scholarly journals Integrating Economics in the Critical Period for Weed Control Concept in Corn

Weed Science ◽  
2014 ◽  
Vol 62 (4) ◽  
pp. 608-618 ◽  
Author(s):  
Martina Keller ◽  
Geoffroy Gantoli ◽  
Jens Möhring ◽  
Christoph Gutjahr ◽  
Roland Gerhards ◽  
...  
Keyword(s):  
Weed Control ◽  
Critical Period ◽  
Logistic Models ◽  
Crop Growth ◽  
Growth Stages ◽  
Corn Yield ◽  
Leaf Stage ◽  
Weed Interference ◽  
Free Interval ◽  
Crop Growth Stages

The effect of weed interference on corn yield and the critical period for weed control (CPWC) were determined in Germany and Benin. Treatments with weed control starting at different crop growth stages and continuously kept weed-free until harvest represented the “weed-infested interval.” Treatments that were kept weed-free from sowing until different crop growth stages represented the “weed-free interval.” Michaelis–Menten, Gompertz, logistic and log–logistic models were employed to model the weed interference on yield. Cross-validation revealed that the log–logistic model fitted the weed-infested interval data equally well as the logistic and slightly better than the Gompertz model fitted the weed-free interval. For Benin, economic calculations considered yield revenue and cost increase due to mechanical weeding operations. Weeding once at the ten-leaf stage of corn resulted already profitable in three out of four cases. One additional weeding operation may optimize and assure profit. Economic calculations for Germany determined a CPWC starting earlier than the four-leaf stage, challenging the decade-long propagated CPWC for corn. Differences between Germany and Benin are probably due to the higher yields and high costs in Germany. This study provides a straightforward method to implement economic data in the determination of the CPWC for chemical and nonchemical weed control strategies.

The Critical Period of Weed Control in Grain Corn (Zea mays)

Weed Science ◽  
1992 ◽  
Vol 40 (3) ◽  
pp. 441-447 ◽  
Author(s):  
Michael R. Hall ◽  
Clarence J. Swanton ◽  
Glenn W. Anderson
Keyword(s):  
Zea Mays ◽  
Leaf Area ◽  
Weed Control ◽  
Critical Period ◽  
Field Studies ◽  
Southern Ontario ◽  
Leaf Stage ◽  
Individual Leaf ◽  
Logistic Equations ◽  
Weed Interference

Field studies were conducted in southern Ontario to determine the critical period of weed control in grain corn and the influence of weed interference on corn leaf area. The Gompertz and logistic equations were fitted to data representing increasing durations of weed control and weed interference, respectively. The beginning of the critical period varied from the 3- to 14-leaf stages of corn development However, the end of the critical period was less variable and ended on average at the 14-leaf stage. Weed interference reduced corn leaf area by reducing the expanded leaf area of each individual leaf and accelerating senescence of lower leaves. In addition, weed interference up to the 14-leaf stage of corn development impeded leaf expansion and emergence in 1989.

scholarly journals Atrazine Reduces the Critical Period of Weed Interference on Narrow Row Corn

2016 ◽  
Vol 34 (4) ◽  
pp. 721-728 ◽  
Author(s):  
M. PADILHA ◽  
A.A.M. BARROSO ◽  
L.B. CARVALHO ◽  
F.R. COSTA ◽  
S. BIANCO
Keyword(s):  
Weed Control ◽  
Crop Yield ◽  
Yield Components ◽  
Critical Period ◽  
Corn Yield ◽  
Weed Species ◽  
Weed Interference ◽  
Conyza Bonariensis ◽  
Narrow Row ◽  
Sida Rhombifolia

