scholarly journals Mechanical and thermal weed control in organic crops

2017 ◽  
Author(s):  
◽  
Ricardo Costa Silva

Effective weed control is one of the most yield-limiting factors in organic corn and soybean production. Additionally, the amount of tillage needed to control weeds in organic practice is often criticized for its negative impacts on soil quality. This research was conducted in central Missouri from 2016-2017 to compare cultivation, flame application, between-row mowing, and hot water spray for in-season weed control in organic corn and soybeans. Between-row mowing and hot water application were paired with notillage and a crimped winter cover crop of cereal rye (Secale cereale L.). When weeds reached 10.2 cm, weed control practices were implemented and repeated as necessary until canopy closure. Grass and broadleaf weed biomass between crop rows was determined at multiple dates throughout the 2016 and 2017 seasons and in-row weed levels were determined at the final collection date for each crop each year. Broadleaf weed biomass at the end of the soybean season in 2016 was lower in the two treatments utilizing no-till and cover crops as primary weed control and hot water and mowing as secondary control. Soybean yield was adversely affected by flaming but not significantly different for the cultivation, mowing and hot water treatments. In 2017, soybean had less between-row grass biomass in the cultivation and flaming treatments than in hot water and mowing, but broadleaf levels were the same in the mowed treatment as the cultivated and flamed treatments. In 2016, grass biomass was lower in the no-till treatments between corn rows and higher in the crop rows than the other two treatments. Weed control treatments led to no significant differences in corn yield in 2016 and higher yields in the no-till treatments in 2017. In-row weed levels were significantly higher in corn in 2017 for the hot water treatment. Hot water at the levels applied in this research was not an effective weed control method. Since the overuse of cultivation can decrease soil organic matter levels and increase soil erosion, alternatives techniques are important to grant farmers the possibility to use their land for a long time. The crimped cover crop used in the no-till treatments limited weed growth in early-season corn and soybean and when coupled with between-row mowing is a potential alternative to cultivation in organic crop production. Flaming is also a potential alternative to cultivation in corn production.

Weed Science ◽  
2015 ◽  
Vol 63 (1) ◽  
pp. 346-352 ◽  
Author(s):  
Nicholas E. Korres ◽  
Jason K. Norsworthy

Cover crops are becoming increasingly common in cotton as a result of glyphosate-resistant Palmer amaranth; hence, a field experiment was conducted in 2009 and 2010 in Marianna, AR, with a rye cover crop used to determine its effects on the critical period for weed control in cotton. Throughout most of the growing season, weed biomass in the presence of a rye cover crop was lesser than that in the absence of a rye cover crop. In 2009, in weeks 2 through 7 after planting, weed biomass was reduced at least twofold in the presence of a rye cover compared with the absence of rye. In 2009, in both presence and absence of a rye cover crop, weed removal needed to begin before weed biomass was 150 g m−2, or approximately 4 wk after planting, to prevent yield loss > 5%. Weed density was less in 2010 than in 2009, so weed removal was not required until 7 wk after planting, at which point weed biomass values were 175 and 385 g m−2in the presence and absence of a cover crop, respectively.


HortScience ◽  
2004 ◽  
Vol 39 (6) ◽  
pp. 1262-1266 ◽  
Author(s):  
Lidia M. Carrera ◽  
Aref A. Abdul-Baki ◽  
John R. Teasdale

Cover crops combined with conservation tillage practices can minimize chemical inputs and improve soil quality, soil water-holding capacity, weed suppression and crop yields. No-tillage production of sweet corn (Zea mays var. `Silver Queen') was studied for 2 years at the USDA Beltsville Agricultural Research Center, Md., to determine cover crop management practices that maximize yield and suppress weeds. Cover crop treatments were hairy vetch (Vicia villosa Roth), rye (Secale cereale L.) and hairy vetch mixture, and bare soil (no cover crop). There were three cover crop killing methods: mowing, rolling or contact herbicide paraquat. All plots were treated with or without atrazine and metolachlor after planting. There was a 23% reduction in sweet corn plant population in the rye-hairy vetch mixture compared to bare soil. Averaged over both years, sweet corn yield in hairy vetch treatments was 43% greater than in bare soil, whereas yield in the rye-hairy vetch mixture was 30% greater than in bare soil. There were no significant main effects of kill method or significant interactions between kill method and cover crop on yield. Sweet corn yields were not different for hairy vetch or rye-hairy vetch treatments with or without atrazine and metolachlor. However, yield in bare soil without the herbicides atrazine and metolachor were reduced by 63% compared to bare soil with these herbicides. When no atrazine and metolachlor were applied, weed biomass was reduced in cover crops compared to the bare soil. Regression analysis showed greater yield loss per unit of weed biomass for bare soil than for the vetch or rye-hairy vetch mixture. This analysis suggests that cover crops increased sweet corn yield in the absence of atrazine and metolachlor not only by reducing weed biomass, but also by increasing the competitiveness of corn to weeds at any given biomass.


