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Pendimethalin Residues from Weed Management in Dry Bean Can Cause Injury in Autumn Seeded Winter Wheat  [PDF]
Nader Soltani, Christy Shropshire, Peter H. Sikkema
Agricultural Sciences (AS) , 2015, DOI: 10.4236/as.2015.61014
Abstract:

There is little information on effect of pendimethalin residues in the soil used for weed management in dry bean, on winter wheat seeded 3 to 4 months after application in Ontario. A total of four field experiments were conducted over a four-year period (2008-2011) in Ontario to evaluate the effect of pendimethalin residues on winter wheat injury and yield grown in rotation with dry bean. Pendimethalin, applied PPI in dry bean, at 1080 and 2160 g ai ha-1 caused 1% to 3% injury and 4% to 9% winter wheat injury evaluated 1 and 4 weeks after emergence (WAE) in the fall and on approximately the first of May, June and July of the following year. Pendimethalin applied PPI in the spring at 1X or 2X manufacturer’s recommended rate (1080 or 2160 g ai ha-1) in dry bean caused no adverse effect on the winter wheat height evaluated in July of the following year and no adverse effect on maturity at harvest. Pendimethalin applied PPI at 1080 g ai ha-1 in dry bean in the spring caused no adverse effect on winter wheat yield, but pendimethalin applied at 2160 g ai ha-1 rate caused a 4% reduction in yield of winter wheat. Based on this study, pendimethalin applied PPI at 2160 g ai ha-1 has potential to cause injury and yield reduction in winter wheat grown in rotation with dry bean under Ontario environmental conditions.

Effect of Weed Management and Seed Rate on Crop Growth under Direct Dry Seeded Rice Systems in Bangladesh  [PDF]
Sharif Ahmed, Muhammad Salim, Bhagirath S. Chauhan
PLOS ONE , 2014, DOI: 10.1371/journal.pone.0101919
Abstract: Weeds are a major constraint to the success of dry-seeded rice (DSR). The main means of managing these in a DSR system is through chemical weed control using herbicides. However, the use of herbicides alone may not be sustainable in the long term. Approaches that aim for high crop competitiveness therefore need to be exploited. One such approach is the use of high rice seeding rates. Experiments were conducted in the aman (wet) seasons of 2012 and 2013 in Bangladesh to evaluate the effect of weed infestation level (partially-weedy and weed-free) and rice seeding rate (20, 40, 60, 80, and 100 kg ha?1) on weed and crop growth in DSR. Under weed-free conditions, higher crop yields (5.1 and 5.2 t ha?1 in the 2012 and 2013 seasons, respectively) were obtained at the seeding rate of 40 kg ha?1 and thereafter, yield decreased slightly beyond 40 kg seed ha?1. Under partially-weedy conditions, yield increased by 30 to 33% (2.0–2.2 and 2.9–3.2 t ha?1 in the 2012 and 2013 seasons, respectively) with increase in seeding rate from 20 to 100 kg ha?1. In the partially-weedy plots, weed biomass decreased by 41–60% and 54–56% at 35 days after sowing and at crop anthesis, respectively, when seeding rate increased from 20 to 100 kg ha?1. Results from our study suggest that increasing seeding rates in DSR can suppress weed growth and reduce grain yield losses from weed competition.
