CONTROLLING GROWTH OF BEARING APPLE-TREES WITH ETHEPHON

Ethephon applied 12 to 26 days after full bloom at 1000 to 1500 mg-lit er-1 not only substantially inhibited apple (Malus domestica Borkh., s pur 'Delicious' strains) tree growth but also caused fruit abscission. Gibberellin plus ethephon did not prevent fruit abscission when ethep hon was used at these rates. Several low weekly doses of ethephon cont rolled tree growth without causing fruit abscission. Ethephon increase d fruit soluble solids concentration and substantially reduced fruit s tarch in the application year. Ethephon greatly increased flowering an d fruit set the following season. Fruit length : diameter ratio was no t altered by the previous seasons' low weekly doses of ethephon. Chemi cal name used: (2-chloroethyl)phosphonic acid (ethephon).