Progress 01/01/09 to 12/31/13
Outputs
Target Audience: The target audience is primarily flue-cured tobacco producers in the United States. A secondary audience would include agronomists and leaf procurement personnel within the tobacco industry (both domestic and internatiionally) as well as representative of the agi-chemical industry. Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided? Research into better methods for applying MH to tobacco have been extended to on-farm tests with cooperating growers. How have the results been disseminated to communities of interest? Results have been presented at extension education meetings conducted for growers and the industry. The concepts of MH residue management and how cultural practices impact residues is central to the proper crop production agent (CPA) stewardship program of tobacco GAP (good agricultural practices). What do you plan to do during the next reporting period to accomplish the goals?
Nothing Reported
Impacts
What was accomplished under these goals?
A three-year field study was conducted to quantify the impact of MH application timing on green leaf MH residues and the corresponding residue levels in the cured tobacco. Maleic hydrazide is traditionally applied approximately 10 to 14 days after topping of the plants and at least 7 days prior to the first harvest. However, application may be delayed until after the first harvest to avoid potential residues on those leaves. In this study, MH was applied on 3 dates: (1) before the first harvest, (2) immediately following the first harvest, and (3) late after the first harvest. These applications occurred 10 to 12 days apart for this study. In addition to 3 application dates, MH was applied at three times of day: (1) 8:00 a.m. (plants fully turgid and dew present on leaves), (2) noon (plants dry but prior to wilting), and (3) 4 p.m. (plants potentially heat stressed or wilted). Applications of MH (2.25 lbs. a.i. per acre) were made in sequence with contact fatty alcohols and flumetralin. No significant differences were observed in sucker control between the application dates; while the 8 a.m. application timing tended to result in somewhat reduced but acceptable control. The primary focus of this study was the impact of MH application timing (particularly time of day) on green and cured leaf residues. Determination of MH residues on the green leaves is a valuable research tool since it removes the confounding effect of rainfall on residues that occur in cured leaf that may be harvested 7 to 12 weeks after application. Rainfall was closely monitored at the test sites and green leaf samples were repeatedly collected to monitor the weathering of MH on the tobacco. Green leaf samples were collected as the 4th leaf at the top of the plant since this leaf is directly contacted by the spray application. In all incidences, MH application made at 8 a.m. resulted in significantly lower green leaf residues the day following application (prior to any rainfall). Applications made at noon and 4 p.m. were 2- to 6-fold higher, though there was no consistent trend in the relative difference between these two application times. The weathering or reduction of green leaf residues with rainfall exhibited similar trends for the three application times. Residue levels were significantly less with the 8 a.m. application because the initial levels were reduced. Over the three years of the study and three application dates in each year, the impact of a lack of rainfall in the early days ( 2 to 7 days) following MH application was illustrated by reduced weathering and overall higher green leaf residue levels. Cured leaf MH residues were determined in the tobacco from the last harvest which included the leaf position sampled in the green leaf sampling protocol. Factorial analysis of these data revealed that both application date and time of day for the application had a significant effect on cured leaf MH residues. An 80 ppm level is the generally recognized tolerance for MH in cured tobacco. All applications made prior to the first harvest harvested resulted in residues below 80 ppm. The role of aging tobacco leaf tissue on MH uptake is difficult to determine for the three application dates. The timing and amount of rainfall would be expected to differ following the three application dates. In all three years, the earliest MH application date received substantially more rainfall within the first week after the application. Cured leaf residues for all three application times for this date were less than 80 ppm. However, for later application dates, MH residues were below 80 ppm only with the 8 a.m. application time. These results illustrate the critical role plant water status may play in MH uptake and binding on the leaf surface. Application of MH early in the morning while plants are fully turgid and with some surface moisture may be an effective production practice in managing MH residues in flue-cured tobacco.
