Progress 09/01/21 to 12/31/24
Outputs
Target Audience:The target audience consists of vegetable growers, pest control advisors and allied industry. Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided?Three technicians and one graduate student have been trained on the project, providing them with the opportunity for gaining new research skills and experience. How have the results been disseminated to communities of interest?The band steam applicator was demonstrated at four field days, one in June 2022, one in February 2024 at Yuma, AZ and one each in June, July and August 2024 at Salinas and Hollister CA. Grower and industry personnel attendance at these events was 50 to 150 persons. Five commercial scale demonstrations were made in the Salinas Valley of CA during May to August 2024 and one in Imperial Valley, CA in September 2024. In Arizona, applied research results and technical information about the project was disseminated to over 663 growers, industry personnel, researchers, and students through presentations at extension meetings (3), scientific meetings (2) and class lectures given to university students (2). Many more were reached through ag industry articles (4) and posting videos of the project results (2) on-line (> 350 views, YouTube]. Additionally, eight newsletter articles were written about project progress and findings. The newsletter is distributed bi-weekly newsletter to over 1,100 subscribers. What do you plan to do during the next reporting period to accomplish the goals?
Nothing Reported
Impacts
What was accomplished under these goals?
During the project period, we operated a prototype band steam applicator and have evaluated it in carrots, lettuce, and spinach. Sixteen trials have been conducted in California as of Dec. 31, 2024. For the past two years we operated the steam applicator with an 80-inch-wide bed shaper injector which facilitated our ability to operate at more locations. We also built a steam injector which could treat two 40-inch carrot beds per pass. 2023 work. Introduction. Three trials were initiated at Soledad, CA in 2023 to evaluate band steam treatment on weed and pathogen control in lettuce fields. The objective is to evaluate the efficacy of this approach and its potential applicability in sustainable agriculture practices. Methods. Trials used a randomized complete block design (RCBD) comprising both a band steam treatment and a no steam control in all trials. All three trials were initiated in commercial fields near Soledad CA June 16, 28 and 30, 2023. Field has a history of Fusarium wilt and soil samples were collected before and after steam application. Weed densities. Weed counts for the three lettuce trials were collected five weeks after the steam treatment and two to three weeks after planting. For each steam trial two 80-inch beds 1,200 ft long received steam injections in six 4-inch-wide bands aligned with the planned location of the lettuce seedline. Within each bed, two sections 30ft long were not treated to serve as no steam controls. Weed counts were recorded for every bed. Statistics: Analysis of variance (ANOVA) and mean separation with least significant differences were performed using Rstudio Notebook (R Studio, Boston, MA). ANOVA and mean separation using Fisher's Protected LSDs at P= 0.05. Results. In trial 1, a difference was found between the steam and the control treatments, with weed densities of 36 and 382 weeds per acre, respectively (P= 0.000167). Similarly, in trial 2, a difference was observed between the steam and control treatments, with weed densities of 460 and 2,743 weeds per acre, respectively (P=<0.0001). Lastly, in trial 3 there was also a significant difference between the steam and control treatments with weed densities of 68 and 305 weeds per acre, respectively (P=0.0102). Lettuce yield was obtained from trial 2, but there wasn't a difference between steam and control treatments with lettuce yields of 33.32 and 29.06 tons per acre, respectively (P=.103). Fusarium was present in 3 samples collected before steam application and in the post samples steam reduced Fusarium in 2 of 3 samples analyzed. Summary. During the initial weed assessment, lettuce trials 1, 2, and 3 had lower weed densities where steam was applied, and this difference was significant in all three cases. Marketable yield was obtained from trial 2, but there wasn't a difference. Nevertheless, there was higher yield observed in the steam treatment vs. the control treatment. Band dimension study. A study was initiated August 29 and 30, 2023 to determine the critical band widths and depths needed for effective pest control in lettuce with steam. Band dimensions were 4 and 5 inches wide by 3 and 5 inches deep. Lettuce was direct seeded August 31 and sprinkler irrigated. Data collected were stand counts, weed densities in the seedline and hand weeding times. The band steam reduced hand weeding times by 66% and weeds by 87% compared to the herbicide standard pronamide. The soil temperature data suggest that steam injection at 5 inches deep is optimal for maximizing the duration of soil heating. 