Potential for Preseason Herbicide Application to Prevent Weed Emergence in the Subsequent Growing Season. 1. Identification and Evaluation of Possible Herbicides

The earliest possible seeding of wheat crops in the southern Australian dryland cropping zone is prevented by the lack of a weed control practice that adequately controls initial weed seedling emergence at the start of the growing season. The objective of this study was to determine the potential for using residual herbicides applied up to 1 mo before the start of the growing season to control rigid ryegrass seedlings that emerge after the season-opening rains. In a series of glasshouse studies, S-metolachlor and propyzamide were found to effectively persist on the soil surface through prolonged exposure to hot, dry, and intense sunlight conditions, preventing the establishment of rigid ryegrass seedlings. In addition, these herbicides caused little or no effect on subsequently seeded wheat. It also was determined that S-metolachlor had the potential to retain efficacy on rigid ryegrass seedlings after 12 wk of exposure on the soil surface to these conditions. These studies have identified two herbicides with the potential for use at the novel application timing, i.e., before the commencement of the growing season, in Mediterranean climates of southern Australia.

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Herbicide Application Timings on Weed Control and Jack-O-Lantern Pumpkin Yield

HortTechnology ◽

10.21273/horttech.22.2.201 ◽

2012 ◽

Vol 22 (2) ◽

pp. 201-206 ◽

Cited By ~ 3

Author(s):

S. Alan Walters ◽

Bryan G. Young

Keyword(s):

Weed Control ◽

Weed Management ◽

Management Practices ◽

Production Systems ◽

Seedling Emergence ◽

Soil Surface ◽

Growing Season ◽

Weed Species ◽

Application Timing ◽

Over The Top

A study was conducted in a no-tillage (NT) jack-o-lantern pumpkin (Cucurbita pepo) field following winter wheat (Triticum aestivum) harvest to determine the effects of using registered herbicides at various timings on weed control and pumpkin yield. All application timings used in this study were important to maximize weed control over the pumpkin growing season. For an initial stale seedbed burndown treatment, paraquat provided better broadleaf weed control than glyphosate, which lead to greater pumpkin yields. The use of s-metolachlor + halosulfuron-methyl preemergence (PRE) and clethodim postemergence (POST) gave the best results for the second series of herbicide applications which related to higher pumpkin yields compared with none or only a PRE application. The last application timing (midseason POST-directed paraquat application between rows) also improved weed control and provided higher pumpkin yields compared with no treatment. Growers who use a stale seedbed burndown treatment in NT pumpkin production, before seedling emergence or transplanting, will generally use glyphosate although this study indicated that paraquat may prove to be a better choice depending on the weed species that are present at this application timing. Most weed control in NT pumpkin production is achieved by a PRE application of various tank-mixed herbicides for both grass and broadleaf weed control, with a POST grass herbicide, a POST application of halosulfuron-methyl, or both [for control of nutsedge (Cyperus sp.), specific broadleaf weed species, or both] applied 3 to 4 weeks later, and this study indicated that the use of labeled PRE and POST herbicides are essential to optimize weed control and pumpkin yields in NT. Most pumpkin growers do not use a POST-directed application of a nonselective herbicide (such as paraquat) before vines cover the soil surface although it appears that this application may be warranted to control weeds that have emerged later in the growing season to maximize pumpkin yield, especially if POST midseason over-the-top herbicide applications are not used. This study indicated that in addition to applying the limited PRE and POST herbicides available for weed control in pumpkin, the use of other chemical weed management practices (e.g., stale seedbed herbicide treatments or POST-directed nonselective herbicide applications) can provide valuable weed control in NT production systems and should be considered by growers to maximize pumpkin yield.

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Glyphosate and Paraquat Effects on Weed Seed Germination and Seedling Emergence

Weed Science ◽

10.1017/s004317450004981x ◽

1978 ◽

Vol 26 (3) ◽

pp. 249-251 ◽

Cited By ~ 26

Author(s):

G. H. Egley ◽

R. D. Williams

Keyword(s):