Influence of Integrated Weed Management Practices on Dynamics and Weed Control Efficiency in Dry Direct Seeded Rice  [PDF]
KP Bhurer,DN Yadav,JK Ladha,RB Thapa,KR Pandey
Nepal Journal of Science and Technology , 2013, DOI: 10.3126/njst.v14i2.10413
Abstract: Field experiment under dry direct seeded rice(O ryza sativa L.) was conducted during rainy season of 2010 and 2011 at Regional Agriculture Research Station (RARS), Parwanipur, Bara to develop appropriate weed management practices for dry direct- seeded rice. The trial was laid-out in randomized complete block design (RCBD) and replicated thrice. Observations were taken on weed, plant growth and yield attributing, yield, and socio-economic parameters. The weed density, dry weed weight and weed control efficiency resulted significantly different as influenced by integrated weed management practices. Low weed population density, low weed index and highest weed control efficiency resulted by pendimethalin followed by 2, 4- D followed by one hand weeding were at par with weed free check. Highest yield resulted from weed free plot followed by pendimethalin followed by two hand weeding and pendimethalin followed by 2, 4- D followed by one hand weeding. However, the net return per unit investment resulted highest in pendimethalin followed by 2, 4- D followed by one hand weeding. This proved that amid increasing wage rate and labour scarcity integrated weed management through pendimethalin 30 EC (Stomp) @1 kg a. i. /ha as pre- emergence herbicide application followed by 2, 4- D sodium salt 80 WP @ 0.5 kg a. i. /ha followed by one hand weeding or stale seed bed followed by pendimethalin 30 EC (Stomp) @1 kg a. i. /ha followed by bispyribac (Nominee gold) @25 g a. i. /ha 10% @200 ml/ha at 20 days of seeding resulted best alternative for manual hand weeding practices giving higher net return per unit investment. DOI: http://dx.doi.org/10.3126/njst.v14i2.10413 ? Nepal Journal of Science and Technology Vol. 14, No. 2 (2013) 33-42
Integrated Use of Herbicide and Crop Mulch in Suppressing Weed Growth in a Dry-Seeded Rice System  [PDF]
Bhagirath Singh Chauhan, Seth Bernard Abugho
American Journal of Plant Sciences (AJPS) , 2013, DOI: 10.4236/ajps.2013.48195
Abstract:

Dry-seeded rice production systems are increasing in many Asian countries because of labor and water scarcities. However, weeds are the main biological constraints in these systems. Herbicides are widely used to manage weeds but they do not provide effective weed control. The use of crop residue as mulch can suppress weed emergence and weed biomass but mulch alone does not provide effective weed control. The integrated use of herbicide and mulch, however, could provide more effective and sustainable weed control in dry-seeded rice systems. A study was conducted in two consecutive rice growing seasons to evaluate the combined effect of herbicide (treated and nontreated) and rice straw mulch (0, 2, and 4 t.ha-1) on weed growth and rice yield in a dry-seeded rice system. In the nontreated plots, weed biomass decreased with increases in mulch amounts, whereas weed biomass in the herbicide-treated plots was similar at different mulch amounts. Overall, herbicide treatments provided better weed control than the mulch treatments. In the nontreated plots, grain yield was similar at different mulch amounts, whereas grain yield in the herbicide-treated plots was greater when the field was mulched with 4 t.ha-1 of rice straw than with no mulch or mulched with only 2 t.ha-1 of rice straw. The results suggest that integrated use of mulch and herbicides can help weed control and increase crop yield in dry-seeded rice.