2024 work. In 2024 we introduced a self-propelled steam applicator, and this machine was the primary applicator for 2024. Cost of operation of the self-Propelled steam applicator The self-propelled steam applicator was evaluated in a commercial field near Soledad, CA. Steam was applied June 5, 6, 2024. The trial included 16 80" beds of 1420 ft long, of which 12 were steamed and 4 were not steamed. Area treated with steam was 2.6 acres and 440 gallons of propane were burned total which is 169 gallons per acre. Propane cost was $1.89 per gallon. The cost per acre of $607.65 includes Fuel $319.41, Labor $138.15, and machine cost $150.09. In a demonstration trial in carrot near Brawley, CA two 40-inch beds were treated per pass at a speed of 35 feet per minute. The cost per acre was $469.84 including costs for Fuel $180.70, Labor $139.05, and Machine $150.09. Pest control with the self-propelled steam applicator. Three trials in 2024 focused on crop disease and weed control. The first trial near Salinas, CA was at a commercial site heavily infested with Fusarium wilt. Treatments were steam applied at 70°C and 90°C plus a control, all were replicated 4 times. Soil samples collected before and after steam application revealed that 90°C was necessary to suppress Fusarium by 88%. The 70°C temperature was not adequate to control this disease. Two trials were conducted on research farms near Spreckels and Salinas, CA. Both sites applied steam at 70°C and 90°C, plus a control and all treatments were replicated 4 times. The trial at Spreckels had been inoculated with Fusarium wilt, Verticillium wilt and lettuce drop inoculum. Both steam treatments reduced infection from all three diseases in lettuce by 98% compared to the control. Both steam treatments reduced hand weeding times by over 90% compared to the control. In the trial at Salinas lettuce drop was reduced by 90% compared to the control and hand weeding times were reduced by 50%. Weed Control in Spinach Two trials were conducted in AZ to determine the effectiveness of controlling weeds in spinach using soil applied steam. In the trials, steam injection shanks were spaced 2.6" apart across the bed top and positioned to inject steam into the soil at a depth of about 2". Travel speed was 0.20 mph. Results showed that steam treatment provided good control of broadleaf weeds (>89%) and significantly reduced hand weeding times (>80%) as compared to the untreated control. Work rates and fuel costs were at 0.14 ac/hr. and $600/ac, respectively. These values are reasonable and show good potential for use of the technique in spinach or spring mix crops where costs for hand weeding are extremely high.
Publications
- Type:
Other Journal Articles
Status:
Published
Year Published:
2022
Citation:
Guerra N, Fennimore SA, Siemens M, Goodhue RE. (2022) Band Steaming for Weed and Disease Control in Leafy Greens and Carrots. HortScience, 57:1453-1459.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2024
Citation:
Siemens, M.C., Pryor, B., Godinez, Jr. V., Bahr, N. & Fennimore, S.A. Design, and evaluation of a novel band-steam applicator for controlling soilborne pathogens and weeds in lettuce crops. ASABE Paper No. 2400537.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2024
Citation:
Precision steam application for weed control in vegetables. S. Fennimore, U.C. Davis, Salinas CA. California Weed Science Society
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2024
Citation:
Erika Escalona, Steve Fennimore, John Rachuy, Cristina Lazcano. 2024. Evaluating Bacterial Diversity and Pest Control Efficacy of Steam Disinfestation Treatments in the Salinas Valley Lettuce Fields. American Society of Horticultural Science, Abstracts
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Progress 09/01/23 to 08/31/24
Outputs
Target Audience:The target audience consists of vegetable growers, pest control advisors and allied industry. Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided?A graduate student, Erika Escalona, is being trained during the course of the project. She will graduate with a Masters degree Fall 2024. Two technicians worked on this project providing them with the opportunity for gaining new research skills and experience. How have the results been disseminated to communities of interest?The band steam applicator was demonstrated at three field days in one each in June, July and August 2024 at Salinas and Hollister CA, and once in February 2024 at Yuma, AZ. Grower and industry personnel attendance at these events was 50 to 100 persons. Five commercial scale demonstrations were made in the Salinas Valley of CA during May to August 2024. In Arizona, applied research results and technical information about the project was disseminated to over 475 growers, industry personnel, researchers, and students through presentations at extension meetings (5), scientific meetings (1) and student group workshops (1). Many more were reached through ag industry articles (2) and posting videos of the project results (2) on-line (> 150 views, YouTube]. Additionally, seven newsletter articles were written about project progress and findings. The newsletter is distributed bi-weekly newsletter to over 1,100 subscribers. What do you plan to do during the next reporting period to accomplish the goals?Work with graduate student to publish the results of this work.
