|Wilson, Jeffrey - Jeff|
Submitted to: Weed Science Society of America Meeting Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: 1/14/2008
Publication Date: 2/4/2008
Citation: Vencill, W.K., Wilson, J.P. 2008. Response of pearl millet to HPPD-inhibiting herbicides. Proc. Weed Sci. Soc. America, February 4-7, 2008, Chicago, IL. Pg. 27.
Interpretive Summary: not required
Technical Abstract: Annual grass control is a limiting factor to production of pearl millet (Pennisetum glaucum). Previous studies indicate that pearl millet displayed is tolerant to mesotrione applied PRE, but limited tolerance was observed from POST applications of mesotrione. Field and greenhouse studies were conducted to evaluate the response of pearl millet to three HPPD inhibiting herbicides when applied PRE and POST. In the greenhouse, most pearl millet varieties exhibited good tolerance to mesotrione applied PRE. In a greenhouse comparison of 20 pearl millet varieties, the ED10 ranged from 15 (Tif 23DB) to 198 g ai/ha (Tif 306) and the ED50 values ranged from 52(Tif 23DB) to 309 g /ha (Tif 306). For mesotrione applied POST (applied at 3-4 leaf stage of pearl millet with 0.25% v/v NIS), the ED10 for Tif102 was 92 g/ha while the ED50 was 140 g/ha. When the safener, isoxadifen, was added at a 1:1 ratio to mesotrionen to POST applications of mesotrione, the ED10 was reduced by 49% to 62 g/ha and the ED50 was reduced by 52% to 67 g/ha. In the field, the ED10 of mesotrione applied PRE to Tif102 was 102 g/ha while the ED50 was 310 g/ha. Pearl millet (Tif 102) treated with mesotrione applied POST (3-4 leaf stage with 0.25% v/v NIS) had injury ratings ranging from 32% 7 DAT at 100 g/ha to 72% at 500 g/ha. When isoxadifen was tank-mixed in a 1:1 ratio with mesotrione applied POST, injury from a 100 g/ha mesotrione treatment was reduced to 8%. At 21 DAT, pearl millet injury declined to 7% at 100 g/ha with or without the addition of isoxadifen. Other HPPD-inhibiting herbicides tembotrione and topremazone were evaluated for pearl millet tolerance. Topremazone applied POST at 18 g ai/ha caused 70% injury 7 DAT and this declined to 35% by 21 DAT. The addition of isoxadifen at a 1:1 ratio to topremazone reduced injury from topremazone applied at 18 g/ha to 43% 7 DAT and this declined to 18% 21 DAT. In greenhouse studies, tembotrione applied POST in a 2:1 ratio with isoxadifen resulted in an ED10 of 42 g ai/ha at 7 DAT and an ED50 of 49 g/ha. These studies indicate that pearl millet has good tolerance to mesotrione applied PRE and when mixed with isoxadifen, good tolerance when applied POST. Pearl millet is not as tolerant to topremazone and tembotrione applied POST as mesotrione.