Volunteer Potato Density Influences Critical Time of Weed Removal in Bulb Onion

2007 ◽  
Vol 21 (1) ◽  
pp. 136-140 ◽  
Author(s):  
Martin M. Williams ◽  
Corey V. Ransom ◽  
W. Mack Thompson
Keyword(s):  
Yield Loss ◽  
Critical Time ◽  
Field Trials ◽  
Growing Degree Days ◽  
Crop Loss ◽  
Yield Losses ◽  
Degree Days ◽  
Potato Plants ◽  
Volunteer Potato ◽  
Weed Removal

Volunteer potato is highly competitive with onion and few control tactics are effective for removing this weed from an onion crop. Both volunteer potato density and duration of interference reduce onion yield, but the interaction of these factors is unknown. Field trials were conducted in 2003 in Idaho, Oregon, and Washington to determine the influence of volunteer potato density on the critical time of weed removal (CTWR) in onion. Yield losses of 2.5, 5.0, and 10% were estimated to occur at 534, 654, and 830 growing degree days (GDD) after onion emergence, respectively, with a volunteer potato density of 0.5 plants/m2. At 2.0 volunteer potato plants/m2, yield losses of 2.5, 5.0, and 10% were estimated to occur at 388, 481, and 598 GDD after onion emergence, respectively. Volunteer potato at 2.0 plants/m2had to be removed at least one onion leaf stage sooner, compared to a weed density of 0.5 plants/m2, to avoid yield loss. Yield loss due to volunteer potato density or duration of interference was greatest among jumbo, colossal, and supercolossal market grades (P ≤ 0.1). Lowering potato tuber density in crops preceding onion will extend the critical time for weed removal and reduce the risk of crop loss.

Preemergence herbicide delays the critical time of weed removal in popcorn

2019 ◽  
Vol 33 (6) ◽  
pp. 785-793 ◽  
Author(s):  
Ethann R. Barnes ◽  
Stevan Z. Knezevic ◽  
Nevin C. Lawrence ◽  
Suat Irmak ◽  
Oscar Rodriguez ◽  
...  
Keyword(s):  
Growth Stage ◽  
Yield Loss ◽  
Critical Time ◽  
Yield Reduction ◽  
Growth Stages ◽  
Growing Degree Days ◽  
Degree Days ◽  
South Central ◽  
Main Plot ◽  
Weed Removal

AbstractUnderstanding the critical time of weed removal (CTWR) is necessary for designing effective weed management programs in popcorn production that do not result in yield reduction. The objective of this study was to determine the CTWR in popcorn with and without a premix of atrazine and S-metolachlor applied PRE. Field experiments were conducted at the University of Nebraska–Lincoln, South Central Agricultural Laboratory near Clay Center, NE in 2017 and 2018. The experiment was laid out in a split-plot design with PRE herbicide as the main plot and weed removal timing as the subplot. Main plots included no herbicide or atrazine/S-metolachlor applied PRE. Subplot treatments included a weed-free control, a non-treated control, and weed removal timing at V3, V6, V9, V15, and R1 popcorn growth stages and then kept weed free throughout the season. A four-parameter log-logistic function was fitted to percentage popcorn yield loss and growing degree days separately to each main plot. The number of growing degree days, when 5% yield loss was achieved, was extracted from the model and compared between main plots. The CTWR was from the V4 to V5 popcorn growth stage in absence of PRE herbicide. With atrazine/S-metolachlor applied PRE, the CTWR was delayed until V10 to V15. It is concluded that, to avoid yield loss, weeds must be controlled before the V4 popcorn growth stage when no PRE herbicide is applied, and PRE herbicide, such as atrazine/S-metolachlor in this study, can delay the CTWR until the V10 growth stage.