Seedling Emergence ◽

Soil Surface ◽

Amaranthus Retroflexus ◽

Sorghum Halepense ◽

Weed Species ◽

Sida Spinosa ◽

Broadleaf Species ◽

Prickly Sida ◽

Grass Weed ◽

Weed Emergence

Glyphosate [N-(phosphonomethyl)glycine] (30, 125, 250 mg/L) in petri dishes had no effect on germination of prickly sida(Sida spinosaL.), velvetleaf(Abutilon theophrastiMedic), barnyardgrass [Echinocloa crus-galli(L.) Beauv.] and johnsongrass [Sorghum halepense(L.) Pers.] seeds, but additional experimentation indicated that glyphosate stimulated germination of redroot pigweed(Amaranthus retroflexusL.) seeds. Paraquat (1,1′-dimethyl-4,4′-bipyridinium ion) (30, 125, 250 mg/L) did not affect germination of the three broadleaf species, but inhibited johnsongrass and barnyardgrass germination. In the greenhouse, soil surface applications of glyphosate (1.1, 2.2, 9.0 kg/ha) did not significantly affect emergence of these five weed species when they were on or beneath the soil surface at time of treatment. Paraquat (same rates) did not affect broadleaf weed emergence but some rates inhibited grass weed emergence when the seeds were treated while on the soil surface. It is unlikely that normal field use rates of glyphosate will influence weed emergence; whereas paraquat may inhibit the emergence of some grass weeds if the herbicide contacts seeds on the soil surface.

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Understanding mechanisms of reduced annual weed emergence in alfalfa

Weed Science ◽

10.1614/p2002-140 ◽

2003 ◽

Vol 51 (6) ◽

pp. 876-885 ◽

Cited By ~ 23

Author(s):

H. R. Huarte ◽

R. L Benech Arnold

Keyword(s):

Field Experiments ◽

Plant Density ◽

Seedling Emergence ◽

Soil Surface ◽

Bare Soil ◽

Winter Period ◽

Soil Temperatures ◽

Bull Thistle ◽

Weed Emergence ◽

Selection Of

Field experiments were carried out at the Facultad de Agronomía, Universidad de Buenos Aires, Argentina (34°25′S, 58°25′W), to evaluate the possibility of reducing weed seedling emergence through the use of alfalfa cultivars with low levels of winter dormancy and by increasing plant density from 200 to 400 plants m−2. It was hypothesized that these treatments would alter the temperature regime and the red (R)–far-red (FR) ratio of radiation to which seeds were exposed. Responses to management treatments were recorded for bull thistle, cotton thistle, plumeless thistle, tall rocket, mustard, curly dock, and pigweed. During the alfalfa establishment year, pigweed and curly dock emergence was reduced by the nondormant cultivar established at high density. This reduction disappeared when soil beneath the canopy was fitted with heaters that mimicked bare-soil temperatures. Crop canopy presence during the establishment year was not effective in reducing mustard, cotton thistle, bull thistle, plumeless thistle, and tall rocket emergence. During the second and third years after crop establishment, the canopy of the nondormant alfalfa cultivar was effective in reducing germination of weed seeds placed on the soil surface during fall and winter. In contrast, the winter-dormant cultivar allowed the establishment of weeds during the winter period. These reductions in weed emergence were associated with a modification in the R–FR ratio perceived by the seeds located at the soil surface and could largely be removed by using FR filters to increase the R–FR ratio. These results suggest that the selection of a nondormant cultivar combined with an increase in plant density could effectively reduce weed populations in alfalfa.

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Burning postharvest sugarcane residue for control of surface-deposited divine nightshade (Solanum nigrescens) and itchgrass (Rottboellia cochinchinensis) seed

Weed Technology ◽

10.1017/wet.2019.65 ◽

2019 ◽

Vol 33 (5) ◽

pp. 693-700 ◽

Cited By ~ 2

Author(s):

Douglas J. Spaunhorst ◽

Albert J. Orgeron ◽

Paul M. White

Keyword(s):