Impacts
What was accomplished under these goals?
During the past year of the project we operated a commercial scale band steam applicator and have tested it in carrots, lettuce and spinach. Severn trials have been initiated in California and two are still in progress as of Sept 30, 2024. In lettuce we operated using an 80 inch injector and for carrot we used two 40 inch bed injectors. A trial was were initiated near Soledad, CA in June 2024 to evaluate the the cost of operation of the band steam applicator. In the trial steam was applied to 2.6 acres at a speed of 3.07 hours per acre at a cost of $608 per acre. Pest pressure at the site was light and no data to report. A replicated trial was conducted near Salinas, CA in a field with a known history of Fusarium wilt of lettuce. Two steam treatments were applied at 70 and 90 degrees C. The trial had Fusarium resistant and susceptible lettuce varieties planted. The 90 degree treatment suppressed Fusarium as indicated by the susceptible varieties, while the 70 degree treatment was not adequate to control Fusarium. Soil Samples indicated that the 90 C treatment reduced Fusarium by 88% while the 70C was not adequate. A trial was conducted near Spreckele, CA August 2024 where steam was applied at 70 and 90C. The site was very weedy and steam reduced weeds densities by 98 to 100% and reduced hand weeding times by 90 to 94%.
Publications
- Type:
Theses/Dissertations
Status:
Under Review
Year Published:
2024
Citation:
Evaluating Bacterial Diversity and Efficacy of Steam Disinfestation Treatments in the Salinas Valley Spinach and Lettuce Fields
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2024
Citation:
Evaluating Bacterial Diversity and Efficacy of Steam Disinfestation Treatments in the Salinas Valley Spinach and Lettuce Fields. American Society for Horticultural Science
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2024
Citation:
Precision steam application for weed control in vegetables
S. Fennimore, U.C. Davis, Salinas CA. California Weed Science Society
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Progress 09/01/22 to 08/31/23
Outputs
Target Audience:The target audience consists of vegetable growers, pest control advisors and allied industry. Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided?A graduate student, Erika Escalona, is being trained during the course of the project. She will graduate with a Masters degree Fall 2024. A postdoctoral scientist, from Malawi was working on the project through the end of 2022. Two technicians worked on this project providing them with the opportunity for gaining new research skills and experience. How have the results been disseminated to communities of interest?The band steam applicator was demonstrated at field days in October 2022 and February 2023 in Yuma, AZ and August 3, 2023 in Salinas, CA. Grower and industry personnel attendance at these events was 175, 200 and 50, respectively. Four commercial scale demonstrations were made June 2023 near Soledad, CA. In Arizona, applied research results and technical information about the project was disseminated to over 475 growers, industry personnel, researchers, and students through presentations at extension meetings (5), scientific meetings (1) and student group workshops (1). Many more were reached through ag industry articles (2) and posting videos of the project results (2) on-line (> 150 views, YouTube]. Additionally, seven newsletter articles were written about project progress and findings. The newsletter is distributed bi-weekly newsletter to over 1,100 subscribers. What do you plan to do during the next reporting period to accomplish the goals?We are fabricating an 80 inch bed steam applicator to deal with the wide beds used with Romaine lettuce and spinach. Work on those crops will be planned for 2024. We plan to modify the steam applicator so that it can also be used on standard 42" and 84" wide beds used in Arizona vegetable production. We also plan to replicate the trials that were conducted in Salinas, CA in Yuma, AZ. We plan to repeat the band dimension studies at a field site where FOL inoculum levels are known to be very high. We also plan to build a steam applicator for use in carrots and demonstrate the device in commercial carrot production.
