Progress 10/01/03 to 09/30/08
Outputs
OUTPUTS: Results of these studies were presented at entomology meetings (Annual and regional ESA meetings, Florida Entomology Annual Meeting, Rocky Mountain Conference of Entomologists, etc.). Field days were used to disseminate this info to sweet potato growers at the Sweet Potato Research Station. Presentations were made at grower meetings every year. The RAMP grant project had an outreach component that targeted growers and scouts with information concerning insect IPM in sweet potatoes. Products of these research efforts included:1) a sampling protocol and treatment threshold for rootworm control to be used by growers and scouts, 2) information on the expected % damage reduction for all the labeled insecticides for rootworm and white grubs used as preplant or as layby applications, 3) a pheromone monitoring system for Phyllophaga, 4) facilitation of new insecticide labeling on sweet potato (bifenthrin, Admire, Assail, Spintor, Rimon, Leverage, Intrepid, Hero, Endigo, Avaunt, Coragen) through product evaluation in the sweet potato system. PARTICIPANTS: Richard Story, principal investigator, entomology professor, conducted the research in conjunction with Jeff Murray, Research Associate, and Abner Hammond, professor. Collaborators include Tara Smith, assistant professor, Sweet Potato Research Station, Don Labonte, professor, Horticulture Department, Chris Clark, professor, Plant Pathology Department, Clinton Hegwood, Burden Research Center, many sweet potato growers, and the Sweet Potato Growers Association. TARGET AUDIENCES: Sweet potato and vegetable growers, packers, and shippers in Louisiana and elsewhere in the US where vegetables are grown. PROJECT MODIFICATIONS: Not relevant to this project.
Impacts
Research conducted on sweet potato insect pest management systems in this project helped growers reduce losses due to insect pests, enabled growers to use insecticides more effectively, and increased their profitability. We focused on the timing of preplant soil incorporated insecticide treatments and the efficacy of lay-by applications (made 3-4 weeks after planting). Preplant insecticides must be applied within a few days of planting to be effective. Most growers apply these treatments a month in advance of planting due to concerns for weed control and moisture conservation. Our research shows that very little control was obtained when these insecticides were used in this way. Lay-by applications may be used as an alternative to the preplant application. We are continuously evaluating new compounds to determine if these new products are effective. Another focus was the development of sampling methods for the adult stages of the soil insect pests. With the banded cucumber beetle we determined the relationship between adult abundance during the growing season and subsequent root damage by rootworms. We provided growers and scouts with a treatment threshold of 2 beetles/ 100 sweeps. This should limit their rootworm damage to no more than 5%. A sweet potato host plant resistance project involved screening germplasm from a polycross nursery for resistance to the sweet potato weevil. Each year the best performers are kept for the next year's nursery. The ultimate goal is a high yielding, weevil resistant cultivar that can be grown in south Louisiana without the use of insecticides. Research from this project provided growers with information on managing their soil insect pests. This includes Information on the effect of timing of insecticide application and product selection on expected damage reduction, monitoring systems for adult stages of these pests with treatment thresholds designed to limit root damage to no more than 5%. This system has been demonstrated in grower's fields. A 3 year comparison between untreated and treated plots revealed a 63% damage reduction where growers followed treatment thresholds and recommended IPM practices. On an average field (10% root damage in untreated plots, 250 bushels per acre, $15.00 per bushel), a savings of about $236.00 per acre was realized.
Publications
- Story, R. N., A. M. Hammond and M. J. Murray. 2008. Evaluation of insecticides for control of cucumber beetles and white grubs in sweet potatoes, 2007. Arthropod Management Tests 33:E53.
- Story, R. N., A. M. Hammond , M. J. Murray and T. P. Smith. 2008. Evaluation of preplant and foliar insecticides in five grower fields for control of banded cucumber beetles and white grubs in sweet potatoes, 2007. Arthropod Management Tests 33:E52.
- Story, R.N., M.J. Murray, A.M. Hammond, D.R. LaBonte. 2008. Evaluation of sweet potato germplasm for resistance to sweetpotato weevil, 2007. Arthropod Management Tests 33:M3
- Hammond, A. M., R. N. Story and M. J Murray. 2008. Evaluation of preplant and lay-by insecticides for control of banded cucumber beetles and white grubs in sweet potatoes, 2007. Arthropod Management Tests 33:E18.
