Field trials of foliar sprays of 3,5-dichlorophenoxyacetic acid (3,5-D) against common scab on potatoes

Summary Foliar sprays of 3,5-dichlorophenoxyacetic acid (3,5-D) in June or early July decreased the incidence of common scab by about 30% in four field trials on cv. Maris Piper and cv. Désirée; however, significant decreases in yield and in mean tuber weight were also common. The effects of 3,5-D on potatoes resembled those of the growth retardant daminozide in some ways, but 3,5-D was not persistent enough to have a useful effect on scab in the field.