Wine Grape (Vitis vinifera) Response to Fall Exposure of Simulated Drift from Selected Herbicides

Abstract

‘Lemberger’ wine grape response to fall application of selected herbicides applied at simulated drift rates was studied in 1992 and 1993. Chlorsulfuron, thifensulfuron, 2,4-D, glyphosate, bromoxynil, and 2,4-D plus glyphosate were applied at 1/100, 1/33, 1/10, and 1/3 of a selected maximum rate for use in wheat or fallow. All herbicides, except bromoxynil and thifensufluron, caused symptoms on grapevines at the highest rate during the spring following fall application. The most severe symptoms were caused by 2,4-D and 2,4-D plus glyphosate, whereas the least symptoms were caused by chlorsulfuron and glyphosate. The severity of symptoms increased and shoot growth, leaf area, internode length, and dry cane weight decreased as the rates of 2,4-D and 2,4-D plus glyphosate increased. Chlorsulfuron and glyphosate reduced the growth of grapevines only when applied at the highest rate during the fall. The data show that exposure of wine grapes to 2,4-D or 2,4-D plus glyphosate during the fall can adversely affect the growth of grapevines the following spring.