DISEASE IN CROPS

Hokitika Guardian, 24 January 1933, Page 7

DISEASE IN CROPS

incidence OF CLUB-ROOT

VARIOUS' EXPERIMENTS,

: One reaeon why a great number of farmers neglect the growing of common crops fo-r the supplementary feeding of .stock is the ■susceptibility of many to disease and the consequent risk of uneconomic yields. Cruciferous crops, such as swedes and brassfea crops, such «r----the various types of kale, fail to appeal as such valuable crops should mainly because of their extreme liability to clubroot infection. Years of investigation by th e Department of Agriculture ’have not been without their reward however, as far as effective means of clubroot control are concerned, aud it has now been established that liming, provided jt irs done about three month? before towing (represents a practical combative measure. In the cas e of swedes the. position has lately been further improved by the testing of disease resistant varieties.

Overseas endeavour has been directed toward securing control, as far as brnssica types are concerned, by the use of disinfectants. Mercuric chloride in particular has been found to be effective in the control of the disease, although there has been a tendency to plant injury with its use, while satisfactory results have been r e corded with strong solutions of formalin, Bordeaux mixture and mercurous chloride. Thus from a consideration of efficiency of control, effect on plant.gi’owth, ease of application and cost of materials th e 0.1 per cent, acidulated mercuric chloride treatment at two gallons per square yard appeared to be the most satisfactory for -practical use.

The concentrated solution of acidulated mercuric chloride wa s prepared according to the following formula making sufficient for the treatment of 50 square • yards of seed-bed;—Mercuric chlorid e powder, lib.; commercial concentrated hydrochloric n-'d. 31b. This solution must ibe kept in a glass bottle. The disinfectant solution for application to seed-beds was made by adding 1.6 fluid oz. (45 c.c.) of the concentrated solution to four gallons' of 'water in a benzine' tin, ■ stirred rapidly,' and . distributed as evenly as possible.over the seed-bed by a watering-can at the rale of two gallons per square yard. The isucc e ss of the method , depended on the •rapidity with which tile metal containers can be emptied after the addition of the mercuric chloride. .To facilitate accurate and rapid distribution the seedbeds should previously be, mark-ed off into areas of two square yards, and the tins of water brought. to- the area to be treated befo re the addition of the disinfectant. The application of a further gallon of water per. square yard about-an hour later served to. wash the disinfectant (farther into the i«oil; ; Mercuric- chloride is very poisonous, and must be kept out of reach of children and stock, and all containers should be carefully washed after use.