scholarly journals Yield Loss and Economic Threshold Level of Soybean due to Leaf Roller (Apoderus cyaneus Hope) in Nepal

1970 ◽  
Vol 6 ◽  
pp. 73-77
Author(s):  
Bishnu K Gyawali
Keyword(s):  
Population Density ◽  
Field Experiments ◽  
Yield Loss ◽  
Threshold Level ◽  
Growth Stages ◽  
Yield Losses ◽  
Adult Beetle ◽  
Economic Threshold ◽  
Leaf Roller ◽  
Research Journal

Yield loss in soybean due to leaf roller (Apoderus cyaneus Hope) was studied at Khumaltarduring 1985 and 1986 seasons. Field experiments were conducted during vegetative as well asreproductive stages of soybean. Rolled leaves of soybean with eggs, grubs and pupae werecollected from the field and reared in the laboratory for adults. Adults were introduced intonylon cages installed at the central rows of each plot just after germination of soybean. Insectswere maintained at population density of 25, 50 and 100 per m2density, the potential grain yield loss of cultivar, Ransom soybean in its vegetative andreproductive stages were 103 and 48 mg per day respectively from each adult of A. cyaneus.Percentages of yield losses were 36.2, 45.2, and 58.0 during vegetative and 37.5, 48.5 and 66.0during reproductive stages from the insect population of 25, 50 and 100, respectively which, wasnot in accordance with the level of two and four fold increased population density of insect.Yield reduction was higher (260 and 108 mg per day) from each adult beetle at lower populationlevel (25) in both vegetative and reproductive stages of soybean.Key words: Economic threshold level; leaf roller; physiological growth stages; yield lossDOI: 10.3126/narj.v6i0.3367Nepal Agriculture Research Journal Vol.6 2005 pp.73-77

scholarly journals The impact of cultivar resistance and fungicide treatment on mycotoxin content in grain and yield losses caused by Fusarium head blight in wheat

2010 ◽  
Vol 46 (No. 1) ◽  
pp. 21-26 ◽  
Author(s):  
V. Šíp ◽  
J. Chrpová ◽  
O. Veškrna ◽  
L. Bobková
Keyword(s):  
Grain Yield ◽  
Fusarium Head Blight ◽  
Field Experiments ◽  
Yield Loss ◽  
Joint Effect ◽  
Yield Losses ◽  
Cultivar Resistance ◽  
Head Blight ◽  
Fungicide Treatment ◽  
The Impact

Reactions to artificial infection with Fusarium graminearum isolates and a new fungicide Swing Top were studied in nine winter wheat cultivars evaluated in field experiments at two sites for three years for expression of symptoms, deoxynivalenol (DON) content in grain and grain yield. The results demonstrate a pronounced and relatively stable effect of cultivar resistance on reducing head blight, grain yield losses and contamination of grain by the mycotoxin DON. It is advantageous that the moderate level of resistance to Fusarium head blight (FHB) was detected also in two commonly grown Czech cultivars Sakura and Simila. Average fungicide efficacy for DON was 49.5% and 63.9% for a reduction in yield loss, however, it was found highly variable in different years and sites. The joint effect of cultivar resistance and fungicide treatment was 86.5% for DON and even 95.4% for reducing the yield loss. A very high risk was documented for susceptible cultivars and also the effects of medium responsive cultivars were found to be highly variable in different environments and therefore not guaranteeing sufficient protection against FHB under different conditions.

scholarly journals Modeling the Competitive Effect of Euphorbia dracunculoides and Astragalus sp. in Zero Input Rainfed Chickpea

2018 ◽  
Vol 36 (0) ◽  
Author(s):  
R.M. IKRAM ◽  
A. TANVEER ◽  
R. MAQBOOL ◽  
M.A. NADEEN
Keyword(s):  
Protein Content ◽  
Critical Period ◽  
Field Experiments ◽  
Seed Protein ◽  
Yield Loss ◽  
Seed Protein Content ◽  
Yield Losses ◽  
Competition Period ◽  
Crop Competition ◽  
Weed Removal

