Herbicide efficacy for control of annual ryegrass (Lolium rigidum Gaud.) is influenced more by wheat seeding rate than row spacing

2013 ◽  
Vol 64 (7) ◽  
pp. 708 ◽  
Author(s):  
Deirdre Lemerle ◽  
Peter Lockley ◽  
Eric Koetz ◽  
Simon Diffey

Conservation cropping systems with no-till and stubble retention improve soil condition and water conservation. However, tillage is replaced by herbicides for weed control in these systems, increasing the threat of herbicide resistance. In the medium to high rainfall zones of the southern wheatbelt of Australia and under irrigation, wider row spacing is used to enable seeding into heavy stubble loads and to avoid stubble burning. Some evidence suggests that wider rows lead to reduced crop competitive ability and crop yields, greater herbicide dependence, and increased spread of resistance. Our aim was to test the hypothesis that increasing seeding rate compensated for reduced competitive ability at wider row spacings, especially when herbicide performance was suboptimal. We examined the impact of two wheat row spacings (18 and 36 cm) and five seeding rates (resulting in a range of densities of ~80–700 plants/m2) on control of Lolium rigidum with five rates of post-emergence application of diclofop-methyl (Hoegrass®), ranging from label rate to lower rates, over two growing seasons. In the presence of L. rigidum, wheat grain yield was unaffected by row spacing but was significantly reduced at low seeding rates, especially at lower herbicide rates. Lolium rigidum was suppressed at higher crop densities but was also unaffected by row spacing. Grain yield was maximised when post-emergence herbicide was applied at 60–100% of the recommended dose at wheat densities >~300 plants/m2. Significant levels of the weed remained in the crop at anthesis in all treatments. Weed dry matter ranged from 525 g/m2 at low crop densities and with no herbicide to 150 g/m2 with the recommended rate of herbicide and high wheat densities. The implications of manipulating crop competitive ability to improve weed control are discussed, especially in conditions where herbicide performance is unreliable due to weeds developing herbicide resistance or adverse environmental conditions.

Author(s):  
Suryakanta Kashyap ◽  
V.P. Singh ◽  
S.K. Guru ◽  
Tej Pratap ◽  
S.P. Singh ◽  
...  

Background: Weeds are the major threat to direct seeded rice and a single strategy of weed control may not be effective for season-long weed control. Intending to accomplish the long-term and sustainable weed management of direct seeded rice, the integration approach of weed management strategies seems a better alternative. The current field study was aimed to evaluate the impact of integration of different weed control methods on direct seeded rice under irrigated ecosystem on weed growth and rice yield. Methods: The experiment was laid out in randomized block design with three replications and twelve treatments during 2017 at G.B. Pant University of Agriculture and Technology, Pantnagar, Uttarakhand, India. The twelve treatments included the combination of cultural, mechanical, physical and chemical weed management methods. Result: Combination of stale seedbed technique integrated with pre-emergence application of pendimethalin with mechanical weeding at 25 DAS followed by 1 hand weeding at 45 DAS, Sesbania (line sowing) fb application of pendimethalin (PE) fb 1 mechanical weeding at 25 DAS fb 1 hand weeding at 45 DAS, stale seedbed with application of pendimethalin (PE) with Sesbania brown manuring supplemented with mechanical weeding (25 DAS) fb hand weeding at 45 DAS, mulching with wheat straw mulch along with post-emergence application of penoxsulam (20 DAS) fb 1 hand weeding at 45 DAS and application of pendimethalin (PE) fb penoxsulum (PoE) at 20 DAS fb 1 hand weeding at 45 DAS with a row spacing of 25 cm found to be similar in the suppression of weed population and weed density at 40 and 60 DAS and crop yields (4.3, 4.1, 4.2, 4.0 and 4.2 t/ha, respectively) were on par with weed free plot i.e. 4.4t/ha. Application of pendimethalin (PE) fb penoxsulum (PoE) at 20 DAS fb 1 hand weeding at 45 DAS with row spacing of 25cm recorded 93.7%, 90.6% and 4.5% weed control efficiency, weed control index and weed index respectively, which was similar with above integrated weed management treatments. A negative correlation of the weed density and dry matter with the yield of rice was recorded.


