The objective of this study was to evaluate the effects of rates and time of AVG (aminoethoxyvinylglycine) application on pre-harvest fruit drop control, ripening delay, and quality of Imperial Gala apple fruit. It was tested 4 application times (45, 30, 15 and 7 days before the predicted harvest date for the control plot - DBPH), and 4 AVG rates (0, 90, 124, and 62 + 62 g.ha-1), during the growing seasons 2003 and 2004. The starch degradation, the loss of firmness, the increase of soluble solids content (SSC), and the development of fruit color were slower on AVG treated than on untreated fruit. As expected, AVG delayed the commercial harvest date by 7 to 16 days, and the pre-harvest fruit drop up to 30 days. The ripening delay by AVG depended on rate and time of application. AVG applied closer to the predicted commercial harvest time (7 DBPH), was more effective on preventing pre-harvest fruit drop and on delaying fruit softening than earlier applications (30 or 45 DBPH). AVG applied at the rates of 90 and 124 g.ha-1 were equally effective when applied at 7 or 15 DBPH. The delay on fruit ripening and the control of pre-harvest fruit drop by AVG were greater at its highest rates and as closer the application was to the predicted harvest date for the control. The results showed that it is possible to manage de degree of harvest delay by varying the time of application from 7 to 30 DBPH, and the rates of AVG from 90 to 124 g.ha-1.
Malus domestica Borkh; Aminothoxyvinilglicine
