The spatial and temporal pattern of noninfectious bud failure (BF) expression (BFexp) was studied during seven growing seasons in a population of 'Carmelʼ almond trees originating from twelve commercial propagation sources. All progeny trees were grown in a single experimental site with high prevailing summer temperatures. BFexp increased continuously but irregularly in each nursery population as measured as the proportion of trees showing BF and as an average BFexp rating. Populations from the 12 nurseries represented increasing clonal generations from the original seedling tree and showed increasing levels of BF, as well as a decreasing shape value and increasing scale value derived by a failure statistics model. Models for development, distribution and hazard functions were defi ned for each of the 12 sources studied. Only sources from the original tree and source A demonstrated potential for com- mercial use. A signifi cant correlation was found between average yearly increase in BFexp and the average daytime temperature for the previous June. The June period coincides with a specifi c stage in the seasonal growth cycle when vegetative buds mature. Noninfectious bud failure (BF) is a genetic disorder of almond (Prunus dulcis (Mill.) D.A.Webb.) (IPM Education and Publica- tion, 2002; Kester, 1974; Kester and Gradziel, 1996). The disorder is identifi ed in individual orchard trees of certain cultivars by failure of vegetative buds to grow in the spring (BF), die-back of terminal shoots (dieback), vigorous and erratic growth from surviving buds (witches-broom) and characteristic bark deforma- tions (roughbark). Flowering and fruiting are not directly affected but bloom can be delayed and fl owering density reduced, and so crop production can be reduced. There is no evidence of a pathological cause (DiTerlizzi et al., 1998; Wilson and Schein, 1956; Fenton et al., 1988a) although some viruses mimic the symptoms of BF (Kester. 1974; Wilson and Schein, 1956). BF is equally inherited in almond x almond reciprocal crosses and is directly proportional to the BF severity in the parents (Kester, 1968a, 1968b; Kester and Jones, 1970). Individual seedlings inherit different levels of the potential for BF (BF pot ) which is manifested in the number of cycles of fu- ture growth required for symptoms to be expressed. Individual seedlings pass through a period of conversion in which the BF pot changes to expression (BF exp ). The pattern is retained during vegetative propagation and is continued during further vegeta- tive generations. BF is also inherited in almond x peach F 1 , F 2 and backcross progeny where BF exp segregation indicates that a major gene for BF occurs in almond which is absent in peach (Kester 1978; Kester and Gradziel, 2002). BF exp fi rst appeared sporadically in 'Nonpareilʼ and 'Peerlessʼ in the early years of the industry and later at a devastating rate in 'Jordanoloʼ and 'Harpareilʼ, both products of a USDA-UC breeding program (Woods, 1938). Later, BF exp has appeared in high numbers in patented cultivars such as 'Mercedʼ, 'Priceʼ