Hexazinone toxicity in red pine and jack pine
1993
Wood, J.E. | Scarratt, J.B. | Stephenson, G.R.
Experiments were conducted under controlled environmental conditions to determine the toxicity of hexazinone (3-cyclohexyl-6-(dimethylamino)-1-methyl-1,3,5-triazine-2, 4(1H,3H)-dione) to red pine (Pinus resinosa Ait.) and jack pine (P. banksiana Lamb.) during their period of rapid shoot elongation in spring and after initiation of overwintering buds in August. Red pine was a minimum of 10- and 12-fold more tolerant to soil-applied hexazinone than was jack pine on the basis of effective concentration values (EC50, the herbicide concentration that results in a 50% growth reduction compared with the control) for root dry weight and shoot fresh weight, respectively. In the spring experiment, EC50 values were approximately 0.062 and 1.75 kg a.i. (active ingredient).ha-1 for jack pine and red pine shoot fresh weights, respectively. For root dry weight. EC50 values were roughly 0.04 and 2.0 kg a.i..ha-1 for jack pine and red pine, respectively. Except for a somewhat reduced sensitivity in jack pine, similar results were obtained with soil applications of hexazinone after bud initiation in August
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