Interference and Interaction of Purple and Yellow Nutsedges (Cyperus rotundusandC. esculentus) with Crops

1987 ◽  
Vol 1 (1) ◽  
pp. 74-81 ◽  
Author(s):  
Paul E. Keeley
Keyword(s):  
Weed Management ◽  
Cost Effective ◽  
Management Systems ◽  
Effective Control ◽  
Ecological Studies ◽  
Crop Losses ◽  
Weed Interference

Ecological studies improve the understanding of crop losses caused by weeds and interactions among weeds and crops. Knowledge of weed-crop interactions can aid in developing more efficient weed management systems. Also, knowledge of the duration of weed interference and the length of the weed-free period required to prevent crop losses is essential for planning cost-effective control practices.

Two-stage chemical-biological treatment at Thessaloniki greater area WWTP - experiences and potentials

1995 ◽  
Vol 32 (9-10) ◽  
pp. 75-84 ◽  
Author(s):  
A. D. Andreadakis ◽  
G. H. Kristensen ◽  
A. Papadopoulos ◽  
C. Oikonomopoulos
Keyword(s):  
Biological Treatment ◽  
Treatment Plant ◽  
Cost Effective ◽  
Primary Treatment ◽  
Effective Control ◽  
Two Stage ◽  
Effluent Quality ◽  
Filamentous Microorganisms ◽  
Sludge Settling ◽  
The City

The wastewater from the city of Thessaloniki is discharged without treatment to the nearby inner part of the Thessaloniki Gulf. The existing, since 1989, treatment plant offers only primary treatment and did not operate since the expected effluent quality is not suitable for safe disposal to the available recipients. Upgrading of the plant for advanced biological treatment, including seasonal nitrogen removal, is due from 1995. In the mean time, after minor modifications completed in February 1992, the existing plant was put into operation as a two-stage chemical-biological treatment plant for 40 000 m3 d−1, which corresponds to about 35% of the total sewage flow. The operational results obtained during the two years operation period are presented and evaluated. All sewage and sludge treatment units of the plant perform better than expected, with the exception of the poor sludge settling characteristics, due to severe and persistent bulking caused by excessive growth of filamentous microorganisms, particularly M. Parvicella. Effective control of the bulking problem could lead to more cost-effective operation and increased influent flows.

Agronomics and Economics of Different Weed Management Systems in Corn and Soybean

1999 ◽  
Vol 91 (4) ◽  
pp. 585-591 ◽  
Author(s):  
William J. Cox ◽  
J. S. Singer ◽  
E. J. Shields ◽  
J. Keith Waldron ◽  
Gary C. Bergstrom
Keyword(s):  
Weed Management ◽  
Management Systems

scholarly journals Periods of Weed Interference on Orange Tree Crops

2018 ◽  
Vol 36 (0) ◽  
Author(s):  
G.S. GONÇALVES ◽  
J.E.B. CARVALHO ◽  
M.V.B. GARCIA ◽  
L.A. GAMA ◽  
C.L.L.L. AZEVEDO ◽  
...  
Keyword(s):  
Weed Management ◽  
Growing Season ◽  
Control Treatment ◽  
Weed Interference ◽  
Orange Tree ◽  
Cultivation Practices ◽  
Fruit Productivity ◽  
Orange Trees ◽  
Production Problems ◽  
Unripe Fruits

ABSTRACT: Current orange tree cultivation practices in the Brazilian State of Amazonas present several production problems, being the inadequate weed management the most important one, and significantly affecting fruit productivity. However, if weeds are managed properly, their coexistence with orange cultivars does not affect the fruit yield of orange trees. Thus, the objective of this research was to identify the period of longer weed interference in orange production. The treatments were conducted during the 2013 and 2014 harvests as follows: one control treatment with no coexistence of weeds and crop throughout the growing season; and six periods of coexistence (October to January, February to May, June to September, October to May, October to January, June to September, and February to September). The coexistence of weeds from October to May with orange trees increased the fall of unripe fruits and reduced the yield and the number of oranges per plant. Therefore, this period was considered as the most critical one for the control of weeds in orange trees.

scholarly journals Prevention of Leptospirosis Infected Vector and Human Population by Multiple Control Variables

2014 ◽  
Vol 2014 ◽  
pp. 1-9 ◽  
Author(s):  
Muhammad Altaf Khan ◽  
Saeed Islam ◽  
Sher Afzal Khan ◽  
Ilyas Khan ◽  
Sharidan Shafie ◽  
...  
Keyword(s):  
Optimal Control ◽  
Optimal Control Problem ◽  
Control Problem ◽  
Human Population ◽  
Cost Effective ◽  
Farm Animals ◽  
Effective Control ◽  
Multiple Control ◽  
Control Variables ◽  
Control Functions

Leptospirosis is an infectious disease that damages the liver and kidneys, found mainly in dogs and farm animals and caused by bacteria. In this paper, we present the optimal control problem applied to a dynamical leptospirosis infected vector and human population by using multiple control variables. First, we show the existence of the control problem and then use analytical and numerical techniques to investigate the existence cost effective control efforts for prevention of indirect and direct transmission of this disease. In order to do this, we consider three control functions two for human and one for vector population. We completely characterize the optimal control problem and compute the numerical solution of the optimality system using an iterative method.

