Nitrogen Fertilizer Rate Effects on Weed Competitiveness is Species Dependent

Information on nitrogen fertilizer effects on crop–weed competitive interactions might aid in developing improved weed management programs. A controlled environment study was conducted to examine the effect of three N rates on the competitive ability of four weed species grown with wheat. The four weed species were chosen to represent species that varied in their growth responsiveness to nitrogen (N): Persian darnel (low), Russian thistle (low), redroot pigweed (high), and wild oat (high). Wheat and each weed species were grown in a replacement series design at N rates of 60, 120, and 240 mg N kg−1soil. The competitive ability of the low N-responsive species, Persian darnel and Russian thistle, was not influenced by N rate, supporting our hypothesis that N rate would have little effect on the competitiveness of species responding minimally to N. Conversely, the competitiveness of the high N-responsive species redroot pigweed progressively improved as N rate increased. However, wild oat competitiveness was unaffected by N fertilizer rate. There is some evidence from this study to suggest that fertilizer management strategies that favor crops over weeds deserve greater attention when weed infestations consist of species known to be highly responsive to higher soil N levels. Information gained in this study will be used to advise farmers of the importance of strategic fertilizer management in terms of both weed management and crop yield.

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Redroot Pigweed (Amaranthus retroflexus) and Barnyardgrass (Echinochloa crus-galli) Interference in Potatoes (Solanum tuberosum)

Weed Science ◽

10.1017/s0043174500056642 ◽

1990 ◽

Vol 38 (4-5) ◽

pp. 338-343 ◽

Cited By ~ 33

Author(s):

Mark J. Vangessel ◽

Karen A. Renner

Keyword(s):

Competitive Ability ◽

Tuber Yield ◽

Correlation Coefficients ◽

Field Studies ◽

Amaranthus Retroflexus ◽

Russet Burbank ◽

Tuber Quality ◽

Weed Species ◽

Replacement Series ◽

Redroot Pigweed

In greenhouse replacement series experiments, ‘Atlantic’ and ‘Russet Burbank’ potatoes and barnyardgrass were more competitive than redroot pigweed as measured by relative competitive ability. In additive design field studies, four redroot pigweed or barnyardgrass per meter of row did not reduce Atlantic tuber yield when planted between the row following hilling (6 to 7 weeks after planting). However, as few as one barnyardgrass or redroot pigweed per meter of row reduced marketable tuber yield 19 to 33% when seeded in the row at the time of potato planting. Redroot pigweed reduced tuber yield more than barnyardgrass did in 1 yr of research. The correlation coefficients were similar for both weed density and weed biomass regressed on tuber yield. Aboveground potato biomass was not consistent in predicting total tuber yield. Furthermore, variability in aboveground potato biomass was not due to increasing weed weight or density. Neither specific gravity nor tuber quality was altered by the presence of any density of either weed species.

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Competitiveness of alexandergrass or Bengal dayflower with soybean

Planta Daninha ◽

10.1590/s0100-83582010000300008 ◽

2010 ◽

Vol 28 (3) ◽

pp. 515-522 ◽

Cited By ~ 7

Author(s):

A.C.R. Dias ◽

S.J.P. Carvalho ◽

L.W. Marcolini ◽

M.S.C. Melo ◽

P.J. Christoffoleti

Keyword(s):