Impacts
What was accomplished under these goals?
During the past year of the project we operated a prototype band steam applicator and have tested it in carrots, lettuce and spinach. Eight trials have been initiated in California and three are still in progress as of Sept 30, 2023. Three more trials were initiated in Arizona in 2023. This year we operated the steam applicator with an 80 inch wide bed shaper injector which facilitated our ability to engage with collaborators. In the latest trial still in progress we are evaluating the dimensions of the width and depth of the band that must be treated. Introduction. Three trials were initiated near Soledad, CA in 2023 to evaluate the impact of band steam treatment on weed control and soilborne pathogens in lettuce fields. The objective is to gain insights into the efficacy of this approach and its potential applicability in sustainable agriculture practices. Methods. Trials used a randomized complete block design (RCBD) comprising both a band steam treatment and a no steam control treatment in all trials. All three trials were initiated in commercial fields near Soledad CA June 16, 28 and 30, 2023. Field has a history of Fusarium wilt and soil samples were collected before and after steam application. Weed densities. Weed counts for the three lettuce trials were collected five weeks after the steam treatment and two to three weeks after planting. For each steam trial two 80 inch beds 1,200 ft long received steam injections in six 4-inch wide bands aligned with lettuce seedline was placed in a subsequent operation. Within each bed, two sections 30ft long were not treated to serve as no steam controls. Weed counts were recorded for every bed. Statistics: Analysis of variance (ANOVA) and mean separation with least significant differences were performed using Rstudio Notebook (R Studio, Boston, MA). ANOVA and mean separation using Fisher's Protected LSDs were performed at a significance level of P= 0.05. Results. In trial 1, a significant difference was found between the steam-only treatment and the control treatment, with weed densities of 36.1 and 381.5 weeds per acre, respectively (P= 0.000167). Similarly, in trial 2, a significant difference was observed between the steam and control treatments, with weed densities of 459.8 and 2,743.4 weeds per acre, respectively (P=<0.0001). Lastly, in trial 3 there was also a significant difference between the steam and control treatments with weed densities of 67.7 and 305.1 weeds per acre, respectively (P=0.0102). Lettuce yield was obtained from trial 2, but there wasn't a significant difference between steam and control treatments with lettuce yields of 33.32 and 29.06 tons per acre, respectively (P=.103). Fusarium was present in 3 samples collected before steam application and in the post samples steam reduced Fusarium in 2 of 3 samples analyzed. Summary. During the initial weed assessment, lettuce trials 1, 2, and 3 had lower weed densities where steam was applied, and this difference was statistically significant in all three cases. Marketable yield was obtained from trial 2, but there wasn't a significant difference. Nevertheless, there was higher yield observed in the steam treatment vs. the control treatment. Band dimension study Studies were conducted in AZ and CA to determine the critical band widths and depths needed for effective pest control in lettuce with steam. In AZ, band widths ranging in size from 4" wide by 2" deep to 6" wide by 4" deep were examined for control of