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Weed management is consistently ranked among the top priorities of the United States sweetpotato industry. To provide additional weed and insect management strategies for sweetpotato, we initiated development of insect-resistant germplasm that also has weed tolerance by breeding and selecting for sweetpotato clones that are fast growing and have semi-erect to erect canopy architecture. Field studies were conducted in 2018 and 2019 in Charleston, South Carolina, to quantify the effects of weed-free interval and sweetpotato clone on weed counts for naturally occurring weed species, storage root yield, and insect resistance to the major pests of sweetpotato. Weed-free intervals included plots that were weedy all season and weed-free for 2, 3, and 4 wk after transplanting. Sweetpotato clones evaluated included ‘Beauregard’, ‘Covington’, ‘Monaco’, and six advanced selections with semi-erect to erect plant habit. Significant weed-free interval and sweetpotato clone main effects were observed for all variables measured, but not for their interaction. Two sweetpotato clones, USDA-17-037 and USDA-17-077, were consistent across both years and had the lowest weed counts, exhibited enhanced insect resistance, and were the highest yielding entries. These results demonstrate the potential for development of insect-resistant sweetpotato germplasm with a vigorous, erect plant habit that may be less susceptible to weed interference than cultivars with spreading shoot growth. The combination of germplasm that is both resistant to insect pests and competitive with weeds can provide organic and subsistence sweetpotato growers solutions to these critical issues related to sweetpotato production. Nomenclature: Sweetpotato, Ipomoea batatas (L.) Lam.

Purple nutsedge is a troublesome weed in tomato grown in plasticulture systems. Field trials were conducted in the fall of 2017 and spring of 2018 at Balm, FL, to evaluate multiple herbicide programs applied pretransplanting (pre-T), post-transplanting (post-T), and pre-T followed by (fb) post-T for purple nutsedge control in plasticulture tomato. Pre-T treatment of sulfentrazone or S-metolachlor alone were ineffective and did not decrease purple nutsedge density compared with the nontreated control. Post-T application of halosulfuron did not reduce purple nutsedge density at 12 wk after initial treatment (WAIT) in fall 2017 but reduced the purple nutsedge density at 17 WAIT in both seasons. Pre-T sulfentrazone or S-metolachlor application fb halosulfuron applied post-T were the most effective treatments and consistently reduced purple nutsedge population in both seasons. Herbicide treatments did not injure or reduce tomato height or yield. Overall, these results suggest sequential herbicide programs, including pre-T application of sulfentrazone or S-metolachlor fb post-T application of halosulfuron generally resulted in greater purple nutsedge control compared with pre-T or post-T application only. Halosulfuron applied post-T is critical to provide season-long purple nutsedge control in plasticulture tomato.

Fomesafen and imazosulfuron are two recently registered herbicides for use in Florida bell pepper. Field studies were conducted in 2012 and 2013 to evaluate PRE, POST-directed (POST-DIR), and PRE followed by (fb) POST-DIR control programs utilizing these new herbicides for nutsedge control in Florida bell pepper. PRE treatments included: S-metolachlor at 0.71 and 1.07 kg ai ha−1, fomesafen at 0.28 and 0.42 kg ai ha−1, S-metolachlor at 0.71 kg ha−1 + fomesafen 0.28 kg ha−1, and S-metolachlor at 1.07 kg ha−1 + fomesafen at 0.42 kg ha−1. POST-DIR treatments included imazosulfuron at 0.21 and 0.34 kg ai ha−1. PRE fb POST-DIR treatments included S-metolachlor at 0.71 or 1.07 kg ha−1 fb imazosulfuron at 0.21 kg ha−1 and fomesafen at 0.28 or 0.42 kg ha−1 fb imazosulfuron at 0.21 kg ha−1. Nutsedge control in both years at 28 d after planting was similar among all PRE treatments providing ≤ 60% control. The addition of imazosulfuron POST-DIR following S-metolachlor or fomesafen PRE provided greater control compared to S-metolachlor or fomesafen alone 14, 21, and 28 d after the POST-DIR application. Plots treated with S-metolachlor resulted in lower marketable weight and marketable fruit count compared to fomesafen in 2012; however, this was not observed in 2013. The results for these studies indicate the importance of a PRE fb POST-DIR herbicide for nutsedge control and that fomesafen or S-metolachlor PRE fb imazosulfuron POST-DIR provides growers with a viable tool capable of achieving season-long control of nutsedge in bell pepper. Nomenclature: Fomesafen; imazosulfuron; S-metolachlor; nutsedge, Cyperus spp.; bell pepper, Capsicum annuum L. Fomesafen e imazosulfuron son dos herbicidas recientemente registrados para uso en pimentón en Florida. Se realizaron estudios de campo en 2012 y 2013 para evaluar programas de control PRE, POST-dirigido (POST-DIR), y PRE seguido por (fb) POST-DIR utilizando estos nuevos herbicidas para el control de Cyperus spp. en pimentón en Florida. Los tratamientos PRE incluyeron: S-metolachlor a 0.71 y 1.07 kg ai ha−1, fomesafen a 0.28 y 0.42 kg ai ha−1, S-metolachlor a 0.71 kg ha−1 + fomesafen 0.28 kg ha−1, y S-metolachlor a 1.07 kg ha−1 + fomesafen 0.42 kg ha−1. Los tratamientos POST-DIR incluyeron imazosulfuron a 0.21 y 0.34 kg ai ha−1. Los tratamientos PRE fb POST-DIR incluyeron S-metolachlor a 0.71 ó 1.07 kg ha−1 fb imazosulfuron a 0.21 kg ha−1, y fomesafen a 0.28 ó 0.42 kg ha−1 fb imazosulfuron a 0.21 kg ha−1. El control de Cyperus spp. en ambos años a 28 d después de la siembra fue similar entre todos los tratamientos PRE siendo ≤ 60% de control. El agregar imazosulfuron POST-DIR después de S-metolachlor o de fomesafen PRE brindó mayor control al compararse con S-metolachlor o fomesafen solos 14, 21, y 28 d después de la aplicación POST-DIR. Los lotes tratados con S-metolachlor resultaron en menor peso y número de fruto comercializable al compararse con fomesafen en 2012, sin embargo esto no se observó en 2013. Los resultados de estos estudios indican la importancia de herbicidas PRE fb POST-DIR para el control de Cyperus spp. y que fomesafen o S-metolachlor PRE fb imazosulfuron POST-DIR brindan a los productores una herramienta viable capaz de alcanzar control de Cyperus spp. a lo largo de toda la temporada de crecimiento del pimentón.