Publications
- Type:
Other
Status:
Published
Year Published:
2014
Citation:
2013 Regional Flue-Cured Tobacco Sucker Control Tests: Advanced Regional Sucker Control Test. Compiled by Joe Priest. Cooperators include: J. Michael Moore and Steve LaHue (University of Georgia), Dewitt Gooden and Glenn Carnell (Clemson University), Loren Fisher, Matthew Vann, and Scott Whitley (NCSU), and T. David Reed and Grant Coffee (Virginia Tech). 55 pp.
|
Progress 10/01/12 to 09/30/13
Outputs
Target Audience: The target audience is primarily flue-cured tobacco producers in the United States. A secondary audience would include agronomists and leaf procurement personnel within the tobacco industry as well as representatives of the agri-chemical industry. Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided? Research into better methods of applying MH to tobacco has been extended to on-farm tests with cooperating growers. How have the results been disseminated to communities of interest? Results have been presented at extension education meetings conducted for growers and the industry. The concept of MH residue management and how cultural practices impact residues is central to the proper crop protection agent (CPA) stewardship program of tobacco GAP (good agricultural practices). What do you plan to do during the next reporting period to accomplish the goals?
Nothing Reported
Impacts
What was accomplished under these goals?
The results of a second year of study evaluating the optimal timing for MH applications continued to emphasize the critical role of plant moisture status and the timing of rainfall following MH. MH was applied on three dates (1) early (typically following only contact fatty alcohol applications and prior to the first harvest), (2) after first harvest (the day after the first harvest and following contact and flumetralin applications), and (3) late (delayed 14 days after the first harvest). A 2.25 lbs a.i. per acre rate of MH was applied to all treatments. In addition to the three dates of application, MH was applied at three times of day for each application date (8 a.m, noon, and 4 p.m.) The intent was to have different plant conditions present for each application (dew covered plants vs. dry plants, and prior to wilting vs. wilted or stressed plants). No significant differences were observed in sucker control between the application dates; while the 8 a.m. timing tended to provide somewhat reduced control. The primary focus of the study was on the treatment impact on green and cured leaf residues of MH. The fourth leaf of plants from the plot was sampled at varying intervals following MH application: the day following the application, and days following significant rainfall. Such sampling allowed for a description of the natural weathering of the MH residues on the tobacco. For all application dates, the 8 a.m. application resulted in significantly lower green leaf residues of MH the day following the application. Residues were 50 to 80 percent lower than applications made at noon and 4 p.m. No substantial differences were observed between the latter two applications times. Residues on green tobacco samples continued to show a weathering or decline over the 28 to 56 days following the three application dates. On the date of the last sampling of green leaves prior to harvest, only the 8 a.m. application time was below the 80 ppm residue tolerance for MH. Subsequent residues on the cured tobacco (fourth harvest) were 60 ppm or less for the early application (8 a.m., noon, and 4 p.m.). For later application dates, only applications made at 8 a.m. were below 80 ppm. Further weathering of residues on the approximately 1 month period between the last green leaf sampling and harvest occurred primarily where green leaf residues exceeded 100 ppm. Residues less than this amount may represent the quantity absorbed into the leaf tissue and thus not subject to weathering factors such as rainfall.
Publications
- Type:
Other
Status:
Other
Year Published:
2013
Citation:
2012 Regional Flue-Cured Tobacco Sucker Control Tests: Advanced Regional Sucker Control Test. Compiled by Joe Priest. Cooperators include: J. Michael Moore and Steve LaHue (University of Georgia), Dewitt Gooden and Glenn Carnell (Clemson University), Loren Fisher, Matthew Vann, Scott Whitley (NCSU), and T. David Reed and Grant Coffee (Virginia Tech). 51 pp.
