Paraffin candles are suitable for protecting against spring frosts. The anti-frost candles are filled in 6-litre metal cans and the additives ensure burning and warm smoke for up to 10 to 12 hours.
Every fruit tree has a critical temperature value in the respective phenological phases which it the tree can endure without damage. In view of this critical temperature, the tasks are determined by a person responsible. (Annex 1.)
1. Planning Frost Protection
A. Use a sufficient amount of anti-frost candles
– Necessary amount: 350-500 pcs. per hectare
– Prepare an installation plan
B. Purchase and install of meteorological devices
– Install meteorological stations or thermometers n in the protected area as well as to the control area.
C. Ensure the sufficient number of personnel for the ignition
– 1 to 1.5 person/ha as well as 1 to 2 people to distribute the candles and organise the work.
– A night shift schedule, an emergency and action plan are necessary.
2. Preparation for Frost Protection
A. Acquire and prepare ignition tools
– Ignition can be done with a jerry can, a big blow torch, or a small blow torch which comply with safety regulations.
– The acquisition and preparation of ignition mixture and other materials for the ignition.
– The purchase of an ignition tool (lighter).
B. Installation of anti-frost candles
– Installation based on plan (1.A.)
– Finish the installation of candles at the beginning of the frost susceptible period the latest.
– A candle must be installed in front of the first and behind the last trees of the rows, as well.
– Do not place candles next to trees and to the irrigation pipes! Do not put them in a highly flammable place!
C. Remove the lids of anti-frost candles
– Lids must be removed by the beginning of the frost susceptible period, before the ignition.
– Half of the anti-frost candles should be prepared for the ignition (every candle of every second row or every second candle of each row.)
– The lids must be placed close to the candles because they will be necessary for the extinguishing. (4.A.)
D. Introduce OSH training and train workers who are taking part in the frost protection
3. The beginning of frost protection and ignition of candles
A. The person in charge alerts the workers (1.C.)
If the temperature is falling suddenly and largely such as 1 Celsius/hour, the person in charge must start the alert (During sunset temperature is falling suddenly. This is a natural phenomenon.).
B. Ignition of candles
Figures in the chart (Annex 1. and Annex 2.) are normative but can be varied in cultivars and varieties: If the temperature reaches a harmful value in a short period of time, the ignition of the candles must be started.
– First Round: Ignite every second candle in every second row, as well as the first and last candles of these rows. (This represent around 25% of the candles, if 450-500 pcs. /ha is used.). If the temperature does not rise, or the control area’s (1.B.) temperature drops below the value temperature of 10% loss, it is necessary to light up more candles.
– Second Round Ignite all the remaining candles in the rows already ignited, or every second candle of the rows which have not been ignited yet. (around 50% of the candles, if 450-500 pcs. /ha is used). If the temperature does not rise or the control area’s (1.B.) temperature reaches minus 5 Celsius (-5°C), all the candles must be lit up.
– Third Round: Ignite all the remaining candles, provided they had not ignited in the second round. It is advisable to start in the most frost susceptible area, and if it is possible the direction of the ignition should follow the airflow. The time factor is important: all the required number of candles must be lit within one hour from the ordainment of the ignition (1.C.) If half of the candles are lit (after the ignition of the second round (3.B.)), it is advisable to remove the lids of the anti-frost candles to prepare them for the next ignition! (2.C)
4. Extinguishing the anti-frost candles, preparing for the next frost period
A. Put back the lids onto the anti-frost candles to extinguish the fire
B. Check the paraffin level in the candles
– The left-hand side candle (not used) is able to burn 10 to 12 hours, whereas the right-hand side in one (half-way burnt, as it is apparent on the outside), can only burn up to 5 to 6 hours.
– Replace the burned candles if it is necessary. (1.A.)
– Replace used ignition mixture and necessary materials for the ignition. (2.A.)
– Plan the next ignition considering the state of the candles.