1 / 56

Theodore M. Webster Crop Protection and Management Research Unit USDA-ARS, Tifton, GA

The Perfect Storm? Why an invasive weed ( Commelina benghelensis ) threatens agriculture in the Southeast US. Theodore M. Webster Crop Protection and Management Research Unit USDA-ARS, Tifton, GA. 1988 Corn: 600,000 ac Cotton: 350,000 ac Soybean: 930,000 ac Peanut: 690,000 ac

trang
Download Presentation

Theodore M. Webster Crop Protection and Management Research Unit USDA-ARS, Tifton, GA

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. The Perfect Storm?Why an invasive weed (Commelina benghelensis)threatens agriculture in the Southeast US Theodore M. Webster Crop Protection and Management Research Unit USDA-ARS, Tifton, GA

  2. 1988 Corn: 600,000 ac Cotton: 350,000 ac Soybean: 930,000 ac Peanut: 690,000 ac Wheat: 575,000 ac Total: 4,268,000 ac 2003 Corn: 340,000 ac Cotton: 1,450,000 ac Soybean: 190,000 ac Peanut: 540,000 ac Wheat: 380,000 ac Total: 3,807,000 ac Georgia Agriculture

  3. Cotton acreage as a % of total summer crop acreage • Boll weevil eradication • Glyphosate-tolerant cultivars ~90%

  4. The Perfect Storm? • Georgia Agriculture: early 1990’s • Reliance on PRE Herbicides with soil residual activity (fluometuron: 90% acres) • Only POST graminicides • Cultivation: 2 to 3 cultivations/season • Conservation tillage: <1% of cotton acres

  5. The Perfect Storm? • Georgia Agriculture: current situation • Reliance Roundup Ready Cotton Cultivars (90%) • Abandonment of PRE Herbicides with soil residual activity (fluometuron: <10% acres) • Cultivation: <15% acres • Reduced tillage on 45% of the acres

  6. Tropical spiderwort in cotton Grady County, GA Photo by Stanley Culpepper, UGA Tropical spiderwort in cotton After 2 Applications of Roundup Roundup: <55% control of tropical spiderwort 2- to 4 glyphosate applications/seasons may be the only herbicide applied Grady County, GA Photo by Stanley Culpepper, UGA

  7. Tropical spiderwort in peanut s-Metolachlor - Rainfall, Cost Imazapic - Rotation Restrictions 2,4-D - Cotton proximity Grady County, GA

  8. Native to Asia and Africa • 1928: Introduced to US • Mid-1930’s: Common throughout Florida • 1983: Federally Noxious Weed • 1998: not considered a serious pest in Georgia • 2001: considered the 9th most troublesome weed in cotton • 2002: Most troublesome weed facing cotton growers TROPICAL SPIDERWORT Commelina benghalensis

  9. Tropical Spiderwort Distribution in Georgia: 1999 Present in 5 Counties 2004 Present in 29 Counties Survey: Culpepper, UGA Weed Science Survey: Georgia Department of Agriculture

  10. Identification

  11. Of the 170 Commelina spp., it is one of a few that is vegetatively distinct (Faden 1992) Alan York, NCSU

  12. TROPICAL SPIDERWORT Tip more blunted Length:Width Ratio <3:1 SPREADING DAYFLOWER Tip sharper L:W Ratio >3:1 4.3 1.0 1.0 1.5 Mike Burton, NCSU

  13. Red Hairs at the apex of the membranous sheath Commelina virginica may also have red or white hairs, but it has narrow, long leaf blades (4:1 or greater)

  14. Field conditions: 240 Aerial flowers/plant (Kaul et al. 2002) Aerial flowers begin forming 8 to 10 Weeks after emergence

  15. Of the nearly 250,000 species of flowering plants… … 36 have underground flowers

  16. Field conditions: 19 Subterranean flowers/plant (Kaul et al. 2002) It’s the only Commelina spp. in the U.S. to have spathes on rhizomes Underground flowers (within spathes) Subterranean flowers begin to form by 6 weeks after emergence 2002 Arlene Mendoza North Carolina State University

  17. Four Types of Seeds!

  18. Tropical Spiderwort Growth

  19. RAPID GROWTH Between 48 and 69 DAP: Number of Shoots More Than Doubled Transplanted 5-Leaf Tropical Spiderwort at Day=0; Greenhouse Study

  20. Between 40 and 69 DAP: 2.5 New Spathes Every Day 1 to 3 Flowers/Spathe Usually 3 seeds/Aerial Flower Maheswari and Maheshwari 1955 Seeds Viable within 25 days of flowering (?) Transplanted 5-Leaf Tropical Spiderwort at Day=0; Greenhouse Study