- Smith, Tara P., A. M. Hammond, R. N. Story and E. Burris. 2008. Insect Pest Management in Louisiana Sweet Potatoes. Louisiana State University Agricultural Center, Pub. No. 2620.
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Progress 01/01/07 to 12/31/07
Outputs
OUTPUTS: The sweet potato host plant resistance project involves screening germplasm from a polycross nursery for resistance to the sweet potato weevil. Each year the best performers are kept for the next year's nursery. Over time we hope to obtain a line with weevil resistance and good horticultural characteristics. The ultimate goal is a high yielding, weevil resistant cultivar that can be grown in south Louisiana without the use of insecticides. Research conducted on sweet potato insect pest management systems will help growers reduce losses due to insect pests, enable growers to use insecticides more effectively, and increase their profitability. We have focused on the timing of preplant soil incorporated insecticide treatments and the efficacy of lay-by applications (made 3-4 weeks after planting). Preplant insecticides must be applied within a few days of planting to be effective. Most growers apply these treatments a month in advance of planting due to concerns for weed
control and moisture conservation. Our research shows that very little control is obtained when these insecticides are used in this way. Lay-by applications may be used as an alternative to the preplant application. Research findings have been disseminated to growers through extension publications and presentations made at grower meetings during the year.
TARGET AUDIENCES: Sweet potato and vegetable growers, packers, processors, and shippers in Louisiana and elsewhere in the US where vegetables are grown.
Impacts
A whole root, no choice bioassay procedure was used for screening 36 sweet potato accessions for resistance to the sweetpotato weevil. Beauregard was the standard susceptible commercial variety. It had 31 mean weevils emerging. 99-35 (Evangeline, a new variety) was the most susceptible, with 46.4 weevils emerging. The lines 06-42 and 06-40 had the fewest number of weevils (0.8 and 2.8, respectively). Field trials were conducted during 2007 in 5 grower fields to determine the efficacy of Capture used as a preplant, soil incorporated insecticide and to evaluate the effectiveness of the growers post planting insecticide spray program. Four treatments were evaluated: 1) Capture preplant, no foliar sprays, 2) Capture preplant followed by foliar sprays, 3) no Capture preplant with foliar sprays, and 4) no Capture preplant and no foliar sprays (control). Only 2 of the growers significantly reduced insect damage with the treatments when compared to the control. Field trials
were conducted during 2007 in 3 grower fields to determine the efficacy of insecticides used as lay-by applications for control of cucumber beetles and white grubs on sweet potato. The lay-by treatments were: Lorsban 4E (4 pt), Capture 2EC (9.6 and 19.2 oz.), Admire 2E (24 oz.), and Mach II 2SC (1 gal.).In each commercial field there were four separate replicated tests set up adjacent to each other. Test 1 had the lay-by treatments used as a stand-alone (no preplant or foliar sprays; control received no insecticides), Test 2 had the lay-by treatments with foliar sprays added (control had no lay-by but received foliar sprays), Test 3 had the lay-by treatments with a preplant application of Capture (19.6 oz.) added(control had no lay-by but received the Capture preplant application), and Test 4 had the lay-by treatments with both the preplant and foliar sprays (control had no lay-by but received both the Capture preplant application and foliar sprays). Lay-by applications were made 4-6
weeks after planting. Across all tests, only Admire performed consistently well for both rootworms and white grubs. Capture and Lorsban were inconsistent in their performance. A field trial was conducted during 2007 at the LSU AgCenter Burden Research Station, Baton Rouge, Louisiana, to determine the efficacy of five soil incorporated insecticides for control of banded cucumber beetles and white grubs on sweet potato. These insecticides were used as either preplant or lay-by applications. With respect to white grubs, all treatments had less damage than the untreated control. However, only the Lorsban (preplant), Capture (lay-by), Admire (lay-by), and Lorsban (preplant) plus Capture (lay-by) treatments were significant. With respect to rootworms, most treatments had less damage than the controls. However, none of these treatments were significantly different.A comparison between treated and untreated plots in our studies revealed a 60 % reduction in soil insect damage where
insecticides were applied in a timely manner. On an average field (10% root damage in untreated plots, 250 bushels per acre, $18.00 per bushel), a savings of about $400.00 per acre was realized.
Publications
- Hammond, A.M., R.N. Story, M.J. Murray. 2006. Evaluation of preplant insecticides for control of banded cucumber beetles and white grubs in sweet potatoes, 2006. Arthropod Management Tests 32:E47.
