 3.31, and 4.51 dS m−1).ResultsData revealed that number and dry weight of broad-leaved, narrow-leaved, and total weeds were significantly reduced by increasing salinity levels of soil from 1.37 to 4.51 dS m−1. In addition, the highest salinity level 4.51 dS m−1 caused the highest significant decreases in growth, yield, and yield attributes of faba bean. Meanwhile, increasing salinity level from 1.3 to 4.51 dS m−1caused significant increases in total soluble sugar, free amino acids, and proline contents of faba bean plant. Two hand hoeing treatment achieved the highest weed depression expressed in the lowest dry matter of total weeds. Also, two hand hoeing was the most effective weed control treatment in increasing growth, yield, yield attributes, and some biochemical constitutes of faba bean seeds followed by of oxadiargyl treatment. No significant differences between application of two hand-hoeing and oxadiargyl treatment on all studied parameters. Foliar treatment of faba bean plants with thiamine different concentrations could alleviate the harmful effects of different salinity levels.ConclusionWe could conclude that foliar application of thiamine at the rate of 100 mg/l caused the highest increases in all growth and yield parameters under investigation of faba bean plant. Interaction of 100 mg/l thiamine treatment and two hand hoeing was the most effective treatments on enhancing faba bean growth, yield, and its attributes under salinity levels. Results also indicated that free amino and proline works to increase faba bean plants ability to withstand salinity stress.