Emergence characteristics of four annual weed species

Hartzler, Robert G.; Buhler, Douglas D.; Stoltenberg, David E.

doi:10.1017/s0043174500092298

Cited by 157 publications

(190 citation statements)

References 18 publications

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“…A mean time of emergence (MTE) value of 41.4 was estimated, which fits into the range (from 30 to 42) observed by Hartzler et al (1999) for this species during three different cropping seasons.…”

Section: Seedling Emergencesupporting

confidence: 88%

“…The phenological behaviour of this weed species in the present trial has been found to be similar to the one observed in the fields of southern and central USA (Hartzler et al 1999) but a bit earlier than the one observed in eastern Canada and northern USA (Warwick and Black 1988) where the flowering starts from late August to September and seed setting occurs from September to October. On the other hand, compared with the observation made in Italy (Cantele et al 1987;Viggiani 1995), the present population shows a slight phenological delay, especially referring to the beginning of emergence.…”

Section: Resultsmentioning

confidence: 95%

“…The extended period of the different phenological stages, and specially the possibility to emerge over a long period of time and their ability to shed seeds several weeks before crop harvest, help to characterize their high phenotypic plasticity. The emergence time of A. theophrasti appeared to be affected by GDD accumulation and rainfall (Hartzler et al 1999). In Mediterranean maize crops, the irrigation replaces the rainfall as a factor favouring the seedling emergence.…”

Section: Implications For Managementmentioning

confidence: 99%

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Phenological and demographic behaviour of an exotic invasive weed in agroecosystems

et al. 2005

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An experimental work was conducted in Lleida (Spain) aiming to characterise the phenology and to quantify the demographic processes regulating the populations of Abutilon theophrasti Medicus in maize fields. Seedling emergence started a few days after crop sowing in early May and continued during two more months. The vegetative phase was very long due to the late seeding emergence; these later emerged plants showed a slower development, and many of them did not reach the fertility stage. A flowering peak was observed 12 weeks after emergence in late July, and fruit dehiscence and seed setting started in mid August, several weeks before crop harvest. Four different cohorts were identified, and two main peaks of emergence were determined 21 and 49 days after crop sowing nearest related with field irrigation. A functional logarithmic relationship between cumulative growing degree-days (GDD) and cumulative emergence was also described. The resulting demographic diagram reflects greater values relating to seedling survival for May cohorts (90.2 vs 7.9%), to fertility (100 vs 75%) and to fecundity (3774 vs 92 seeds pl )1 ) than those determined for the June cohorts. The late emerged plants are subjected to a high density and are strongly affected by light competition, and their reproductive phase initiation delay is of about 10-20 days. In an assay conducted in Petri dishes, the seeds provided from plants emerged earlier were found more vigorous and germinated more than those from late emerged plants, which seem to be affected by incomplete fruit and seed ripening. Following the crop cycle without any weed control, the population rate increase was about 21.2. These values explain the high invasion capacity of this weed in the local summer irrigated fields, which consists in assuring their presence through a persistent soil seed bank and increasing the probability to spread to other fields.

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Section: Seedling Emergencesupporting

confidence: 88%

Section: Resultsmentioning

confidence: 95%

Section: Implications For Managementmentioning

confidence: 99%

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Phenological and demographic behaviour of an exotic invasive weed in agroecosystems

et al. 2005

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“…A primary reason given for this later spring time frame is to ensure the soil is warm enough for more rapid seedling emergence and to avoid the peak emergence period for many summer annual weeds. Previous research determined that weed species exhibit specific patterns of emergence (Hartzler et al 1999;Ogg and Dawson 1984;Stoller and Wax 1973). Hartzler et al (1999) reported that common waterhemp (Amaranthus rudis Sauer), velvetleaf (Abutilon theophrasti Medicus), giant foxtail (Setaria faberi Herrm.…”

mentioning

confidence: 99%

Effects of Seeding Date and Weed Control on Switchgrass Establishment

et al. 2012

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We tested the effects of seeding date and weed control during switchgrass establishment in a field experiment that was conducted in central Pennsylvania in 2007 and repeated in 2008. Switchgrass was no-till seeded in early May, late May, and mid-June, and three postemergence weed management treatments were evaluated, including Mow (only a single mowing), Broadleaf (2,4-D + dicamba), and Broad Spectrum (2,4-D + dicamba + atrazine + quinclorac). Switchgrass density increased at later seeding dates, except in 2008, when the middle seeding date had the lowest density. In both years, weed biomass in late summer was lowest in the last seeding date of the Broad Spectrum treatment. In contrast, switchgrass biomass in late summer was greatest in the first seeding date of the Broad Spectrum treatment in both years. In the year after establishment (production year), plots were split to test the effects of supplemental weed control, composed of metsulfuron + 2,4-D applied in May, on total aboveground yield. Supplemental control in the production year increased total aboveground yield in the Mow treatment only, indicating that effective weed control during the establishment year might reduce the need for weed control in the following year. Although maximum aboveground yield was achieved when switchgrass was seeded in May and herbicides were used, results from our experiment suggest that seeding switchgrass at a relatively high seeding rate in June in our study region and mowing annual weeds to reduce competition and prevent seed production could be an effective strategy if minimizing herbicide use is a priority.

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“…Thus, N response should be greater with earlier, rather than later, emergence. Emergence times of species and cohorts (Hartzler et al 1999) may need to be considered when predicting responses to N fertilization.…”

mentioning

confidence: 99%

Influence of relative time of emergence on nitrogen responses of corn and velvetleaf

Harbur¹,

Owen

2006

Weed sci.

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Nitrogen (N) management markedly affects weed competition with crops. The effect of N availability on plant competition varies with a plant's abilities to capture and use N. Accordingly, we expected the N effect on plant competition to change with the relative emergence time of competing individuals. This hypothesis was tested by growing corn and velvetleaf plants in target and neighbor roles and comparing their N responses. Sowing times were varied, so that target plant emergent dates were constant, whereas neighbor plants were sown to emerge 7 d before, with, or 7 d after targets. Seedlings were fertilized daily with 2.5 mmol (“low N”) or 10.0 mmol (“high N”) ammonium nitrate (NH4NO3). Corn had greater total weight, leaf area, and root-to-shoot ratio (RSR) than velvetleaf. Different dry weights may have reflected seed weights; corn seed weight was greater than velvetleaf. Regardless of role, corn and velvetleaf dry weight and leaf area were greater with high N than low N; in contrast, RSR was lower with high N than low N. The RSR response to N availability suggested plant resources were shifted from N foraging, toward competition for photosynthetically active radiation (PAR). In target plants of each species, dry weight and leaf area increased linearly with time between target and neighbor emergence. Conversely, dry weight and leaf area of neighbor plants decreased with time between target and neighbor emergence. The N response of neighbor plants increased with time of emergence between target and neighbor emergence. Larger plants likely required more N to sustain growth than smaller plants; plants that emerged earlier likely had greater daily N requirements than those that emerged later. These results support factoring in emergence when predicting N effects on plant competition. Optimal N provisioning for integrated weed management may differ with emergence times of competing plants.

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Emergence characteristics of four annual weed species

Cited by 157 publications

References 18 publications

Phenological and demographic behaviour of an exotic invasive weed in agroecosystems

Phenological and demographic behaviour of an exotic invasive weed in agroecosystems

Effects of Seeding Date and Weed Control on Switchgrass Establishment

Influence of relative time of emergence on nitrogen responses of corn and velvetleaf

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