Weed Science ◽  
2008 ◽  
Vol 56 (4) ◽  
pp. 596-605 ◽  
Author(s):  
Kendra Baumgartner ◽  
Kerri L. Steenwerth ◽  
Lissa Veilleux

Vineyard weed communities were examined under four dormant-season cover-crop systems representative of those used in the north-coastal grape-growing region of California: no-till annuals (ANoT) (rose clover, soft brome, zorro fescue), no-till perennials (PNoT) (blue wildrye, California brome, meadow barley, red fescue, yarrow), tilled annual (AT) (triticale), and a no-cover-crop tilled control (NoCT). Treatments were carried out for 3 yr in the interrows of a wine grape vineyard. Glyphosate was used to control weeds directly beneath the vines, in the intrarows. Treatments significantly impacted weed biomass, community structure, and species diversity in the interrows. Orthogonal contrasts showed that tillage, and not the presence of a cover crop, impacted interrow weed biomass. Distance-based redundancy analyses (db-RDA) revealed significant effects of the cover-crop systems and of tillage on weed community structure in the interrows. For scarlet pimpernel and spiny sowthistle, the combination of ANOVA and orthogonal contrasts confirmed their association with the tilled treatments, as revealed by db-RDA. This same approach identified the association between California burclover and the no-till treatments. Our findings of no significant effects of the cover-crop systems on weed biomass, community structure, or diversity in the intrarows demonstrate that the impacts the cover-crop management systems had on the interrows did not carry over to adjacent intrarows. In addition, the fact that the cover crops did not affect vine yield, growth, or nutrition relative to the no-cover-crop control suggests that cover crops are likely to minimize soil erosion from winter rains, which is the primary purpose of vineyard cover cropping in northern California, without adversely affecting vine health or weed control.


Weed Science ◽  
2012 ◽  
Vol 60 (4) ◽  
pp. 624-633 ◽  
Author(s):  
Eric A. Nord ◽  
Matthew R. Ryan ◽  
William S. Curran ◽  
David A. Mortensen ◽  
Steven B. Mirsky

Knowledge of weed emergence periodicity can inform the timing and choice of weed management tactics. We tested the effects of weed management system (conventional [CNV] and herbicide-free [HF]), timing of rye sowing (two dates), timing of soybean planting (5 planting dates, 3 in each system), and supplemental control (with and without) on weed suppression and weed community composition in soybean no-till planted into a cereal rye cover crop. Cereal rye was terminated with a roller-crimper and herbicide (CNV) or with a roller-crimper alone (HF), and supplemental weed control was achieved with a postemergence glyphosate application (CNV) or with interrow high-residue cultivation (HF). Supplemental control with glyphosate in CNV was more effective than high-residue cultivation in HF. When soybean was planted on the same date, CNV resulted in less weed biomass and a more even community composition, whereas HF resulted in greater weed biomass, dominated by common ragweed. When we controlled for cereal rye biomass and compared the effects of cereal rye sowing and termination timing within each system, earlier management reduced weed biomass in HF, but tended to increase weed biomass in CNV. Our results suggest the ability to control emerged weeds prior to soybean planting is an important factor that influences the optimal cereal rye cover crop management timing for weed suppression.


2016 ◽  
Vol 32 (5) ◽  
pp. 463-473 ◽  
Author(s):  
Rick A. Boydston ◽  
Martin M. Williams

AbstractFall-planted cover crops offer many benefits including weed suppressive residues in spring sown crops when controlled and left on the soil surface. However, vegetable growers have been slow to adopt direct-seeding (no-till) into cover crop residues. Field studies were conducted in 2009 and 2010 near Paterson, WA and Urbana, IL to evaluate mortality of rye and common vetch (WA) hairy vetch (IL) cover crops, weed density and biomass, and snap bean growth and yield following four cover crop control methods utilizing a roller–crimper. Rye had higher mortality than common and hairy vetch by roller-crimping, and carfentrazone applied after roller crimping only slightly increased vetch mortality. Heavy residues of rye and escaped vetch were difficult to plant into, often resulting in lower snap bean populations. Rye and hairy vetch residues suppressed final weed biomass, while common vetch reduced weed biomass 1 of 2 years. Escaped plants of both vetch species became a weed. Snap bean yields were inconsistent and often lower following cover crops compared with a fallow treatment. Being able to completely control cover crops and to plant, manage escaped weeds and mechanically harvest in the presence of heavy residues are challenges that deter vegetable growers from readily adopting these systems.