Nutsedge control is challenging in commercial vegetable production in the absence of methyl bromide, and therefore, an effective alternative is needed. This study investigated allyl isothiocyanate (ITC) as a methyl bromide alternative for purple nutsedge control under polyethylene-mulch. Greenhouse experiments were conducted to compare the retention of allyl ITC in treated soil (3,000 nmol g−1) under low-density polyethylene (LDPE) and virtually impermeable film (VIF) mulches. Field experiments were conducted to evaluate the effectiveness of allyl ITC (6 rates: 0, 15, 75, 150, 750, 1500 kg ai ha−1) under VIF mulch against purple nutsedge. Additionally, a standard treatment of methyl bromide+chloropicrin (67 : 33%) at 390 kg ai ha−1 under LDPE mulch was included for comparison. In the greenhouse experiment, the predicted half-life of allyl ITC under LDPE and VIF mulch was 0.15 and 0.59 d, respectively. In the field experiment, it was predicted that allyl ITC at 1,240 and 1,097 kg ha−1 under VIF mulch is required to control purple nutsedge shoot and tubers equivalent to methyl bromide + chloropicrin at 4 wk after treatment (WAT). It is concluded that allyl ITC under VIF mulch would need to be applied at 2.8 to 3.2 times the standard treatment of methyl bromide + chloropicrin under LDPE mulch for commercially acceptable purple nutsedge control. Nomenclature: Allyl isothiocyanate; purple nutsedge; Cyperus rotundus L. CYPRO. El control de Cyperus rotundus es un reto en la producción comercial de vegetales en ausencia de methyl bromide, y por esto se necesita una alternativa efectiva. Este estudio investigó el uso de allyl isothiocyanate (ITC) como alternativa al methyl bromide para el control de C. rotundus bajo cobertura de polyethylene. Se realizaron experimentos de invernadero para comparar la retención de allyl ITC en suelos tratados (3,000 nmol g−1) bajo coberturas de polyethylene de baja densidad (LDPE) y de láminas virtualmente impermeables (VIF). Se realizaron experimentos de campo para evaluar la efectividad contra C. rotundus de allyl ITC (6 dosis: 0, 15, 75, 150, 1500 kg ai ha−1) bajo cobertura VIF. Adicionalmente, se incluyó un tratamiento estándar de methyl bromide + chloropicrin (67:33%) a 390 kg ai ha−1 bajo cobertura LDPE para fines de comparación. En el experimento de invernadero, la vida media predicha de allyl ITC bajo coberturas de LDPE y VIF fue 0.15 y 0.59 d, respectivamente. En el experimento de campo, se predijo que se requiere allyl ITC a 1,240 y 1,097 kg ha−1 bajo cobertura VIF para controlar la parte aérea y los tubérculos de C. rotundus a niveles equivalentes a methyl bromide + chloropicrin a 4 semanas después del tratamiento (WAT). Se concluyó que allyl ITC bajo cobertura VIF debería ser aplicado de 2.8 a 3.2 veces el tratamiento estándar de methyl bromide + chloropicrin bajo cobertura LDPE para controlar C. rotundus a niveles comercialmente aceptables.