YIELD LOSSES IN WHEAT DUE TO WEED COMMUNITIES DOMINATED BY GREEN FOXTAIL [Setaria viridis (L.) BEAUV.]: A MULTISPECIES APPROACH

1989 ◽  
Vol 69 (2) ◽  
pp. 521-529 ◽  
Author(s):  
L. HUME
Keyword(s):  
Yield Loss ◽  
Triticum Aestivum L ◽  
Crop Loss ◽  
Setaria Viridis ◽  
Yield Losses ◽  
Degree Days ◽  
Relative Time ◽  
Weed Communities ◽  
Green Foxtail ◽  
Multispecies Competition

A model was developed to predict wheat (Triticum aestivum L.) loss due to interference by multi-species weed communities dominated by green foxtail [Setaria viridis (L.) Beauv.], 3–4 wk after seeding. Results indicated that green foxtail-dominated weed communities averaging 427 plants m−2 over 4 yr reduced yield by about 7.8%. When plots were kept free of green foxtail, different species became important components of a second model developed to predict the yield loss. The combined effect of precipitation and growing degree days was an important component of both models. It is postulated that these environmental variables reflected the relative time of emergence of the weeds and the crop. Advantages of models based upon multispecies tests over those determined from one-weed one-crop tests are discussed as they relate to crop loss in multispecies situations.Key words: Setaria viridis, green foxtail, crop loss, multispecies competition, weed communities, modeling

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

2019 ◽  
Vol 33 (6) ◽  
pp. 800-807 ◽  
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.

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.

Changing of Vegetative to Reproductive Ratio as a Response to Different Sowing Dates in Sunflower

Helia ◽  
2018 ◽  
Vol 41 (69) ◽  
pp. 253-266
Author(s):  
Ali Asghar Aliloo
Keyword(s):  
Edible Oils ◽  
Sowing Date ◽  
Biodiesel Production ◽  
Growing Degree Days ◽  
Comprehensive Model ◽  
Yield Losses ◽  
Degree Days ◽  
North West ◽  
Long Period ◽  
Sowing Dates

AbstractSunflower is an important source for edible oils and biodiesel production. Its productivity is limited by many agronomical practices one of which is the sowing date. In this study, the effects of different sowing dates from early April to late June on phenology and yield of sunflower cultivars were investigated. The results showed that sunflower has a relatively long period of possible sowing dates, stretching from early April to late June in North West of Iran. However, delayed sowing dates significantly decreased the number of days needed for phenophases. For every day of delay, the model predicted (R2=0.97) a losing rate in achene yield by 22.2 kg h−1 from the first sowing date. For relationships between growing degree days (GDD) and yield, almost the same results were obtained. About 22 kg h−1 reduction (R2=0.79) in yield per day was estimated by GDD index when the average GDDs per day was 14.2. However, helio-thermal units (HTU) did not predict this reduction accurately. A suggested comprehensive model, that used the percent of yield losses and changes in vegetative to reproductive ratio, found a significant and positive relationship between the indices and yield losses. For all indices, an increase in vegetative to reproductive ratio resulted in increased grain yield losses.

Potential impacts of climate change on corn, soybeans and barley yields in Atlantic Canada

2005 ◽  
Vol 85 (2) ◽  
pp. 345-357 ◽  
Author(s):  
A. Bootsma ◽  
S. Gameda ◽  
D. W. McKenney
Keyword(s):  
Climate Change ◽  
Direct Effect ◽  
Crop Production ◽  
Field Trials ◽  
Growing Degree Days ◽  
Degree Days ◽  
Atlantic Region ◽  
Water Deficits ◽  
Heat Units ◽  
Impacts Of Climate Change

In this paper, relationships between agroclimatic indices and average yields of grain corn (Zea mays L.), soybeans (Glycine max L. Merr.) and barley (Hordeum vulgare L.) in field trials conducted in eastern Canada are explored and then used to estimate potential impacts of climate change scenarios on anticipated average yields and total production of these commodities for the Atlantic region for the 2040 to 2069 period. Average yields of grain corn and soybeans were highly correlated (R2 = 0.86 and 0.74, respectively) with average available crop heat units (CHU), with yields increasing by about 0.006 t ha-1 CHU-1 for corn and 0.0013 t ha-1 CHU-1 for soybeans. The explained variance was not improved significantly when water deficit (DEFICIT) was included as an independent variable in regression. Correlations between average yields of barley and effective growing degree-days (EGDD) were low (R2 ≤ 0.26) and negative, i.e., there was a tendency for slightly lower yields at higher EGDD values. Including a second-order polynomial for DEFICIT in the regression increased the R2 to ≥ 0.58, indicating a tendency for lower barley yields in areas with high water deficits and with water surpluses. Based on a range of available heat units projected by multiple General Circulation Model (GCM) experiments, average yields achievable in field trials could increase by about 2.6 to 7.5 t ha-1 (40 to 115%) for corn, and by 0.6 to 1.5 t ha-1 (21 to 50%) for soybeans by 2040 to 2069, not including the direct effect of increased atmospheric CO2 concentrations, advances in plant breeding and crop production practices or changes in impacts of weeds, insects and diseases on yield. Anticipated reductions in barley yields are likely to be more than offset by the direct effect of increased CO2 concentrations. As a result of changes in potential yields, there will likely be significant shifts away from production of barley to high-energy and high-protein crops (corn and soybeans) that are better adapted to the warmer climate. However, barley and other small grain cereals will likely remain as important crops as they are very suited for rotation with potatoes. There is a need to evaluate the potential environmental impacts of these possible shifts in crop production, particularly with respect to soil erosion in the region. Key words: Crop heat units, growing degree-days, water deficits, crop yields, climate change, Atlantic region

