PLANT DISEASES.

New Zealand Herald, Volume LXVIII, Issue 20977, 14 September 1931, Page 14

PLANT DISEASES.

PREVENTING CLUB-ROOT. USE OF MERCURIC CHLORIDE. | Harper Adams College Ims been experimenting with a number of substances likely to help in controlling finger and toe disease (club-root), and lias found data sufficient to advocate the use «jt mercuric chloride (corrosive sublimate) as a preventive of the disease where it has been in any degree prevalent. A general improvement in cabbage crops following mercuric chloride treatment is obvious. The treatment suggested as being most efficient is to " water in " (lie young plants with a solution of mercuric chloride of 107,. in 10 to 12 gallons of water, applying about half a pint of (he solution lo each hole before pressing down the plant. All hough it is not suggested that such treatment of the plants will entirely eliminate the disease, it- is asserted that it will, under normal conditions, enable the grower to obtain reasonably good crops even on heavily infected soils. A single treatment appears (o be all that is necessary under ordinary conditions, since, successive applications up to three, in number during the growing season gave no markedly superior results. Where the seedlings have lo be raised in soil actually infected, preliminary treatment of t-ho seed bed is undoubtedly essential, and the use of 0.1 per cent, of mercuric chloride or of 2 per cent, formalin at the rate, of about two gallons per square yard of bed is recommended for this purpose. The solution is best applied three or four weeks before sowing if formalin is used, but with mercuric chloride so long an interval is unnecessary. Care should be taken when transplanting that only seedlings with perfectly clean roots are selected.