Critical Period of Quackgrass (Elytrigia repens) Removal in Potatoes (Solanum tuberosum)

Field trials were carried out in 1989 and 1990 at St-Augustin, near Québec City, Canada, to determine the critical periods of quackgrass control in potato submitted to three levels of infestation. Potato yield losses due to quackgrass interference increased with quackgrass infestation and length of duration of interference. Quackgrass interference influenced marketable tuber yields more than total tuber yields. Duration of the critical period varied depending on the level of quackgrass infestation and year. Based on an arbitrary 5% level of marketable yield loss, the critical period started at ca. 15 days after emergence (DAE) of potato at low level of infestation, and at ca. 3 DAE at medium level of infestation. At high level of infestation, the critical period began prior to the emergence of potato. The end of the critical period of quackgrass removal was extremely variable across quackgrass infestation level and year and ranged from 23 to 68 DAE of potato at a 5 % yield loss level. It appears that onset of interference varied less than the end of it, indicating that early quackgrass control is necessary to prevent yield loss.

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Determining the critical period for weed control in high-yielding cotton using common sunflower as a mimic weed

Weed Technology ◽

10.1017/wet.2019.68 ◽

2019 ◽

Vol 33 (6) ◽

pp. 800-807 ◽

Cited By ~ 3

Author(s):

Graham W. Charles ◽

Brian M. Sindel ◽

Annette L. Cowie ◽

Oliver G. G. Knox

Keyword(s):

Weed Control ◽

Critical Period ◽

Yield Loss ◽

Field Studies ◽

Growing Degree Days ◽

Degree Days ◽

Weed Density ◽

High Level ◽

The Cost ◽

Planting Season

AbstractField studies were conducted over six seasons to determine the critical period for weed control (CPWC) in high-yielding cotton, using common sunflower as a mimic weed. Common sunflower was planted with or after cotton emergence at densities of 1, 2, 5, 10, 20, and 50 plants m−2. Common sunflower was added and removed at approximately 0, 150, 300, 450, 600, 750, and 900 growing degree days (GDD) after planting. Season-long interference resulted in no harvestable cotton at densities of five or more common sunflower plants m−2. High levels of intraspecific and interspecific competition occurred at the highest weed densities, with increases in weed biomass and reductions in crop yield not proportional to the changes in weed density. Using a 5% yield-loss threshold, the CPWC extended from 43 to 615 GDD, and 20 to 1,512 GDD for one and 50 common sunflower plants m−2, respectively. These results highlight the high level of weed control required in high-yielding cotton to ensure crop losses do not exceed the cost of control.

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Determining the critical period for grass control in high-yielding cotton using Japanese millet as a mimic weed

Weed Technology ◽

10.1017/wet.2019.113 ◽

2019 ◽

Vol 34 (2) ◽

pp. 292-300 ◽

Cited By ~ 1

Author(s):

Graham W. Charles ◽

Brian M. Sindel ◽

Annette L. Cowie ◽

Oliver G. G. Knox

Keyword(s):

Weed Control ◽

Critical Period ◽

Yield Loss ◽

Field Studies ◽

Cotton Yield ◽

Degree Days ◽

Cropping Season ◽

High Level ◽

The Cost ◽

Grass Weed

AbstractField studies were conducted over five seasons from 2004 to 2015 to determine the critical period for weed control (CPWC) in high-yielding, irrigated cotton using a competitive mimic grass weed, Japanese millet. Japanese millet was planted with or after cotton emergence at densities of 10, 20, 50, 100, and 200 plants m−2. Japanese millet was added and removed at approximately 0, 150, 300, 450, 600, 750, and 900 degree days of crop growth (GDD). Data were combined over years. Japanese millet competed strongly with cotton, with season-long interference resulting in an 84% reduction in cotton yield with 200 Japanese millet plants m−2. The data were fit to extended Gompertz and logistic curves including weed density as a covariate, allowing a dynamic CPWC to be estimated for densities of 10 to 200 Japanese millet plants m−2. Using a 1% yield-loss threshold, the CPWC commenced at 65 GDD, corresponding to 0 to 7 d after crop emergence (DAE), and ended at 803 GDD, 76 to 98 DAE with 10 Japanese millet plants m−2, and 975 GDD, 90 to 115 DAE with 200 Japanese millet plants m−2. These results highlight the high level of weed control required throughout the cropping season in high-yielding cotton to ensure crop losses do not exceed the cost of weed control.