- Smith, Tara P., A. M. Hammond, R.N. Story and E. Burris. 2007. Sweet potato Insect Pests in Louisiana. Louisiana State University Agricultural Center, Pub. No. 2620
- Smith, Tara P., A. M. Hammond, R. Story and E. Burris. 2007. Bug Biz, Pest Management and Insect Identification Series. Managing cucumber beetles (rootworms), in Louisiana sweet potato production. Louisiana State University Agricultural Center, Pub. No. 2960.
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Progress 01/01/06 to 12/31/06
Outputs
We have completed a 3 year survey of sweet potato grower pest management programs in 63 fields in Louisiana. Rootworms (Diabrotica balteata) were the most damaging pest across all years. Damage by rootworms in untreated plots was 14.4%, 14.3%, and 17.1%, respectively in 2004, 2005, and 2006. The spotted cucumber beetle accounted for less than 20% of the total Diabrotica collected in sweep nets. White grubs were second in importance in untreated plots, with 2.6%, 2.7%, and 9.1% root damage, respectively, in 2004, 2005, and 2006. Other insect pests (flea beetles, wireworms, sugarcane beetles, and whitefringed beetles) damaged less than 1% of the roots across the 3 year period. Control of Diabrotica balteata with grower applied preplant and foliar applications resulted in an average reduction in damage of 73%, 63%, and 68%, respectively, in 2004, 2005, and 2006. The preplant only treatments (no foliar sprays) did not have a significant effect on Diabrotica damage
relative to the untreated controls (2005: control = 19.6%, preplant = 26%; 2006: control = 21.1%, preplant = 16.4%) These data suggest that the preplant soil-incorporated insecticides contribute little if any to rootworm control. Control of white grubs with the grower applied preplant and foliar applications resulted in an average reduction in damage of 73%, 50%, and 0%, respectively, in 2004, 2005, and 2006. White grubs were more prevalent in 2006 (control mean = 9.1%) compared to 2004 (2.6%) and 2005 (2.7%). The preplant only applications provided a 40% damage reduction in 2005 and no reduction in 2006 relative to the untreated controls. The contribution that both the preplant and foliar applied insecticides make to damage reduction was variable, ranging from moderate to none. The predominant insect collected with sweep nets was the banded cucumber beetle. Diabrotica counts (mean beetles/100 sweeps) averaged across the season correlated positively with root damage. Using regression
analysis, the relationship between these 2 variables were explored using linear regression (forcing the line through the origin). A predictive equation was obtained that related sweep count numbers to root damage, and indicated a treatment threshold of 2 beetles/100 sweeps. Field trials were conducted to determine the efficacy of three soil incorporated insecticides for control of banded cucumber beetles and white grubs on sweet potato. Insecticides were applied according to the label rate (Mocap: 3 lbs and 6 lbs, Lorsban: 4 pt, Capture 0.3 lb). At harvest all roots in the middle row were dug and evaluated for insect damage. With respect to banded cucumber beetle control, Mocap at both the low rate and the high rate had damage similar to the control. Lorsban had fewer damaged roots relative to the control, but Capture was the only insecticide that was associated with significantly less damage than the control. With respect to white grub control, both Mocap and Capture had less damage
than the control, but only Lorsban was associated with significantly less damage than the control.
Impacts
Research conducted on sweetpotato insect pest management systems will help growers reduce losses due to insect pests, enable growers to use insecticides more effectively, and increase their profitability. A comparison between treated and untreated plots in our study revealed a 63 % reduction in soil insect damage where growers followed treatment thresholds. On an average field (10% root damage in untreated plots, 250 bushels per acre, $15.00 per bushel), a savings of about $236.00 per acre was realized.
Publications
- Diagne, A., R.N.Story, and A.M. Hammond. 2006. Partial Life Cycle of Phyllophaga ephilida Say (Coleoptera: Scarabaeidae) in South Louisiana. J. Entomol. Sci. 41(4):409-411.
- Diagne, A., R.N.Story, and A.M. Hammond. 2006. Adult Phyllophaga ephilida Say Host Plant Feeding Preference. Florida Entomologist. 83(3):391-395.
- Hammond, A.M., R.N. Story, and M.J. Murray. 2006. Evaluation of Mocap for Phytotoxicity in Sweet Potatoes, 2005. Arthropod Management Tests 31:E66.
