THE RELATIONSHIP BETWEEN DATE OF HULL SPLITTING AND DECAY OF PISTACHIO NUTS BY ASPERGILLUS SPECIES

Atypical pistachio (Pistacia vera) nuts that have split hulls, known a s ''early splits,'' frequently have kernels decayed by Aspergillus spp . In 1992 and 1993 pistachio nuts that had split hulls were marked in commercial orchards at approximately 2-week intervals. Depending on th e orchard, 15 to 48% of the early splits had formed more than 4 weeks before harvest and 10 to 30% formed within 2 weeks before harvest. Ar harvest these nuts were also evaluated for kernel decay, insect infest ation, and several physical characteristics. The incidence of decay ca used by Aspergillus spp. (predominantly Aspergillus niger) was three t imes greater in the oldest early splits than in early splits formed in the period before harvest (no decay was found in normal nuts with non split hulls). The oldest early splits also had the most shriveled hull s, which is a feature associated with aflatoxin contamination. At harv est the oldest early splits had less fruit fresh weight, lower kernel moisture, smaller shells, and more shell discoloration compared with e arly splits formed in the period before harvest and with normal nuts. These characteristics could be used to remove decayed nuts during proc essing.