Effect of integrated weed management practices on performance of dry direct seeded rice (Oryza sativa L.)  [PDF]
KP Bhurer, DN Yadav, JK Ladha, RB Thapa, K Pandey
Agronomy Journal of Nepal , 2013, DOI: 10.3126/ajn.v3i0.9006
Abstract: Weeds are serious problem in dry direct seeded rice (DDSR). A field experiment was conducted during rainy seasons of 2010 and 2011 at research farm of the Regional Agricultural Research Station (RARS) Parwanipur, to study the effect of integrated weed management practices on the performance of dry direct seeded rice. Ten treatment combinations viz; weedy, weed free (weekly), Pendimethalin fb (followed by) Bispyribac, Pendimethalin fb two hand weeding, Stale seedbed fb Bispyribac, Stale seedbed fb Pendimethalin fb Bispyribac, Mulch 4 t/ha fb Bispyribac fb one hand weeding, Stale seedbed fb mulch 4 t/ha fb Bispyribac, Pendimethalin and Sesbania co-culture fb 2,4-D Na salt fb one hand weeding and Pendimethalin fb 2,4-D fb one hand weeding were tested in a randomized complete block design and replicated thrice. Observations were taken on weed, plant growth and yield attributes, yield, and socio-economic parameters. All weed control treatments significantly reduced the weed density and dry weight of weed resulting significant increase in yield of DSR over weedy check in both years. Weed free treatment resulted the highest yield, however, it was not economical due to high cost of cultivation. The use of Pendimethalin fb 2,4-D fb one hand weeding produced yield (5161 in 2010 and 6160 kg/ha in 2011) which were statistically at par with yield (5305 in 2010 and 6319 kg/ha in 2011) obtained under the weed free treatment. Further, the highest benefit cost ratio (CBR) 1.77 and 2.22 and net return Rs 47700 and 75084/ha during 2010 and 2011, respectively, were obtained under this treatment indicating its superiority over other treatments. The grain yield, yield attributing characters viz. panicles per m2, panicle weight, filled grain per panicle, thousand grain weight as influenced by different weed management practices revealed that higher yield resulted from weed free plot followed by Pendimethalin followed by two hand weeding and Pendimethalin followed by 2,4-D followed by one hand weeding. However, the net return per unit investment resulted highest in Pendimethalin followed by 2,4-D followed by one hand weeding. This proved that amid increasing wage rate and labor scarcity integrated weed management through Pendimethalin 30 EC (stomp) @ 1 kg a. i./ha as pre- emergence herbicide application followed by 2,4-D sodium salt 80 WP @ 0.5 kg a.i./ha followed by one hand weeding or stale seed bed followed by Pendimethalin 30 EC (stomp) @ 1 kg a. i./ha followed by Bispyribac (nominee gold) @ 25 g a. i./ha 10 % @ 200 ml/ha at 20 days of seeding resulted best alternative for
Effect of Integrated Weed Management Practices on Total Weed Dry Weight, Nutrient Removal of Weeds in Rice-Rice Wet Seeded System  [PDF]
N.K. Sathyamoorthy,S. Mahendran,R. Babu,T. Ragavan
Journal of Agronomy , 2004,
Abstract: Intercropping of green manure significantly reduced the total weed dry weight, nutrient removal by weeds as compared to non-green manured plots. When comparing the fallow with intercropping, summer ploughing with intercropping recorded least. Regarding the weed management practices, presowing application of glyphosate @ 1.6 kg a.i ha-1+ pre-emergence application of butachlor @ 1.25 kg a.i ha-1 followed by (fb) 1 and 2 hand weeding (HW) are being at par with each other and significantly superior to all other treatments. At 35 days after sowing, hand-weeding treatment recorded lowest dry weight and nutrient removal by weeds, however, this treatment was on par with above treatments during kharif season and some variations are observed in rabi season. At 55 days after sowing, similar trend of results as like that of 35 days after sowing except in two occasions.
