Prevention of frost in pistachio trees

Proper management of the garden

Since the soil surface heat has a significant effect on frost protection. The plowed soils cool faster so that the grasses on the surface of the soil are a kind of conductor of heat from the soil to the air.

In this case, depending on the management of the garden floor, the amount of damage varies.

On visits, 100% frost was observed where the ground was tilled, while in adjacent gardens where the ground was not tilled, there was no sign of frost.

Most of the colds we have in the garden are of the radiation type, which can be reduced with measures. During the day, the sun warms the earth, and this heat is stored in the soil and emitted from the earth during the night.

On days when the weather is cloudy, the soil temperature does not rise and at night the heat that comes out of the ground is not enough to keep the tree environment warm and the soil surface temperature drops below zero, on these nights there is a possibility of frost.

Low temperatures usually occur half an hour to an hour before sunrise. It is the  best way  for the gardener to have a the rmometer with him and when the temperature reaches positive 4, he should take measures to deal with frost.

Heating the garden

If there is a possibility of frost, it is better to keep the garden environment somewhat warm.

Some people set fire to tires, which is not recommended at all; Because the ceiling changes the temperature inversion and the temperature rises directly and does not have much effect on increasing the temperature of the garden.

A practical recommendation for heating the garden is to place the pistachio garbage in the middle streets of the garden in a heap with a distance of 5 meters and it is better to have about 40 heaps per hectare.

Each compartment is about the size of a sack of chemical fertilizer at about 20 kg. Pistachio garbage and its bony skin are usually used. Mix 4 to 5 liters of diesel and water on each coupe and set it on fire.

Mixing water with diesel is to prevent the material from burning quickly and also to create thick and heavy smoke that stays on the ground and near the trees and keeps the heat and does not allow heat to move up and cold to penetrate down. .

Using wind generators

In some gardens, a wind generating machine has been placed at a height of 10 to 12 meters above the ground, which mixes the hot air above with the cold air on the garden floor and can prevent frost to some extent.

Of course, a moisture and wind generator has also been built that keeps the ambient temperature high and has responded well.

What does temperature inversion mean?

Normally, the temperature decreases with altitude, but in the case of frost, the opposite is true, while the garden floor is cold, with increasing altitude, the air becomes warmer, for example, at a height of 15 meters, the temperature is 10 to 15 degrees. But at lower altitudes the temperature is lower. This is called temperature inversion or thermal inversion.

Irrigation during frost

Irrigation during frost is another way to deal with it. But it is better to irrigate the garden in two ridges in between so that a large amount of water remains in the ground.

But if irrigation is done and the temperature drops the next night and the temperature inversion occurs, it will increase the severity of the frost, because the ground gets too cold.

Selection of late pistachio cultivars

In areas where there is a possibility of frost and are exposed to spring cold almost every year, it is better to use late cultivars for cultivation,

Due to the fact that the cooling needs of different  types  are  different

Koleghoochi between 500 to 600, Ahmad Aghaei  is estimated to be 600 hours Fandoghi (Round) is 800 hours Akbari is 1000 hours but the younger the tree, the less cold it needs.

Using chemical compounds

The use of potash fertilizer increased the tree's tolerance to cold and could prevent frost damage to some extent. Foliar application of amino acid fertilizer can also be effective.

Using windbreaks around the garden

If you remember, there were brick walls around most of the old gardens, these walls are significantly prevented from frost and wind.

Planting windbreak trees such as maple, sparrow and… trees in the cold path can protect the trees to some extent from frost.

Heating the garden with garden

Maybe advanced heaters in gardens will put an end to the frost on trees forever. these heaters that are placed in a network and under the trees Each device can produce 13,000 cubic meters of 250-degree air and deliver it to an extensive network under trees.

Does frostbite on pistachio trees only occur at sub-zero and zero temperatures?

Yes But at positive temperatures close to zero, there is a possibility of frost, especially if these temperatures are present in the garden for a long time.

But according to the growth stage in which the plant is, its tolerance to different temperatures is different. In some years,Ahmad AghaeiandKoleghoochidid not need to be sprayed, but spraying was done in many areas, and this caused the trees to turn green sooner, and on March 16th, sprout swelling began in almost all types. In particular, Koleghoochi suffered from frost and up to 30% of the lower branches of trees were damaged.

Are frosts different at different tree heights?

Yes ,In the first of April frost, the lower branches had more frost to the upper branches and the frost was very low from a height of one meter up.