Influence of establishment timing on growth and fecundity of two itchgrass (Rottboellia cochinchinensis) biotypes grown in Louisiana

Weed Science ◽  
2020 ◽  
Vol 68 (4) ◽  
pp. 418-425
Author(s):  
Douglas J. Spaunhorst
Keyword(s):  
Yield Loss ◽  
Seedling Emergence ◽  
Common Garden ◽  
Growing Season ◽  
Growing Degree Days ◽  
Initial Growth ◽  
Common Garden Experiment ◽  
Degree Days ◽  
Humid Climate ◽  
Rottboellia Cochinchinensis

AbstractItchgrass [Rottboellia cochinchinensis (Lour.) W.D. Clayton] is among the most troublesome weeds in subtropical climates where sugarcane (Saccharum spp. interspecific hybrids) is cultivated. Two R. cochinchinensis biotypes commonly infest sugarcane in Louisiana. The Louisiana-1 biotype is daylength neutral, but Louisiana-2 flowered when daylength decreased to 13 h. Coupled with biotype diversity, seedling emergence has been reported to occur earlier in the growing season, as sugarcane emerged from winter dormancy. Both R. cochinchinensis biotypes were established in a common garden experiment in Louisiana during periods of sugarcane development and field preparation to simulate discontinuous emergence. Plant height and raceme production were recorded weekly for each biotype and establishment timing; aboveground biomass was harvested in autumn. Louisiana’s subtropical humid climate stimulated rapid plant growth that typically began in May and persisted through September. Without sugarcane competition, maximum R. cochinchinensis heights for Louisiana-1 and Louisiana-2 were 206 and 179 cm and growing degree days to 20-cm height in 2017 ranged from 546 to 832 and 865 to 1,160, respectively. Slower initial growth reported with Louisiana-2 would allow more time for growers to treat escaped plants with POST herbicides. Total raceme production, by autumn, was zero for Louisiana-2 established in June or later, but Louisiana-1 established in June produced up to 202 racemes. The present study demonstrated the importance of managing the Louisiana-2 biotype in March and April to limit seed production, but fields infested with Louisiana-1 were at greater risk for potential crop yield loss, because plants produced high quantities of seed when established over a wide period of time.

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

2020 ◽  
Vol 34 (5) ◽  
pp. 689-698
Author(s):  
Graham W. Charles ◽  
Brian M. Sindel ◽  
Annette L. Cowie ◽  
Oliver G. G. Knox
Keyword(s):  
Weed Control ◽  
Critical Period ◽  
Yield Loss ◽  
Critical Time ◽  
Field Studies ◽  
Cotton Field ◽  
Control Input ◽  
Degree Days ◽  
Weed Density ◽  
The Relationship

AbstractResearch using the critical period for weed control (CPWC) has shown that high-yielding cotton crops are very sensitive to competition from grasses and large broadleaf weeds, but the CPWC has not been defined for smaller broadleaf weeds in Australian cotton. Field studies were conducted over five seasons from 2003 to 2015 to determine the CPWC for smaller broadleaf weeds, using mungbean as a mimic weed. Mungbean was planted at densities of 1, 3, 6, 15, 30, and 60 plants m−2 with or after cotton emergence and added and removed at approximately 0, 150, 300, 450, 600, 750, and 900 degree days of crop growth (GDD). Mungbean competed strongly with cotton, with season-long interference; 60 mungbean plants m−2 resulted in an 84% reduction in cotton yield. A dynamic CPWC function was developed for densities of 1 to 60 mungbean plants m−2 using extended Gompertz and exponential curves including weed density as a covariate. Using a 1% yield-loss threshold, the CPWC defined by these curves extended for the full growing season of the crop at all weed densities. The minimum yield loss from a single weed control input was 35% at the highest weed density of 60 mungbean plants m−2. The relationship for the critical time of weed removal was further improved by substituting weed biomass for weed density in the relationship.

