According to research conducted by the Pistachio Research Institute of the country, in winter, when the trees are dormant, there is no need for irrigation, except in areas that suffer from water and soil salinity. In areas with saline soil and water, increased salinity in the root zone of trees may cause undergrowth of branches, sunburn and shrinkage of the brain.
Burning of the tips and margins of leaves is also a sign of increased salinity uptake and accumulation in plant tissues. Although pistachio trees survive under high salinity and saturated soils, the combination of these conditions reduces the evapotranspiration and growth of trees.
In areas that are prone to these conditions and due to soil permeability problems during the leaching season, irrigation during the dormant period (winter) is often recommended for soil leaching. Since in this season, fertilization operations (animal and chemical fertilizers) are also performed in the manure, in order to create suitable conditions for plant uptake by the plant at the beginning of the season, it is useful to irrigate at least once after filling the manure.