Effects of Aminoethoxyvinylglycine (AVG) on Preharvest Fruit Drop and Maturity of ‘Delicious’ Apples

Abstract

Aminoethoxyvinylglycine (AVG) applied 2 to 6 weeks before the optimum harvest date dramatically reduced preharvest drop of 'Delicious' apples (Malus domestica Borkh).The loss of fruit firmness, starch, and water core was reduced by AVG sprays particularly when harvest was delayed beyond the optimum harvest date.Color development and soluble solids concentration (SSC) generally was unaffected.Equivalent dilute airblast concentration (EDAC) of 44 mg L 1 AVG was no more effective than a standard rate of napthalene acetic acid (NAA), but a rate of 44 mg L 1 AVG EDAC + a silicone surfactant ABG 7011 or 88 mg L 1 AVG EDAC was more effective than NAA.When fruit were left on the tree for periods of 3 to 5 weeks after the optimum harvest date, NAA enhanced softening and loss of starch and increased water core of 'Delicious'.Soluble solids and red color generally were unchanged by NAA.Ethephon sprays hastened the rate of fruit drop.When NAA was tank mixed with ethephon, it delayed fruit drop caused by ethephon, but AVG did not.The use of superior oil or Regulaid surfactant did not affect NAA or AVG responses; however, the silicone surfactant ABG 7011 promoted the effectiveness of AVG.Tank mixing with pesticides (Guthion + Lannate + Captan) did not affect the responses of AVG or NAA on fruit drop.Chemicals used: Aminoethoxyvinylglycine hydrochloride (N-(phenylmethyl)-1H-purin-6-amine, (AVG));