|
Progress 10/01/11 to 09/30/12
Outputs
OUTPUTS: Maleic hydrazide (MH) is the stalwart of effective sucker control under the widest range of conditions and with a minimal amount of hand labor. The highly systemic activity of MH makes it effective when other compounds, local-systemics (flumetralin and butralin) and contact fatty alcohols, are not effective because of crooked or leaning plants. However, the residues of MH in cured tobacco are significantly higher than other compounds and can be rather unpredictable. Plant related factors impacting MH residues are not well understood and are further impacted by the timing and intensity of rainfall following application. A study was conducted in 2010 to investigate plant factors impacting sucker control obtained from MH applications and the resulting residue levels. MH was applied (1.5 lbs a.i. per acre) at three different times of the day: (1) 8:00 a.m. - before plants had dried from overnight dew and were still fully turgid, (2) noon - plant foliage dry, temperatures high but plants not wilted or excessively stressed, and (3) 4:00 p.m. - plants potentially stressed and wilted from afternoon heat. Additionally, applications were made on three different dates relative to the first harvest of leaves from the bottom of the stalk. The application dates included: (1) prior to first harvest, (2) 6 days after first harvest, and (3) 14 days after first harvest. Treatments were evaluated for sucker control at the end of season and MH residues on both green and cured leaf samples. Green leaves were sampled periodically after applications to quantify MH residues relative to rainfall. Samples were taken the day after each application and following significant rainfall events. Such green leaf sampling allows for better evaluation of treatment effects without the compounding influence of rainfall that occurs with cured leaf sampling PARTICIPANTS: Additional sucker control research trials were conducted under the auspices of the Regional Tobacco Plant Growth Regulator Committee of the Tobacco Workers' Conference. TARGET AUDIENCES: Tobacco growers, primarily flue-cured, are the primary target audience of this research. Additional audiences include tobacco industry representatives as well as individuals in the agri-chemical industry supplying tobacco sucker control chemicals. Research data were presented at Extension tobacco grower education meetings as well as industry sponsored grower meetings. PROJECT MODIFICATIONS: Not relevant to this project.
Impacts
The time of day for MH application and the timing of these applications with respect to the first harvest had a significant impact on both sucker control and MH residues. Sucker control resulting from the early MH application (before first harvest) was significantly less than later applications (101 lbs of sucker per 100 plants compared to 26 and 20 lbs). Residue sampling of green leaf following the MH applications revealed significantly higher residues with the 4:00 p.m. application and lowest with the 8:00 a.m. application timing. Continued sampling revealed a pattern of MH degradation with rainfall occurring over the days and weeks after application (up to 35 days). Delay in MH application until 2 weeks after first harvest resulted in MH residues of 95 ppm on leaf grade tobacco compared to 27 and 34 ppm for the earlier application timings. Time of day for MH application had a greater impact on cured leaf MH residues than the corresponding level of sucker control. Sucker control did not significantly differ between applications at 8:00 a.m. and noon, but was significantly lower for applications made at 4:00 p.m. The response was more evident for applications made before or shortly after the first harvest compared to applications made 14 days after first harvest. This response appeared more dependent on changes in leaf physiology or age more so than rainfall occurring after MH applications as all applications had at least 1 in. of rainfall or irrigation within the first week after application.
Publications
- 2011 Regional Flue-Cured Tobacco Sucker Control tests: Advanced Regional Sucker Control Test. 2012. Compiled by Joe Priest. Cooperators include: J. Michael Moore and Steve LaHue (UGa), Dewitt Gooden and Glenn Carnell (Clemson Univ.), Joe Priest, Loren Fisher, and Scott Whitley (NCSU), and T. David Reed and Grant Coffee (Virginia Tech). 30 pp.
