COMBATING FROSTS

Ashburton Guardian, Volume 57, Issue 253, 6 August 1937, Page 3

COMBATING FROSTS

ADVICE TO ORCHARDISTS. METHODS IN CALIFORNIA. (Per Press Association.) WELLINGTON, August 5. After investigating frost fighting methods employed in the orchards of California, Mr Lloyd Williams, of the Department of Agriculture, considers that only four methods can be lecommended to New Zealand growers—lard pail oil heaters, cow and stock oil heaters, briquette heaters, and central heating with hot air. Mr Williams today told the annual conference of the New Zealand Fruitgrowers’ Federation the results of his investigation. The conference decided to ask the Govern•ment to make Mr Williams available to give advice to districts affected by frost. Mr Williams said there were two main methods of fighting frost—by preventing losses of heat, and by actually adding heat. The first method, which included the use of glasshouses, and scrim and smoke, was not greatly used. Smoke, generally speaking, was of little use in preventing heat loss, retarding not more than 10 per cent, of heat radiation from the ground. Spraying with water was looked upon as a standby means of adding heat; but there was a danger of the water freezing and splitting the trees. Electricity as a. direct means of producing heat wa9 impracticable, as the cost was too heavy, 1000 liorse-power being needed to heat one acre of ground. Air circulation by wind machines had not been altogether successful, and the machines cost £ISOO. A machine with a. furnace attached to it was now being made; but the cost was still higher. With the lard pail heater it had been found in California that it was not necessary to use the “spreader.” Combustion could be retarded by the use of the lid, which meant a. reduction in cost. Low stack heaters were popular, 2,500,000 being in use. In California the heaters cost 6s or 7s each, and 80 were needed to an acre. Petroleum, of which Mr Williams had had hopes, would prove too expensive, and owing to its inflammability, was also dangerous. Mr Williams saw one system of central heating with which he was impressed. Hot air was radiated from a furnace through tapering mains, with laterals punctured with holes. The initial cost of the plant was £375 for five acres, but the running cost was lower than that of any other system, the oil consumption being only 21 gallons an acre an hour. Because of the low cost of oil in America, few experiments had in the past been made with solid fuel; but the smoke nuisance was beginning to Force research in this and other directions. The chief disadvantage of the solid fuel heater in New Zealand had been the waste, caused by the fact that the fire could not be extinguished until the charge had burnt out; but the briquette heater had been introduced in America, from which air could be excluded to extinguish the fire at any time. The heater 9 cost 10s, and 100 were needed to an acre. If briquettes could be obtained at £3 a ton, delivered, this would be the cheapest method of heating orchards to prevent frost damage.