scholarly journals Perspectives for using light quality knowledge as an advanced ecophysiological weed management tool

2009 ◽  
Vol 27 (2) ◽  
pp. 407-419 ◽  
Author(s):  
A. Merotto Jr. ◽  
A.J. Fischer ◽  
R.A. Vidal

The current knowledge of light quality effects on plant morphogenesis and development represents a new era of understanding on how plant communities perceive and adjust to available resources. The most important consequences of light quality cues, often mediated by decreasing in red far-red ratios with respect to the spectral composition of incident sunlight radiation, affecting weed-crop interaction are the increased plant height and shoot to root ratio in anticipation of competition by light quantity, water or nutrients. Although the concepts related to light quality have been extensively studied and several basic process of this phenomenon are well known, little applications of photomorphogenic signaling currently are related to agricultural problems or weed management. The objectives of this review are to describe how light quality change can be a triggering factor of interspecific interference responses, to analyze how this phenomenon can be used to predict weed interference, to reevaluate the critical periods of interference concept, and to discuss its potential contribution towards developing more weed competitive crop varieties. Knowledge on light quality responses involved in plant sensing of interspecific competition could be used to identify red/far-red threshold values, indicating when weed control should be started. Light quality alterations by weeds can affect grain crop development mainly in high yielding fields. Unlike the traditional concept or the critical period of competition, light quality mediated interference implies that the critical period for weed control could start before the effects of direct resource (water, nutrients and available light) limitation actually occur. The variability in light quality responses among crop genotypes and the identification of mutants insensitive to light quality effects indicate that this characteristic can be selected or modified to develop cultivars with enhanced interspecific interference ability. Knowledge on light quality-elicited responses represents a new possibility to understand the underlying biology of interspecific interference, and could be used in the development of new weed management technologies.

Weed Science ◽  
2012 ◽  
Vol 60 (1) ◽  
pp. 86-91 ◽  
Author(s):  
Emily Green-Tracewicz ◽  
Eric R. Page ◽  
Clarence J. Swanton

The critical period for weed control (CPWC) is an integral component of integrated weed management strategies. Several studies have defined the CPWC in soybean under varying agronomic conditions, yet none have described the mechanisms involved in crop yield losses caused by weed competition. We hypothesized that under nonresource-limiting conditions, morphological changes resulting from the expression of shade avoidance could be used to define a period of developmental sensitivity to low red-to-far-red ratio (R : FR) that would overlap with the defined CPWC in soybean. Two experiments (a sequential harvest and a weed addition/removal series) were conducted in 2008 and 2009 under controlled environmental conditions to address this hypothesis. Two light-quality treatments were used: (1) high R : FR ratio (i.e., weed-free), and (2) low R : FR ratio (i.e., weedy). The low R : FR ratio treatment induced shade avoidance responses in soybean, which included increases in height, internode length, and the shoot : root ratio, as well as a reduction in biomass accumulation and leaf number. Using the morphological changes in biomass and leaf number observed in the weed addition/removal series, a period of developmental sensitivity to low R : FR was defined between the first trifoliate (V1) and third trifoliate (V3) stages of soybean development. This period was found to be very similar to the CPWC previously defined by field studies of soybean–weed competition.


2015 ◽  
Vol 43 (2) ◽  
pp. 355-360 ◽  
Author(s):  
Dogan ISIK ◽  
Adem AKCA ◽  
Emine KAYA ALTOP ◽  
Nihat TURSUN ◽  
Husrev MENNAN

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.


2019 ◽  
Vol 29 (6) ◽  
pp. 866-873
Author(s):  
S. Christopher Marble ◽  
Shawn T. Steed ◽  
Debalina Saha ◽  
Yuvraj Khamare

Mulches have been evaluated extensively as a weed management tool in container plant production, but most research has focused on loose-fill wood-derived mulch materials, such as pine bark or wood chips. In this experiment, pine (mixed Pinus sp.) bark (PB), shredded hardwood (HW), and pine sawdust were evaluated for weed control and crop response both alone and in combination with a guar gum tackifier alongside a plastic film mulch, a paper slurry mulch, and the paper slurry mulch + PB and compared with a nonmulched, nontreated control and a single application of preemergence herbicide (oxyfluorfen + pendimethalin). Mulch materials were applied to nursery containers ranging from 7 to 25 gal at two different nurseries and at two research centers in central Florida in 2017 and 2018. Results showed that the plastic mulch provided more than a 90% reduction in hand weeding time and weed weight over a 6-month period, and similar control was achieved with PB, paper slurry + PB, and the HW treatment (64% to 91% reduction in weeding time and weed weight). No growth differences were observed with any mulch treatment in any species evaluated including ligustrum (Ligustrum japonicum), Chinese elm (Ulmus parvifolia), or podocarpus (Podocarpus macrophyllum).


