Final Thrips Flight and TSWV Risk Assessment Report – June 11, 2018

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This is the eighteenth, and final, thrips flight and TSWV risk assessment report. Read about why we are posting these reports and more in our first reportRead more about tobacco thrips biology and TSWV transmission.

This is the final of our 2018 reports. Fourth generation thrips flights are predicted or have begun at all of our report sites, and below, we summarize disease incidence observations as reported by local extension agents in these areas to date. TSWV symptoms usually continue to develop in tobacco through topping, so we will likely post one more updated incidence summary later this summer.

General trends at all our report sites include: highly variable planting dates, thrips flights 1 to 2 weeks later than last year, and average infection rates more in line of typical years thus far. As you will see below, however, some areas still experienced locally high TSWV infection and associated loss. We are interested in teasing out why these locations were so high via future research experiments.

Kenly is a relatively low TSWV risk site, situated within large acreage production areas in Johnston and Wilson Counties. Last year the third generation thrips flight occurred on May 10. This year, the third generation tobacco thrips flight (the generation that typically transmits the most TSWV) was expected to begin on May 23. The fourth generation thrips flight, which can also contribute to some TSWV transmission was predicted to begin on June 9. TSWV infection risk in Kenly was predicted to be about the same as in a typical year. Infection in Johnston County is tracking 3 to 4% on average this year with a few locations higher than expected per Bryant Spivey, county extension director.

Beulaville is a higher TSWV risk site in Duplin County. Last year the third generation thrips flight occurred on May 4. This year, the third generation tobacco thrips flight (the generation that typically transmits the most TSWV) was expected to begin on May 18. The fourth generation thrips flight, which can also contribute to some TSWV transmission was predicted to begin on June 3. TSWV infection risk in Beulaville was predicted to be less than in a typical year. Infection in Duplin County is estimated at 5% on so far this year according to extension agent Blake Sandlin.

Kinston is a moderate TSWV risk site in Lenior County and also houses the NCDA & CS Cunningham Research Station where we conduct tobacco research. Last year the third generation thrips flight occurred on May 5. This year, the third generation tobacco thrips flight (the generation that typically transmits the most TSWV) was expected to begin on May 20. The fourth generation thrips flight, which can also contribute to some TSWV transmission was predicted to begin on June 5. TSWV infection risk in Kinston was predicted to be less than in a typical year. Infection in our TSWV research plots at the Cunningham Research Station ranged from 2 to 30% last week. This experiment contains plots aggressively treated to prevent TSWV with both Admire Pro and Actigard timed to third generation thrips flights and plots that were completely pesticide free.

New Bern is a higher TSWV risk site in Craven County. Last year the third generation thrips flight occurred on May 4. This year, the third generation tobacco thrips flight (the generation that typically transmits the most TSWV) was expected to begin on May 18. The fourth generation thrips flight, which can also contribute to some TSWV transmission was predicted to begin on June 3. TSWV infection risk in New Bern was predicted to be slightly less than in a typical year. From Mike Carroll, Craven County extension agent, “Most fields are in the 5-8% TSW incidence range with some scattered fields here and there up to 13%. Isolated small cases do exists in the 18-25% ranges but again, this is not the normal finding.”

Windsor is a moderate TSWV risk site in Bertie County. Last year the third generation thrips flight occurred on May 19. This year, the third generation tobacco thrips flight (the generation that typically transmits the most TSWV) was expected to begin on May 27. The fourth generation thrips flight, which can also contribute to some TSWV transmission is predicted to begin on June 13. TSWV infection risk in Windsor was predicted to be about the same as in a typical year. We do not have TSWV estimates for Bertie County at this time and will update this post with that information as it is available.

Whiteville is a higher TSWV risk site in Columbus County and also houses the NCDA & CS Border Belt Tobacco Research Station where we conduct tobacco research. Last year the third generation thrips flight occurred on May 2. This year, the third generation tobacco thrips flight (the generation that typically transmits the most TSWV) was expected to begin on May 17. The fourth generation thrips flight, which can also contribute to some TSWV transmission was predicted to begin on June 3. TSWV infection risk in Whiteville was predicted to be about the same as a typical year, but the Border Belt has proven to be the most surprising locations for TSWV this year. From Georgia Love, NCDA & CS Region 5 Agronomist: “Columbus County is by far the hardest hit. I estimate several hundred acres are at 40% TSWV incidence or above for several growers. The highest incidence [observed] is 85%. Other [areas of the county] are at about 40% on tobacco that is not quite layby size. Robeson County is at about 20% for the oldest tobacco and less than 5% for the younger. Bladen county is in the less than 5% to 20%  range. Cumberland is quite a bit behind the other counties and looks to be less than 2% right now. Brunswick [County] estimates are 10 to 15% TSWV as of now.”

Clinton is a higher TSWV risk site in Sampson County. Last year the third generation thrips flight occurred on May 3. This year, the third generation tobacco thrips flight (the generation that typically transmits the most TSWV) was expected to begin on May 16. The fourth generation thrips flight, which can also contribute to some TSWV transmission was predicted to begin on June 2. TSWV infection risk in Clinton was predicted to be less than in a typical year. Per Della King, Sampson County extension agent, infection rates are tracking 10 to 15% on average this year with localized higher infection rates, ranging from 25 to 35%. Earlier set tobacco generally has higher infection rates than later set fields.

More Information

Tobacco thrips – Tobacco Growers Information

Written By

Photo of Hannah Burrack, N.C. Cooperative ExtensionDr. Hannah BurrackProfessor and Extension Specialist (Berry, Tobacco and Specialty Crops) (919) 513-4344 hannah_burrack@ncsu.eduEntomology & Plant Pathology - NC State University
Updated on Jun 11, 2018
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