HPPD plus growth regulator herbicides for control of divine nightshade (Solanum nigrescens Mart. & Gal.) in ratoon sugarcane

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

Submitted to: Weed Science Society of America Meeting Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: 1/15/2018
Publication Date: 1/29/2018
Citation: Spaunhorst, D.J., Orgeron, A.J. 2018. HPPD plus growth regulator herbicides for control of divine nightshade (Solanum nigrescens Mart. & Gal.) in ratoon sugarcane [abstract]. Weed Science Society of America Meeting Proceedings. 2018:262. http://www.wssaabstracts.com/public/54/proceedings.html

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 and broadcast-direct apply under 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: 105 g ha-1 of mesotrione, 2.9 kg ha-1 of a premix formulation of S-metolachlor plus atrazine plus mesotrione plus bicyclopyrone, and 24.5 g ha-1 of topramezone and the synthetic auxin herbicides: 1.1 kg ha-1 of 2,4-D, 87 g ha-1 of aminopyralid, 0.56 kg ha-1 of dicamba, 157 g ha-1 of fluroxypyr, 0.56 kg ha-1 of picloram, and 1.1 kg ha-1 of triclopyr applied alone. Herbicide tank-mixture treatments were also applied. A single growth regulator 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 5-10, 11-20, and 21-30 cm tall divine nightshade. 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 a HPPD-inhibiting herbicide resulted in 43, 63, and 53% greater control of 5-10, 11-20, and 21-30 cm tall plants as compared to 2,4-D alone, respectively. Increased control of smaller plants (5-10 cm) was marginal with tank-mixtures of HPPD-inhibiting herbicides plus dicamba when compared to dicamba alone; however, the former tank-mixture resulted in 25% more control of larger plants (11-20 cm) compared to smaller plants (5-10 cm). Overall, control with synthetic auxin herbicides applied alone generally followed: picloram > triclopyr > aminopyralid > 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.