Why will spraying fruit trees with water before a frost help toprotect the fruit from freezing?

Question

Why will spraying fruit trees with water before a frost help toprotect the fruit from freezing?

Answer 1

As the water freezes, it loses heat to the cold air, but at the same time, it loses heat to the leaves, stems and fruit of the tree too, so it actually warms up the tree a small amount as well.  Once the ice is frozen on the tree, it also acts as an insulator to prevent more cold from getting to the tree itself.  

Water is a great insulator.  It takes alot of heat or cold to change the temperature of the water even one degree.

This can only help if the tree is at this cold temperature for a few hours.  If it goes on for several hours, the tree and fruit will definitely freeze into the plant's tissues as well.  

This is why you would NOT be able to do this while growing an orange tree in Buffalo, New York...just spray it every time there's a snowstorm and it'll be fine...unfortunately, there's so much snow and ice that the tree would be overwhelmed and freeze through it's tissues.

Answer 2

Actually what you are seeing is only part of the process. Irrigation prior to a freeze is best done a couple of days prior to the freeze. Moist soil will hold more heat than dry soil, if the farmer has time to irrigate and let the sun warm up the moist soil. Irrigation just prior to a freeze can actually cool the soil, as wind blows over the soil surface, evaporating the water.

Water sprayed on the leaves can protect any plant from freeze damage, with a couple of VERY important provisos.

Water has to be applied CONTINUOUSLY after the temps reach freezing to the point at which temps rise above freezing, usually the following morning. The continuous flow of water keeps the ice which forms, and therefore the plant, at 32 degrees. Without the continuous water flow the temperature will continue to drop, causing MORE damage to the plant than would have occurred if no water was applied. Also it takes a lot of water to cold protect with this method. Something like one inch per hour. If less water is used, the temps drop and the freeze/ice damage will be more severe than if no water was applied.

Modern citrus groves use micro-sprinklers placed under the trees. These are turned on during a freeze, and help keep temperatures above freezing under the canopy of the tree. In a severe freeze (citrus is not damaged until 27 degrees F) outer branches and fruit may be damaged, but the trunk and main branches can be saved. This is probably why you see ice on the ground under the trees, but not on the leaves.

Answer 3

I think you spray them before the sun hits them in the morning.    Don't do it before the frost.

****  Sorry....I gave the wrong advice.   It's just what I had been told.

Answer 4

Because of the special characteristics of hydrogen bonding, water releases energy as it freezes. Consider that water droplets have collected around the fruit. Some of that released energy will go into the fruit, preventing it from freezing.

Answer 5

I know it works with strawberries - as it forms a shell that forms an insulator that holds the ground warmth in and keeps

the cold out

new stuff is like dish soap suds - once sprayed it stays for about 8 hours - does the same thing -

and keeps water usage down to a minimum

all the best

Answer 6

When the water freezes, that is as cold as it gets.  If the outside temperature drops below freezing, the temperature inside the ice "tent" is still just freezing, no colder.

Answer 7

It turns to ice and that insulates the fruit from the freezing air.