- Story, R.N., M.J. Murray, A.M. Hammond, and D.R. LaBonte. 2006. Evaluation of Sweet Potato Germplasm for Resistance to Sweetpotato Weevil, 2005. Arthropod Management Tests 31:M6.
- Story, R.N., A.M. Hammond, M.J. Murray, and D.R. LaBonte. 2006. Field Evaluation of Sweet Potato Cultivars for Resistance to Sweetpotato Weevils and Banded Cucumber Beetles, 2005. Arthropod Management Tests 31:M7.
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Progress 01/01/05 to 12/31/05
Outputs
A study was conducted to determine the treatment threshold for adult cucumber beetles in sweet potatoes. The effect of harvest date on root damage also was investigated. Treatments consisted of 1) an untreated strip (no insecticides) 2) a strip in which only preplant insecticides were applied, and 3) an area where both preplant and foliar sprays were used. Insects were sampled with sweep nets at biweekly intervals through the growing season (4 sets of 25 sweeps in both treated and untreated strips) in 21 commercial fields. Diabrotica and whitefringed beetles were collected and counted. Root damage was sampled by digging roots in six locations (15 foot section) in each treatment. Roots were returned to the lab for washing and damage evaluation. Damage present on each root was recorded (Diabrotica, wireworm, Phyllophaga, flea beetle, and whitefringed beetle). Diabrotica predominated in sweep net counts, followed by whitefringed beetles. Fewer insects were collected in
treated strips (mean of 0.54 beetles) as compared to untreated strips (mean of 0.69 beetles). Mean Diabrotica adult capture through the season was positively correlated with percent rootworm damage in plots (r = 0.62). Day of harvest was not correlated with rootworm damage. A regression analysis using Diabrotica counts and harvest date as independent variables and percent rootworm damaged roots as the dependent variable was conducted. The model predicts percent rootworm damage as a function of mean Diabrotica in sweep nets and projected harvest date (r2 = 0.37). A whole root, no choice bioassay test was used for screening 16 sweetpotato accessions for resistance to the sweetpotato weevil. Individual roots were placed in one quart, cylindrical (3 3/8" dia) paper containers. A randomized complete block design was used where blocks were replicated through time for a total of 10 replications. Six female weevils were placed with the root in each container for 4 days. Starting at
approximately 30 calendar days after the first day of exposure to the weevils, containers were examined on Monday, Wednesday, and Friday to count the number of emerging adults. Counts were made for a period of 3 weeks, for a total of 9 counts. The mean number of weevils emerging from sweetpotato roots varied considerably. Differences in weevil emergence may be a function of oviposition non-preference, larval antibiosis, or a combination of both. Beauregard is the standard commercial variety. It had 25.6 mean weevils emerging. 03-449 was the most susceptible, with 36.4 weevils emerging. The lines 03-438 and 03-436 had the fewest number of weevils (11.2 and 10.4, respectively). Regal, a resistant cultivar, had a mean of 6.6 weevils/root.
Impacts
Research conducted on sweetpotato insect pest management systems will help growers reduce losses due to insect pests, enable growers to use insecticides more effectively, and increase their profitability. A comparison between treated and untreated plots in our study revealed a 63 % reduction in soil insect damage where growers followed treatment thresholds. On an average field (10% root damage in untreated plots, 250 bushels per acre, $15.00 per bushel), a savings of about $236.00 per acre was realized.
Publications
- Story, R.N., Hammond, A.M., and M.J. Murray. 2005. Evaluation of sweet potato germplasm for resistance to sweetpotato weevil, 2004. Arthropod Management Tests 30:M5: http://www.entsoc.org/Protected/AMT/AMT30/Text/amt30.aspx?Report=M5.h tm
- Story, R.N., Abner Hammond, Deana Sexson, Jeff Wyman, Carlos Granadino, Susan Rice Mahr, Catherine Eastman, and William Chaney. 2005. Root Crops, pp 108-122. In: Vegetable Insect Management. Rick Foster and Brian R. Flood, Eds. Willoughby, Ohio. Meister Media Worldwide. 264 pp.
