scholarly journals Density and Time of Emergence of Yellow Nutsedge Affect Squash Yield

HortScience ◽  
2004 ◽  
Vol 39 (4) ◽  
pp. 845D-846
Author(s):  
J. Pablo Morales-Payan* ◽  
William M. Stall
Keyword(s):  
Crop Yield ◽  
Cucurbita Pepo ◽  
Yield Loss ◽  
Cyperus Esculentus ◽  
Yield Losses ◽  
Crop Season ◽  
Yellow Nutsedge ◽  
Live Oak ◽  
Significant Yield ◽  
Direct Seeded

A field experiment was conducted in Live Oak, Fla., to determine the effect of yellow nutsedge (Cyperus esculentus L.) (YN) density and time of emergence on the yield of direct-seeded squash (Cucurbita pepo L.). YN densities (0, 20, 40, 60, and 100 plants/m2) were established from tubers planted at different times onto polyethylene-mulched beds, so that YN would emerge the same day as the crop or 5, 15, or 25 days later than the crop (DLTC). YN was not controlled after its emergence. The extent of squash yield loss was affected by YN density and time of emergence. When YN emerged the same day as the crop, the yield of squash was reduced by ≈7% (20 YN/m2) to 20% (100 YN/m2). When YN emerged 15 DLTC, crop yield loss was ≈13% at the density of 100 YN/m2>. Regardless of density, YN emerging 25 DLTC did not significantly reduce crop yield as compared to weed-free squash. Thus, in soils with high YN densities (≈100 viable tubers/m2) herbicides and/or other means of YN suppression in squash should be effective for at least 25 days after crop emergence to prevent significant yield loss. If squash yield losses <5% were acceptable, YN control may not be necessary when densities <20 YN/m2 emerge at any time during the squash season or when <100 YN/m2 emerge >25 DLTC. However, YN emerging during the first 15 days of the squash season may produce tubers, which could increase the YN population at the beginning of the following crop season.

Round-leaved Mallow (Malva pusilla) Interference in Spring Wheat (Triticum aestivum) and Lentil (Lens culinaris) in Saskatchewan

Weed Science ◽  
1995 ◽  
Vol 43 (3) ◽  
pp. 381-388 ◽  
Author(s):  
Roberte M. D. Makowski
Keyword(s):  
Crop Yield ◽  
Spring Wheat ◽  
Lens Culinaris ◽  
Yield Loss ◽  
Yield Losses ◽  
Variable Model ◽  
Early Season ◽  
Crop Density ◽  
Density And Biomass ◽  
Tiller Density

The competitive ability of annual round-leaved mallow was determined in spring wheat and lentil at Indian Head and Regina, Saskatchewan, in 1985 and 1986 using paired quadrats. Significant biomass and seed yield loss occurred in three of four tests in lentil and two of three tests in spring wheat. Differences in numbers of wheat tillers produced between weedy and weed-free plots were found in three of four tests. A two-variable model comprised of early season crop density loss and round-leaved mallow biomass best accounted for the majority of variation in crop yield loss for both lentil and wheat, and tiller density loss in wheat. In 1985 at Indian Head, where no yield loss occurred for either wheat or lentil, round-leaved mallow had been seeded immediately before the crop. Greater yield losses occurred at Regina, in the presence of an older, well-established infestation. In the years and locations with the greatest crop yield losses, round-leaved mallow emerged before the crop causing poor crop emergence. At Regina in 1986, crop yield losses were more than 60% in wheat and 90 to 100% in lentil because of large differences in crop density between weed-free and weedy subplots. Round-leaved mallow exhibited great variability in growth, producing more biomass per plant, more capsules per plant, and more capsules per gram of biomass in the less competitive crop, lentil, than in wheat. Density and biomass of round-leaved mallow were not correlated; with a density of 200 plants m−2, round-leaved mallow biomass in wheat ranged from 100 to 500 g m−2; while in lentil, from 200 to as high as 1000 g m−2, approximately double the range found in wheat. The type of round-leaved mallow infestation (newly seeded or well-established) and environmental conditions (mainly early season precipitation) account for differences between sites and between years.

