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Funded Project |
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Funding Program:
IPM Enhancement Grants |
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Project Title:
Improvement of Sweet Potato Insect Pest Management in the Southeast |
Project Directors (PDs):
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Lead State: MS Lead Organization: Mississippi State University |
| Undesignated Funding: $29,952 |
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Start Date: Mar-01-2017 End Date: Feb-28-2018 |
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Pests Involved: larvae of click beetles (wireworms), Diabrotica beetles, and Systena beetles (WDS complex) |
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Site/Commodity: sweet potatoes |
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Area of Emphasis: Thresholds and resistant varieties |
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Summary:
Sweet potatoes are a major Southeastern crop valued at almost $500,000,000 in 2015. Sweet potato roots are damaged by several soil-dwelling insect pests which can affect approximately 30% of marketable roots under standard insecticide practices in the Southeast United States but according to USDA standards less than 10 % of the roots can have been damaged (insect, disease, physical, etc.) and maintain a U.S. No. 1 or No. 2 status. Based on this, insect damage alone causes price reductions that cost Southeast producers approximately $11,000,000 or $95 an acre above the $66 per acre paid for insecticides. Many of the pests are managed with soil applied insecticides, but these have little or inconsistent efficacy against mid- to late-season pests in the WDS (wireworm, Diabrotica, Systena) complex, which is responsible for damage to approximately 8 % of marketable roots under standard insecticide practices. This pest complex is primarily managed with foliar insecticide applications targeting the adult stage of the insect.
Economic thresholds for foliar insecticides targeting the species within the WDS complex have not been validated and are complicated by hard to distinguish damage and the population of Diabrotica beetles in Mississippi being of a different species than in Louisiana where most of the Diabrotica work has been conducted. Varieties of sweet potatoes with resistance to the WDS complex have been discovered but not evaluated in Mississippi. Improving economic thresholds and introducing insect resistant varieties could lead to decreased or more effective insecticide usage and improved grower profits. Field trials will be conducted to evaluate the current economic threshold for the WDS complex. These trials will evaluate foliar insecticide applications at the current and higher thresholds and compare these treatments with no foliar applied insecticide plus other standard practices (pre-plant and lay-by treatments. Insect populations will be monitored throughout the growing season, roots will be dug at three dates past lay-by and at maturity to evaluate damage, yield will be calculated, and an economic analysis will be conducted. Field trials will also be conducted to evaluate resistance to the WDS complex. These trials will evaluate five to ten varieties with known insect resistance and compare them to current grower standard varieties typical in Mississippi. Roots will be dug to evaluate insect damage, yield will be calculated, and an economic analysis will be conducted. The short term impact of the results of these trials will help guide future research to determine an accurate economic threshold for pests in the WDS complex, as well as, help determine if any insect resistant varieties exist that may be an economically feasible alternative to current varieties used in Mississippi. Medium and long term impacts include: potential future funding and multi-state collaboration opportunities, more effective insecticide usage, improved grower profits, and improved interaction between Mississippi State University extension entomologists and sweet potato growers. Objectives: Objective 1) Evaluate the current thresholds for the WDS complex to determine if the current thresholds need further evaluation. The outcomes of this research will lead to future directions for additional threshold studies that may help improve insecticide usage and IPM plans, thus improving grower profits. Objective 2) Determine if any insect resistant sweet potato varieties are suitable for Mississippi. These objectives will be studied using field trials in Northeast Mississippi. The outcomes of this research will lead to future directions to evaluate insect resistant varieties that may reduce insecticide usage, thus improving grower profits and reducing environmental impacts of insecticides. |
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Final Report: |
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Outputs 1. Threshold (2 site years) and Variety trials (3 site years) were planted, sampled and harvested and analyzed as planned in grant proposal. 2. Three oral presentations were made to a total of 115 growers and 50 academics during and after the growing season. 3. Research trials and presentations were publicized on Mississippi Crop Situation blog and Twitter. 4. Discussions have started with USDA-ARS regarding future funding, but nothing has been secured at this time. 5. More research is needed to complete the objectives and recommend changes in sweet potato insect pest management. |
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Outcomes 1. Findings of research trials were shared with growers and academics. 2. Collaboration among sweet potato entomologists has increased. 3. The long-term objectives of this research is more economical insecticide use in sweet potato production and adoption of more insect-resistant varieties, both of which will require multiple years of research and collaboration with other researchers. |
| Report Appendices |
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