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Smooth Amaranth Interference with Watermelon and Muskmelon Production

HortScience ◽

10.21273/hortsci.32.4.630 ◽

1997 ◽

Vol 32 (4) ◽

pp. 630-632 ◽

Cited By ~ 13

Author(s):

Ernest R. Terry ◽

William M. Stall ◽

Donn G. Shilling ◽

Thomas A. Bewick ◽

Steven R. Kostewicz

Keyword(s):

Cucumis Melo ◽

Regression Models ◽

Critical Period ◽

Yield Loss ◽

Total Yield ◽

Critical Periods ◽

Exponential Regression ◽

Maximum Period ◽

Best Fit ◽

Fruit Mass

Studies were conducted to determine the critical period of smooth amaranth interference in watermelon (Citrullus lunatus L.) and muskmelon (Cucumis melo L. var. reticulatus). Best-fit linear or exponential regression models were used to predict the maximum period of competition and the minimum weed-free period for 10% yield loss. The maximum period of competition and minimum weed-free period was 0.50 and 2.97 weeks after watermelon emergence, respectively, and 1.0 and 3.9 weeks after muskmelon emergence, respectively. The critical periods of smooth amaranth interference for the crops were between those intervals. In both crops, late emerging smooth amaranth had little effect on total yield. Smooth amaranth introduced at crop emergence reduced total yield. The effect of competition on yield components, i.e., fruit number per hectare and fruit mass, varied by crop. Muskmelon fruit count was more sensitive to smooth amaranth competition than was watermelon fruit count. Conversely, mass per fruit of muskmelon was less sensitive to this competition than was mass per fruit of watermelon.

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The Critical Period for Weed Control in Corn in Turkey

Weed Technology ◽

10.1614/wt-05-102.1 ◽

2006 ◽

Vol 20 (4) ◽

pp. 867-872 ◽

Cited By ~ 11

Author(s):

Dogan Isik ◽

Husrev Mennan ◽

Bekir Bukun ◽

Ahmet Oz ◽

Mathieu Ngouajio

Keyword(s):

Weed Control ◽

Critical Period ◽

Yield Loss ◽

Relative Yield ◽

Field Studies ◽

The Black Sea ◽

Yield Data ◽

Black Sea Region ◽

Weed Interference ◽

Loss Level

Field studies were conducted in 2001 and 2002 in the Black Sea Region of northern Turkey to determine the critical period for weed control (CPWC) in corn and the effects of weed interference on corn height. Treatments of increasing duration of weed interference and weed-free period were imposed at weekly intervals from 0 to 12 wk after crop emergence (WAE). The CPWC was determined with the use of 2.5, 5, and 10% acceptable yield loss levels by fitting logistic and Gompertz equations to relative yield data. With 5% yield loss level, the CPWC was 5 wk, starting at 0.2 WAE and ending at 5.2 WAE, which corresponded to the one- to five-leaf stage of corn. The CPWC increased to 8.9 wk, starting at 0 WAE and ending at 8.9 WAE, at the 2.5% yield loss level. At 10% yield loss level, the CPWC decreased to 1.7 wk, starting at 2.1 WAE and ending at 3.8 WAE.

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Penentuan Tempoh Kritikal Untuk Mengawal Rumpai dalam Kawasan Penanaman Padi Wangi MRQ 76, Q 88 dan Q 89

Jurnal Teknologi ◽

10.11113/jt.v70.3529 ◽

2014 ◽

Vol 70 (6) ◽

Author(s):

Chong Tet Vun ◽

Azimah Abd Kadir ◽

Azmi Man ◽

Chew See Eng ◽

Baharudin Abas ◽

...

Keyword(s):

Weed Control ◽

Critical Period ◽

Yield Loss ◽

Slow Growth ◽

The Other ◽

Fragrant Rice ◽

Other Hand ◽

Hot Climate ◽

Competition Ability ◽

Loss Level

A study on critical period (CP) for weed control in fragrant rice MRQ 76, Q 88 and Q 89 was conducted in main season 2012/2013 and off season 2013 at MARDI Seberang Perai. The results showed that the CPs (based on 5% acceptable yield loss level (AYL)) for weed control of MRQ 76, Q 88 and Q 89 planted in main season were from 5 to 64, 13 to 68 and 8 to 66 DAS (Days after sowing), respectively. On the other hand, CPs of MRQ 76, Q 88 and Q 89 planted in off season were from 6 to 73, 9 to 81 and 3 to 83 DAS, respectively. If based on 10% AYL, CPs of MRQ76, Q 88 and Q 89 planted in main season were from 19 to 38, 28 to 41 and 14 to 53 DAS, respectively. CPs (based on 10% AYL) of MRQ76, Q 88 and Q 89 planted in off season were from 15 to 55, 19 to 68 and 10 to 66 DAS, respectively. The study clearly demonstrated that CPs of off season were longer than CPs of main season. The dry and hot climate in off season probably caused the slow growth of fragrant rice and eventually affected the competition ability of rice against the weeds.