Viable horseradish roots of various sizes remain in the soil after harvest and can develop into volunteer plants in subsequent crops. Experiments were conducted to evaluate POST herbicides on volunteer horseradish control and to determine if efficacy is dependent upon horseradish root segment size, herbicide rate, horseradish cultivar, or horseradish shoot size at application. In the greenhouse, horseradish root segment size did not affect herbicide efficacy. Chlorimuron, cloransulam, imazamox, (2,4-dichlorophenoxy)acetic acid (2,4-D) amine, halosulfuron, and imazethapyr plus imazapyr provided greater than 95% foliar control of volunteer horseradish. Chlorimuron, halosulfuron, and 2,4-D amine were also among the herbicides that provided the greatest reduction in horseradish root biomass (69% or greater). Glyphosate provided little foliar control (76%) and root biomass reduction (57%) after one application. The efficacy of 2,4-D amine on horseradish foliage and root biomass increased with increasing herbicide rate; however, the response of horseradish to halosulfuron was similar for all rates evaluated. Root biomass reduction of the horseradish cultivar ‘1573’ was less responsive to 2,4-D amine and halosulfuron applications compared with ‘1038’ and ‘1722’. However, foliar injury from 2,4-D amine and halosulfuron was less for the horseradish cultivar ‘1038’ compared with ‘1573’ and ‘1722’. In field studies, 2,4-D amine applied to 15- and 30-cm-tall horseradish and halosulfuron applied to 15-cm-tall horseradish resulted in the greatest foliar and root biomass reduction. This study indicated that in-season control of volunteer horseradish in rotational crops may be achieved through proper herbicide selection. Nomenclature: Chlorimuron; clopyralid; cloransulam-methyl; 2,4-D amine; dicamba; diflufenzopyr; flumetsulam; glyphosate; halosulfuron; imazamox; imazapyr; imazethapyr; mesotrione; primisulfuron; corn, Zea mays L. ‘Pioneer 33P69LL’; horseradish, Armoracia rusticana (Gaertn., Mey., Scherb.); soybean, Glycine max (L.) Merr.

Greenhouse studies were conducted to evaluate halosulfuron tolerance of several squash and cucumber cultivars commonly grown in Georgia. There was an inverse linear relationship between squash plant biomass and rate of halosulfuron (r2 = 0.70 to 0.92). With the exception of 'Supersett', the slopes from regression of all squash cultivars were equivalent. The estimated amount of halosulfuron required to reduce growth by 20%, based on regression, ranged from 8.2 to 45 g ai/ha (for Supersett and 'Dixie', respectively). Squash plant height was also reduced by halosulfuron, though plants began to recover from the injury by the end of the study. There was no effect of halosulfuron rate on cucumber plant biomass or height. Cucumber cultivars appeared to be more tolerant to halosulfuron than did squash cultivars.

Additive series studies were conducted under greenhouse conditions to determine the effects of nitrogen (N) rate and purple nutsedge densities on the yield of 'California Wonder' bell pepper. Initial densities of purple nutsedge were 0, 100, 200, and$300\\ \\text{plants}/{\\rm m}^{2}$. Nitrogen was applied at 70, 140, and 210 kg/ha. Plants were allowed to interfere for 10 wk. There were significant purple nutsedge population density by N rate interactions on bell pepper fruit yield. At 70 kg N/ha, no significant effect of weed population densities was found on fruit yield, whereas at the rates of 140 and 210 kg N/ha there were significant nutsedge density effects. As N rates and nutsedge densities increased, so did purple nutsedge biomass. Linear regression models described the interference. Bell pepper fruit yield reduction was 73% at 210 kg N/ha with an initial nutsedge population density of$300\\ \\text{plants}/{\\rm m}^{2}$.

