Evaluation of Pistacia vera 'Pete I' yield characteristics
California's 300,000 acre pistachio industry consists of over 90% Pistacia vera. Cultivars with different harvest timing would relieve the pressure on processing facilities. A recently identified cultivar, 'Pete I' harvests earlier, but is producing unacceptably high percentages of early season aborted nuts, which abscise, as well as partially filled and blank nuts. Both overload the hullers and float tanks. Field observations suggested insect pressure and/or fungal infestation. In an insect exclusion study, flower buds were both covered by insect-impermeable mesh and left uncovered on the 'Pete I' trees for the season until harvest. The resulting clusters showed no significant difference in the final percentage of aborted nuts between the bagged and unbagged samples. Laboratory plating of early- and mid- season nuts for fungal pathogens detected none beyond background levels. Therefore, high percentages of blanking and partially filled nuts in the 'Pete I' pistachio cultivar were not due to either insect or fungal pressures. Other possibilities are pollen or ovule incompatibility, or self-thinning through embryo abortion.
Allan, C., Crisosto, C.H., Michailides, T., Brar, G.S. and Ferguson, L. (2016). Evaluation of Pistacia vera 'Pete I' yield characteristics. Acta Hortic. 1109, 57-60
insect exclusion, blanking, botrytis, excessive aborting, nut quality