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Radiosensitivitas dan Heritabilitas Ketahanan terhadap Penyakit Antraknosa pada Tiga Populasi Cabai yang Diinduksi Iradiasi Sinar Gamma

Jurnal Agronomi Indonesia (Indonesian Journal of Agronomy) ◽

10.24831/jai.v43i3.11245 ◽

2016 ◽

Vol 43 (3) ◽

pp. 201

Author(s):

Nura , ◽

Muhamad Syukur ◽

Nurul Khumaida ◽

Widodo ,

Keyword(s):

Gamma Rays ◽

Yield Loss ◽

Gamma Ray ◽

Control Method ◽

Resistant Genotype ◽

Anthracnose Disease ◽

Medium Level ◽

New Varieties ◽

Gamma Ray Irradiation ◽

High Level

ABSTRACTCommercial varieties of chili is still susceptible to anthracnose disease. Anthracnose is one of diseases which caused yield loss about 10-80% in rainy season and 2-35% in dry season. One of the disease control method is to develop new varieties resistant to anthracnose through gamma-ray irradiation. This research was aimed to determine radiosensitivity level and heritability of chili which generated by mutation inductions of three genotypes: IPB C2, IPB C10, and IPB C15. Seed of the three genotypes were irradiated by gamma rays at dosages of 100, 200, 300, 400, 500, 600, 700, 800, 900 and 1,000 Gy. The LD50 in IPB C2, IPB C10, and IPB C15 were 317.9, 591.4, and 538.8 Gy, respectively. The character of IPB C2 mutants ranged between very susceptible to resistant against anthracnose disease, IPB C10 tended to very susceptible to highly resistant, and genotype IPB C15 tended to susceptible to highly resistant. Genotype IPB C2 had high level in heritability for disease resistance character, while medium level in heritability value was obtained on genotype IPB C10 and IPB C15.Keywords: genotype, LD50, mutant, mutation, seed

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Critical Period of Interference between American Black Nightshade and Triploid Watermelon

Weed Technology ◽

10.1614/wt-d-10-00014.1 ◽

2010 ◽

Vol 24 (3) ◽

pp. 397-400 ◽

Cited By ~ 6

Author(s):

Joshua I. Adkins ◽

William M. Stall ◽

Bielinski M. Santos ◽

Stephen M. Olson ◽

Jason A. Ferrell

Keyword(s):

Critical Period ◽

Yield Loss ◽

Field Trials ◽

Black Nightshade ◽

Maximum Period ◽

American Black ◽

Triploid Watermelon

Field trials were conducted in the spring of 2007 and 2008 to investigate the critical period of interference between American black nightshade and triploid watermelon. To determine the critical period, the maximum period of competition and minimum weed-free period were examined. American black nightshade (2 plants m−2) was established into watermelon plots at watermelon transplanting and removed at 0, 1, 2, 3, 4, and 5 wk after transplanting to determine the maximum period of competition. American black nightshade (2 plants m−2) was established into watermelon plots at 0, 1, 2, 3, 4, and 5 wk after transplanting and remained until watermelon harvest to determine the minimum weed-free period. To avoid yield loss from exceeding 10% of a crop grown weed-free, the maximum period of competition and minimum weed-free period were found to be 3.9 and 3.6 weeks after transplanting, respectively. Therefore, if American black nightshade is controlled at any time during the critical period of 3.6 to 3.9 wk after transplanting, yield loss should not exceed 10% of a crop grown weed-free.

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Critical Period of Weed Control in Aerobic Rice

The Scientific World JOURNAL ◽

10.1100/2012/603043 ◽

2012 ◽

Vol 2012 ◽

pp. 1-10 ◽

Cited By ~ 6

Author(s):

M. P. Anwar ◽

A. S. Juraimi ◽

B. Samedani ◽

A. Puteh ◽

A. Man

Keyword(s):

Weed Control ◽

Weed Management ◽

Critical Period ◽

Yield Loss ◽

Field Trials ◽

Integrated Weed Management ◽

Aerobic Rice ◽

View Point ◽

Weed Interference ◽

Economic View

Critical period of weed control is the foundation of integrated weed management and, hence, can be considered the first step to design weed control strategy. To determine critical period of weed control of aerobic rice, field trials were conducted during 2010/2011 at Universiti Putra Malaysia. A quantitative series of treatments comprising two components, (a) increasing duration of weed interference and (b) increasing length of weed-free period, were imposed. Critical period was determined through Logistic and Gompertz equations. Critical period varied between seasons; in main season, it started earlier and lasted longer, as compared to off-season. The onset of the critical period was found relatively stable between seasons, while the end was more variable. Critical period was determined as 7–49 days after seeding in off-season and 7–53 days in main season to achieve 95% of weed-free yield, and 23–40 days in off-season and 21–43 days in main season to achieve 90% of weed-free yield. Since 5% yield loss level is not practical from economic view point, a 10% yield loss may be considered excellent from economic view point. Therefore, aerobic rice should be kept weed-free during 21–43 days for better yield and higher economic return.

