Winter oil application in pistachio production in Australia
Future sustainable food production is faced with the challenge of changing environmental conditions, especially global warming. In the past 12 years, pistachio production in Australia has experienced quite a number of winters with low chill accumulation which has led to late bloom and crop reduction. To overcome environmental threats chemicals have been used to manage and promote bud break. Winter oil has been applied to pistachio trees since the winter of 2005. To compare the effects between high concentration (6%) and low concentration (3%), 6 years of data showed high concentrations produced better results only when the chill portions were below 59. Major components for such sprays were timing, concentration and water volume application. To improve tree performance in low chill seasons a study of different water volume applications was implemented. In the winter of 2014, an experimental trial was established in an 8.6 ha block with 5 replications in a randomized complete-block design. In the trial, when chill portions were below 59.6% winter oil was applied; when chill portions were equal or above 59.3% winter oil was applied. The differences in the treatments were: one area was treated with a water volume of 2000 L while the other area was treated with a water volume of 4000 L. In the 3-year trial, when chill portions were below the 59 critical portions for 'Sirora' pistachio trees the 4000 L water treatment showed early bloom, early maturity and significantly better crop yield, nut size, edible closed and blank nuts than the 2000 L water treatment. When chill portions were equal to or above 59 portions, bloom timing and yield differences were not obvious. The effects for both concentration and water volume application of winter oil are also discussed.
Ranford, T. and Zhang, J. (2018). Winter oil application in pistachio production in Australia. Acta Hortic. 1219, 105-110
Pistacia vera, chill, yield, water volume, concentration