1. Control of Tropical Spiderwort in Peanut with Selected Herbicides J. Tim Flanders Grady County Extension Coordinator Eric P. Prostko Dept. of Crop & Soil Sciences University of Georgia APRES July 2003

2. Tropical spiderwort Tropical spiderwort Commelina benghalensis noxious and invasive annual or perennial seeds and rhizomes above and below ground flowers 1,600 seeds/plant alternate host of southern root-knot nematode problem weed in other countries (Holm’s)

3. Dayflower/Spiderwort Flowers (Commelina spp.) Asiatic Spreading Tropical spiderwort From SWSS Weed ID Guide

4. Tropical Spiderwort Distribution in Georgia

5. Tropical spiderwort Tropical spiderwort How bad is it????? Grady County, GA CottonAfter Corn Harvest

6. Why has it become such a problem? u weed shift resulting from.. * glyphosate use * reduced tillage * reductions in conventional herbicides u ideal climate * 86-96 0 F u limited research data

7. Objective To evaluate Cadre, Dual Magnum, Outlook, and Strongarm applied at various timings for the control of tropical spiderwort in peanuts.

8. Materials and Methods - I Grady County, GA dryland field 4 X 5 factorial in RCBD timings (4) - PRE, 7 DAP, 13 DAP, 17 DAP herbicides (5) - None, Cadre (1.44 oz/A), Dual Magnum (1.33 pt/A), Outlook (14 ozs/A), Strongarm (0.45 ozs/A) 4 replications

9. Materials and Methods - II Planting Date: May 21, 2002 Variety: Georgia Green first rainfall event did not occur until 17 DAP Gramoxone Max (5.5 ozs/A) included with all 7, 13, and 17 DAP timings except with Cadre. 80/20 @ 0.25% v/v with all POST treatments. Spiderwort stage of growth: 7 DAP = 1 leaf, 13 DAP = 3 leaf; 17 DAP = 4-5 leaf. timing X herbicide interactions were significant evaluated 13, 17, 31, 49, 79, and 113 DAP.

10. Results Crop Injury

11. Peanut Stunting - 49 DAP LSD 0.05 = 6 *Included Gramoxone Max @ 5.5 ozs/A + 80/20 @ 0.25% v/v

12. Results Control

13. Tropical spiderwort control in peanuts with Cadre @ 1.44 ozs/A Grady County, 2002 - 113 DAP LSD 0.05 = 30

14. Figure 1. Tropical spiderwort control in peanuts. A = untreated; B = Cadre applied 7 DAP. Photos taken 49 DAP. AB

15. Tropical spiderwort control in peanuts with Dual Magnum @ 1.33 pt/A Grady County, 2002 - 113 DAP LSD 0.05 = 30 *Included Gramoxone Max @ 5.5 ozs/A + 80/20 @ 0.25% v/v

16. AB Figure 2. Tropical spiderwort control in peanuts. A = untreated; B = Gramoxone Max + Dual Magnum applied 17 DAP. Photos taken 49 DAP.

17. Tropical spiderwort control in peanuts with Outlook @ 14 ozs/A Grady County, 2002 - 113 DAP LSD 0.05 = 30 *Included Gramoxone Max @ 5.5 ozs/A + 80/20 @ 0.25% v/v

18. Figure 3. Tropical spiderwort control in peanuts. A = untreated; B = Gramoxone Max + Outlook applied 17 DAP. Photos taken 49 DAP AB

19. Tropical spiderwort control in peanuts with Strongarm @ 0.45 ozs/A Grady County, 2002 - 113 DAP LSD 0.05 = 30 *Included Gramoxone Max @ 5.5 ozs/A + 80/20 @ 0.25% v/v

20. Figure 4. Tropical spiderwort control in peanuts. A = untreated; B = Gramoxone Max + Strongarm applied 17 DAP. Photos taken 49 DAP AB

21. Summary - I All treatments applied 13 and 17 DAP caused significant peanut stunting. When applied with Gramoxone Max at 13 and 17 DAP, Dual Magnum, Outlook, and Strongarm were more injurious than Cadre. Gramoxone Max + Dual Magnum caused the most peanut injury.

22. Summary - II Gramoxone Max provided excellent burndown control of spiderwort. PRE applications of Dual Magnum and Outlook were less effective than POST applications. PRE applications of Cadre, Dual Magnum, and Outlook provided poor control of spiderwort (< 65%). All POST applications of Cadre provide good control of spiderwort (80-86%).

23. Summary - III All POST applications of Dual Magnum provided good to excellent control of spiderwort (89-94%). All POST applications of Outlook provided poor to fair control of spiderwort (49-73%). PRE and 7 DAP applications of Strongarm provided fair control of spiderwort (71- 72%). 13 DAP and 17 DAP applications of Strongarm provided good to excellent control of spiderwort (84-90%).

24. University of Georgia Extension Weed Science (gaweed.com)