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The Critical Period of Weed Control in Faba Bean and Chickpea in Mediterranean Areas

Weed Science ◽

10.1614/ws-d-12-00137.1 ◽

2013 ◽

Vol 61 (3) ◽

pp. 452-459 ◽

Cited By ~ 13

Author(s):

Alfonso S. Frenda ◽

Paolo Ruisi ◽

Sergio Saia ◽

Benedetto Frangipane ◽

Giuseppe Di Miceli ◽

...

Keyword(s):

Weed Control ◽

Faba Bean ◽

Critical Period ◽

Yield Loss ◽

Grain Legume ◽

Yield Reduction ◽

Mediterranean Areas ◽

Full Flowering ◽

Legume Crops ◽

Loss Level

Weeds are often the major biological constraint to growing legume crops successfully, and an understanding of the critical period of weed control (CPWC) is important for developing environmentally sustainable weed management practices to prevent unacceptable yield loss. Therefore, we carried out two field experiments to identify the CPWC for two grain legume crops traditionally grown in Mediterranean areas: chickpea and faba bean. The experiments were conducted at two sites both located in the Sicilian inland (Italy). In chickpea, when weeds were left to compete with the crop for the whole cycle, the grain yield reduction was on average about 85% of the weed-free yield, whereas in faba bean the reduction was less severe (on average about 60% of the weed-free yield). The onset of the CPWC at a 5% yield loss level varied by species, occurring later in faba bean than in chickpea (on average, 261 and 428 growing degree days after emergence for chickpea and faba bean, respectively). In both species, the end of the CPWC occurred at the early full-flowering stage when the canopy of each crop enclosed the interrow space. On the whole, the CPWC at a 5% yield loss level ranged from 50 to 69 d in chickpea and from 28 to 33 d in faba bean. The results highlight the fact that faba bean has a higher competitive ability against weeds than chickpea. This could be attributable both to more vigorous early growth and to the plant's greater height, both factors related to a greater shading ability and, consequently, to a better ability to suppress weeds.

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Pre-harvest field application of enhanced freshness formulation reduces yield loss in orange

Chemical and Biological Technologies in Agriculture ◽

10.1186/s40538-020-00191-7 ◽

2020 ◽

Vol 7 (1) ◽

Author(s):

Jaspa Samwel ◽

Theodosy Msogoya ◽

Abdul Kudra ◽

Hosea Dunstan Mtui ◽

Anna Baltazari ◽

...

Keyword(s):

Yield Loss ◽

Sweet Orange ◽

New Technology ◽

Significant Negative Correlation ◽

Field Application ◽

Yield Losses ◽

Factorial Experiments ◽

Marketable Yield ◽

Pest Damage ◽

Marketable Fruit

Abstract Background Orange (Citrus sinensis L.) production in Tanzania is constrained by several pre-harvest factors that include pests. Hexanal, sprayed as Enhanced Freshness Formulation (EFF) is a relatively new technology that has been reported to reduce pre-harvest loss in fruits. However, the effects of hexanal on pre-harvest yield loss of orange are not known. We studied the effects of hexanal as EFF on yield losses of three sweet orange cultivars namely, Early Valencia, Jaffa, and Late Valencia. Factorial experiments tested the effects of EFF concentration, variety, and time of EFF application on number of dropped fruit, percentage of non-marketable fruit and incidence of pest damage. Results Results showed significant negative correlation (p < 0.001) between EFF and the percentage of dropped fruit, non-marketable yield, and incidence of pest damage. An increase in hexanal concentration by 1%, is expected to reduce number of dropped fruit by 50, percentage of non-marketable by 35.6, and incidences of pest damage by 36.5% keeping other factors constant. Results also show significant association (p < 0.001) between time of hexanal application and non-marketable yield. Percentage of dropped fruit is expected to increase by 1 for each day away from harvest, keeping other factors constant. Conclusion Pre-harvest application of hexanal as EFF can significantly reduce number of dropped fruits, percentage of non-marketable fruit and incidence of pest damage.

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