FROST AND FRUIT

Dominion, Volume 30, Issue 266, 6 August 1937, Page 7

FROST AND FRUIT

Methods of Protecting Orchards RESEARCH IN AMERICA After investigating frost-lighting methods employed in the orchards ot California, Sir. Lloyd Williams, of the Department of Agriculture, considers that only four methods can be recommended to New Zealand growers : —-Lard pail oil heaters, low stock oil heaters, briquette heaters, and central heating with hot air. Mr. Williams yesterday, told the annual conference of the New Zealand Fruit-growers’ Federation at »» elhngton the results of his investigation. Conference decided to ask the Government to make Mr. Williams available to give advice to districts affected by frost. Main Methods. 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, 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 trom the ground. , x ~. Mr Williams found that frost-fighting in the United States had been developed to the highest pitch in the citrus-grow-ing areas. Californian in January, 1937, had burned 10 to 80 million gallons of oil in the protection ot their orange and lemon crops. Spraying with water was looked upon as a standby means of adding beat, but there was a danger of the water freezing and splitting the trees. Electricity as a direct means of producing heat was impracticable, as the cost was too heavy 1000 horse-power being needed to beat one acre of ground. Air <nrculation by wind-machines had not been successful, and the machines cost tloOOA machine, with a furnace attached to it. was now being made, but the cost was St ln regard to the lard pail heater, it had been found in California ’t w“s not necessary to use the spreader » bustion could be retarded by use of the lid, which meant a reduction in cost Low stack heaters were popular, 2.500,000 be in»- in use in California. The heaters coSt 6/- or 7/- each, and 80 were needed to the acre. Petroleum liquid gas, ot which Mr. Williams had had hopes, won d prove too expensive, and, owing to its inflammability, was also dangerous. Central Heating. Mr. Williams saw oho system of central heating with which he was impressed. Hot air was radiated from . a Birnace 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 or any other system, the oil consumption being only two gallons and a half an acre an hour. „ . Because of the low cost ot oil in America—2ld. to sd. compared with Bd. in New Zealand —few experiments had m 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 a briquette heater had been introduced in America from which the air could be excluded to extinguish the fire at any time. Heaters cost 10/-, and 100 were needed to the acre. If briquettes could be obtained at £3 a ton. delivered, this would be the cheapest method of heating orchards to prevent frost damage.