Competitive Ability ◽

Dry Mass ◽

Total Density ◽

Weed Species ◽

Replacement Series ◽

Commelina Benghalensis ◽

Randomized Design ◽

Full Flowering ◽

Completely Randomized Design ◽

Soybean Plants

Weeds compete with field crops mainly for water, light and nutrients, and the degree of competition is affected by the weed density and the intrinsic competitive ability of each plant species in coexistence. The objective of this research was to compare the competitiveness of alexandergrass (Brachiaria plantaginea) or Bengal dayflower (Commelina benghalensis) in coexistence with soybean, cv. M-Soy 8045. A factorial experiment (2 x 5) with two weed species and five competition proportions was carried out in a completely randomized design with four replicates. Proportions were based on a replacement series competition design, always maintaining the total density of four plants per 10 L plastic pots, which corresponded to 60 plants m ². The weed-crop proportions were: 0:4; 1:3; 2:2; 3:1; 4:0; that corresponded to the proportion of 100, 75, 50, 25 and 0% of soybean plants and the opposite for weeds, B. plantaginea or C. benghalensis plants. Leaf area, shoot dry mass of the weeds and soybean and number of soybean trifoliate leaves were evaluated when the soybean reached the phenologic stage of full flowering. B. plantaginea was a better competitor than soybean plants. Otherwise, C. benghalensis revealed a similar competitive ability that of the soybean. In both cases, there were evidences that intraspecific competition was more important.

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Phosphorus effects on competitive interactions of smooth pigweed (Amaranthus hybridus) and common purslane (Portulaca oleracea) with lettuce (Lactuca sativa)

Weed Science ◽

10.1017/s0043174500089463 ◽

1998 ◽

Vol 46 (3) ◽

pp. 307-312 ◽

Cited By ~ 17

Author(s):

Bielinski M. Santos ◽

Joan A. Dusky ◽

William M. Stall ◽

Donn G. Shilling ◽

Thomas A. Bewick

Keyword(s):

Competitive Ability ◽

Organic Soils ◽

Weed Species ◽

Population Densities ◽

Replacement Series ◽

Amaranthus Hybridus ◽

Extractable P ◽

Common Purslane ◽

Smooth Pigweed ◽

Water Extractable

Replacement series studies were conducted under controlled conditions to determine the effect of phosphorus (P) rates and population densities on the competitiveness of smooth pigweed and common purslane with lettuce. Densities were 2, 4, and 8 plants per 113 cm2, whereas P rates were 0, 0.4, and 0.8 g PL−1soil. A P-deficient Histosol (0.3 mg water-extractable P L−1soil) was used. High P fertility enhanced the competitive ability of lettuce in smooth pigweed-lettuce mixtures. Smooth pigweed was not responsive to P rates. However, luxurious P consumption by smooth pigweed occurred, reducing the amount of the nutrient available for lettuce absorption. In common purslane-lettuce mixtures, the weed was responsive to P rates, increasing its competitive ability, whereas no increase in lettuce competitive ability was observed. Both weed species were more competitive than lettuce. Competition for P appears to be the main mechanism of common purslane interference on lettuce grown in low-P organic soils. Alternative fertilization strategies (i.e., banded applications) may reduce the effect of smooth pigweed on lettuce.

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Competition between ACCase-Inhibitor Resistant and Susceptible Sterile Wild Oat (Avena sterilis) Biotypes

Weed Science ◽

10.1614/ws-d-12-00065.1 ◽

2013 ◽

Vol 61 (1) ◽

pp. 26-31 ◽

Cited By ~ 14

Author(s):

Ilias S. Travlos

Keyword(s):

Seed Germination ◽

Plant Height ◽

Competitive Ability ◽

Plant Biomass ◽

Wild Oat ◽

Seedling Vigor ◽

Acetyl Coa Carboxylase ◽

Replacement Series ◽

Avena Sterilis ◽

Canopy Area

Studies were conducted to determine the growth, fecundity, and competitive ability of an acetyl-CoA carboxylase (ACCase)–inhibitor resistant (R) sterile wild oat biotype compared with a susceptible (S) biotype. Seed germination studies indicated that there were no differences in seed germination and seedling vigor between R and S biotypes at any temperature regime. R and S biotypes were grown under noncompetitive and competitive arrangement in the greenhouse. Under noncompetitive greenhouse conditions, growth of the R biotype was similar to that of the S biotype on the basis of plant height, canopy area, and plant biomass. Seed production and weight of R and S plants were also at the same levels. Furthermore, relative competitiveness among the R and S sterile wild oat biotypes was investigated by means of replacement series experiments. The R and S biotypes were compared under seven mixture proportions (6 : 0, 5 : 1, 4 : 2, 3 : 3, 2 : 4, 1 : 5, and 0 : 6). No significant differences in competitive ability were observed between R and S biotypes on the basis of plant height, canopy area, or plant biomass. In most cases, relative crowding coefficient (RCC) values at 20, 60, and 100 d after transplanting (DAT) were close to one, indicating equal competitiveness between the R and S biotypes of wild oat used in this competitive study. However, in some cases, the RCC value was 1.31 for plant height, evident of a slight competitive advantage for the R biotype at 100 DAT. In general, ACCase-inhibitor R and S sterile wild oat biotypes were equally competitive, clearly without any growth penalty for R plants in either noncompetitive or competitive conditions.

