Response of Tokay grapes to spray applications of 2,4-D

Tokay vines were sprayed, at different stages of development, with 2,4-D at 2 and 8 ppm, in 1958, 1959, and 1960. The effects from 2,4-D varied from year to year, with much injury in 1958 and 1959, and little or none in 1960. There was little or no cumulative injury from low concentrations from one year to the next. Most malformed foliage occurred from sprays applied when shoots were about 1 foot long and from sprays applied at the bloom or shatter stage. These sprayings were also most injurious to fruit. Only extremely low concentrations of 2,4-D were found in fruit of sprayed vines, and only in berries sprayed in 1960 either at the shatter stage or at the final spraying.