Utafiti ◽  
2015 ◽  
Vol 11 (1-2) ◽  
pp. 33-66
Author(s):  
Onesmo Selijio

Land management and conservation have been considered the most important aspects of sustainable productivity in economically developing countries where land degradation is a major challenge. In Tanzania, both the government and international organizations have been promoting adoption of land management and conservation technologies (LMCTs) for a long time. This paper establishes the impact of three LMCTs – soil water conservation technologies and erosion control (SWCEC), organic and inorganic fertilizers – on maize crop yields in different rainfall zones, using national panel survey data. The study employs static panel models to analyse the two-period data sets for 2008-2009 and 2010-2011. The results indicate that adoption of LMCTs do contribute significantly to maize yield. The greatest effects of organic and SWCEC methods on crop yield were realized in low rainfall zones, while that of inorganic fertilizers was observed in high rainfall zones. These findings support previous cross-sectional data analyses, suggesting for policy makers that a blanket land management and conservation programme applied uniformly to all agro-ecological zones is not strategically beneficial. The advisability of a technology employed in a given zone should be supported by local knowledge and research findings culled from that particular area.


2002 ◽  
Vol 82 (4) ◽  
pp. 687-692 ◽  
Author(s):  
B. D. Gossen ◽  
J. J. Soroka ◽  
H. G. Najda

Little information is available on the management of turfgrass species for seed production in the Canadian prairies. The objective of these studies was to assess the impact of residue management and row spacing on seed yield under irrigation. A factorial experiment was seeded at Saskatoon, SK, in 1993 to assess the impact of burning or scalping (very close mowing with residue removal) vs. mowing, and 20- vs. 40-cm row spacing on seed yield of Kentucky bluegrass (KBG) (Poa pratensis), creeping red fescue (CRF) (Festuca rubra subsp. rubra) and creeping bentgrass (CBG) (Agrostis palustris). Also, a residue management trial on KBG was seeded at Brooks, AB, in 1993. At Saskatoon, yield was higher at 20-cm spacing across all three species in 1994, but spacing had no impact on winter survival, stand density, tiller growth or yield in subsequent years. Burning and scalping consistently resulted in earlier spring green-up, a higher proportion of fertile tillers, and higher seed yield than mowing. Even with residue management, yield declined after one harvest in CBG and CRF, and after two harvests in KBG. At Brooks, residue management had a similar impact on yield of KBG. A second trial at Brooks examined the impact of row spacing (20, 40, 60 cm) and seeding rate (0.5 to 6 kg seed ha-1) on KBG. Seed yield was highest at 40-cm spacings in 1994, at 60 cm in 1995, and at 40 to 60 cm in 1996. Seeding rate did not have a consistent effect on yield. We conclude that a combination of residue management and 20- to 40-cm spacings provide the highest, most consistent seed yields for these turfgrass species in this region. Key words: Burning, clipping, turfgrass, seed production, row spacing, Poa, Festuca, Agrostis


1992 ◽  
Vol 6 (1) ◽  
pp. 129-135 ◽  
Author(s):  
David L. Barton ◽  
Donald C. Thill ◽  
Bahman Shafii

The effect of barley seeding rate and row spacing, and triallate, diclofop, and difenzoquat herbicide rate on barley grain yield and quality, and wild oat control were evaluated in field experiments near Bonners Ferry, Idaho, in 1989 and 1990. The purpose of the study was to develop integrated control strategies for wild oat in spring barley. Barley row spacing (9 and 18 cm) did not affect barley grain yield. Barley grain yield was greatest when barley was seeded at 134 or 201 kg ha–1compared to 67 kg ha–1. Wild oat control increased as wild oat herbicide rate increased and barley grain yield was greatest when wild oat herbicides were applied. However, barley grain yield was similar when wild oat biomass was reduced by either 65 or 85% by applications of half and full herbicide rates, respectively. Net return was greatest when the half rate of herbicide was applied to 100 wild oat plants per m2and was greatest when half or full herbicide rates were applied to 290 wild oat plants per m2. Net return increased when the seeding rate was increased to 134 or 201 kg ha–1when no herbicide was applied and when 290 wild oat plants per m2were present.