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Competition of Amaranthus species with dry bean plants

Scientia Agricola ◽

10.1590/s0103-90162008000300003 ◽

2008 ◽

Vol 65 (3) ◽

pp. 239-245 ◽

Cited By ~ 18

Author(s):

Saul Jorge Pinto de Carvalho ◽

Pedro Jacob Christoffoleti

Keyword(s):

Competitive Ability ◽

Total Density ◽

Weed Species ◽

Replacement Series ◽

Dry Bean ◽

Series Design ◽

Bean Plants ◽

Species Proportions ◽

Expanded Cotyledon ◽

Vegetal Species

Weeds compete with field crops mainly for water, light and nutrients, and this competition is among other factors, a function of the occurrence of weed density, and the intrinsic competitive ability of each vegetal species. The objective of this research was to evaluate the competitive ability of five weed species of the Amaranthus L. genus (A. deflexus, A. hybridus, A. retroflexus, A. spinosus and A. viridis) with dry bean plants (Phaseolus vulgaris L. - 'Carioca Precoce' cultivar), using the replacement series design. A fixed total density equivalent to 80 plants m-2 was used in pots of 2.8 L capacity varying the proportions between the species in coexistence. To install the experiment, Amaranthus seedlings were transplanted to the pots at the phenological stage of completely expanded cotyledon leaves, while the crop was seeded. A factorial scheme (5 x 5) was used to carry out the experiment, consisting of five species of Amaranthus (pigweeds) and five species proportions (beans:pigweeds): 4:0, 3:1, 2:2, 1:3 and 0:4. Randomized blocks with four replicates were installed and the experiment was repeated twice. Dry bean plants were more competitive than each one of the five Amaranthus species when the species proportion was equivalent. A. deflexus and A. viridis were the weed species which phenology were less affected by the competition with dry bean; the intraspecific competition was more damaging for dry bean plants, suggesting that the damages caused by the weeds are more related to high density of infestation than to the intrinsic competitive ability of the species.

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Evaluating Seed Shatter of Economically Important Weed Species

Weed Science ◽

10.1614/ws-d-16-00081.1 ◽

2016 ◽

Vol 64 (4) ◽

pp. 673-682 ◽

Cited By ~ 11

Author(s):

Nikki R. Burton ◽

Hugh J. Beckie ◽

Christian J. Willenborg ◽

Steven J. Shirtliffe ◽

Jeff J. Schoenau ◽

...

Keyword(s):

Weed Management ◽

Field Experiments ◽

Management Strategies ◽

Wild Oat ◽

Population Abundance ◽

Weed Seed ◽

Weed Species ◽

Wild Mustard ◽

Green Foxtail ◽

Crop Maturity

The increasing occurrence of herbicide resistance, along with no new herbicide modes of action developed in over 30 yr, have increased the need for nonherbicidal weed management strategies and tactics. Harvest weed seed control (HWSC) practices have been successfully adopted in Australia to manage problematic weeds. For HWSC to be effective, a high proportion of weed seeds must be retained on the plant at crop maturity. This 2-yr (2014, 2015) study evaluated seed shatter of wild oat, green foxtail, wild mustard, and cleavers in both an early (field pea) and late (spring wheat) maturity crop in field experiments at Scott, Saskatchewan. Seed shatter was assessed using shatter trays collected once a week during crop ripening stage, as well as at two crop maturation or harvest stages (swathing, direct-combining). Seed shatter differed among weed species, but was similar between crops at maturity: ca. 30% for wild oat, 5% for cleavers, < 2% for wild mustard, and < 1% for green foxtail. Overall, seed shatter of wild oat occurred sooner and at greater levels during the growing season compared with the other weed species. Viability of both shattered and plant-retained seeds was relatively high for all species. The small amount of seed shatter of cleavers, wild mustard, and green foxtail suggests that these species may be suitable candidates for HWSC. Due to the amount and timing of wild oat seed shatter, HWSC may not reduce population abundance of this grassy weed.