scholarly journals Estimating Yield and Economic Loss from Constriction Canker of Peach

Plant Disease ◽  
2000 ◽  
Vol 84 (9) ◽  
pp. 941-946 ◽  
Author(s):  
Norman Lalancette ◽  
Dean F. Polk
Keyword(s):  
Yield Loss ◽  
Disease Incidence ◽  
Economic Loss ◽  
Control Measures ◽  
Economic Losses ◽  
Crop Loss ◽  
Friedman Test ◽  
Yield Losses ◽  
Yield Level ◽  
Total Crop

Constriction cankers, caused by Phomopsis amygdali, girdle and kill fruiting twigs which results in a direct crop loss. To quantitatively determine this loss from 1996 to 1998, the number of fruit lost per infected shoot was estimated as a function of disease incidence in 21 severely infected orchards in New Jersey. For each cultivar in 1997 and 1998, the distribution of fruit sizes at harvest and prices at shipping were used to calculate total crop value for typical expected yields. Economic loss was then calculated from yield loss and crop value estimates. The overall percent yield loss mean across all sites and cultivars, unadjusted for fruit remaining on infected shoots, was 22.2, 30.7, and 23.7% for 1996, 1997, and 1998, respectively. The frequency of these losses were not normally distributed, and the nonparametric Friedman test indicated that yield loss was significantly different among years. Assuming the remaining fruit on infected shoots were harvested, yield losses for 1997 and 1998 were 28.5 and 21.0%, which translated into average economic losses of $4,009 and 2,803/ha, respectively, for an expected yield level of 14,010 kg/ha. These loss values justify control measures for management of constriction canker in severely infected orchards.

scholarly journals Understanding Yield Loss and Pathogen Biology to Improve Disease Management: Septoria Nodorum Blotch - A Case Study in Wheat

Plant Disease ◽  
2018 ◽  
Vol 102 (4) ◽  
pp. 696-707 ◽  
Author(s):  
Andrea Ficke ◽  
Christina Cowger ◽  
Gary Bergstrom ◽  
Guro Brodal
Keyword(s):  
Disease Management ◽  
Plant Pathogens ◽  
Management Practices ◽  
Yield Loss ◽  
Control Measures ◽  
Crop Loss ◽  
Yield Losses ◽  
Disease Epidemiology ◽  
Economic Thresholds ◽  
Host Pathogen

The estimated potential yield losses caused by plant pathogens is up to 16% globally and most research in plant pathology aims to reduce yield loss in our crops directly or indirectly. Yield losses caused by a certain disease depend not only on disease severity, but also on the weather factors, the pathogen’s aggressiveness, and the ability of the crop to compensate for reduced photosynthetic area. The yield loss-disease relationship in a certain host-pathogen system might therefore change from year to year, making predictions for yield loss very difficult at the regional or even at the farmer’s level. However, estimating yield losses is essential to determine disease management thresholds at which acute control measures such as fungicide applications, or strategic measures such as crop rotation or use of resistant cultivars are economically and environmentally sensible. Legislation in many countries enforces implementation of integrated pest management (IPM), based on economic thresholds at which the costs due to a disease justify the costs for its management. Without a better understanding of the relationship between disease epidemiology and yield loss, we remain insufficiently equipped to design adequate IPM strategies that will be widely adapted in agriculture. Crop loss studies are resource demanding and difficult to interpret for one particular disease, as crops are usually not invaded by only one pest or pathogen at a time. Combining our knowledge on disease epidemiology, crop physiology, yield development, damage mechanisms involved, and the effect of management practices can help us to increase our understanding of the disease-crop loss relationship. The main aim of this paper is to review and analyze the literature on a representative host-pathogen relationship in an important staple food crop to identify knowledge gaps and research areas to better assess yield loss and design management strategies based on economic thresholds.

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