Fusarium wilt of lettuce (FOL). Although the field site had a known history of FOL, disease incidence was less than 5% and no significant differences between treatments were found. We plan to repeat the study next year at a site where inoculum levels are known to be very high. In CA, a trial was initiated August 29 and 30. Band dimensions were 4 and 5 inches wide by 3 and 5 inches deep. Lettuce was direct seeded August 31 and sprinkler irrigated. Data collected were stand counts, weed densities in the seedline and hand weeding times. The study is still in progress but regardless of the dimension band steam reduced hand weeding times by 66% and weeds by 87% compared to the herbicide standard pronamide." Integrated steam/herbicide evaluation in bulb onion Steam was injected into raised with a custom built steam applicator to determine if soil disinfestation with steam could be an alternative to DCPA herbicide. Treatments included steam, Dacthal 8 pt/A, Nortron 1 pt/A all applied alone, and a second set of treatments included steam, Dacthal, and Nortron, each followed by Goaltender at 6 oz/A followed by bromoxynil at 1 pt/A. Hand weeded and weedy checks were included. Herbicides were applied in 30 GPA with a CO2 backpack sprayer equipped with 8002 flat fan nozzles. The steam applicator was equipped with a steel bed shaper and injectors that placed 7 PSI steam 3" below the soil surface. Trial design was a RCBD and treatments were replicated 4 times. Steam was applied June 7, 2023. Onion was seeded June 9, 2023. Dacthal and Nortron were applied June 12, 2023. Goaltender was applied July 10, 2023 and Bromoxynil was applied July 17, 2023. Data collected were weed density counts and crop injury estimates. Data were analyzed using ARM, and mean separation utilized LSD's. Weed control with Steam alone was as good or better than Dacthal or Nortron alone. All of the treatments with sequential Goaltender and Bromoxynil were effective on weeds. Onion was not injured by Steam, Dacthal or Nortron. Onion injury from sequential treatments of Goaltender and Bromoxynil were comparable. Onion harvest will occur in October 2023. Summary Steam disinfestation provided better weed control than Dacthal at 8 pints/A. However more work is needed to develop a steam applicator that will be cost effective in onion. Weed Control in Spinach Two trials were conducted in AZ to determine the effectiveness of controlling weeds in spinach using soil applied steam. In the trials, steam injection shanks were spaced 2.6" apart across the bed top and positioned to inject steam into the soil at a depth of about 2". Travel speed was 0.20 mph. Results showed that steam treatment provided very good control of broadleaf weeds (>89%) and significantly reduced hand weeding times (>80%) as compared to the untreated control. Work rates and fuel costs were at 0.14 ac/hr and $600/ac respectively. These values are reasonable and show good potential for use of the technique in spinach or spring mix crops where costs for hand weeding are very high.
Publications
- Type:
Conference Papers and Presentations
Status:
Awaiting Publication
Year Published:
2023
Citation:
SOIL PEST CONTROL IN VEGETABLES WITH STRATEGIC STEAM PLACEMENTE. Escalona, S. Fennimore,, J.S. Rachuy. U.C. Davis, Salinas CA. Methyl Bromide Alternative Outreach.
- Type:
Conference Papers and Presentations
Status:
Awaiting Publication
Year Published:
2023
Citation:
Smart weed control in vegetables with band steaming. Fennimore S.
Weed Science Society of America Abstracts.