Estimating yield losses in wheat resulting from infestation by doublegee (Emex australis)

1974 ◽  
Vol 14 (70) ◽  
pp. 656 ◽  
Author(s):  
DJ Gilbey
Keyword(s):  
Crop Yield ◽  
Field Trial ◽  
Yield Loss ◽  
Wheat Yield ◽  
Yield Reduction ◽  
Yield Losses ◽  
Seedling Mortality ◽  
Emex Australis ◽  
Percentage Yield

The effect of doublegee (Emex australis) density on wheat yield was studied in a field trial. Percentage yield reduction (y) was related to doublegee plants m-2 at 1 week (x1) and 8 weeks (x2) after seeding thus: y = 10.3 + 0.24 x1 r = 0.78*** y = 5.6 + 0.44 x2 r = 0.86*** showing that estimates of doublegee density could be used for forecasting crop yield losses before it is too late to spray. No further yield loss occurred when x1 was greater than 120 plants metre-2. Doublegee seedling mortality that occurred during the seven weeks between plant counts was strongly related to the initial counts (x1) thus: r = 0.88***.

Ethametsulfuron Interactions with Grass Herbicides on Canola (Brassica napus, B. rapa)

1995 ◽  
Vol 9 (1) ◽  
pp. 91-98 ◽  
Author(s):  
K. Neil Harker ◽  
Robert E. Blackshaw ◽  
Ken J. Kirkland
Keyword(s):  
Brassica Napus ◽  
Brassica Rapa ◽  
Field Experiments ◽  
Yield Loss ◽  
Growth And Yield ◽  
Yield Response ◽  
Sulfonylurea Herbicides ◽  
Yield Losses ◽  
Significant Yield ◽  
Injury Potential

Field experiments were conducted from 1986 to 1988 at Lacombe and Lethbridge, Alberta and Scott, Saskatchewan to determine growth and yield response of canola to mixtures of ethametsulfuron with specific grass herbicides. Ethametsulfuron did not usually cause canola injury when mixed with sethoxydim. However, ethametsulfuron mixtures with the following grass herbicides listed in decreasing order of injury potential, often caused canola injury and yield loss: haloxyfop > fluazifop > fluazifop-P > quizalofop > quizalofop-P. Canola yield losses were severe in some experiments, ranging from 59% with quizalofop mixtures to 97% with haloxyfop mixtures; in other experiments, the same mixtures did not cause significant yield losses. ‘Tobin,’ aBrassica rapacultivar, tended to be more susceptible to injury than theB. napuscultivars ‘Pivot’ and ‘Westar.’ Canola injury symptoms were consistent with those expected from sulfonylurea herbicides. Therefore, we suggest that specific grass herbicides differentially impair the ability of canola to metabolize ethametsulfuron to inactive forms.

Lettuce big-vein disease: sources, patterns of spread, and losses

2004 ◽  
Vol 55 (2) ◽  
pp. 125 ◽  
Author(s):  
L. J. Latham ◽  
R. A. C. Jones ◽  
S. J. McKirdy
Keyword(s):  
Weight Loss ◽  
Yield Loss ◽  
Yield Losses ◽  
Fresh Weight ◽  
Straight Line ◽  
Sigmoid Curve ◽  
History Of ◽  
Significant Yield ◽  
Vein Disease ◽  
Leaf Symptoms

