THE EFFECTS OF APPLYING PARAQUAT, ATRAZINE AND SIMAZINE FOR WEED CONTROL IN RASPBERRIES IN COASTAL BRITISH COLUMBIA

Early spring and fall applications of a mixture of paraquat 2.2 kg and simazine 2.2 to 3.4 kg/ha repeated over a 3-year period provided excellent weed control without adversely affecting raspberry yield. Paraquat 2.2 kg/ha applied in April gave good broadleaf weed control for 2 months and fairly good grass control for 3 months. Fall applications suppressed grasses and controlled winter annuals through to spring. Combining paraquat with simazine eliminated the need for pre-treatment hoeing or cultivation and prolonged weed control. Atrazine 3.4 and 5.6 kg/ha applied in the spring resulted in excellent control of grass and broadleaf weeds. But, fall applications were not as effective for weed control as the paraquat and hoe-plus-simazine treatments. Atrazine 5.6 kg/ha caused chlorosis and necrosis of the raspberry leaves and reduced yields. Simazine, on the other hand, caused little or no leaf injury, but it also reduced yields at the 5.6-kg rate. Fruit quality was not affected significantly by any treatment, although atrazine and simazine tended to increase ascorbic acid content.