Field experiments were conducted to determine the critical period for weed control (CPWC) in nongrafted ‘Amelia’ and Amelia grafted onto ‘Maxifort’ tomato rootstock grown in plasticulture. The establishment treatments (EST) consisted of two seedlings each of common purslane, large crabgrass, and yellow nutsedge transplanted at 1, 2, 3, 4, 5, 6, and 12 wk after tomato transplanting (WAT) and remained until tomato harvest to simulate weeds emerging at different times. The removal treatments (REM) consisted of the same weeds transplanted on the day of tomato transplanting and removed at 2, 3, 4, 5, 6, 8, and 12 WAT to simulate weeds controlled at different times. The beginning and end of the CPWC, based on a 5% yield loss of marketable tomato, was determined by fitting log-logistic and Gompertz models to the relative yield data representing REM and EST, respectively. In both grafted and nongrafted tomato, plant aboveground dry biomass increased as establishment of weeds was delayed and tomato plant biomass decreased when removal of weeds was delayed. For a given time of weed removal and establishment, grafted tomato plants produced higher biomass than nongrafted. The delay in establishment and removal of weeds resulted in weed biomass decrease and increase of the same magnitude, respectively, regardless of transplant type. The predicted CPWC was from 2.2 to 4.5 WAT in grafted tomato and from 3.3 to 5.8 WAT in nongrafted tomato. The length (2.3 or 2.5 wk) of the CPWC in fresh market tomato was not affected by grafting; however, the CPWC management began and ended 1 wk earlier in grafted tomato than in nongrafted tomato.
Studies were conducted in 2012 and 2013 to determine the effect of fomesafen based Palmer amaranth control program in ‘Covington' and ‘Evangeline' sweetpotato cultivars. Treatments consisted of fomesafen pretransplant alone at 0.20, 0.28, 0.36, 0.42, 0.56, and 0.84 kg ai ha−1or followed by (fb)S-metolachlor at 1.12 kg ai ha−10 to 7 d after transplanting (DAP), fomesafen at 0.28 kg ha−1fbS-metolachlor at 1.12 kg ha−114 DAP, flumioxazin pretransplant at 0.105 kg ai ha−1,S-metolachlor at 1.12 kg ha−10 to 7 DAP, clomazone at 0.63 kg ha−10 to 7 DAP, napropamide at 2.24 kg ha−10 to7 DAP, flumioxazin fbS-metolachlor 0 to 7 DAP, and flumioxazin fb clomazone fbS-metolachlor 14 DAP. Fomesafen pretransplant at 0.28 to 0.84 kg ha−1alone or followed byS-metolachlor at 1.12 kg ha−10 to 7 DAP provided 80 to 100% Palmer amaranth control without reduction of yield and significant (< 13%) injury in Covington and Evangeline sweetpotato. Flumioxazin alone or fbS-metolachlor and flumioxazin fb clomazone fbS-metolachlor provided Palmer amaranth control (≥ 95%) with little injury (≤ 5%) and similar yield to the weed-free check. Clomazone alone did not cause injury, but controlled only 24 to 32% of Palmer amaranth at 50 DAP, which resulted in reduced no. 1, marketable, and total sweetpotato yield. Napropamide provided inconsistent control of Palmer amaranth in both years; therefore jumbo and total sweetpotato yield was reduced as compared to the weed-free check in 2012. Palmer amaranth control, sweetpotato cultivar tolerance, and yield in treatments with fomesafen fbS-metolachlor were similar to flumioxazin fbS-metolachlor. In conclusion, a herbicide program consisting of pretransplant fomesafen (0.28 to 0.42 kg ha−1) fbS-metolachlor (1.12 kg ha−1) is a potential option to control Palmer amaranth without causing significant injury and yield reduction in sweetpotato.
Palmer amaranth is the most common and troublesome weed in North Carolina sweetpotato. Field studies were conducted in Clinton, NC, in 2016 and 2017 to determine the critical timing of Palmer amaranth removal in ‘Covington’ sweetpotato. Palmer amaranth was grown with sweetpotato from transplanting to 2, 3, 4, 5, 6, 7, 8, and 9 wk after transplanting (WAP) and maintained weed-free for the remainder of the season. Palmer amaranth height and shoot dry biomass increased as Palmer amaranth removal was delayed. Season-long competition by Palmer amaranth interference reduced marketable yields by 85% and 95% in 2016 and 2017, respectively. Sweetpotato yield loss displayed a strong inverse linear relationship with Palmer amaranth height. A 0.6% and 0.4% decrease in yield was observed for every centimeter of Palmer amaranth growth in 2016 and 2017, respectively. The critical timing for Palmer amaranth removal, based on 5% loss of marketable yield, was determined by fitting a log-logistic model to the relative yield data and was determined to be 2 WAP. These results show that Palmer amaranth is highly competitive with sweetpotato and should be managed as early as possible in the season. The requirement of an early critical timing of weed removal to prevent yield loss emphasizes the importance of early-season scouting and Palmer amaranth removal in sweetpotato fields. Any delay in removal can result in substantial yield reductions and fewer premium quality roots.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
customersupport@researchsolutions.com
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
This site is protected by reCAPTCHA and the Google Privacy Policy and Terms of Service apply.
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.