Modelo de Desarrollo Floral en Manzanos [Malus sylvestris (L.) Mill. var. domestica (Borkh) Mansf.] Red Delicious y Golden Delicious como Herramienta de Toma de Decisiones en el Manejo Integrado de Enfermedades

dynamics of flower bud development in apple trees cvs. red delicious (rd) and golden delicious (gd) was monitored in 1996, 1997, and 1998. the phenological stages evaluated were: eco-dormant, green tip, half-inch green, tight cluster, full pink, bloom, petal fall, and fruit set. sample size varied from 330 to 556 buds. data analysis was done by a weibull distribution, and a time scale expressed as thermic units (ut) was used, considering a threshold of 7°c. results indicate that the period from initial break to bloom required 354 ± 33 ut in rd and 431 ± 45 ut in gd. the bloom stage lasted for 106 ± 9 ut in rd and 187 ± 45 ut in gd. the budbreak process in rd started on march 15, 1996, march 13, 1998, and on march 19 in 1999; while for gd started on april 1, march 24 and 30 in the same years. weather data showed that winter quality decreased in a continuous fashion from 1992 to 1999.