Most batches of lettuce seedlings taken over an 18-month period from a vegetable nursery were infested with lettuce big-vein disease (LBVD) with an up to 31% incidence. Using lettuce seedlings in bait tests, contamination was detected at the nursery in potting mix composted for different periods and in dirt from under the benches, and at the bark supplier's site in this ingredient of the potting mix and waste 'bark' from the ground. In a field experiment in which lettuce seedlings from the infested nursery were inoculated with infested roots or left uninoculated before transplanting into subplots on land with no history of lettuce planting, disease progress followed a sigmoid curve with the former but an almost straight line with the latter. However, significant clustering of symptomatic plants was found only in the subplot with the uninoculated plants. Leaf symptoms of LBVD were more severe in lettuces infested later, whereas symptoms in those infested earlier were obvious initially but then became milder. The disease impaired formation of hearts: the proportion of symptomatic plants that lacked hearts was 24–36% when leaf symptoms first appeared 5–7 weeks after transplanting, but 14–16% after 8–9 weeks. When leaf symptoms first appeared at 5–6 weeks, there was a fresh weight loss of 14–15% for heads (all plants) and 39% for hearts (excluding plants without hearts). When leaf symptoms first appeared 7 weeks after transplanting, there was no significant yield loss for heads and only a 14% loss for hearts. At 8–9 weeks, there were no significant yield losses for heads or hearts.

Comparison of different methods used in calculating the effect of stripe rust on wheat grain yields

2007 ◽  
Vol 55 (1) ◽  
pp. 89-98
Author(s):  
N. Bolat ◽  
F. Altay
Keyword(s):  
Stripe Rust ◽  
Yield Loss ◽  
Agricultural Research ◽  
Yellow Rust ◽  
Yield Reduction ◽  
Yield Losses ◽  
Grain Yields ◽  
Unit Increase ◽  
Significant Yield ◽  
Disease Free

One of the most important diseases of wheat in Turkey is yellow rust. The severe epidemic in the 1997–1998 growing season, which caused significant yield reductions, and the absence of infection at the Hamidiye Substation of the Anatolian Agricultural Research Institute made it possible to calculate the yield losses due to stripe rust. This calculation was based on yield differences between genotypes at infected and disease-free locations using various methods.Using the method suggested by Campbell et al. (1975) the calculated yield loss due to stripe rust varied among genotypes and locations with an overall range of 12.7 to 87.0%.By the second method, entries were divided into five groups according to their Average Coefficients of Infection (ACI) and the yield losses in each group were calculated. Yield reductions when ACI was over 70 reached up to 57.5 % in Regional Yield Trials.In the third method, regression analysis was applied to estimate the effect of ACI on grain yields. A highly significant linear relationship was found between the ACI values of the entries and their grain yields, with an estimate of 21.4 kg/ha yield reduction per unit increase in ACI.

scholarly journals Perspectives on Potential Soybean Yield Losses from Weeds in North America

2017 ◽  
Vol 31 (1) ◽  
pp. 148-154 ◽  
Author(s):  
Nader Soltani ◽  
J. Anita Dille ◽  
Ian C. Burke ◽  
Wesley J. Everman ◽  
Mark J. VanGessel ◽  
...  
Keyword(s):  
North America ◽  
Weed Control ◽  
Crop Yield ◽  
Yield Loss ◽  
Census Data ◽  
Commodity Prices ◽  
Yield Losses ◽  
Soybean Yield ◽  
Weed Interference ◽  
The Us

Weeds are one of the most significant, and controllable, threats to crop production in North America. Monetary losses because of reduced soybean yield and decreased quality because of weed interference, as well as costs of controlling weeds, have a significant economic impact on net returns to producers. Previous Weed Science Society of America (WSSA) Weed Loss Committee reports, as chaired by Chandler (1984) and Bridges (1992), provided snapshots of the comparative crop yield losses because of weeds across geographic regions and crops within these regions after the implementation of weed control tactics. This manuscript is a second report from the current WSSA Weed Loss Committee on crop yield losses because of weeds, specifically in soybean. Yield loss estimates were determined from comparative observations of soybean yields between the weedy control and plots with greater than 95% weed control in studies conducted from 2007 to 2013. Researchers from each US state and Canadian province provided at least three and up to ten individual comparisons for each year, which were then averaged within a year, and then averaged over the seven years. These percent yield loss values were used to determine total soybean yield loss in t ha−1and bu acre−1based on average soybean yields for each state or province as well as current commodity prices for a given year as summarized by USDA-NASS (2014) and Statistics Canada (2015). Averaged across 2007 to 2013, weed interference in soybean caused a 52.1% yield loss. Based on 2012 census data in the US and Canada soybean was grown on 30,798,512 and 1,679,203 hectares with production of 80 million and 5 million tonnes, respectively. Using an average soybean price across 2007 to 2013 of US $389.81 t−1($10.61 bu−1), farm gate value would be reduced by US $16.2 billion in the US and $1.0 billion in Canada annually if no weed management tactics were employed.