Weed Science ◽  
2008 ◽  
Vol 56 (4) ◽  
pp. 588-595 ◽  
Author(s):  
Mayank S. Malik ◽  
Jason K. Norsworthy ◽  
A. Stanley Culpepper ◽  
Melissa B. Riley ◽  
William Bridges

Field experiments were conducted near Blackville, SC, and Tifton, GA, in 2004 and 2005, to evaluate the effect of wild radish and rye cover crops on weed control and sweet corn yield when used in conjunction with lower-than-recommended herbicide rates. Cover crop treatments included wild radish, rye, and no cover crop, alone and in conjunction with half and full rates of atrazine (0.84 and 1.68 kg ai ha−1) plusS-metolachlor (0.44 and 0.87 kg ai ha−1) applied before sweet corn emergence. Florida pusley, large crabgrass, spreading dayflower, ivyleaf morningglory, and wild radish infested the test sites. Wild radish and rye cover crops without herbicides reduced total weed density by 35 and 50%, respectively, at 4 wk after planting (WAP). Wild radish in conjunction with the full rate of atrazine plusS-metolachlor controlled Florida pusley, large crabgrass, and ivyleaf morningglory better than rye or no cover crop treated with a full herbicide rate in 2004 at Blackville. In 2005, at Blackville, weed control in sweet corn following wild radish cover crop plots alone was not different from that following rye. Wild radish or rye in conjunction with a half or full rate of atrazine andS-metolachlor controlled > 95% Florida pusley, wild radish, and large crabgrass in sweet corn at Tifton during both years. Ten glucosinolates, potential allelopathic compounds, were identified in wild radish, including glucoiberin, progoitrin, glucoraphanin, glucoraphenin, glucosinalbin, gluconapin, glucotropaeolin, glucoerucin, glucobrassicin, and gluconasturtin. Sweet corn yields at Blackville and Tifton following wild radish or rye cover crops were similar between the half and full rates of atrazine plusS-metolachlor. Sweet corn in wild radish or rye cover crop plots without herbicides produced less-marketable ears than herbicide-treated plots, indicating that a combination of cover crops and herbicides are required to optimize yields and to obtain desirable weed control.


1996 ◽  
Vol 10 (4) ◽  
pp. 893-899 ◽  
Author(s):  
Nilda R. Burgos ◽  
Ronald E. Talbert

Studies were conducted at the Vegetable Substation in Kibler, AR, in 1992 and 1993, in the same plots, to evaluate weed suppression by spring-seeded cover crops and to determine the effects of cover crop and imazethapyr on no-till southern pea. A plot without cover, conventionally tilled before planting southern pea, served as control. Weed control treatments, applied as subplots in each cover crop, included a weedy check, handweeded check, and half and full rates of imazethapyr (0.035 and 0.07 kg/ha) followed by sethoxydim (0.22 kg/ha). Biomass of Palmer amaranth 6 WAR without herbicides, was less in Italian ryegrass and sorghum-sudangrass residues than in oat residue and no cover crop. Over the years, Palmer amaranth density increased 333% without cover crops and 28% with cover crops. Rice flatsedge density increased four to five times in oat and sorghum-sudangrass residues but remained the same in Italian ryegrass residue. In general, Italian ryegrass residue suppressed the most weeds. Oat residue was least suppressive. Italian ryegrass and sorghum-sudangrass also reduced southern pea stand. Regardless of cover crop and year, half and full rates of imazethapyr followed by sethoxydim equally reduced density of Palmer amaranth, goosegrass, large crabgrass, southwestern cupgrass, and rice flatsedge compared with the untreated check. Residual control of Palmer amaranth by imazethapyr was higher at the full rate than the reduced rate, regardless of cover crop. Half rate of imazethapyr followed by sethoxydim controlled 94 to 100% of Palmer amaranth, rice flatsedge, large crabgrass, and southwestern cupgrass late in the season, regardless of cover crop in 1992 and 1993. Southern pea yield in untilled plots with cover crops was two to three times lower than yield in plots with preplant tillage and no cover crops mostly because of reduction in crop stand in the presence of cover crops.


