Effect of Feeding and Oviposition by the Plum Curculio on Apple and Plum Fruit Abscission12

The only factor implicated in premature abscission of set ‘Stanley’ plums and ‘Golden Delicious’ apples was activity by larvae of Conotrachelus nenuphar (Herbst). Fruit abscission was most likely to take place when fruits were smaller than 30 mm diam; seed damage was not necessary for abscission to occur. Larvae in fruits that did not fall prematurely generally did not complete larval development. Fruit abscission induced by plum curculio larvae was similar to the process of mature fruit drop. Adult feeding or egg cavity preparation did not cause fruit abscission.