  21. Emergence Patterns

  22. Can we predict tropical spiderwort emergence?

  23. 82% 65% June 24 29% June 17 20% May 28 May 28 220 GDD 378 GDD 170 GDD 374 GDD 84% 46% August 3 27% 25% July 13 182 GDD 166 GDD June 15 July 7 390 GDD 386 GDD

  24. Can We Control Tropical Spiderwort? Grady County, Georgia

  25. ABILITY TO RESIST CONTROL TACTICS Does cultivation control spiderwort or sprig it? Tropical Spiderwort: Hoed 1 week ago

  26. ABILITY TO RESIST CONTROL TACTICS Tip Cutting: 100% Stem -1 Node, No Leaf: 10% One Leaf, No Nodes: 0% One Leaf & Two Nodes: 100% One Leaf & One Node: 57% Cuttings placed in water solution; Root growth evaluated after 3 weeks

  27. 3 Node Pieces Buried: 2.5, 5, 7.5, 10 cm 3 Node Pieces: Sprigged, 1 Node Above Ground 3 Weeks After Planting Mike Burton, NCSU

  28. Hoeing weather… Can I minimize my cotton yield loss? Hypothesis • Cotton planting date will affect the impact of spiderwort on cotton yield • Early-planted cotton will be more competitive with spiderwort than late-planted cotton

  29. Cotton Planted: • 30 April 2003 (DP 555 BG/RR) • 18 May 2004* (DP 555 BG/RR) • 13 June 2004 (DP 424 BGII/RR) • Pendimethalin applied PRE • Center-pivot irrigation as needed • Naturalized population of spiderwort How long can cotton tolerate the presence of tropical spiderwort before yield is affected? WEEDY Duration - Spiderwort competed for: 2 Wks 4 Wks 6 Wks 8 Wks 10 Wks WEED-FREE Duration – Plots Free of Spiderwort for: 2 Wks 4 Wks 6 Wks 8 Wks 10 Wks

  30. Weed-free intervals maintained through hand-hoeing 960 Worker-Hours in 2004

  31. Weed-Free All Season 6 Wks Weedy, then Weed-Free Spiderwort interferencereduced cotton canopy growth 8 Wks Weedy, then Weed-Free 10 Wks Weedy, then Weed-Free 22 July 2003

  32. Weedy All Season 2 Wks Weed-Free Then Weedy 4 Wks Weed-Free, then Weedy 6 Wks Weed-Free, then Weedy 22 July 2003

  33. Yield Data

  34. 4 WY Then WF WF All Season 6 WY Then WF 10 WY Then WF 2 WY Then WF WY All Season 8 WY Then WF: 45% Field Study, Grady County, Georgia; Cotton Planted April 30, 2003

  35. 6 WF Then WY: <10% WF All Season 8 WF Then WY 2 WF Then WY 10 WF Then WY 4 WF Then WY WY All Season Field Study, Grady County, Georgia; Cotton Planted April 30, 2003

  36. 200 GDD ~3 WAP 350 GDD ~6 WAP 95% Yield Field Study, Grady County, Georgia; Cotton Planted April 30, 2003

  37. <20% Field Study, Grady County, Georgia; Cotton Planted May 18, 2004

  38. A single weed control event initiated between 225 to 238 GDD, Just prior to 6 WAP Field Study, Grady County, Georgia; Cotton Planted May 18, 2004

  39. ~45% Field Study, Grady County, Georgia; Cotton Planted June 13, 2004

  40. 454 GDD ~8 WAP 85 GDD ~2 WAP Field Study, Grady County, Georgia; Cotton Planted June 13, 2004

  41. Critical Period of Spiderwort Control April ‘03: 200 to 350 GDU May ‘04: 225 to 238 GDU June ’04: 85 to 454 GDU May 18, 2004 June 13, 2004 April 30, 2003

  42. Critical Period of Spiderwort Control in Peanut Continuous spiderwort competition with peanut, 2 WAP

  43. 4 Weeks Later Effective weed control Continuous spiderwort competition with peanut, 6 WAP

  44. Weed-free Peanuts Weedy Peanuts No peanuts to harvest

  45. What Other Factors Have Contributed To The Rapid Explosion of Tropical Spiderwort in Georgia?

  46. The Amazing Rate of Spread? • How’s it spreading so fast? • How long has it been here? • Are we just selecting for it with • our current management programs? • 1. It’s probably been around for a while County Maintained Road Adjacent to Test Site Grady County, Georgia

  47. Cotton Gin Trash

  48. 2. We’re probably moving it around with cotton lint

  49. The secret to it’s success? Corn planted in March

  50. Corn is too tall for control tactics as Commelina benghalensis begins to germinate Atrazine has dissipated prior to June

More Related