Search Results
The performance of five cv. Souri selections designated as “clones” were compared in two consecutive plots for ≈20 years each and three additional ones for 18 years. Fruit morphology, yield, oil production, and tree growth were monitored. The major results are presented as mean values of five sequential “on” years as well as the characteristic production of young and mature trees. The DNA identity was determined using both simple sequence repeats (SSRs) and single nucleotide polymorphisms (SNPs). The performance of two “clones,” SLO and SBU, showed stable diverse production characteristics and could be designated as defined clones, although no clear differences of the DNA between them or the other “clones” were apparent. Another “clone,” SGS, was also designated as a true clone as a result of both unique fruit morphology and DNA markers. The differences between the other “clones” were minute in fruit production morphology and oil production as well as on a DNA basis and their designation as being true clones is doubtful.
Severe damage has been observed in Israeli date palm (Phoenix dactylifera L.) plantations of the Medjool cultivar as a result of drying and dropping of fruit bunches. Both fractures and rot occurred during peduncle (fruit stalk) development at proximal points located deep within the crown. The phenomenon has been previously described as “cross–cut” or “V-cut.” The present study aimed to characterize the phenomenon and identify the main causal factors. Annual surveys have revealed high levels of fruit bunch drop in all ‘Medjool’ cultivation areas in Israel. Arenipses sabella and other insects were only occasionally detected in the damaged fruit stalks. Similar damage levels observed in insecticide-treated and untreated plots suggested that insects were not directly responsible for this phenomenon. Tissue decay was detected in many of the freshly fallen fruit stalks. The pathogenic fungus, Fusarium proliferatum, was detected in most of the necrotic fruit stalks. Fusarium proliferatum isolates from infected fruit stalks generated necrotic lesions in fruit stalk tissue in vitro. However, fungicide treatments on trees in the orchards were ineffective in reducing bunch drop. On the other hand, restraining the growth rate of the fruit stalk, by reducing irrigation levels (to 20%) during the period of fruit stalk development and growth, significantly reduced bunch drop levels in most of the examined plots. These data suggest that bunch drop in ‘Medjool’ date palm is caused mainly by physiological disorders related to fruit stalk development and growth.