Weed Management

Crop-herbicide matching:

• Wheat: Sulfosulfuron (selective for Phalaris minor and broadleaf weeds) (A-III)
• Sorghum: Atrazine (pre-emergence broadleaf & grass weed control) (B-IV)
• Soybean: Quizalofop-p-ethyl (selective post-emergence graminicide) (C-I)
• Sugarcane: Halosulfuron-methyl (Sempra, highly selective against purple nutsedge Cyperus rotundus) (D-II)

• Dicamba (3,6-dichloro-2-methoxybenzoic acid) is a synthetic auxin herbicide belonging chemically to the benzoic acid or arylcarboxylic acid family (HRAC/WSSA Group 4).
• Aryloxy alkanoic acids (phenoxy acids) include herbicides such as 2,4-D, 2,4-DB, and MCPA.
• Thiocarbamates include volatile soil-incorporated herbicides such as EPTC, butylate, and molinate.
• Dinitroanilines include root/microtubule assembly inhibitors like pendimethalin, trifluralin, and fluchloralin.

• Glyphosate herbicidal activity was discovered in 1970 and patented/field tested widely starting in 1971 by John E. Franz of Monsanto -> (A) - (II).
• 2,4-D selective weed killing properties were recognized independently during World War II and published in 1944 by Marth and Mitchell -> (B) - (IV).
• Diclosulam (a triazolopyrimidine sulfonamide herbicide for broadleaf control in legumes) was synthesized and introduced in 1995 by Dow AgroSciences -> (C) - (I).
• Atrazine (a symmetrical s-triazine herbicide) was synthesized and patented in 1958 by J. R. Geigy Ltd. -> (D) - (III).
  
  Matching sequence: (A) - (II), (B) - (IV), (C) - (I), (D) - (III), corresponding to Option 2.

• Bispyribac-sodium (pyriminobac family, ALS inhibitor) is a highly selective, broad-spectrum post-emergence herbicide applied at 20–25 g a.i./ha at 15–20 days after transplanting or direct seeding (2–4 weed leaf stage) in rice to control grasses, sedges, and broadleaf weeds.
• Pretilachlor and Butachlor are standard selective pre-emergence herbicides applied within 0–3 days after transplanting.
• Tembotrione is a selective 4-HPPD inhibitor herbicide recommended for post-emergence broadleaf and grass control in maize, not rice.
• Hence, Bispyribac-sodium (Option 3) is the correct selective post-emergence herbicide for rice.