Weed Science ◽  
2006 ◽  
Vol 54 (5) ◽  
pp. 928-933 ◽  
Author(s):  
Martin M. Williams

The critical period for weed control (CPWC) identifies the phase of the crop growth cycle when weed interference results in unacceptable yield losses; however, the effect of planting date on CPWC is not well understood. Field studies were conducted in 2004 and 2005 at Urbana, IL, to determine CPWC in sweet corn for early May (EARLY) and late-June (LATE) planting dates. A quantitative series of treatments of both increasing duration of interference and length of weed-free period were imposed within each planting-date main plot. The beginning and end of the CPWC, based on 5% loss of marketable ear mass, was determined by fitting logistic and Gompertz equations to the relative yield data representing increasing duration of weed interference and weed-free periods, respectively. Weed interference stressed the crop more quickly and to a greater extent in EARLY, relative to LATE. At a 5% yield-loss level, duration of weed interference for 160 and 662 growing-degree days (GDD) from crop emergence marked the beginning of the CPWC for EARLY and LATE, respectively. When maintained weed-free for 320 and 134 GDD, weeds emerging later caused yield losses of less than 5% for EARLY and LATE, respectively. Weed densities exceeded 85 plants m−2for the duration of the experiments and predominant species included barnyardgrass, common lambsquarters, common purslane, redroot pigweed, and velvetleaf. Weed canopy height and total aboveground weed biomass were 300% and 500% higher, respectively, for EARLY compared with LATE. Interactions between planting date and CPWC indicate the need to consider planting date in the optimization of integrated weed management systems for sweet corn. In this study, weed management in mid-June–planted sweet corn could have been less intensive than early May–planted corn, reducing herbicide use and risk of herbicide carryover to sensitive rotation crops.


2021 ◽  
Vol 1 (1) ◽  
pp. 46-51
Author(s):  
A. Duwadi ◽  
A. Acharya ◽  
S. Gautam

Weed is omnipresent species that compete with major crops for light, nutrients, space, and water for their growth and development and ultimately deteriorate the ideal environment for crops growth. In the present context, herbicide application is the easiest and seemingly economical approach for weed control in south-Asian countries. In contrary, the side effects of herbicide on health and environment impose to adopt for the non-chemical method of weed management. This paper reviewed the menace of herbicide, crop weed association, the critical period of crop-weed competition, and different methods of organic weed control implemented especially for maize. The main objective of this review is to maneuver a weed control strategy for maize other than the chemical application. The findings of different research suggested that a critical period of crop-weed competition in maize lies between 2 to 8 weeks after crop sowing. Many mechanical methods for weed control in maize proved efficient but seemed labour intensive and biological methods provided maximum security against specific weed species. The cultural method in combination with other methods effectively reduced the weed population in the maize field. It was found that, if various components of non-chemical weed management are implemented systematically, we can control the weed population with higher economic return and achieve the goal of organic food production with sustainable solutions. Weed control in the organic system focuses on management techniques designed to prevent weed emergence, give a competitive advantage to the main crop, and act for sustainable solutions. The non-chemical integrated weed management system is recommended to reduce the use of herbicide and for sustainable production. A review of non-chemical weed management in maize could be helpful for researchers to provide useful, sustainable, and environmentally friendly solutions to farmers to solve the problem of weed infestation in the maize crop along with substantial yield improvement.


2019 ◽  
Vol 37 ◽  
Author(s):  
D. MARTINS ◽  
C.C. MARTINS ◽  
A.C. SILVA JR.

ABSTRACT: Floriculture and landscaping sector has the same problems as other crops regarding weed management. Weeds affect the yield and quality of the harvested product, in which the visual aspect and aesthetics stand out as the most important factors in flower production and landscaping. Weed control in floriculture and landscaping is critical and costly because maintaining the beauty of the product and the use of herbicides is a low-cost management tool compared to manual management. However, it implies knowing herbicide selectivity, as ornamental species may present some injury depending on the active ingredient and the degree of selectivity of the compound. Because the use of this practice in flower production and landscaping both abroad and mainly in Brazil is incipient, aspects of selectivity, chemical weed control, and safe application of different herbicides are addressed in this paper.