ABSTRACT: Brown chickpea (Cicer arietinum L.) is one of the two chickpea types grown in Pakistan and other countries. The critical period for weed removal in a rainfed chickpea system is an important consideration in devising weed management strategies. Field experiments were conducted in the winter season of 2011 and 2012 to determine the extent of yield loss with different periods of weed crop competition. Seven weed crop competition periods (0, 45, 60, 75, 90, 105 and 160 days after sowing - DAS) were used to identify the critical period for weed removal in rainfed chickpea. Experimental plots were naturally infested with Euphorbia dracunculoides and Astragalus sp. in both years. Individual, composite density and dry weights of E. dracunculoides and Astragalussp. increased significantly with an increase in the competition period. However, yield and yield-contributing traits of chickpea significantly decreased with an increase in the competition period. Chickpea seed yield loss was 11-53% in different weed crop competition periods. Euphorbia dracunculoides and Astragalus sp. removed 39.9 and 36.9 kg ha-1 of N, 9.61 and 7.27 kg ha-1 of P and 38.3 and 36.9 kg ha-1 of K, respectively. Season long weed competition (160 days after sowing) resulted in 19.5% seed protein content compared with 24.5% seed protein content in weed-free chickpea. A Logistic equation was fitted to yield data in response to increasing periods of weed crop competition. The critical timing of weed removal at 5 and 10% acceptable yield losses were 26 and 39 DAS, respectively. The observed critical period suggests that in rainfed chickpea, a carefully timed weed removal could prevent grain yield losses.

scholarly journals Economic Threshold of Volunteer Corn GR® in Soybean as a Function of Emergence Time and Origin of Corn

2018 ◽  
Vol 36 (0) ◽  
Author(s):  
C. PIASECKI ◽  
M.A. RIZZARDI
Keyword(s):  
Field Experiments ◽  
Individual Plant ◽  
Yield Losses ◽  
Emergence Time ◽  
Economic Threshold ◽  
Control Cost ◽  
Soybean Yield ◽  
Volunteer Corn ◽  
Corn Plants

ABSTRACT: Volunteer corn is extremely competitive with soybean and the degree of interference varies with the corn density, time of emergence and origin. The objectives of this work were to determine the economic threshold (ET) of volunteer corn GR® F2 in soybean as a function of the time of emergence (same day and nine days after soybean) and origin (individual plants or clumps). Each clump was manually adjusted to have seven corn plants. Four field experiments were conducted in randomized blocks design with four replicates in Passo Fundo, RS, Brazil. The soybean yield losses (%) were calculated and adjusted to the model of the rectangular hyperbola and generated the parameters for the determination of the ET, that was calculated based on the volunteer corn control costs (US$ ha-1), efficiency of control (%), price paid for soybean (US$ kg-1) and soybean yield (kg ha-1). The ET mean was 0.3 and 0.48 for individual corn plants m-2 emerged together and nine days after soybean, and 0.08 and 0.03 m-2 for individual plants and clumps, respectively. Increases in grain yield and price paid for soybean, greater control efficiency of corn and lower control cost promote reduction in the ET of volunteer corn in soybean. The control of volunteer corn is justified in a density less than 0.5 individual plant m-2 and is close to zero when corn originates from clumps. Volunteer corn is one of the most competitive weed in soybean crops.

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

2019 ◽  
Vol 99 (4) ◽  
pp. 437-443
Author(s):  
Nader Soltani ◽  
Robert E. Nurse ◽  
Amit J. Jhala ◽  
Peter H. Sikkema
Keyword(s):  
Growth Stage ◽  
Field Experiments ◽  
Yield Loss ◽  
Growth Stages ◽  
Weed Species ◽  
Weed Biomass ◽  
Weed Density ◽  
Weed Interference ◽  
Beginning Of Flowering ◽  
Minimal Reduction

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.

Economic and interference threshold densities of quackgrass (Elytrigia repens) in potato (Solanum tuberosum)

Weed Science ◽  
1998 ◽  
Vol 46 (2) ◽  
pp. 176-180 ◽  
Author(s):  
Régis Baziramakenga ◽  
Gilles D. Leroux
Keyword(s):  
Yield Loss ◽  
Dry Weight ◽  
Field Studies ◽  
Potato Yield ◽  
Hyperbolic Function ◽  
Yield Losses ◽  
Economic Threshold ◽  
Elytrigia Repens ◽  
Shoot Number ◽  
Dry Biomass

Field studies were conducted in 1989 and 1990 at St-Augustin, Quebec, Canada, to determine the economic threshold density of quackgrass in potato. Potato yield losses due to quackgrass interference increased with quackgrass population density. Potato yield ranged from 33 to 73% in 1989, and from 19 to 44% in 1990. The relationship between potato yield losses and quackgrass densities was described by a rectangular hyperbolic function. Dry weight of quackgrass proved to be the best predictor of potato yield loss compared to shoot number. The interference thresholds for 10% potato yield loss amounted to 25 shoots m−2or 20 g total dry biomass m−2. The economic threshold varied between 0.04 and 2 shoots m−2or 0.0165 and 1.5 g total dry biomass m−2, depending on the variables considered.