Specialty crops, like flowers, herbs, and vegetables, generally do not have an adequate spectrum of herbicide chemistries to control weeds and have been dependent on hand weeding to achieve commercially acceptable weed control. However, labor shortages have led to higher costs for hand weeding. There is a need to develop labor-saving technologies for weed control in specialty crops if production costs are to be contained. Machine vision technology, together with data processors, have been developed to enable commercial machines to recognize crop row patterns and control automated devices that perform tasks such as removal of intrarow weeds, as well as to thin crops to desired stands. The commercial machine vision systems depend upon a size difference between the crops and weeds and/or the regular crop row pattern to enable the system to recognize crop plants and control surrounding weeds. However, where weeds are large or the weed population is very dense, then current machine vision systems cannot effectively differentiate weeds from crops. Commercially available automated weeders and thinners today depend upon cultivators or directed sprayers to control weeds. Weed control actuators on future models may use abrasion with sand blown in an air stream or heating with flaming devices to kill weeds. Future weed control strategies will likely require adaptation of the crops to automated weed removal equipment. One example would be changes in crop row patterns and spacing to facilitate cultivation in two directions. Chemical company consolidation continues to reduce the number of companies searching for new herbicides; increasing costs to develop new herbicides and price competition from existing products suggest that the downward trend in new herbicide development will continue. In contrast, automated weed removal equipment continues to improve and become more effective.

The performance of the Robovator (F. Poulsen Engineering ApS, Hvalsø, Denmark), a commercial robotic intrarow cultivator, was evaluated in direct-seeded broccoli and transplanted lettuce during 2014 and 2015 in Salinas, CA, and Yuma, AZ. The main objective was to evaluate the crop stand after cultivation, crop yield, and weed control efficacy of the Robovator compared with a standard cultivator. A second objective was to compare hand weeding time after cultivation within a complete integrated weed management (IWM) system. Herbicides were included as a component of the IWM system. The Robovator did not reduce crop stand or marketable yield compared with the standard cultivator. The Robovator removed 18 to 41% more weeds at moderate to high weed densities and reduced hand-weeding times by 20 to 45% compared with the standard cultivator. At low weed densities there was little difference between the cultivators in terms of weed control and hand-weeding times. The lower-hand weeding time with the Robovator treatments suggest that robotic intrarow cultivators can reduce dependency on hand weeding compared with standard cultivators. Technological advancements and price reductions of these types of machines will likely improve their weed removal efficacy and the long-term viability of IWM programs that will use them. Nomenclature: Broccoli, Brassica oleracea L. ‘Marathon'; lettuce, Lactuca sativa L. ‘Sunbelt'. El desempeño del Robovator (F. Poulsen Engineering ApS, Hvalsø, Denmark), un cultivador robótico comercial para uso dentro de las hileras de siembra, fue evaluado en brócoli de siembra directa y lechuga trasplantada durante 2014 y 2015 en Salinas, California y Yuma, Arizona. El objetivo principal fue evaluar el cultivo establecido después de la labranza, el rendimiento del cultivo, y la eficacia para el control de malezas del Robovator, al compararse con un cultivador estándar. Un segundo objetivo fue comparar el tiempo de deshierba manual después de la labranza dentro de un sistema de manejo integrado de malezas (IWM) completo. Se incluyó herbicidas como un componente del sistema IWM. El Robovator no redujo el número de plantas del cultivo establecidas ni el rendimiento comercializable al compararse con el cultivador estándar. El Robovator eliminó 18 a 41% más malezas en densidades de moderadas a altas y redujo el tiempo de deshierba manual en 30 a 45% al compararse con el cultivador estándar. A bajas densidades hubo pocas diferencias entre los cultivadores en términos de control de malezas y tiempos de deshierba manual. El mejor tiempo de deshierba manual con los tratamientos con Robovator sugiere que cultivadores robóticos para uso dentro de las hileras de siembra pueden reducir la dependencia en la deshierba manual en comparación con cultivadores estándar. Los avances tecnológicos y las reducciones en precio de este tipo de máquinas probablemente mejorará la eficacia en la remoción de malezas y la viabilidad en el largo plazo de los programas IWM que los usen.

Vegetables are an essential part of people’s daily diet, and weeds can cause serious losses in vegetable yield and quality. Intelligent weeding technology for vegetables will be one of the mainstream technologies in modern agricultural development. This article reviews the current research status of intelligent weeding technology for vegetables, including vegetable and weed detection technology, weeding actuators, and weeding robots. Firstly, the vegetable and weed detection technology was introduced in detail from three aspects: global weed detection, crop-rows detection, and vegetable/weed precise recognition technology. The research results of some researchers were summarised, and the vegetable/weed precise recognition technology, including machine learning and proximal sensor technology, was introduced. Secondly, the weeding actuators and robots were introduced, including intelligent chemical weeding, mechanical weeding, physical weeding, and integrated weed management methods. Some weeding actuators and robots developed by researchers and agricultural companies were showcased. Finally, the challenges and future development directions of intelligent weeding technology were discussed and analysed. Intelligent weeding technology for vegetables is still mainly limited by natural conditions and a lack of technology. In the future, it will be possible to develop in the direction of multi-algorithm and multi-sensor fusion technologies. It is necessary to improve the applicability of intelligent weeding equipment for various environments, crops, and weeds. This article can provide a reference for future research in the field of intelligent weeding for vegetables.