2019 ◽  
Vol 70 (2) ◽  
pp. 140 ◽  
Author(s):  
Gulshan Mahajan ◽  
Kerry McKenzie ◽  
Bhagirath S. Chauhan

Annual ryegrass (ARG) (Lolium rigidum Gaudin) is a problematic weed for chickpea (Cicer arietinum L.) production in Australia. Understanding the critical period of control of ARG in chickpea is important for developing effective integrated management strategies to prevent unacceptable yield loss. Experiments were conducted over 2 years at the research farm of the University of Queensland, Gatton, to evaluate the effect of chickpea row spacing (25 and 75cm) and cultivar (PBA Seamer and PBA HatTrick) and ARG infestation period (from 0, 3 and 6 weeks after planting (WAP), and weed-free) on ARG suppression and grain yield of chickpea. Year×treatment interactions were not significant for any parameter, and none of the treatment combinations showed any interaction for grain yield. Average grain yield was greater (20%) with 25-cm than 75-cm rows. On average, PBA Seamer had 9% higher yield than PBA HatTrick. Average grain yield was lowest in season-long weedy plots (562kg ha–1) and highest in weed-free plots (1849kg ha–1). Grain yield losses were lower when ARG emerged at 3 WAP (1679kg ha–1). Late-emerged ARG (3 and 6 WAP) had lower biomass (4.7–22.2g m–2) and number of spikes (5–24m–2) than ARG that emerged early; at 0 WAP, weed biomass was 282–337g m–2 and number of spikes 89–120m–2. Compared with wide row spacing, narrow row spacing suppressed ARG biomass by 16% and 52% and reduced number of spikes of ARG by 26% and 48% at 0 WAP and 3 WAP, respectively. PBA Seamer suppressed ARG growth more effectively than PBA HatTrick, but only in the season-long weedy plots. Our results imply that in ARG-infested fields, grain yield of chickpea can be increased by exploring narrow row spacing and weed-competitive cultivars. These cultural tools could be useful for developing integrated weed management tactics in chickpea in combination with pre-emergent herbicides.


Weed Science ◽  
1995 ◽  
Vol 43 (4) ◽  
pp. 634-639 ◽  
Author(s):  
Claudio M. Dunan ◽  
Philip Westra ◽  
Edward E. Schweizer ◽  
Donald W. Lybecker ◽  
Frank D. Moore

The question of when to control weeds traditionally has been approached with the calculation of critical periods (CP) based on crop yields. The concept of economic critical period (ECP) and early (EEPT) and late (LEFT) economic period thresholds are presented as a comprehensive approach to answer the same question based on economic losses and costs of control. ECP is defined as the period when the benefit of controlling weeds is greater than its cost. EEPT and LEFT are the limits of the ECP and can be used to determine when first and last weed control measures should be performed. Calculation of EEPT accounts for the economic losses due to weed competition that occur between planting and postemergence weed control. In this way it is possible to better evaluate the economic feasibility of using preplant or preemergence control tactics. The EEPT for DCPA application is analyzed in the context of onion production in Colorado. The EEPT for DCPA application was calculated from an empirical regression model that assessed the impact of weed load and time of weed removal on onion yields. The EEPT was affected by control efficacy, weed-free yield, DCPA cost, and onion price. DCPA application was economically advisable in only one of 20 fields analyzed because of the tow DCPA efficacy (60%).


Plant Disease ◽  
2017 ◽  
Vol 101 (9) ◽  
pp. 1621-1626 ◽  
Author(s):  
F. Workneh ◽  
S. O’Shaughnessy ◽  
S. Evett ◽  
C. M. Rush

Wheat streak mosaic (WSM) caused by Wheat streak mosaic virus, which is transmitted by the wheat curl mite (Aceria tosichella), is a major yield-limiting disease in the Texas High Plains. In addition to its impact on grain production, the disease reduces water-use efficiency by affecting root development. Because of the declining Ogallala Aquifer water level, water conservation has become one of the major pressing issues in the region. Thus, questions are often raised as to whether it is worthwhile to irrigate infected fields in light of the water conservation issues, associated energy costs, and current wheat prices. To address some of these questions, field experiments were conducted in 2013 and 2016 at two separate locations to determine whether grain yield could be predicted from disease severity levels, assessed early in the spring, for potential use as a decision tool for crop management, including irrigation. In both fields, disease severity assessments started in April, using a handheld hyperspectral radiometer with which reflectance measurements were taken weekly in multiple plots in arbitrarily selected locations across the fields. The relationship between WSM severity levels and grain yield for the different assessment dates were determined by fitting reflectance and yield values into the logistic regression function. The model predicted yield levels with r2 values ranging from 0.67 to 0.85 (P < 0.0001), indicating that the impact of WSM on grain yield could be fairly well predicted from early assessments of WSM severity levels. As the disease is normally progressive over time, this type of information will be useful for making management decisions of whether to continue irrigating infected fields, especially if combined with an economic threshold for WSM severity levels.


