Chemical Defoliation of Nursery Stock. I. Initial Experiments with Fruit Tree Material

Both 50 000 ppm FeEDTA and 1000 ppm N252 (2, 3-dihydro-5,6-dimethyl-l,4-dithiin-1,1,4,4-tetroxide) effectively defoliated Cox’s Orange Pippin and Golden Delicious maiden apple trees on M.9 rootstock when applied in mid-September. Defoliation of MM. 104 apple rootstocks by 30 000 ppm FeEDTA was enhanced by pretreatment with 3000 ppm MH, and defoliation of Quince A rootstocks by 30 000 ppm FeEDTA, 250 ppm N252 or 750 ppm ethephon with 13 500 ppm urea was enhanced by prior treatment with 3 000 ppm butralin.