ABSTRACT The objective was to determine whether a change occurs in the critical period of weed interference prevention in narrow row corn with the use of atrazine and whether there is influence of the herbicide on crop yield components. The treatments consisted of periods without or with an initial weed control (0, 21, 35, 49, 63, 77, and 91 days after emergence), with or without application of atrazine in spikely post-emergence. The experiment was carried out in a 2 x 7 randomized blocks design (with and without weed control and seven periods with three replications). The use or not of atrazine was arranged in a split plot design. The most important weed species were Senecio brasiliensis, Urochloa plantaginea, Conyza bonariensis, Sida rhombifolia, and Solanum spp. Corn yield reduced by 15% and 18% with and without application of atrazine, respectively. The number of grains per spike and corn yield were negatively influenced by coexistence with weeds, while the number of rows per spike, the diameter and length of spike were not affected. Corn yield components were not affected by the use of atrazine. The critical period of weed interference prevention was 35 days without atrazine and 23 days with application of atrazine. There is a reduction of the critical period of weed interference prevention on narrow row corn by using atrazine, with no influence of the herbicide on crop yield.

Determination of the Critical Period for Weed Control in Corn

2013 ◽  
Vol 27 (1) ◽  
pp. 63-71 ◽  
Author(s):  
Geoffroy Gantoli ◽  
Victor Rueda Ayala ◽  
Roland Gerhards
Keyword(s):  
Weed Control ◽  
Critical Period ◽  
Field Experiments ◽  
Critical Time ◽  
Weed Competition ◽  
Growth Stages ◽  
Leaf Stage ◽  
Time Period ◽  
Weed Infestation ◽  
Hand Weeding

Field experiments were conducted in western Atakora, Benin, to determine the critical time period of weed competition in hand-weeded corn. Weeds were removed until different crop growth stages and then allowed to reemerge. Other treatments began weed control at different growth stages (four-, eight-, and ten-leaf stages and flowering) and were maintained until harvest. One treatment was permanently kept weed-free and one treatment was uncontrolled until harvest. Yields without weed competition ranged from 2.8 to 3.4 t ha−1. As expected, yield loss increased with duration of weed infestation and ranged from 38 to 65% compared to permanent weed-free plots. In three out of four site-years, the critical period for weed control started at the four- to six-leaf stage and continued until ten-leaf stage or flowering of corn. Approximately four hand-weeding applications were required in this critical period of weed control.

Effect of crop growth stage on tolerance to low doses of thifensulfuron:tribenuron

Weed Science ◽  
1997 ◽  
Vol 45 (4) ◽  
pp. 538-545 ◽  
Author(s):  
David A. Wall
Keyword(s):  
Field Studies ◽  
Crop Growth ◽  
Growth Stages ◽  
Low Doses ◽  
Seed Oil Content ◽  
Leaf Stage ◽  
Time Of Application ◽  
Crop Growth Stages ◽  
Sublethal Doses ◽  
Crop Growth Stage

Field studies were conducted at Morden, Manitoba, in 1994 and 1995 to investigate the effect of crop growth stages on canola and sunflower tolerance to sublethal doses of thifensulfuron:tribenuron (2:1). Thifensulfuron:tribenuron at doses of 0, 0.23, 0.45, 0.9, 1.8, and 3.6 g ai ha−1plus a nonionic surfactant at 0.5% v/v were applied to canola and sunflower at the two- to three-leaf, four- to five-leaf, and six- to seven-leaf stages. Crop leaf stage at the time of application affected tolerance of both crops to thifensulfuron:tribenuron. Crop injury was lowest, and flowering, seed yield, and seed oil content were least affected when low doses of thifensulfuron:tribenuron were applied at the two- to three-leaf stage. At the highest dose, there was little practical difference among growth stages since yield of both crops was severely reduced. Producers with drift-affected canola or sunflower can expect less effect on crop yield when thifensulfuron:tribenuron injury occurs during early crop growth.

scholarly journals TIME SERIES ANALYSIS OF REMOTE SENSING OBSERVATIONS FOR CITRUS CROP GROWTH STAGE AND EVAPOTRANSPIRATION ESTIMATION

2016 ◽  
Vol XLI-B8 ◽  
pp. 1037-1042 ◽  
Author(s):  
S. A. Sawant ◽  
M. Chakraborty ◽  
S. Suradhaniwar ◽  
J. Adinarayana ◽  
S. S. Durbha
Keyword(s):  
Remote Sensing ◽  
Time Series ◽  
Growth Stage ◽  
Crop Growth ◽  
Water Requirement ◽  
Growth Stages ◽  
Crop Water ◽  
Horticultural Crops ◽  
Crop Growth Stages ◽  
Crop Growth Stage