Dicamba, Chlorsulfuron, and Clopyralid as Sprayer Contaminants on Sunflower (Helianthus annuus), Mustard (Brassica juncea), and Lentil (Lens culinaris), Respectively

Weed Science ◽  
1989 ◽  
Vol 37 (4) ◽  
pp. 616-621 ◽  
Author(s):  
Douglas A. Derksen
Keyword(s):  
Helianthus Annuus ◽  
Lens Culinaris ◽  
Field Experiments ◽  
Yield Loss ◽  
Dry Weight ◽  
Yield Losses ◽  
Crop Tolerance ◽  
Crop Injury ◽  
Untreated Check ◽  
Grass Weed

Simulated sprayer tank residues of the broadleaf weed herbicides dicamba, chlorsulfuron, and clopyralid applied alone and with the grass weed herbicides sethoxydim and diclofop on sunflower, tame mustard, and lentil, respectively, caused visible crop injury and reduced dry weight and yield. Dry weight production in the greenhouse and crop tolerance ratings in the field indicated that the grass weed herbicides enhanced crop injury from dicamba, chlorsulfuron, and clopyralid. Yield reductions in field experiments were also greater when dicamba and clopyralid were mixed with grass weed herbicides and applied on sunflower and lentil, respectively. This did not occur with chlorsulfuron applied to mustard. When mixed with simulated broadleaf weed herbicide residues, diclofop enhanced dry weight reductions and crop injury and reduced yield to a greater extent than sethoxydim. Crop tolerance ratings differentiated treatments and rates but were not a good estimate of the extent of yield loss. When broadleaf weed herbicides were applied at rates simulating sprayer tank residues alone or combined with grass weed herbicides, yield losses ranged up to 40% in sunflower, 70% in mustard, and 95% in lentil, compared to the untreated check.

scholarly journals CANOLA YIELD AND PROFITABILITY AS INFLUENCED BY VOLUNTEER WHEAT INFESTATIONS

1989 ◽  
Vol 69 (4) ◽  
pp. 1235-1244 ◽  
Author(s):  
J. T. O’DONOVAN ◽  
K. J. KIRKLAND ◽  
A. K. SHARMA
Keyword(s):  
Triticum Aestivum ◽  
Multiple Regression ◽  
Seed Yield ◽  
Field Experiments ◽  
Yield Loss ◽  
Brassica Campestris ◽  
Triticum Aestivum L ◽  
Economic Threshold ◽  
Rectangular Hyperbola

The effects of different densities of volunteer wheat (Triticum aestivum L. ’Neepawa’) on the yield of canola (Brassica campestris L. ’Tobin’ and B. napus L. ’Westar’), and the seed yield of the volunteer wheat were determined in field experiments conducted at Vegreville, Alberta and Scott, Saskatchewan. Hyperbolic models provided a good fit to the data in most instances and indicated that volunteer wheat can severely reduce canola yield. A model pooled over locations and years indicated that volunteer wheat populations as low as one plant m−2 reduced canola yield by approximately 1%. Yield loss predictions from the models were used to determine the economics of volunteer wheat control with herbicides. In some cases, revenue losses due to reduced canola yield could be alleviated when the value of the volunteer wheat was considered.Key words: Volunteer wheat, canola, rectangular hyperbola, multiple regression, economic threshold, volunteer cereals

Field Pea and Lentil Tolerance to Interrow Cultivation

2017 ◽  
Vol 32 (2) ◽  
pp. 205-210 ◽  
Author(s):  
Katherine A. Stanley ◽  
Steven J. Shirtliffe ◽  
Dilshan Benaragama ◽  
Lena D. Syrovy ◽  
Hema S. N. Duddu
Keyword(s):  
Weed Control ◽  
Field Experiments ◽  
Yield Loss ◽  
Growing Season ◽  
Field Pea ◽  
Crop Damage ◽  
Growth Stages ◽  
Row Crops ◽  
Narrow Row ◽  
Mechanical Weed Control

