Abstract

RAMIREZ-LEGARRETA, Manuel Rafael; JACOBO-CUELLAR, Juan Luis; GARDEA-BEJAR, Alfonso Antero  and  PARRA-QUEZADA, Rafael Ángel. Model on floral development of apple [Malus sylvestris (L.) Mill. var. domestica (Borkh) Mansf.] Red and Golden Delicious as a decision-making tool for integrated disease management. Rev. mex. fitopatol [online]. 2008, vol.26, n.2, pp.153-163. ISSN 2007-8080.

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.

Keywords : Phenology; thermic units; Weibull distribution.

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