GROW BETTER “SPUDS”

Te Awamutu Courier, Volume 53, Issue 3802, 31 August 1936, Page 3

GROW BETTER “SPUDS”

SPRAYING WITH SULPHURIC ACfID. The current number of the Ministry’s Journal (London) contains an account of experimental spraying with sulphuric acid to prevent late infection of potato tubers with blight. The experiment was carried out on a crop of King Edward potatoes on a farm in Norfolk.

The crop was sprayed on September 16, 1934, on a hot sunny day, with a drying wind. Sulphuric acid solution of two strengths (10 per cent and 20 per cent 8.0. V.) was sprayed at .100 gallons per acre. The acid was applied by a horse drawn spraying machine of standard type, having a time of spraying only a few plants fitted with 22 delivery nozzles. At the horizontal spray bar 16ft 6in wide were affected by blight, but within three weeks the disease had spread all over the “control” plots. Before, it was sprayed , the haulm was, green and the crop very weedy. Both haulm and weeds were rapidly killed by the acid, becoming brown and withered w’ithin two hours. A striking feature of the sprayed plots was the complete destruction of annual weeds in contrast with the dense growth of weeds on the controls. The total cost of spraying per acre including labour, cost of acid, and depreciation, was estimated at 14s 6d. Taking into account the increased crop obtained (which was carefully worked out) a net profit of Ils Id per acre, due to spraying, was left. If the blight attack had been heavier the profit would have been greater. Another advantage of spraying is that the destruction of the haulm enables the grotver to lift as soon as he likes, without waiting for the haulm to die down. He can then select the most favourable date for marketing his crop. Further, it he wishes to obtain “mature” seed he can stop growth at the correct time by spraying with acid. Sulphuric acid needs very careful handling. The water should never be poured into the acid, but the acid into the water. Workers should wear rubber boots and goggles. A soda solution should be kept handy in case the acid gets into cuts and sores.