AbstractInterrow cultivation is a selective, in-crop mechanical weed control tool that has the potential to control weeds later in the growing season with less crop damage compared with other in-crop mechanical weed control tools. To our knowledge, no previous research has been conducted on the tolerance of narrow-row crops to interrow cultivation. The objective of this experiment was to determine the tolerance of field pea and lentil to interrow cultivation. Replicated field experiments were conducted in Saskatchewan, Canada, in 2014 and 2015. Weekly cultivation treatments began at the 4-node stage of each crop, continuing for 6 wk. Field pea and lentil yield linearly declined with later crop stages of cultivation. Cultivating multiple times throughout the growing season reduced yield by 15% to 30% in both crops. Minimal yield loss occurred when interrow cultivation was conducted once at early growth stages of field pea and lentil; however, yield loss increased with delayed and more frequent cultivation events.

Cotton Growth and Yield Response to Simulated 2,4-D and Dicamba Drift

2009 ◽  
Vol 23 (4) ◽  
pp. 503-506 ◽  
Author(s):  
John D. Everitt ◽  
J. Wayne Keeling
Keyword(s):  
Good Predictor ◽  
Field Experiments ◽  
Yield Loss ◽  
Lint Yield ◽  
Growth And Yield ◽  
Yield Response ◽  
Growth Stages ◽  
Cotton Lint ◽  
Late Season ◽  
Crop Injury

Field experiments were conducted in Hale Co., TX, in 2005 and 2006 to determine the effects of 2,4-D amine and dicamba applied at varying rates and growth stages on cotton growth and yield, and to correlate cotton injury levels and lint yield reductions. Dicamba or 2,4-D amine was applied at four growth stages including cotyledon to two-leaf, four- to five-leaf, pinhead square, and early bloom. Dicamba and 2,4-D amine were applied at 1/2, 1/20, 1/200, and 1/2000 of the recommended use rate. Crop injury was recorded at 14 days after treatments and late-season, and cotton lint yields were determined. Across all growth stages, 2,4-D caused more crop injury and yield loss than dicamba. Cotton lint was reduced more by later applications (especially pinhead square) and injury underestimated yield loss with 2,4-D. Visual estimates of injury overestimated yield loss when 2,4-D or dicamba was applied early (cotyledon to two leaf) and was not a good predictor of yield loss.

scholarly journals Growth and Yield Losses of Roundup Ready Soybean as Influenced by Micro-rates of 2,4-D

2021 ◽  
Vol 10 (4) ◽  
pp. 27
Author(s):  
Ivan Cuvaca ◽  
Stevan Knezevic ◽  
Jon Scott ◽  
O. Adewale Osipitan
Keyword(s):  
Plant Height ◽  
Yield Loss ◽  
Maximum Growth ◽  
Growth And Yield ◽  
Growth Stages ◽  
Spray Drift ◽  
Canopy Closure ◽  
Yield Losses ◽  
Roundup Ready ◽  
Timing Of Exposure

Widespread resistance to glyphosate has made weed control very challenging. In response, new approaches to managing resistant biotypes such as the Enlist E3TM have been developed. This technology allows in-crop use of 2,4-D but there is fear associated with unintentional application of the herbicide (e.g. direct application, tank contamination, or spray drift) to sensitive crops. A study was conducted to evaluate Roundup Ready (RR) soybean growth and yield loss as influenced by 2,4-D [six micro rates of 1/5, 1/10, 1/50, 1/100, 1/500 and 1/1000 of the 1,120 g ae ha-1 label recommended dose, and a check with no herbicide applied] applied at V2, R1 and R2 growth stages. In general, RR soybean was more sensitive to 2,4-D at R1 than V2 and R2. The highest 2,4-D rate, 1/5 of the label recommended rate, caused 51% soybean injury symptom, 13 d canopy closure delay, 41.2% plant height reduction, and 68.9% yield loss at R1. Based on effective dose (ED) estimates, 37.7 g ae ha-1 2,4-D caused 5% yield loss (0.23 Mg ha-1) at R1 compared with a 2.5- and 2.0-fold higher dose at V2 and R2, respectively. With respect to number of days to canopy closure, both reproductive stages (R1 and R2) were equally less sensitive to 2,4-D than the vegetative one (V2) as the plants had already achieved maximum growth recorded. On the other hand, ED estimates for plant height have shown that both V2 and R2 were equally more sensitive to 2,4-D than R1. These results clearly indicated that RR soybean growth and yield loss were significantly influenced by the timing of exposure and amount of 2,4-D.

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