2008 ◽  
Vol 22 (3) ◽  
pp. 493-498 ◽  
Author(s):  
Bradley D. Hanson ◽  
Sally A. Schneider

Open field production of fruit and nut-tree nursery stock depends upon preplant soil fumigation, extensive tillage, and hand-labor throughout the growing season for adequate weed control. Because methyl bromide, the favored fumigant, is being phased out because of environmental concerns and the costs of both fuel and labor continue to rise, herbicides are likely to become a more important weed management tool in the tree nursery industry. Two trials were conducted to evaluate weed control and crop safety with several herbicides applied following fumigation with methyl bromide or 1,3-dichloropropene in central California stone-fruit nurseries. PRE and POST-directed applications of several labeled and unlabeled materials were applied in a band over seeded peach rootstock or applied after emergence with a drop-nozzle spray boom. Crop productivity and weed control were monitored throughout the 1-yr growing season. PRE oryzalin and dithiopyr treatments provided the best weed control with very little crop injury. PRE applications of flumioxazin, rimsulfuron, and sulfentrazone did not have adequate crop safety at the rates and timings tested. However, POST-directed applications of flumioxazin and rimsulfuron were much safer to the peach and almond crops and should be evaluated in future trials. Additional herbicides and application techniques are needed to find acceptable, safe control measures for weeds, such as California burclover, common mallow, and redstem filaree, which often are poorly controlled with preplant fumigation in tree nurseries.


Author(s):  
Sheeja K Raj ◽  
Elizabeth K Syriac

Weeds are the major biological constraint in direct seeded rice (DSR) due to the concurrent emergence of competitive weeds, absence of water to suppress weeds at the time of seedling emergence and emergence of difficult to control weeds. Strategies on weed management in direct seeded rice depend on critical period of weed control, weed flora and method to be adopted. In order to achieve the long term and sustainable management of weeds in DSR an integration of different weed management strategies like integrated weed management (IWM) are essential. The literature regarding the critical period of weed control, weed flora and different methods for the sustainable management of weeds in direct seeded rice are reviewed in this paper.


Weed Science ◽  
1999 ◽  
Vol 47 (1) ◽  
pp. 107-111 ◽  
Author(s):  
Rajender Singh Chhokar ◽  
Rajender Singh Balyan

Two field experiments were carried out from 1993 to 1995 to evaluate the critical period of weed control and to develop suitable weed management practices for jungle rice, horse purslane, and cockscomb in soybean. Horse purslane was more competitive during early growth stages (up to 45 days after sowing [DAS]) and cockscomb was more competitive during later growth stages, whereas jungle rice was competitive throughout the growing season. The critical period of weed control was found to be 30 to 45 DAS. Weed-free maintenance up to 45 DAS resulted in a 74% increase in grain yield of soybean over the unweeded control. Keeping soybean weed free for 45 d or allowing weeds to remain in the crop for less than 30 d resulted in no significant yield loss. Sequential application of a reduced rate of soil-applied trifluralin 1.0 kg ha–1(0.67 ×) with postemergence fluazifop 0.75 kg ha–1(0.75 ×) or a reduced rate of soil-applied trifluralin or pendimethalin at 1.0 kg ha–1(0.67 ×) followed by hand hoeing 35 DAS provided better control of a broad spectrum of weeds than a single application of a postemergence herbicide applied at reduced or recommended rates. Integration of reduced rates of soil-applied herbicides with post-emergence herbicides or hand hoeing 35 DAS produced soybean yields similar to the hand-weeded treatment. Compared to the weed-free or integrated weed control, a single application of soil-applied or postemergence herbicide did not control a broad spectrum of weeds and reduced soybean yield.


2012 ◽  
Vol 2012 ◽  
pp. 1-10 ◽  
Author(s):  
M. P. Anwar ◽  
A. S. Juraimi ◽  
B. Samedani ◽  
A. Puteh ◽  
A. Man

Critical period of weed control is the foundation of integrated weed management and, hence, can be considered the first step to design weed control strategy. To determine critical period of weed control of aerobic rice, field trials were conducted during 2010/2011 at Universiti Putra Malaysia. A quantitative series of treatments comprising two components, (a) increasing duration of weed interference and (b) increasing length of weed-free period, were imposed. Critical period was determined through Logistic and Gompertz equations. Critical period varied between seasons; in main season, it started earlier and lasted longer, as compared to off-season. The onset of the critical period was found relatively stable between seasons, while the end was more variable. Critical period was determined as 7–49 days after seeding in off-season and 7–53 days in main season to achieve 95% of weed-free yield, and 23–40 days in off-season and 21–43 days in main season to achieve 90% of weed-free yield. Since 5% yield loss level is not practical from economic view point, a 10% yield loss may be considered excellent from economic view point. Therefore, aerobic rice should be kept weed-free during 21–43 days for better yield and higher economic return.


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