2008 ◽  
Vol 23 (2) ◽  
pp. 107-114
Author(s):  
Milena Simic ◽  
Nebojsa Momirovic ◽  
Zeljko Dolijanovic ◽  
Zeljko Radosevic

The effects of different herbicide combinations: control (1), alachlor+linuron (2), and alachlor+linuron+imazethapyr (3) were investigated in double-cropped soybean grown in two row spacing variants, 38 cm and 76 cm, under conventional tillage (CT) or no-tillage (NT). In trials conducted on a sandy loam soil at Zemun Polje, high weediness had a negative effect of on the yield of double-cropped soybean, especially at the higher row spacing tested and with no-tillage. Regression and correlation data revealed a dependence of weediness in double-cropped soybean on tillage system and herbicide combination, and dependence of soybean yield on tillage system.


2015 ◽  
Vol 76 (15) ◽  
Author(s):  
Umar Mohammed ◽  
Aimrun Wayayok ◽  
Mohd Amin Mohd Soom ◽  
Khalina Abdan

Weed emergence is among the most important problems in system of rice intensification (SRI) due to extensive planting geometry of at least 25 × 25 cm and moist environment, thereby leading to water loss by means of evaporation from the broad space as a result of the extensive planting geometry, and transpiration by the weeds. This reduces the additional water saving which affect the potential of SRI water productivity.  It also reduces rice crop yields up to 70% if there is no weed control attempted. Nowadays, weed is being controlled by manual weeder which is labour demanding, while motorized weeders overcome the problem but still, it able to remove the weeds before rice canopy closure or 30 days after transplanting (DAT). This research was designed to evaluate the performance of UMAR-SRImat on soil moisture conservation and weed control. UMAR-SRImat was made using flaked rice straw and biodegradable adhesive. The design was laid out using randomized complete block design (RCBD) with three treatments [without soil cover (T1), SRImat (T2), UMAR-SRImat (T3)] and three replications. The analysis was conducted using analysis of variance (ANOVA). Volumetric moisture content (VMC) was determined at 18 and 25 DAT.  Weeds were observed and recorded to determine the weed dry weight and weed control efficiency at 20, 40 and 60 DAT. Plant height per hill was measured at 30 and 50 DAT, likewise, the number of tillers were counted at 30 and 50 DAT. The result of VMC showed that UMAR-SRImat significantly conserved water higher than the control treatment at 18 and 25 DAT of 3100.0a and 2680.0a m3/ha, respectively. The effectiveness of UMAR-SRImat mulched was 100% at 20 DAT 99.64% at 40 DAT and 97.99% at 60 DAT. This research revealed that UMAR-SRImat mulch could retain soil moisture and suppressed weeds up to 60 DAT.


2018 ◽  
Vol 36 (0) ◽  
Author(s):  
M.A. NADEEM ◽  
T. ABBAS ◽  
F. BASHIR ◽  
R. MAQBOOL

ABSTRACT: Crop row spacing adjustment and adjuvants have a significant role in decreasing herbicide cost and environmental damage by reducing herbicide application rate. A field study was conducted to assess the impact of two row spacing values and reduced herbicide rates along with adjuvant on weeds in maize in 2014 and 2015. The experiment consisted of atrazine plus mesotrione plus halosulfuran methyl (pre-mixed herbicide) at label rate (719.2 g a.i. ha-1); reduced rates of 75% (539.4 g a.i. ha-1) and 50% (359.6 g a.i. ha-1) alone and in combination with alkyl ether sulphate at 396.8 mL ha-1 as an adjuvant along with weedy check in maize sown at 60 and 75 cm row spacing. Alkyl ether sulphate increased weed control efficacy (13-35%) of the pre-mixed herbicide. Herbicide along with adjuvant provided effective weed control at 60 cm as compared to 75 cm apart sown maize. The most effective control of weeds, and increase in maize grain yield (33-45% as compared to non-treated control) and net income were obtained by the pre-mixed herbicide at 539.4 g a.i. ha-1 (75% of recommended rate) with adjuvant and pre-mixed herbicide at 719.2 g a.i. ha-1 (recommended dose) without adjuvant. The results revealed that the rate of pre-mixed herbicide can be reduced by up to 25% of the recommended field rate by the addition of alkyl ether sulphate as an adjuvant at 60 cm row spacing of maize to increase maize yield and net income.


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