STERILISATION HINTS

Wairarapa Times-Age, 3 February 1939, Page 3

STERILISATION HINTS

USE OF FORMALIN. Although soil sterilisation by steam for use in seed nurseries and glasshouses, particularly where tomatoes are grown extensively—is the most popular and efficient method, the cost of the plant for this work is fairly heavy. Amateurs and small growers often prefer to use formaeldehyde. This is available as formalin, which should contain 40 per cent formaeldehyde. The standard application as advised by Dr Bewley, at Cheshunt, is one gallon of formalin to 49 gallons of water, which is sufficient for 12 to 18 square yards of soil, the heavier application being suggested where disease is bad. This is approximately a 2 per cent solution, so gardeners requiring to sterilise a small quantity of soil for seed boxes, etc, can mix the amount of solution to meet their needs.

Where large areas are being treated, such as big glasshouses, the chemical is watered on to the surface and the soil then turned over one spit deep the same day. Another, and better, method is to double-dig and treat both top and second spit.

With small quantities of soil this is spread out and sprayed with the chemical solution, and then heaped and covered with bags. In both instances the soil should not be used for at least two and preferably three weeks after treatment and, with heavy soils, five to six weeks is advisable before use for planting.