|
Progress 10/01/10 to 09/30/11
Outputs
OUTPUTS: Maleic hydrazide (MH) remains an important tobacco sucker control chemical due to the compound's high level of systemic activity. However, chemical residues that are one to three-orders of magnitude higher than other crop protection agents (CPAs) used on tobacco have long been a source of concern for the industry. Relatively little has changed in the application procedure for MH other than the use of low pressure, full-cone spray tips rather than hollow-cone tips for high pressure application. The result is a spray pattern of coarser droplets with potentially less of the spray material being deposited on the underside of leaves and thus exposed to less natural weathering. An alternative application method called the conveyor application was initially evaluated in 2009 and further field tested in subsequent years. The conveyor application technique involves enclosing the typical three-nozzle spray tip arrangement in a metal shroud or hood with a 12 to 16 inch wide by 1 inch opening at the bottom. The spray pattern from the nozzles strike the inside of the hood and runs out the bottom as very large size droplets in an even band directed over the center of the plants. The spray pattern appears as a conveyor belt being laid down the row of plants, hence the name of the application method. The result is a higher portion of the spray material being directed down the plant stalk with minimal application to the underside of the leaves and to the upper leaf surfaces below the top 5 to 6 leaves. Field tests were conducted to evaluate the impact of the conveyor application of MH on tobacco sucker control and the corresponding residues of MH on both green leaf tissue and cured tobacco. If the conveyor application proved to be more effective than the traditional method, perhaps the application rate of MH could be reduced to further impact residue levels. Rainfall occurring in the weeks following MH application will have an influence on cured leaf residues and confound the impact of the application treatment. In order to better quantify treatment effects of MH residues, green leaves were sampled in the days following MH treatment applications but before rainfall. Results of field tests of the conveyor application technique have been disseminated through Extension grower education meetings, field day programs, industry sponsored grower meetings, and industry newsletters. PARTICIPANTS: Some of the field research trials conducted as part of this project have been conducted in cooperation with members of the Regional Tobacco Growth Regulator Committee conducted under the auspices of the Tobacco Workers' Conference. TARGET AUDIENCES: Tobacco growers, primarily flue-cured but also burley tobacco, are the primary target audience for this research. Additional audiences include tobacco industry representatives as well as individuals in the agri-chemical business supplying tobacco sucker control chemicals. Demonstrations of the conveyor application technique were conducted at field-days attended by each of the above audiences. Research data presented at Extension tobacco grower education meetings as well as industry sponsored grower meetings. PROJECT MODIFICATIONS: The most significant modification to this project has been the evaluation of the conveyor spray application procedure. The evaluation of potential new sucker control chemicals has been de-emphasized since the likelihood of a company labelling such a compound is highly unlikely.
Impacts
The initial field trials of the conveyor application of MH have proved very successful. Sucker control with equal rates of MH with and without the conveyors were unchanged (94%). No significant impact on sucker control (96%) was observed with a reduced rate of MH (1.125 pounds active ingredient per acre compared to 1.5 lbs a.i.) Subsequent tests to quantify the impact on MH residues were conducted. Residues present on green leaf samples taken 3 days after application were reduced by more than 40 % at an application rate of 2.25 lbs a.i. The relative difference was reduced by 15% with an application rate of 1.5 lbs a.i. A similar trend was observed with MH residues on the cured leaves. At the 2.25 lbs a.i. rate, residues were reduced by 64% on cutter leaves (mid-stalk) and 69% on tip leaves (top of stalk) using the conveyor application hoods. No significant differences were observed between the two application methods at an application rate of 1.5 lb a.i., though residues were generally reduced by two-thirds at this rate. All cured leaf residues were well below the industry tolerance level of 80 ppm using the conveyor application.
Publications
- 2010 Regional Flue-Cured Tobacco Sucker Control Tests: Advanced Regional Sucker Control Test. 2011. Compiled by Joe Priest. Cooperators include: J. Michael Moore and Steve LaHue (UGa) Dewitt Gooden and Glenn Carnell(Clemson), Joe Priest, Loren Fisher, Sandy Stewart and Scott Whitley (NCSU), and T. David Reed and Grant Coffee (VT). 35 pp.