Fertilizer Placement Affects Weed Growth and Grain Yield in Dry-Seeded Rice (Oryza sativa L.) Systems  [PDF]
Bhagirath S. Chauhan, Seth B. Abugho
American Journal of Plant Sciences (AJPS) , 2013, DOI: 10.4236/ajps.2013.46155
Abstract:

A study was conducted in a split-plot design to evaluate the effect of fertilizer placement method on weed growth and grain yield in a dry-seeded rice (DSR) system. Main-plot treatments were four fertilizer placement methods: between narrow rows (between 15-cm-wide rows of the pattern 25-15-25 cm), between uniform rows (between 20-cm-wide rows), within uniform rows, and surface broadcast. Subplot treatments were three weed control methods: herbicide-treated, nontreated, and weed-free. Weed biomass was greater in the nontreated plots than in the herbicide-treated plots. Herbicide application reduced weed biomass by 89% to 99% compared with the nontreated control. Fertilizer placement did not influence weed biomass in the herbicide-treated plots; however, it greatly influenced biomass in the nontreated plots. Fertilizer placement on the surface increased weed biomass (69 -71 g·m2) compared with the placement of fertilizer below the soil surface (37 -57 g·m–2). Fertilizer placement did not influence weed density and biomass at 60 days after planting. Nontreated plots yielded 700 to 2080 kg·ha–1. Grain yield was similar between the herbicide-treated (2660-3250 kg

Weed Infestation in Direct Seeded and Transplanted Aus Rice as Affected by Method of Planting and Weeding Regime  [PDF]
M.Y. Sarker,M. Mosaddeque Hossain,M.K. Hasan,M.A.H. Khan
Journal of Biological Sciences , 2002,
Abstract: The experiment was conducted to determine the weed vegetation due to the effect of planting methods and weeding regime. Two factors included in the experiment were: methods of planting and weeding regime. The results revealed that weed vegetation in the two methods of planting varied remarkable. Fifty-five weed species belonging to 17 families infested the crop. Among the weed species, Fimbristylis miliacea (L.) Vahl was the principal weed in direct seeded aus rice and Panicum repens L. in the transplanted aus rice. Twenty-four weed species were found to grow only in the direct seeded crop and only eight in the transplanted crop. Weed density and weed dry weight was significantly affected by the method of planting and weeding regime. Weed density and dry weight was significantly higher in direct seeded than in transplanted crop.
Weed Vegetation of Direct Seeded Ricefields in Muda Rice Granary Areas of Peninsular Malaysia  [PDF]
M. Begum,A.S. Juraimi,M. Azmi,A. Rajan
Pakistan Journal of Biological Sciences , 2005,
Abstract: A survey was carried out at heading stage of direct seeded rice to determine the major weed flora in Muda area, Kedah, Peninsular Malaysia. Thirty five weed species belonging to 17 families were identified in this area. Of these, 15 species were broadleaves, 10 sedges, 6 grasses and 4 aquatics. According to % field infestation and infestation rating score the six most widespread and abundant species were Oryza sativa complex (weedy rice), Leptochloa chinensis, Echinochloa crus-galli, Ischaemum rugosum, Fimbristylis miliacea and Ludwigia hyssopifolia. The hierarchy of weed type according to % field infested ratio was in the order of grasses (G)> broadleaved weeds (BL)> sedges (SG)> aquatics.
Effects of the inhibition of weed communities by winter-flooding  [PDF]
Korehisa Kaneko, Toshihiko Nakamura
Agricultural Sciences (AS) , 2011, DOI: 10.4236/as.2011.24050
Abstract: Winter-flooded paddy field is an agricultural method which putting a water among the winter, it is paid attention as an environmental friendly agriculture. Especially, it is said, winter-flooding is control paddy weeds and there is the farming potential that the annual rice yield is high. However, there is no detailed research about the effects of weed communities by winter-flooding, as the purpose of this study, we investigated the effects of the inhibition of weed communities (life cycle, harmful weed) by winter-flooding at a shore of Inba Lake, Chiba Prefecture, Japan, and compared them to paddy weeds in a dry paddy field. Methods examined the plant height (cm) and the cover degree class of all appearance species in each quadrant frame (1 m2). Quadrant in the two type paddies were 10 frames (D1-D10) at the control, and were 10 frames (W1-W10) at the treatment (Figure 1). In a winter-flooded paddy field, species number and plant volume of winter-annual plants decreased in the third winter after winter-flooding, In particular, the plant volume of Alopecurus aequalis, Cardamine flexuosa decreased significantly. We considered that the cause of this decrease was due to the depth of flooding (more than 10 cm). Eleocharis kuroguwai and Echinochloa oryzoides, which are perennial plants, Sagittaria trifolia, which is an annual plant, increased in a winter-flooded paddy field in the third summer after winter-flooding. We considered that these species grew thicker at places where the seeds germinated, and grew easily, because the conservation situation of the seeds fitted well under the winter-flooding conditions. They started to grow immediately after the drainage of water. The period of drainage coincided with increasing light intensity and temperature. In addition, the annual rice yield of the third year after winter-flooding was higher than that of the habitual practice rice field.
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