1993 ◽  
Vol 7 (2) ◽  
pp. 425-430 ◽  
Author(s):  
Gregg A. Johnson ◽  
Michael S. Defelice ◽  
Zane R. Helsel

Field experiments were conducted in central Missouri in 1989 and 1990 to evaluate weed control practices in conjunction with cover crops and cover management systems in reduced tillage corn. There was no difference in weed control among soybean stubble, hairy vetch, and rye soil cover when averaged over cover management systems and herbicide treatments. However, mowed hairy vetch and rye covers provided greater weed control in the no-till plots than soybean stubble when no herbicide was used. Differences in weed control among cover management systems were reduced or eliminated when a PRE herbicide was applied. corn population and height were reduced by hairy vetch and rye soil cover. Corn grain yield was reduced in rye plots both years. There was no difference in grain yield between tilled and no-till plots.


2020 ◽  
Vol 34 (6) ◽  
pp. 787-793
Author(s):  
Stephanie A. DeSimini ◽  
Kevin D. Gibson ◽  
Shalamar D. Armstrong ◽  
Marcelo Zimmer ◽  
Lucas O.R. Maia ◽  
...  

AbstractField experiments were conducted in 2017 and 2018 at two locations in Indiana to evaluate the influence of cover crop species, termination timing, and herbicide treatment on winter and summer annual weed suppression and corn yield. Cereal rye and canola cover crops were terminated early or late (2 wk before or after corn planting) with a glyphosate- or glufosinate-based herbicide program. Canola and cereal rye reduced total weed biomass collected at termination by up to 74% and 91%, in comparison to fallow, respectively. Canola reduced horseweed density by up to 56% at termination and 57% at POST application compared to fallow. Cereal rye reduced horseweed density by up to 59% at termination and 87% at POST application compared to fallow. Canola did not reduce giant ragweed density at termination in comparison to fallow. Cereal rye reduced giant ragweed density by up to 66% at termination and 62% at POST application. Termination timing had little to no effect on weed biomass and density reduction in comparison to the effect of cover crop species. Cereal rye reduced corn grain yield at both locations in comparison to fallow, especially for the late-termination timing. Corn grain yield reduction up to 49% (4,770 kg ha–1) was recorded for cereal rye terminated late in comparison to fallow terminated late. Canola did not reduce corn grain yield in comparison to fallow within termination timing; however, late-terminated canola reduced corn grain yield by up to 21% (2,980 kg ha–1) in comparison to early-terminated fallow. Cereal rye can suppress giant ragweed emergence, whereas canola is not as effective at suppressing large-seeded broadleaves such as giant ragweed. These results also indicate that early-terminated cover crops can often result in higher corn grain yields than late-terminated cover crops in an integrated weed management program.


Weed Science ◽  
2017 ◽  
Vol 65 (3) ◽  
pp. 426-439 ◽  
Author(s):  
Jeffrey A. Liebert ◽  
Antonio DiTommaso ◽  
Matthew R. Ryan

Maximizing cereal rye biomass has been recommended for weed suppression in cover crop–based organic no-till planted soybean; however, achieving high biomass can be challenging, and thick mulch can interfere with soybean seed placement. An experiment was conducted from 2012 to 2014 in New York to test whether mixing barley and cereal rye would (1) increase weed suppression via enhanced shading prior to termination and (2) provide acceptable weed suppression at lower cover crop biomass levels compared with cereal rye alone. This experiment was also designed to assess high-residue cultivation as a supplemental weed management tool. Barley and cereal rye were seeded in a replacement series, and a split-block design with four replications was used with management treatments as main plots and cover crop seeding ratio treatments (barley:cereal rye, 0:100, 50:50, and 100:0) as subplots. Management treatments included high-residue cultivation and standard no-till management without high-residue cultivation. Despite wider leaves in barley, mixing the species did not increase shading, and cereal rye dominated cover crop biomass in the 50:50 mixtures in 2013 and 2014, representing 82 and 93% of the biomass, respectively. Across all treatments, average weed biomass (primarily common ragweed, giant foxtail, and yellow foxtail) in late summer ranged from 0.5 to 1.1 Mg ha−1in 2013 and 0.6 to 1.3 Mg ha−1in 2014, and weed biomass tended to decrease as the proportion of cereal rye, and thus total cover crop biomass, increased. However, soybean population also decreased by 29,100 plants ha−1for every 1 Mg ha−1increase in cover crop biomass in 2013 (P=0.05). There was no relationship between cover crop biomass and soybean population in 2014 (P=0.35). Soybean yield under no-till management averaged 2.9 Mg ha−1in 2013 and 2.6 Mg ha−1in 2014 and was not affected by cover crop ratio or management treatment. Partial correlation analyses demonstrated that shading from cover crops prior to termination explained more variation in weed biomass than cover crop biomass. Our results indicate that cover crop management practices that enhance shading at slightly lower cover crop biomass levels might reduce the challenges associated with excessive biomass production without sacrificing weed suppression in organic no-till planted soybean.


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