|
Progress 10/01/09 to 09/30/10
Outputs
OUTPUTS: The primary focus of sucker control tests was the evaluation of an alternative sucker control application technique. Over-the-top foliar applications of sucker control chemicals are made with three nozzles over the row. A new technique described as the "conveyor" application utilizes a metal shroud to enclose the same 3-nozzle arrangement and an approximately 12 in. band of spray material is deposited from a narrow opening at the bottom of the shroud. The result is a spray pattern composed of very coarse droplets directly over the plant stalk. Full coverage of the plant foliage is avoided as an increased amount of spray material is deposited on the basal portion of the leaves and directed down the stalk of the plant. Conveyor applications of contact fatty alcohols, flumetralin, and maleic hydrazide (MH) were evaluated. Sequential applications of contact fatty alcohols are made at concentrations of 4 to 5 percent with application rates of 50 gal. per ac. Test results show sucker control using the conveyors with fatty alcohols applications rates of both 50 and 35 gal. per ac. were similar to that resulting from 50 gal. per ac with the traditional 3-nozzle application technique. Similar results were obtained with flumetralin using the conveyor application. No difference in sucker control was observed between 0.42 lbs a.i. per ac of flumetralin and the conveyor application technique compared to 0.6 lbs a.i. per ac and the standard application procedure, 95 and 94 percent control respectively. No differences in sucker control were observed with a 1.5 lbs a.i. per ac rate of MH with and without the conveyor spray application, 94 percent control for both. Reducing the MH rate to 1.125 lbs a.i. per ac using the conveyor application also provided a similar level of control (96 percent). A major point of interest for this test was the MH residues levels in the cured tobacco and a weighted sample of the cured tobacco were collected for each harvest made after MH was applied. However, application treatment differences could not be determined due to the fact that a majority of samples contained residues below laboratory detection limits. Results of this research have been disseminated to growers through Extension production meetings, industry sponsored grower meetings, and research station field days. PARTICIPANTS: The research reported herein was conducted at the Virginia Tech Southern Piedmont Center and was funded by Philip Morris International and the Virginia Bright Flue-Cured Tobacco Board. TARGET AUDIENCES: The target audience for this project is primarily tobacco growers as well as the pesticide manufacturers that supply sucker control products, vendors that supply growers with application equipment, and tobacco buyers and manufacturers. PROJECT MODIFICATIONS: Due to the favorable results of earlier preliminary studies, a greater emphasis will be given to the evaluation of the conveyor spray application technique. Less priority will be given to evaluation of any new sucker control materials as the likelihood of labeling such a product is remote.
Impacts
Test results indicate the potential to reduce application rates of both contact fatty alcohol and flumetralin by 30 percent with the conveyor application technique without adversely impacting sucker control. Although residues of these compounds are not generally of concern, the opportunity to reduce application rates has positive benefits with regard to reducing the quantity of pesticide active ingredients applied in the environment. Additionally, the cost of sucker control for the grower is correspondingly reduced. Sucker control obtained with the conveyor application of MH was equivalent to the standard application method and a treatment with 1.125 lbs a.i. per ac with the conveyor was not significantly different than the 1.5 lbs a.i. per ac standard. Unfortunately MH residues in the cured leaf were insignificant to make judgments on the impact of the conveyor application on residues. Future research will include earlier green leaf sampling for MH residues to avoid confounding effects of later season rainfall on residues. An additional benefit observed with the conveyor application was reduced disturbance of the spray pattern by the wind, thus reducing spray drift and off-target application.
