The effects of standard and new generation spray oils repeated application on“Tarocco” orange tree productivity in Sicily


Abstract: Petroleum spray oils are widely used on citrus pest in Integrated Pest Managementprograms, but they may have side effects on trees development and fruits quality. Recently,new oil formulations have been introduced in Italy for use on citrus. Four oils with various50% distillation temperatures, oil 213, oil 226, oil 230 and oil 230 EC (EmulsifiableConcentrate), were applied in consecutive years (2000-2007) to a early-ripening “Tarocco”orange in different seasons (winter and summer) to observe their chronic effects on yield andacute effects on fruit’s external quality. The treatments were applied each year to trees atrates of 1.6-1.8% of active ingredient (v/v) in two experimental plots (“A” and “B”). Thewinter application, in the plot “A”, did not cause statistical reduction in the yield (5-yearsaverage) compared with the untreated. In plot “B”, data were not sufficient for a multi-yearstatistical analysis; nevertheless in the 2003, the winter application of oil 230, oil 230 EC andoil 213 did not reduce the yield. The summer application did not reduce statistically the yield(7-years average in the plot “A” and 4-year avg. in the plot “B”). In applications repeated for5 years, the summer treatments produced permanent marks on fruit rind in 3 years (2003,2005, 2006), in coincidence with very high temperature (> 42°C), particularly when the oil230 was utilized. This kind of phytotoxicity did not cause a severe downgrading of the fruits.

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