Satellite based earth observation (EO) platforms have proved capability to spatio-temporally monitor changes on the earth's surface. Long term satellite missions have provided huge repository of optical remote sensing datasets, and United States Geological Survey (USGS) Landsat program is one of the oldest sources of optical EO datasets. This historical and near real time EO archive is a rich source of information to understand the seasonal changes in the horticultural crops. Citrus (Mandarin / Nagpur Orange) is one of the major horticultural crops cultivated in central India. Erratic behaviour of rainfall and dependency on groundwater for irrigation has wide impact on the citrus crop yield. Also, wide variations are reported in temperature and relative humidity causing early fruit onset and increase in crop water requirement. Therefore, there is need to study the crop growth stages and crop evapotranspiration at spatio-temporal scale for managing the scarce resources. In this study, an attempt has been made to understand the citrus crop growth stages using Normalized Difference Time Series (NDVI) time series data obtained from Landsat archives (<a href="http://earthexplorer.usgs.gov/"target="_blank">http://earthexplorer.usgs.gov/</a>). Total 388 Landsat 4, 5, 7 and 8 scenes (from year 1990 to Aug. 2015) for Worldwide Reference System (WRS) 2, path 145 and row 45 were selected to understand seasonal variations in citrus crop growth. Considering Landsat 30 meter spatial resolution to obtain homogeneous pixels with crop cover orchards larger than 2 hectare area was selected. To consider change in wavelength bandwidth (radiometric resolution) with Landsat sensors (i.e. 4, 5, 7 and 8) NDVI has been selected to obtain continuous sensor independent time series. The obtained crop growth stage information has been used to estimate citrus basal crop coefficient information (Kcb). Satellite based Kcb estimates were used with proximal agrometeorological sensing system observed relevant weather parameters for crop ET estimation. The results show that time series EO based crop growth stage estimates provide better information about geographically separated citrus orchards. Attempts are being made to estimate regional variations in citrus crop water requirement for effective irrigation planning. In future high resolution Sentinel 2 observations from European Space Agency (ESA) will be used to fill the time gaps and to get better understanding about citrus crop canopy parameters.

scholarly journals The Critical Period for Weed Control (CPWC) in Potato (Solanum tuberosum L.)

2015 ◽  
Vol 43 (2) ◽  
pp. 355-360 ◽  
Author(s):  
Dogan ISIK ◽  
Adem AKCA ◽  
Emine KAYA ALTOP ◽  
Nihat TURSUN ◽  
Husrev MENNAN
Keyword(s):  
Weed Control ◽  
Weed Management ◽  
Critical Period ◽  
Field Experiments ◽  
Yield Loss ◽  
Cropping Systems ◽  
Control Period ◽  
Relative Yield ◽  
Yield Data ◽  
Weed Interference

Accurate assessment of crop-weed control period is an essential part for planning an effective weed management for cropping systems. Field experiments were conducted during the seasonal growing periods of potato in 2012 and 2013 in Kayseri, Turkey to assess critical period for weed control (CPWC) in potato. A four parameter log-logistic model was used to assist in monitoring and analysing two sets of related, relative crop yield. Data was obtained during the periods of increased weed interference and as a comparison, during weed-free periods. In both years, the relative yield of potato decreased with a longer period of weed-interference whereas increased with increasing length of weed free period. In 2012, the CPWC ranged from 112 to 1014 GDD (Growing Degree Days) which corresponded to 8 to 66 days after crop emergence (DAE) and between 135-958 GDD (10 to 63 DAE) in the following year based on a 5% acceptable yield loss. Weed-free conditions needed to be established as early as the first week after crop emergence and maintained as late as ten weeks after crop emergence to avoid more than 5% yield loss in the potato. The results suggest that CPWC could well assist potato producers to significantly reduce the expense of their weed management programs as well as improving its efficacy.

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