Publications
- 2009 Regional Flue-Cured Tobacco Sucker Control Tests: Advanced Regional Sucker Control Test. 2010. Compiled by Joe Priest. Cooperators include: J. Michael Moore and Steve LaHue (UGa) Dewitt Gooden (Clemson), Joe Priest, Loren Fisher, and Scott Whitley (NCSU), and T. David Reed and Grant Coffee (VT). 24 pp.
|
Progress 10/01/08 to 09/30/09
Outputs
OUTPUTS: A cooperative maleic hydrazide (MH) field trial was conducted as part of the Regional Flue-Cured Tobacco Growth Regulator Committee. Funding for extensive MH residue analysis was provided from the Tobacco Education and Research Council (TERC). The trial was described as the Regional MH Wash-off Study with test sites in Georgia, South Carolina, North Carolina, and Virginia. The MH Wash-off Study protocol involved an application of MH at a rate of 2.25 lbs a.i. per acre applied after the first harvest of leaves at the bottom of the stalk. MH was applied with and without the addition of a spray surfactant to investigate the effect of such adjuvants on sucker control and MH residues. A simulated rainfall wash-off treatment (0.1 ac-in.) was applied at 3, 8, 24, and 96 hours after the MH treatment application. Green leaf samples where collected from respective field plots following each wash-off application and from corresponding plots not receiving a wash-off treatment application. Following harvest completion, sucker growth was quantified to evaluate the effect of MH wash-off timing and the addition of a spray surfactant on sucker control and cured leaf samples. PARTICIPANTS: The MH Wash-off Study reported herein was conducted under the auspices of the Regional Tobacco Growth Regulator Committee of the Tobacco Workers' Conference. The principle state cooperators of this program include: J. Michael Moore (UGa), Dewitt Gooden (Clemson Univ.), Loren Fisher (NCSU), and T. David Reed (VT). Funding for the MH residue testing was provided by the Tobacco Education and Research Council (TERC). A presentation of the results from this study is planned for the 44th Tobacco Workers' Conference and the Burley Tobacco Expo in Lexington, KY. TARGET AUDIENCES: The target audience for this project is tobacco growers, primarily but not limited to flue-cured tobacco. Results of this research are currently being shared with growers through Extension tobacco production meetings. PROJECT MODIFICATIONS: Not relevant to this project.
Impacts
Data for sucker control, green leaf MH residues, and cured tobacco MH residues were obtained from three of the four tests sites (SC, NC, VA). A maximum potential MH residue level of 921 ppm was obtained from green leaf tissue sampled in NC 3 hours after MH application. Comparative values were 746 and 887 ppm for SC and VA, respectively. In the absence of the wash-off treatment or natural rainfall, residue levels did not vary significantly at 3, 8, and 24 hours post MH application. Values at 96 hours were lower for NC and VA while rainfall occurred prior to 96 hours in SC and samples were not taken. Average green leaf MH residue levels in VA at 96 post wash-off were 648 ppm. Heavy rainfall (3.75 in.) occurred approximately 7 days after MH application and green leaf samples taken afterwards had an average MH residue level of 327 ppm. The assumption would be that this represents the level of MH that had been absorbed by the leaves as any chemical present on the surfaces of the leaves would have been washed off. The addition of the spray surfactant to the MH application did not appear to have any effect on MH residue or the resulting level of sucker control. With and without the spray surfactant, sucker control was significantly reduced by wash-off treatments at 3 and 8 hours post MH application. Sucker control resulting from the 24 hours wash-off treatment was comparable to no wash-off while residue levels were reduced by 24 to 62 percent. Analyses of the MH residues from the cured leaf samples have not been completed. Preliminary results suggest that the cured leaf data will follow the trends observed with the green leaf residue data. Results of the study have shown the effect of a simulated rainfall wash-off on MH residue levels. The use of a spray surfactant did not have a beneficial effect on rainfastness and subsequent sucker control. For growers with recurring problems with excessive MH residues, the study suggests that an overhead irrigation the day after MH application may be a potential management practice.
Publications
- 2008 Regional Flue-Cured Tobacco Sucker Control Tests: Advanced Regional Sucker Control Test. 2009. Compiled by Joe Priest. Cooperators include: J. Michael Moore and Steve LaHue (UGa) Dewitt Gooden (Clemson), Joe Priest, Loren Fisher, and Scott Whitley (NCSU), and T. David Reed and Grant Coffee (VT). 36 pp.
|
|