scholarly journals Estimating and Analyzing the Spatiotemporal Characteristics of Crop Yield Loss in Response to Drought in the Koshi River Basin, Nepal

2021 ◽  
Author(s):  
Nirmal Mani Dahal ◽  
Donghong XIONG ◽  
Nilhari Neupane ◽  
Su Zhang ◽  
Yong Yuan ◽  
...  
Keyword(s):  
River Basin ◽  
Crop Yield ◽  
Agricultural Sector ◽  
Yield Loss ◽  
Interpolation Method ◽  
Wheat Yield ◽  
High Yield ◽  
Yield Losses ◽  
Koshi River Basin ◽  
Crop Yield Loss

Abstract The quantitative assessment of crop yield loss in response to drought is crucial in the development of the agricultural sector to improve the productivity. This study estimated and analyzed the spatiotemporal patterns of crop yield loss in response to drought using the Lagrange interpolation method, wavelet analysis, and sequential Mann-Kendall test in the mountain, hill, and Terai (low-land) regions of Nepal's Koshi River Basin from 1987 to 2016. According to the findings, average crop yield loss was common after 2000, with the Terai, hill, and mountain experiencing the greatest loss in maize, rice, and wheat, respectively. Average annual rice and wheat yield losses rate were highest in the mountains, while maize yield losses were highest in the Terai. There was an abrupt change in wheat yield loss in the mountain, with significant increasing trend. In the hill, significant increment in maize and wheat yield loss, and decrement in rice yield loss, were observed. Between 1987 and 2016, periodic variations of maize, rice, and wheat revealed significant yield loss after 2000. The characteristics of the first and second key periods for crop yield loss demonstrated variation period which predicted that crop yield loss would either enter high yield loss or low yield loss period shortly after 2016. The findings of the study provide a detailed intervention in assessing crop yield loss at the river basin level and can provide an important pathway for developing a crop yield loss mitigation plan in the agricultural sector to achieve self-reliance and sustainable agricultural productivity.

Systems of Weed Control for Soybeans in the Coastal Plain

Weed Science ◽  
1972 ◽  
Vol 20 (6) ◽  
pp. 592-598 ◽  
Author(s):  
Ellis W. Hauser ◽  
M. D. Jellum ◽  
Clyde C. Dowler ◽  
W. H. Marchant
Keyword(s):  
Control Systems ◽  
Weed Control ◽  
Coastal Plain ◽  
Sandy Loam ◽  
Cyperus Esculentus ◽  
Crop Tolerance ◽  
Yellow Nutsedge ◽  
Significant Yield ◽  
The Common