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Progress 01/01/04 to 12/31/04
Outputs
A study was conducted to determine the relationship between insect counts in sweetpotato grower fields and subsequent root damage at harvest. The effect of harvest date and soil texture on root damage was also investigated. Growers left an untreated strip (no insecticides) along the side of each field. Insects were sampled with sweep nets at biweekly intervals through the growing season (4 sets of 25 sweeps in both treated and untreated strips) in 20 commercial fields. Diabrotica and whitefringed beetles were counted. Root damage was sampled by digging roots in six locations (15 foot section) in both treated and untreated strips. Roots were returned to the lab for washing and damage evaluation. Damage present on each root was recorded (Diabrotica, wireworm, Phyllophaga, flea beetle, and whitefringed beetle). Soil characteristics were measured with soil samples taken from each field. Percent organic matter, sand, silt, and clay were determined. Diabrotica predominated
in sweep net counts, followed by whitefringed beetles. Significantly fewer insects were collected in treated strips (mean of 0.53 beetles) as compared to untreated strips (mean of 0.91 beetles). Mean Diabrotica adult capture through the season was positively correlated with percent rootworm damage in plots (r = 0.41). Day of harvest was likewise positively correlated with rootworm damage (r = 0.43). A regression analysis using Diabrotica counts and harvest date as independent variables and percent rootworm damaged roots as the dependent variable was conducted. A separate analysis was used in treated (r2 = 0.37) and untreated strips (r2 = 0.31). The model predicts percent rootworm damage as a function of mean Diabrotica in sweep nets and projected harvest date. Soil organic matter and percent sand, silt, and clay were not correlated with rootworm damage. A whole root, no choice bioassay test was used for screening 19 sweetpotato accessions for resistance to the sweetpotato weevil.
Individual roots were placed in one quart, cylindrical (3 3/8" dia) paper containers. A randomized complete block design was used where blocks were replicated through time for a total of 10 replications. Six female weevils were placed with the root in each container for 4 days. Starting at approximately 30 calendar days after the first day of exposure to the weevils, containers were examined on Monday, Wednesday, and Friday to count the number of emerging adults. Counts were made for a period of 3 weeks, for a total of 9 counts. The mean number of weevils emerging from sweetpotato roots varied considerably. Differences in weevil emergence may be a function of oviposition non-preference, larval antibiosis, or a combination of both. Beauregard is the standard commercial variety. It had 20.4 mean weevils emerging. 03-440 was the most susceptible, with 37.0 weevils emerging. The lines 03-407 and 03-452 had the fewest number of weevils (7.8 and 6.0, respectively)
Impacts
Research conducted on sweetpotato insect pest management systems will help growers reduce losses due to insect pests, enable growers to use insecticides more effectively, and increase their profitability. A comparison between treated and untreated plots in our study revealed a 70% reduction in soil insect damage where growers followed treatment thresholds. On an average field (10% root damage in untreated plots, 250 bushels per acre, $15.00 per bushel), a savings of about $250.00 per acre was realized.
Publications
- Mao, L., L.E. Jett, R.N. Story, A.M. Hammond, J.K. Peterson, and D.R. LaBonte. 2004. Influence of drought stress on sweet potato resistance to sweetpotato weevil and storage root chemistry. Florida Entomologist 87(3):261-267.
- Hammond, A.M., R.N. Story, and M.J. Murray. 2004. Evaluation of preplant insecticides for control of white grubs, banded cucumber beetles, and whitefringed beetles, 2003. Arthropod Management Tests29:E80: http://www.entsoc.org/Protected/AMT/AMT29/Text/amt29.asp.?Report=E80
- Story, R.N., A.M. Hammond, and M.J. Murray. 2004. Evaluation of insecticides for control of sweet potato weevils in weevil infested roots at seed bed establishment, 2003. Arthropod Management Tests29:L15: http://www.entsoc.org/Protected/AMT/AMT29/Text/amt29.asp.?Report=L15
- Story, R.N., Hammond, A.M., and M.J. Murray. 2004. Evaluation of sweet potato germplasm for resistance to sweetpotato weevil, 2003. Arthropod Management Tests29:M7: http://www.entsoc.org/Protected/AMT/AMT29/Text/amt29.asp.?Report=M7
- Story, R.N., Hammond, A.M., Murray, M.J., and D.R. LaBonte. 2004. Field evaluation of sweet potato cultivars for resistance to banded cucumber beetles, 2003. Arthropod Management Tests29:M8: http://www.entsoc.org/Protected/AMT/AMT29/Text/amt29.asp.?Report=M8
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