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Economics of Pronamide and Pendimethalin Use in Weed Management during Artichoke Stand Establishment

HortScience ◽

10.21273/hortsci.36.4.650 ◽

2001 ◽

Vol 36 (4) ◽

pp. 650-653 ◽

Cited By ~ 4

Author(s):

Milton J. Haar ◽

Steven A. Fennimore ◽

Cheryl L. Lambert

Keyword(s):

Weed Management ◽

Financial Analysis ◽

Field Studies ◽

Avena Fatua ◽

Wild Oat ◽

Weed Species ◽

Cynara Scolymus ◽

A Site ◽

Heavy Infestation ◽

Better Than

Field studies were conducted to determine the potential economic impact of the loss of pronamide herbicide to artichoke (Cynara scolymus L.) growers, and to evaluate pendimethalin as an alternative herbicide during establishment of artichoke. Two rates of pronamide and one rate of pendimethalin were applied to perennial and annual artichokes. With the exception of wild oat (Avena fatua L.), pendimethalin controlled weeds as well as or better than pronamide. Financial analysis of treatment effects was based on weed management expenses and value of yield. The financial effect of using pronamide in perennial artichoke ranged from a loss of $247 to a gain of $326 per ha, whereas its use in annual artichoke increased revenue $542 to $5499 per ha. The effects on revenue of using pendimethalin varied with weed species composition and density. For three sites, revenue increased from $267 to $5056 per ha, while a loss of $1034 per ha occurred at a site with a heavy infestation of wild oat. We conclude that pendimethalin has potential as a pronamide replacement, or as a complement to pronamide. Chemical names used: 3,5-dichloro (N-1,1-dimethyl-2-propynyl)benzamide (pronamide); N-(1-ethylpropyl)-3,4-dimethyl-2,6-dinitrobenzenamine (pendimethalin).

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Competitive ability of corn in coexistence with goosegrass

Planta Daninha ◽

10.1590/s0100-83582013000200005 ◽

2013 ◽

Vol 31 (2) ◽

pp. 281-289 ◽

Cited By ~ 10

Author(s):

A.C.D. Wandscheer ◽

M.A. Rizzardi ◽

M. Reichert

Keyword(s):

Plant Height ◽

Competitive Ability ◽

Dry Mass ◽

Agricultural Systems ◽

Weed Species ◽

Replacement Series ◽

Eleusine Indica ◽

Randomized Design ◽

Completely Randomized Design ◽

Corn Plants

Competition between plants is one of the main interferences that occurs in agricultural systems and accounts for significant crop yield reductions. The aim of this study was to assess the competitive ability of corn in coexistence with the weed species Eleusine indica. The experiments were conducted in a greenhouse, in the growing season 2010/2011, and were arranged in a completely randomized design with four replications. The experimental units consisted of plastic pots with a volumetric capacity of 8 L. Treatments were arranged in a replacement series with five proportions of corn plants and weed: 100:0, 75:25, 50:50, 25:75, and 0:100, respectively, with a constant population of eight plants per pot, at the end of each treatment. The competitiveness analysis was conducted through diagrams applied to the replacement series experiment and competitiveness index, and the variables evaluated were root, shoot, and total dry mass, and plant height. When in equal proportions, corn showed competitive ability equivalent to goosegrass in relation to the variables shoot, root, and total dry mass. Goosegrass was more competitive than the crop in relation to plant height.

