Tropical Spiderwort Management in Peanut, Corn, and Soybean Eric P. Prostko Extension Weed Specialist Dept. Crop & Soil Sciences University of Georgia Tifton

Control Strategies in Peanut row spacing * twins vs. singles residuals * Dual Magnum * Strongarm POST’s * Gramoxone Max * Cadre * Basagran

Tropical spiderwort control in peanut as influenced by row spacing Source: Yoder et al. 2003 (FL)

Tropical spiderwort control in peanuts with Dual Magnum applied preemergence, Grady Co., 2003. Dual Magnum 7.64EC @ 1.33 pts/A

Tropical spiderwort control with Gramoxone Max + Dual Magnum Tank-Mixes Gramoxone Max @ 5.5 ozs/A + Dual Magnum @ 1.33 pts/A Grady County

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

How much Dual Magnum can we use? 1-1.33 pt/A 2.8 pts/year 90 day PHI cost/A $90/gal $31.50/2.8 pts

Other Metolachlor Formulations Cinch Dupont same as Dual II Magnum cannot use POST Stalwart C Sipcam Agro USA Inc. “old” Dual EC formulation (7.8 lbs/gal) not labeled for peanut Me-Too-Lachlor Drexel “old Dual EC formulation (8 lbs/gal) rates are too low

Strongarm in Peanut PPI or PRE thru cracking* not labeled for POST use at this time but working on this issue * cracking = soil displaced by germinating seedlings just prior to emergence

Tropical spiderwort control in peanuts with Strongarm @ 0 Tropical spiderwort control in peanuts with Strongarm @ 0.45 ozs/A, Grady Co., 2003. a a ab cd abc ab b c e PRE = 5 DAP EPOST = 17 DAP (2”, 3 leaf) LPOST = 31 DAP (up to 6”)

Tropical spiderwort control with POST applied Strongarm, 2003 Untreated Strongarm applied 17 DAP Strongarm applied 31 DAP PE-24-03 46 DAP

Gramoxone Max and Cadre Tank-Mixed or Split Applications?

Tropical spiderwort control with Gramoxone Max and Cadre (LSD 0.05 = 11) (LSD 0.05 = 15) (LSD 0.05 = 22) Tank-mix applied 17 DAP/Split applied 17 and 31 DAP

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

What About Cadre + Dual Combos?

Tropical Spiderwort Control with Cadre + Dual Magnum 114 DAP LSD 0.05 = 22

Tropical spiderwort control in peanuts with Valor applied preemergence, Grady Co., 2003. Valor 51 WP @ 3 ozs/A

Tropical Spiderwort in Field Corn * preemergence Dual II Magnum Atrazine (?) * postemergence 2,4-D Basagran * post-directed Gramoxone Max Aim Evik

Tropical Spiderwort in Soybeans * narrow rows * preemergence Sencor Dual Magnum Boundary Canopy SP Canopy XL * postemergence Basagran * post-directed Gramoxone Max

Post-Harvest Control Strategies prevent seed production re-growth after harvest time before first frost Gramoxone Max 2,4-D tillage

Tropical spiderwort control with various herbicides - 14 DAT Applied October 31, 2003 6” tall spiderwort LSD 0.05 = 13

Tropical Spiderwort in Australia Weed problem for 20-30 years control in other crops important corn 2,4-D Dual peanut Pursuit E.P. with Australian peanut farmer, Wayne Learmonte