Performance of synthetic auxin and HPPD-inhibiting herbicides for control of divine nightshade (Solanum nigrescens Mart. & Gal.) in Louisiana sugarcane

Authors: Spaunhorst, Douglas; ORGERON, ALBERT - LSU Agcenter

Submitted to: American Society of Sugar Cane Technologists
Publication Type: Abstract Only
Publication Acceptance Date: 4/22/2018
Publication Date: 9/1/2018
Citation: Spaunhorst, D.J., Orgeron, A.J. 2018. Performance of synthetic auxin and HPPD-inhibiting herbicides for control of divine nightshade (Solanum nigrescens Mart. & Gal.) in Louisiana sugarcane [abstrct]. Journal of the American Society of Sugar Cane Technologists. 38:45.

Interpretive Summary:

Technical Abstract: Divine nightshade has become an increasingly problematic weed in Louisiana sugarcane production and has been identified in 17 of the 24 sugarcane producing parishes. After final cultivation, the current standard layby herbicide program is to tank-mix the synthetic auxin herbicides 2,4-D and/or dicamba plus pendimethalin plus metribuzin. This mixture is applied broadcast and is directed underneath the crop canopy for control of emerged morningglory spp. and provide residual grass and broadleaf weed control. The first objective of this research was to evaluate the HPPD-inhibiting herbicides: of mesotrione (105 g ha-1 ), a premix formulation of S-metolachlor plus atrazine plus mesotrione plus bicyclopyrone (2.9 kg ha-1), and topramezone (24.5 g ha-1) and the synthetic auxin herbicides: 2,4-D (1.1 kg ha-1), aminopyralid (87 g ha-1), dicamba (0.56 kg ha-1), fluroxypyr (157 g ha-1), picloram (0.56 kg ha-1), and triclopyr (1.1 kg ha-1) applied alone. Herbicide tank-mixture treatments were also applied. A single synthetic auxin herbicide was tank-mixed with an HPPD-inhibiting herbicide (mesotrione, premix formulation of S-metolachlor plus atrazine plus mesotrione plus bicyclopyrone, or topramezone) for control of large (30-45 cm tall) divine nightshade plants. The second objective was to determine if herbicide treatments reduce theoretical recoverable sucrose (TRS), sugarcane yield, and sucrose yield when treated to the sugarcane cultivar L 01-299. Results from the data showed spring applied herbicide treatments did not reduce TRS, sugarcane yield, or sucrose yield when compared to the nontreated. A tank-mixture of 2,4-D plus the premix formulation of S-metolachlor plus atrazine plus mesotrione plus bicyclopyrone and dicamba plus the premix formulation of S-metolachlor plus atrazine plus mesotrione plus bicyclopyrone resulted in 63 to 65, and 23 to 47% greater divine nightshade control as compared to 2,4-D and dicamba alone, respectively. At Alma Plantation, tank-mixing the synthetic auxin herbicide 2,4-D plus mesotrione and 2,4-D plus topramezone resulted in 53 and 64% more control when compared to 2,4-D alone, respectively. However, increased control was not observed at Georgia Plantation with the aforementioned herbicide tank-mixtures when compared to 2,4-D alone. This result was likely due to larger divine nightshade plants that were treated at Georgia compared to Alma. Overall, control with synthetic auxin herbicides applied alone generally followed: picloram > aminopyralid > triclopyr > fluroxypyr > dicamba > 2,4-D. Although not currently labeled for use in sugarcane, the results of this study show early-season treatment with synthetic auxin herbicides picloram, aminopyralid, and fluroxypyr and the premix formulation of S-metolachlor plus atrazine plus mesotrione plus bicyclopyrone resulted in greater divine nightshade control than 2,4-D and did not negatively affect L 01-299 yield.