Moisture Content ◽

Prolonged Exposure ◽

Soil Surface ◽

Simulated Rainfall ◽

High Wind ◽

Moisture Condition ◽

Wind Speeds ◽

Smoldering Fire ◽

Rottboellia Cochinchinensis ◽

Weed Emergence

AbstractBurning postharvest sugarcane residue is a standard practice to remove extraneous leaf material before spring regrowth. Live-fires were simulated from field-collected postharvest sugarcane residue and seeds of divine nightshade and itchgrass were exposed to dry and moistened postharvest residue (PHR) at four densities (6.1, 12.1, 18.2, and 24.2 Mg ha−1) and a nonburned control. The moisture content of residue exposed to simulated rainfall was 14% more in Experiment 2 than Experiment 1; however, burning PHR with 44% moisture when wind speeds were lower allowed the fire to continue and created a smoldering effect that reduced weed emergence by 23% when compared with burning PHR with 30% moisture during breezy conditions. The moistened 6.1 Mg ha−1 PHR treatment resulted in 53% more divine nightshade and itchgrass emergence when compared with dry 6.1 Mg ha−1 PHR after burning, and greater emergence was attributed to more seed survival for divine nightshade than itchgrass. The PHR moisture condition failed to influence the burn duration; however, the burn duration increased 103% and 56% as the amount of PHR increased from 6.1 to 12.1 Mg ha−1 and 12.1 to 18.2 Mg ha−1, respectively. The combination of high wind speeds and moistened PHR did not enhance the maximum burn temperature near the soil surface, but surface-deposited divine nightshade and itchgrass seeds were susceptible to prolonged exposure times at 100 C. Burning PHR from fields with poor stands or older ratoon, especially when PHR is abundantly wet, will not produce temperatures lethal to divine nightshade and itchgrass seeds. The fluid-filled and fleshy content that comprises divine nightshade fruit protected seed from short durations of high temperatures, but may not insulate seeds long enough when exposed to a smoldering fire.

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Seedbank Dynamics of Two Swallowwort (Vincetoxicum) Species

Invasive Plant Science and Management ◽

10.1017/inp.2017.10 ◽

2017 ◽

Vol 10 (2) ◽

pp. 136-142 ◽

Cited By ~ 3

Author(s):

Antonio DiTommaso ◽

Lindsey R. Milbrath ◽

Scott H. Morris ◽

Charles L. Mohler ◽

Jeromy Biazzo

Keyword(s):

United States ◽

Management Strategy ◽

Seedling Emergence ◽

Soil Surface ◽

Growing Season ◽

First Year ◽

Northeastern United States ◽

The Third ◽

Viable Seeds ◽

Filled Seeds

Pale swallowwort and black swallowwort are European viny milkweeds that have become invasive in many habitats in the northeastern United States and southeastern Canada. A multiyear seedbank study was initiated in fall 2011 to assess annual emergence of seedlings and longevity of seeds of pale swallowwort and black swallowwort at four different burial depths (0, 1, 5, and 10 cm) over 4 yr. One hundred swallowwort seeds were sown in seed pans buried in individual pots, and emerged seedlings were counted and removed from May through September each year. A subset of seed pans was retrieved annually in October, and recovered seeds were counted and tested for viability. The majority of seedling emergence occurred during the first year (92% in 2012), and no new seedlings emerged in the third (2014) or fourth (2015) years. Pale swallowwort had relatively poor emergence at sowing depths of 0 cm (11%), 5 cm (6%), and 10 cm (0.05%—only one seedling), while 37% of pale swallowwort seeds emerged at 1 cm. The larger-seeded black swallowwort was more successful, with two-thirds of all sown seeds emerging at depths of 1 cm (71%) and 5 cm (66%), and 26% emerging at 10 cm. Only 16% of the surface-sown black swallowwort emerged. A large portion of the seeds that germinated at 10 cm, as well as at 5 cm for pale swallowwort, died before reaching the soil surface. Of filled seeds that were recovered in 2012 (black swallowwort at the 0-cm depth), 66% were viable. No viable seeds were recovered after the second growing season. Seeds recovered following the third year had become too deteriorated to accurately assess. Swallowwort seeds do not appear to survive more than 2 yr in the soil, at least in our experiment, suggesting that the elimination of seed production over 3 yr will exhaust the local seedbank. Seeds would need to be buried at least 10 cm for pale swallowwort but more than 10 cm for black swallowwort to prevent seedling emergence. Burial of swallowwort seeds as a management strategy may, however, only be practical in natural areas where high swallowwort densities occur.

