The spatial and temporal pattern of noninfectious bud failure (BF) expression (BFexp) was studied during seven growing seasons in a population of `Carmel' 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 defined for each of the 12 sources studied. Only sources from the original tree and source A demonstrated potential for commercial use. A significant correlation was found between average yearly increase in BFexp and the average daytime temperature for the previous June. The June period coincides with a specific stage in the seasonal growth cycle when vegetative buds mature.
Dale E. Kester, Kenneth A. Shackel, Warren C. Micke, Mario Viveros, and Thomas M. Gradziel
Jeanine M. Davis
In recent years there has been an increase in the incidence of “gold flecking,” which develops on the surface of ripe tomato fruit. Gold flecking looks like a light sprinkling of gold on the skin of the fruit. There are no lesions and the interior of the fruit is not affected. Usually, gold flecking is barely noticeable. In 1998, however, gold flecking was severe enough in some cases to cause economic losses. It has been suggested that gold flecking is due to use of the insecticide Asana or it may be a genetic disorder. The objective here was to determine if gold flecking is caused by Asana and/or is cultivar-dependent. Treatments consisted of three cultivars (Mountain Fresh, Celebrity, and Mountain Pride) and four insecticides (Asana XL, Karate 1 EC, Thiodan 50 WP, and a water control). There were two plantings. Only red fruit was harvested. For both plantings, there was more gold flecking in the control than any of the insecticide treatments. There were no differences among the insecticides. For the early planting, `Mountain Fresh' had more gold fleck than the other cultivars. In the late planting, there were no differences between cultivars. This study demonstrates that Asana was not responsible for gold flecking and actually reduced it compared to the control. These results also suggest that insects may play a role in gold flecking.
D.E. Kester, T.M. Gradziel, K.A. Shackel, and W.C. Micke
Noninfectious bud-failure (BF) is a genetic disorder in almond, associated with nursery source selection. Previously (Kester, PASHS, 1968), the latent potential for BF (BFpot) was shown to be heritable but its phenotypic expression (BFexp) varied among individual seedlings of a populations as a function of age. Vegetative propagation perpetuates BFpot of individual propagules (Kester and Asay, JASHS, 1978b) but the subsequent age of BFexp within individual plants is a function of accumulated exposure to high summer temperature and growth (Kester and Asay, JASHS 1978a). A recent 7-year “somatic heritability” study of 12 commercial nursery sources (Kester et al., HortScience 1998abst) portrays the total range of variability of BFpot and BFexp within the entire `Carmel' almond clonal population and includes a pattern of BF increase in consecutive vegetative propagation cycles that mimics patterns produced by phase change (i.e., juvenile > mature) phenomena (Hartmann et al., 1997). Although phase change potential is heritable in seedling populations, phase change expression is not (Kester, HortScience 1983). Furthermore phase changes can be reversed under particular conditions during consecutive vegetative propagations (Hartmann et al., 1997). In contrast, evidence shows that BF produces permanent changes in genotype that are heritable and irreversable. High correlations exist between BFpot of individual source blocks, individual trees and individual budsticks and the age and severity of BFexp in progeny trees. The apparent continuous change in BFpot and BFexp within clones appears to be the pattern of expression of different populations of increasingly defective (?) somatic cells that result from consecutive sequences of change during annual cycles of growth and generations of vegetative propagation.
Andrés Olivos, Scott Johnson, Qin Xiaoqiong, and Carlos H. Crisosto
mealiness or woolliness), FB, black pit cavity, flesh translucency (gel breakdown), red pigment accumulation (bleeding), lack of flavor, and failure to ripen ( Lurie and Crisosto, 2005 ). Nectarine FB is a genetic disorder that can be triggered by a