Influence of Weed Management Practices and Crop Rotation on Glyphosate-Resistant Horseweed (Conyza canadensis) Population Dynamics and Crop Yield-Years III and IV

Weed Science ◽  
2009 ◽  
Vol 57 (4) ◽  
pp. 417-426 ◽  
Author(s):  
Vince M. Davis ◽  
Kevin D. Gibson ◽  
Thomas T. Bauman ◽  
Stephen C. Weller ◽  
William G. Johnson
Keyword(s):  
Population Dynamics ◽  
Crop Rotation ◽  
Crop Yield ◽  
Cover Crops ◽  
Weed Management ◽  
Management Practices ◽  
Plant Density ◽  
Crop Yields ◽  
Management Systems ◽  
No Till

Horseweed is an increasingly common and problematic weed in no-till soybean production in the eastern cornbelt due to the frequent occurrence of biotypes resistant to glyphosate. The objective of this study was to determine the influence of crop rotation, winter wheat cover crops (WWCC), residual non-glyphosate herbicides, and preplant application timing on the population dynamics of glyphosate-resistant (GR) horseweed and crop yield. A field study was conducted from 2003 to 2007 in a no-till field located at a site that contained a moderate infestation of GR horseweed (approximately 1 plant m−2). The experiment was a split-plot design with crop rotation (soybean–corn or soybean–soybean) as main plots and management systems as subplots. Management systems were evaluated by quantifying in-field horseweed plant density, seedbank density, and crop yield. Horseweed densities were collected at the time of postemergence applications, 1 mo after postemergence (MAP) applications, and at the time of crop harvest or 4 MAP. Viable seedbank densities were also evaluated from soil samples collected in the fall following seed rain. Soybean–corn crop rotation reduced in-field and seedbank horseweed densities vs. continuous soybean in the third and fourth yr of this experiment. Preplant herbicides applied in the spring were more effective at reducing horseweed plant densities than when applied in the previous fall. Spring-applied, residual herbicide systems were the most effective at reducing season-long in-field horseweed densities and protecting crop yields since the growth habit of horseweed in this region is primarily as a summer annual. Management systems also influenced the GR and glyphosate-susceptible (GS) biotype population structure after 4 yr of management. The most dramatic shift was from the initial GR : GS ratio of 3 : 1 to a ratio of 1 : 6 after 4 yr of residual preplant herbicide use followed by non-glyphosate postemergence herbicides.

scholarly journals Interactions of Nitrogen Source and Rate and Weed Removal Timing Relative to Nitrogen Content in Corn and Weeds and Corn Grain Yield

2017 ◽  
Vol 2017 ◽  
pp. 1-8 ◽  
Author(s):  
Alexandra M. Knight ◽  
Wesley J. Everman ◽  
David L. Jordan ◽  
Ronnie W. Heiniger ◽  
T. Jot Smyth
Keyword(s):  
Grain Yield ◽  
Weed Management ◽  
Management Strategies ◽  
Field Studies ◽  
Weed Species ◽  
Weed Interference ◽  
Coated Urea ◽  
N Fertility ◽  
Corn Grain ◽  
Corn Grain Yield

Adequate fertility combined with effective weed management is important in maximizing corn (Zea mays L.) grain yield. Corn uptake of nitrogen (N) is dependent upon many factors including weed species and density and the rate and formulation of applied N fertilizer. Understanding interactions among corn, applied N, and weeds is important in developing management strategies. Field studies were conducted in North Carolina to compare corn and weed responses to urea ammonium nitrate (UAN), sulfur-coated urea (SCU), and composted poultry litter (CPL) when a mixture of Palmer amaranth (Amaranthus palmeri S. Wats.) and large crabgrass (Digitaria sanguinalis L.) was removed with herbicides at heights of 8 or 16 cm. These respective removal timings corresponded with 22 and 28 days after corn planting or V2 and V3 stages of growth, respectively. Differences in N content in above-ground biomass of corn were noted early in the season due to weed interference but did not translate into differences in corn grain yield. Interactions of N source and N rate were noted for corn grain yield but these factors did not interact with timing of weed control. These results underscore that timely implementation of control tactics regardless of N fertility management is important to protect corn grain yield.

Weed Management Systems for Turfgrass

2017 ◽  
pp. 603-665
Author(s):  
S. Wayne Bingham ◽  
William J. Chism ◽  
Prasanta C. Bhowmik
Keyword(s):  
Weed Management ◽  
Management Systems
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