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Changes with time in the germination of buried scentless chamomile (Matricaria perforata Mérat) seeds

Canadian Journal of Plant Science ◽

10.4141/cjps95-049 ◽

1995 ◽

Vol 75 (1) ◽

pp. 277-281 ◽

Cited By ~ 8

Author(s):

G. G. Bowes ◽

A. G. Thomas ◽

L. P. Lefkovitch

Keyword(s):

Seed Bank ◽

Seedling Emergence ◽

Soil Surface ◽

Growing Season ◽

Early Spring ◽

First Year ◽

Temperature Regimes ◽

Buried Seed ◽

Second Year ◽

Persistent Seed Bank

Change with time in the germination of scentless chamomile (Matricaria perforata Mérat) seeds was investigated. Seeds were placed in nylon net bags, buried 7 cm deep in soil, exhumed at monthly intervals for 2 yr and allowed to germinate in temperature regimes of 10/2 °C, 20/5 °C, 25/10 °C and 35/20 °C (16/8 h), simulating temperatures found during early spring or late fall, spring or fall, summer and mid-summer on the soil surface, respectively. Exhumed and refrigerator-stored (2 °C) check seeds exhibited no yearly dormancy/nondormancy germination cycle, but mortality of buried seed increased to 36%, after 10 mo in contrast with that of the check seeds which remained low for two years. Light was required for germination during the first year but was not required for a portion of the seed during the second year. The retention of viability in buried seed explains the persistent seed bank and seedling emergence throughout the growing season when moisture and temperature are nonlimiting. Key words: Seed burial, germination, Matricaria perforata Mérat

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(343) Weed Controlin Vineyard Following Fall and Spring Application of Selected Herbicide Combinations

HortScience ◽

10.21273/hortsci.40.4.1024e ◽

2005 ◽

Vol 40 (4) ◽

pp. 1024E-1025

Author(s):

Sorkel Kadir ◽

Kassim Al-Khatib

Keyword(s):

Weed Control ◽

Residual Activity ◽

Growing Season ◽

Early Spring ◽

Herbicide Application ◽

Herbicide Degradation ◽

Warm Weather ◽

Weed Emergence ◽

Fall Application

Soil residual herbicides registered for use on grapes can be applied from fall to spring, before weed emergence. However, ample early-spring moisture and warm weather may enhance weed emergence before herbicide application in the spring and prevent timely application. Therefore, fall application of herbicides can be beneficial if herbicides would provide adequate weed control in the following spring. Warm and wet winters may enhance herbicide degradation and shorten herbicide residual activity that result in poor weed control the following spring. Fall and spring application of oryzalin or norflurazon applied alone or in combination with diuron, simazine, or oxyfluorfen were evaluated for weed control in commercial vineyards at Oskaloosa and Eudora in northeast Kansas in 2003 and 2004. Weeds were not controlled adequately with oryzalin or norflurazon applied alone. At the end of the growing season, however, weed control was greater with spring than fall application. In addition, weed control with norflurazon was slightly greater than oryzalin. Norflurazon or oryzalin applied in combination with simazine, diuron, or oxyfluorfen controlled more weeds than norflurazon or oryzalin applied alone. The greatest control was with norflurazon or oryzalin applied with oxyfluorfen. In general, all herbicide combinations applied in the spring and fall provided similar weed control 4 months after spring application. However, at the end of the growing season, weed control was 10% to 20% greater when herbicides applied in the spring than fall. This study showed that acceptable weed control can be achieved when norflurazon or oryzalin is applied with oxyfluorfen and diuron in the fall.

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Microtopography, Microenvironments, and Weed Populations in Ridge-Tilled Soybean

Weed Technology ◽

10.1614/wt-05-015r1.1 ◽

2006 ◽

Vol 20 (3) ◽

pp. 593-604

Author(s):

Thomas W. Jurik

Keyword(s):

Seedling Emergence ◽

Growing Season ◽

Growing Degree Days ◽

Degree Days ◽

Weed Species ◽

Redroot Pigweed ◽

Giant Foxtail ◽

Green Foxtail ◽

Weed Emergence

The effects of microtopographic position on soil microenvironment and weed populations in ridge-tilled soybean were evaluated on three farms in Iowa in 1989 and 1990. In both years, over all weed species (primarily giant foxtail, green foxtail, yellow foxtail, redroot pigweed, and Pennsylvania smartweed), seedling emergence was highest in late May and early June, with few seedlings emerging after mid-June. Weed populations were highest in May and early June, after which rotary hoeing and cultivation reduced weed numbers in all plots. Microtopographic position (row, shoulder, and furrow) had a large effect on soil microenvironment and weed populations. Furrows were the wettest position through most of the growing season. Rows were the warmest position early in the season and the coolest position late in the season. Cumulative weed emergence early in the season was closely related to growing degree days, which accumulated faster in the row position than the furrow position. Following rotary hoeing and cultivation, the row position had significantly more total weeds than the shoulder and furrow positions on all farms in August of both years.

