Which set of chemicals is listed as effective for grass control, including triazines such as simazine and atrazine (and hexazinone), with conifers resistant?

• A. Triazines—simazine, atrazine, and hexazinone
• B. Glyphosate
• C. Sulfometuron (oust)
• D. Imazapyr

Answer: (A)

Grass control in forestry relies on selective herbicides that can kill competing vegetation without harming the conifers. The triazine family, including simazine, atrazine, and hexazinone, is known for providing this kind of selective control. They work as photosystem II inhibitors, which disrupts energy production in susceptible plants, making them effective against many grasses and other weeds. Conifers tend to tolerate these chemicals at labeled rates, so they’re described as resistant, allowing the herbicide to suppress the competing vegetation while the conifers survive. Other options like glyphosate are non-selective and would injure or kill conifers, while sulfometuron and imazapyr are different classes used in other contexts. Therefore, the triazines—simazine, atrazine, and hexazinone—fit the description best.