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Progress 09/01/21 to 08/31/22
Outputs
Target Audience:The target audience consists of vegetable growers, pest control advisors and allied industry. Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided?A graduate student, Nelly Guerra, was trained during the course of the project. She graduated with a Masters degree December 2021. A postdoctoral scientist, from Malawi is currently working on the project. Two technicians worked on this project providing them with the opportunity for gaining new research skills and experience. How have the results been disseminated to communities of interest?The band steam applicator was demonstrated at a field day June 8, 2022 at Salinas, CA where 150 growers and industry personnel attended. Three commercial scale demonstrations were made on August 11, 2022 near Soledad, CA. In Arizona, applied research results and technical information about the project was disseminated to over 300 growers, industry personnel, researchers, and students through presentations at field days (1), extension meetings (2), scientific meetings (2) and student group workshops (1). Many more were reached through ag industry articles (1) and posting videos of the device in action (2) on-line (> 300 views, YouTube]. Additionally, five newsletter articles were written about project progress and findings. The newsletter is distributed bi-weekly newsletter to over 1,100 subscribers. What do you plan to do during the next reporting period to accomplish the goals?We are fabricating an 80 inch bed steam applicator to deal with the wide beds used with Romaine lettuce and spinach. Work on those crops will be planned for 2023. We plan to modify the steam applicator so that it can also be used on standard 42" and 84" wide beds used in Arizona vegetable production. We also plan to replicate the trials that were conducted in Salinas, CA in Yuma, AZ.
Impacts
What was accomplished under these goals?
Band steam accomplishments During the past year of the project we built a prototype band steam applicator and have tested it in carrots and lettuce. Two trials have been initiated in California and two more are in progress as of Sept 30, 2022. In the first two trials the basic performance of the new steam applicator was verified. In the second set of trials still in progress we are evaluating the dimensions of the width and depth of the band that must be treated. Methods. Two trials, one for lettuce and one for carrot were conducted at the University of California Hartnell research station at Salinas, CA from May 2022 to August 2022. For each trial, two treatments replicated four times were established in a complete randomized design: steam and no steam. Steam was injected 2 inches into the soil in 4 inch wide bands centered on the seed lines using a steam applicator built at the Keithly Williams shop at Yuma, AZ. Steam was applied in the lettuce trial, May 3, 2022 and in the carrot trial May 4, 2022. Soil temperatures in the treated area were monitored using HOBO data loggers (Onset computers). Lettuce cultivar Romaine Green tower and carrot cultivar Morelia were seeded on May 5, 2022. Soil samples were collected before and after steaming in the treated area. Soil samples (500g) were collected on one bed per replicate at two sample plots 60 and 120 ft from the edge of the plot. Soil samples were analyzed for abundance of Pythium spp. pre and post treatment using a wet plating method on a semi-selective media. Weed densities and hand weeding times were measured in the treated area May 25, 2022 for both trials and on June 9, 2022 for the lettuce trial only. Weeds were counted by species in two sample zones of 4 inches wide by 3 ft long. In the lettuce trial, time taken to weed two seedlines 30 ft each for each replicate was recorded. For the carrot trial hand weeding was timed in two 5 ft sample plots per bed. The number of diseased and healthy lettuce plants were assessed along a 105 ft section on each bed. Lettuce was harvested on July 15 and 20, 2022. The numbers and weights of lettuce heads, marketable and cull were recorded Data were analyzed in JMP 16.0.0 (SAS Institute, Cary, NC, USA, 2021). Independent sample t-test was used to compare means between treatments. Results. Steam reduced Pythium ultimum abundance by 86% in lettuce and 73% in the carrot trial. Steam reduced weed densities up to 100% in both the lettuce and carrot trials. In the two lettuce weeding times, steam reduced weeding times 43 and 70 percent compared to the no steam control in first and second assessment respectively. Steam reduced hand weeding times by 94% in the carrot trial. On June 27, 2022 the number of plants with symptoms of lettuce drop was higher in the no steam control compared