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Decline of Weed Seeds and Seedling Emergence Over Five Years as Affected by Soil Disturbances

Weed Science ◽

10.1017/s0043174500051389 ◽

1990 ◽

Vol 38 (6) ◽

pp. 504-510 ◽

Cited By ~ 46

Author(s):

Grant H. Egley ◽

Robert D. Williams

Keyword(s):

Seedling Emergence ◽

Soil Surface ◽

First Year ◽

Weed Species ◽

Native Seed ◽

Seed Population ◽

Soil Disturbances ◽

Viable Seeds ◽

Prickly Sida ◽

Weed Emergence

Weed emergence and viable weed seed numbers were determined in field plots during a 5-yr period where reseeding was prevented. Known numbers of seeds of seven weed species were added to the native seed population at the beginning of the study. Plots were nontilled or tilled to depths of 0, 5, 10, and 15 cm early in the spring of each year. Velvetleaf, spurred anoda, hemp sesbania, morningglory species, and pigweed species emergence was significantly greater from the nontilled plots during the first year after seeds were added to the native seed population. Tillage, regardless of depth, reduced weed emergence during the first year where seeds were added to the plots but had no effect on emergence from plots where no seeds were added. Tillage during the second through the fifth year did not affect emergence regardless of the addition of seeds. of the 5-yr emergence totals, 61 to 88% of all weeds in all plots emerged during the first year and 9 to 23% emerged during the second year. The 5-yr decline rate for emergence of all weeds was exponential. Viable seeds of prickly sida, spurges, and pigweeds in the nontilled plots declined from 590, 1531, and 4346 m−2, respectively, to zero by the third year. Tillage did not affect the decline. However, weed emergence in the field indicated that a few (1.0 to 5.6 m−2) seeds of those weeds were still viable after 3 yr. In nontilled plots, many recently added seeds were on or near the soil surface and germinated during the first year. Tillage moved many seeds to sites that were unfavorable for germination and emergence during the first year.

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Impact of postemergence herbicides on soybean injury and canopy formation

Weed Technology ◽

10.1017/wet.2020.55 ◽

2020 ◽

Vol 34 (5) ◽

pp. 727-734

Author(s):

Grant L. Priess ◽

Jason K. Norsworthy ◽

Trenton L. Roberts ◽

Edward E. Gbur

Keyword(s):

Growth Stage ◽

Yield Loss ◽

Soil Surface ◽

Growing Season ◽

Field Studies ◽

Herbicide Application ◽

Canopy Volume ◽

Herbicide Treatments ◽

Soybean Canopy ◽

Postemergence Herbicides

AbstractField studies were conducted in 2017 and 2018 in Arkansas to evaluate the injury caused by herbicides on soybean canopy formation and yield. Fomesafen, acifluorfen, S-metolachlor + fomesafen, and S-metolachlor + fomesafen + chlorimuron alone and in combination with glufosinate were applied to glufosinate-resistant soybean at the V2 growth stage. Soybean injury resulting from these labeled herbicide treatments ranged from 9% to 25% at 2 wk after application. This level of injury resulted in a 4-, 5-, 6-, and 6-d delay in soybean reaching 80% groundcover following fomesafen, acifluorfen, S-metolachlor + fomesafen, and S-metolachlor + fomesafen + chlorimuron, respectively. There was a 2-d delay in soybean reaching a canopy volume of 15,000 cm3 following each of the four herbicide treatments. The addition of glufosinate to the herbicide applications resulted in longer delays in canopy formation with every herbicide treatment except glufosinate + fomesafen. Fomesafen, acifluorfen, S-metolachlor + fomesafen, and S-metolachlor + fomesafen + chlorimuron, each applied with glufosinate, delayed soybean from reaching 80% groundcover by 2, 7, 8, and 9 d, respectively, and delayed the number of days for soybean to reach a canopy volume of 15,000 cm3 by 2, 3, 2, and 2 d, respectively. No yield loss occurred with any herbicide application. A delay in percent groundcover in soybean allows sunlight to reach the soil surface for longer periods throughout the growing season, possibly promoting late-season weed germination and the need for an additional POST herbicide application.

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