HERBICIDES FOR WEED CONTROL IN SAFFLOWER (Carthamus tinctorius)

Abstract

Field studies were conducted in 1986, 1987 and 1988 at Lethbridge, Alberta and in 1987 and 1988 at Indian Head, Saskatchewan to determine herbicides suitable for selective control of weeds in safflower (Carthamus tinctorius L.). Safflower exhibited acceptable tolerance to trifluralin, ethalfluralin, sethoxydim, fluazifop-p-butyl, clethodim, diclofop methyl, difenzoquat, imazamethabenz, chlorsulfuron, thiameturon, metsulfuron and DPX-A7881 over all years and locations. These herbicides offer the grower the option of preplant incorporated or postemergent herbicide application or a combination of the two. A mixture of thiameturon plus DPX-L5300 caused severe injury to safflower, reducing yield, oil content, and seed weight. Desmedipham, phenmedipham, and mixtures of these herbicides injured safflower at Lethbridge but not at Indian Head. Weeds reduced safflower yield by 39–73% over the 3 yr of the study. Control of weeds in safflower is essential to obtain optimum yields.Key words: Crop tolerance, seed yield, oil content, seed weight, weed competition