to steam treated beds. Overall INSV (viral disease) was the most prevalent disease followed by Pythium and INSV incidence increased 8 times between the first and last assessment dates. No diseases were observed in the carrot trial. Weight of marketable crop did not differ between the two treatments for both lettuce and carrot trials. The lack of yield differences between the treatments could be a result of low disease pressure for the soil borne pathogens (Pythium spp. and Sclerotinia spp.). Abstract for the band width by depth study To evaluate the effect of steam treatment band width and depth, two factorial design trials for lettuce and carrot were initiated in August and September 2022 respectively at University of California Hartnell Research station (Salinas). In both trials two band widths and three depths steam treatments were evaluated, 2- and 4-inch width for the lettuce trials and 3.5- and 5.5-inch width for the carrot trial and depths 2, 4 and 6 inches for both. In total each trial had six steam treatments and a non-treated control treatment replicated four times (Lettuce, width (W) X depth (D): 2WX2D, 2Wx4D, 2Wx6D, 4Wx2D, 4Wx4D, 4Wx6D) and Carrot (3.5Wx2D, 3.5Wx4D, 3.5Wx6D, 5.5Wx2D, 5.5Wx4D, 5.5Wx6D). For the Lettuce trial, steam was applied on August 2, and August 3, 2022 using a steam applicator built at the Keithly Williams shop at Yuma, AZ was. After steam application, soil temperature was monitored in the treated area using HOBO data loggers (Onset computers). For the Lettuce trial cultivar Romaine Green towers was seeded on August 4, 2022. Soil samples were collected before and after steaming in the treated area. Samples were analyzed for abundance of Pythium spp. pre and post treatment using a wet plating method on a semi-selective media. Weed density and hand weeding time were measured in the treated area on August 18, 2022. Weeds were counted by species in two sampling zones of 4 inches wide and 3ft long. Time taken to weed a 30 ft section of each replicate was recorded. Data were analyzed in JMP 16.0.0 (SAS Institute, Cary, NC, USA, 2021). A factorial analysis was conducted to determine the influence of width, depth and interaction between width and depth on soil temperature, weed densities, hand weeding time and soil pathogen density. Results In the lettuce trial, soil temperature after steam application was influenced by both treatment width and depth but not by the interaction between the two factors. Soil temperatures were higher in the 4-inch wide treated bands than in the 2-inch wide treated bands. Soil temperature were also lower in the 2-inch deep treated bands compared to the 4-inch and 6-inch depths. Band width influenced weed densities for Purslane (P=0.032), nettleleaf goosefoot (P=0.010), Mallow (P=0.018) and Hairy nightshade (P=0.013). Weed densities were higher where 2-inch-wide bands were used than for 4-inch-wide bands (P<0.05). For instance, Purslane density averaged 18,300 weeds/acre in the 2-inch treated bands vs 3,300 weeds/acre in the 4-inch treated bands (P = 0.032). Treatment depth only influenced Hairy nightshade density with higher weed densities observed in the shallow treated beds (2-inch deep) compared to 6-inch deep treated beds (51,300weeds/ acre vs 5,000 weeds/acre) (P=0.021). Overall, weed densities were significantly lower in the steam treated beds compared to the non-treated beds (P = 0.001) Hand weeding time was influenced by treatment width (P=0.001) and depth (P=0.035) but not by the interaction between the two factors (P=0.167). Weeding time was significantly higher in the 2-inch wide band treated beds, (average 137hrs/acre) than in the 4-inch wide band treated beds (average 73hrs/acre). Weeding time was also shorter in the 4-inch-deep treated beds (82hrs/acre) than the 2-inch deep treated beds (138hrs/acre). Overall, weeding time was significantly shorter in all steam treatments compared to non-treated control (P<0.05) Soil pathogen density (Pythium spp) after steam application was influenced by treatment depth (P<0.001) and not by treatment band width (P=0.275) or the interaction between width and depth factors (P=0.263). Pythium spp. density was significantly higher in the 2-inch deep treated beds (231 CFU/g) compared to 4-inch treated beds (13CFU/g) and 6-inchtreated beds (4CFU/g). Overall Pythium spp. propagules were significantly lower in the steam treated beds with post treatment reductions up to 100% in the 2Wx4D and 4Wx6D treatments.
Publications
- Type:
Journal Articles
Status:
Awaiting Publication
Year Published:
2022
Citation:
Guerra N, Fennimore SA, Siemens MC, Goodhue RE. Band Steaming for Weed and Disease Control in Leafy Greens and Carrots. HortScience10.21273/HORTSCI16728-22
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