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Growth, competitiveness, and seed germination of triallate/difenzoquat-susceptible and -resistant wild oat populations

Canadian Journal of Plant Science ◽

10.4141/p98-060 ◽

1999 ◽

Vol 79 (2) ◽

pp. 303-312 ◽

Cited By ~ 14

Author(s):

J. T. O'Donovan ◽

J. C. Newman ◽

R. E. Blackshaw ◽

K. N. Harker ◽

D. A. Derksen ◽

...

Keyword(s):

Seed Germination ◽

Leaf Area ◽

Weed Management ◽

Field Experiments ◽

Dry Weight ◽

Avena Fatua ◽

Integrated Weed Management ◽

Wild Oat ◽

Replacement Series ◽

Shoot Dry Weight

Understanding the relative competitiveness and seed germination patterns of herbicide-resistant weeds has implications for integrated weed management. Replacement series experiments were conducted in the greenhouse to compare interspecific competition among two triallate/difenzoquat susceptible (S) and 10 resistant (R) wild oat (Avena fatua L.) populations. Each series included monocultures of each of the populations and three mixtures at relative S:R proportions of 3:1, 1:1 and 1:3. Shoot dry weight tended to be greater in the R than S populations, but results were not always statistically significant at the 5% level. Leaf area was more variable, but in most cases did not differ between R and S populations. With a few exceptions, relative crowding coefficients for shoot dry weight and leaf area were similar for S and R populations indicating little or no differences in competitiveness. In field experiments where two S and five R populations were grown in competition with wheat (Triticum aestivum L.), two of the R populations produced significantly (P < 0.05) greater shoot dry weight and seed yield than the S populations. Otherwise populations did not differ significantly. In seed germination studies, the S populations consistently displayed lower cumulative germination than the R populations. The higher seed germination associated with the R populations suggests that producers should be able to manage these populations effectively with a combination of alternative herbicides and cultural practices. Key words: Avena fatua, herbicide resistance, triallate, difenzoquat, relative competitiveness, seed germination

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Interference of large crabgrass (Digitaria sanguinalis), redroot pigweed (Amaranthus retroflexus), and hairy galinsoga (Galinsoga ciliata) with bell pepper

Weed Science ◽

10.1614/ws-05-053r1.1 ◽

2006 ◽

Vol 54 (02) ◽

pp. 364-372 ◽

Cited By ~ 23

Author(s):

Rongwei Fu ◽

Richard A. Ashley

Keyword(s):

Hyperbolic Equation ◽

Competitive Ability ◽

Yield Loss ◽

Maximum Yield ◽

Bell Pepper ◽

Nonlinear Hyperbolic Equation ◽

Emergence Time ◽

Weed Species ◽

Redroot Pigweed ◽

Large Crabgrass

Large crabgrass, redroot pigweed, and hairy galinsoga are three important weed species in bell pepper and other crops in the northeastern United States. Field experiments were conducted in 1998 and 1999 to determine the influence of density and relative emergence time of the three weed species on bell pepper fruit yield. Densities of 0, 1, 2, 4, 8, 16, and 32 plants m−1row were established for each weed species from naturally occurring weed populations. The effects of relative emergence time were studied by investigating the different yield responses to weeds emerging at two different times: 3 d or 2 wk after transplanting of pepper. Both weed density and relative emergence time affected pepper yield loss. The relative competitive ability of weed species varied between years. Large crabgrass was the most competitive species in 1998 and the measure of yield loss at low weed densities,I, was estimated to be 34% on the basis of the nonlinear hyperbolic equation. Redroot pigweed was most competitive in 1999 with an estimate of 88% forI.Hairy galinsoga was the least competitive weed in both years. Maximum yield loss under 32 plants m−1row ranged from 19% with late-emerging hairy galinsoga in 1998 to 99% with early-emerging redroot pigweed in 1999. A new equation was proposed to characterize the relation between yield loss and weed pressure by expanding the nonlinear hyperbolic equation to include a parameter to account for the change of maximum yield loss with emergence time. The expanded equation generally provided a more accurate prediction of yield loss. In addition, several models are introduced to describe both the effects of density and relative emergence time of multiple weed species on crop yield. Generally these models provided an adequate fit of the data and a good description of the competitive ability of the mixed population.

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