Systems of weed control composed of (a) intensive cultivation only, (b) herbicides only, or (c) herbicides plus cultivation controlled weeds in soybeans(Glycine max(L.) Merr.) with acceptable crop tolerance. On Ocilla sandy loam, systems withS-propyl dipropylthiocarbamate (vernolate) as a preplanting treatment and 3[p-(p-chlorophenoxy)phenyl]-1,1-dimethylurea (chloroxuron) as an early postemergence treatment, followed by either sweep cultivations or directed postemergence applications of other herbicides, controlled yellow nutsedge(Cyperus esculentusL.) satisfactorily and controlled 99 to 100% of the common cocklebur(Xanthium pensylvanicumWallr.) and Florida beggarweed [Desmodium tortuosum(Sw.) DC.]. As directed postemergence treatment, 2-seobutyl-4,6-dinitrophenol (dinoseb) controlled common cocklebur and Florida beggarweed about as well as 3-(3,4-dichlorophenyl)-1-methoxy-1-methylurea (linuron). However, for the broad spectrum of weeds encountered on the Greenville soil, linuron was superior to dinoseb, especially on Texas panicum(Panicum texanumBuckl.). Systems containing only cultivation controlled 84 to 98% of the common cocklebur and 78 to 99% of the Florida beggarweed. On Greenville sandy clay loam, several systems of weed control significantly reduced the stand but not the yield of soybeans. Vernolate reduced stands when used as a preplanting incorporated treatment but not when injected at planting. No significant yield differences among the weed control systems were apparent in the 3-year averages. Costs of weed control ranged from $20 to $30/ha for cultivation only, from $55 to $73/ha for herbicides only, and from $45 to $53/ha for herbicides combined with cultivation. Uncontrolled weeds, primarily common cocklebur and Florida beggarweed, in the weedy check plots reduced the average yield of soybeans 74% on the Ocilla soil during the 3-year period. The different systems of weed control did not affect commercial quality of soybean oil.

Cyperus esculentusinterference inCucumis sativus

Weed Science ◽  
1999 ◽  
Vol 47 (3) ◽  
pp. 327-331 ◽  
Author(s):  
W. Carroll Johnson ◽  
Benjamin G. Mullinix
Keyword(s):  
Cucumis Sativus ◽  
Plant Biomass ◽  
Total Yield ◽  
Response Prediction ◽  
Field Studies ◽  
Cyperus Esculentus ◽  
Yellow Nutsedge ◽  
Direct Seeded ◽  
Natural Infestation ◽  
Density And Biomass

Field studies were conducted near Tifton, GA, from 1995 to 1997 to measureCyperus esculentus(yellow nutsedge) interference with ‘Fancipack’Cucumis sativus(cucumber) using a response prediction experiment with a natural infestation ofC. esculentus. Cucumis sativuswas direct-seeded each year. Plots (1.8 by 1.8 m) were established immediately after crop emergence.Cyperus esculentusplants were counted 2 wk after crop emergence in each plot, at which time four weed-free plots were randomly established.C. esculentusdensities ranged from 0 to 955 plants m−2. Total yield, plant biomass, andC. sativusstand were regressed againstC. esculentusdensity and biomass. Regression analysis showed a 5% reduction inC. sativusyield with aC esculentusinfestation of approximately 15 plants m−2. A uniformC. sativusstand maximized its competitive ability and minimized interference fromC. esculentus. Cyperus esculentuswas more competitive and reducedC. sativusyields whenC. sativusstands were low and nonuniform.

Cost of crop losses in processing tomato and cabbage in southwestern Ontario due to insects, weeds and/or diseases

2004 ◽  
Vol 84 (3) ◽  
pp. 915-921 ◽  
Author(s):  
J. H. Tolman ◽  
D. G. R. McLeod ◽  
C. R. Harris
Keyword(s):  
Yield Loss ◽  
Management Program ◽  
Yield Losses ◽  
Crop Losses ◽  
Control Programs ◽  
Processing Tomato ◽  
Key Words Tomato ◽  
Significant Yield ◽  
Control Disease ◽  
One Year

The relative importance of insects, weeds and diseases to yield losses in processing tomato (Lycopersicon esculentum Mill.) and cabbage (Brassica oleracea L. var. capitata L.) was measured by comparing yields in the presence and absence of appropriate control programs. In the absence of any pest control, average crop losses exceeded 80% in both crops. Average yield losses due to weeds alone approached 80% in processing tomato and 60% in cabbage. Insects alone did not significantly reduce yield of processing tomato in either year. In the absence of insect control, significant yield loss in cabbage approached 50% in only one year. When diseases were not controlled, yield of processing tomato declined significantly by nearly 30% in one trial. Failure to control disease had no significant impact on cabbage yield in this study. Monetary losses and costs of each management program were calculated. Key words: Tomato, cabbage, yield loss, insects, weeds, diseases

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