CLUB-ROOT.

Auckland Star, Volume LVIII, Issue 45, 23 February 1927, Page 18

CLUB-ROOT.

AN INCREASING MENACE

PREVENTIVE MEASURES.

(By PLOUGHSHARE.)

Ihis disease, which is also known a* finger-and-toe, lias for some vears seriously handicapped the cultivation of turnips in the South Island, and now bids fair to ravace districts in this province that have hitherto been considered comparatively clean. The disease is due to the activities of a minute slime funEns, nlasmodiophora hras«icac, that is capable of lying dormant in the soil for some years. The symptoms are so characteristic as to have given the disease its name. Tn the early stages there appear irregular shaped swellings on the bulb, "that steadily increase in size till the whole of the lower part of the root becomes mis-shapen. In late autumn these swellings turn brown and rot, the whole bulb becoming soft and slimy. The crop can be infected at quite an early sta<:e. in fact, there is already evidence of this season's attack. No Cure For Infected Crop.

Unfortunately, there is no way of protecting the crop once the disease has made it« appearance. Liberal manuring and favourable weather will, however, minimise the disease by enabling the crop to "grow away" from it. It is also thought that a proportion of lime nnd iiotash in the fertiliser makes the crop more resistant to the disease. Wellfanned crops suffer least. At one time it was thought that heavy dressings of lime would check this disease, but recent investigations have shown that no amount of lime will enable healthy crops to be grown on land that has recently carried a diseased crop. It was also laid down in the past that "acid" manures such as superphosphate and sulphate of ammonia should be avoided, but the efficacy of this is at least doubtful. Probably the best fertiliser to use where the disease is feared is basic super combined with guano or bonedust and a little potash. Means of Control. Farmers must remember that the spores of the disease can live in the soil for a number of years; they can. moreover, be readily carried about the farm by the hooves of animals, the wheels or working parts of implements, and the boots worn by workers. Clubroot is in fact highly 'infectious. When the disease appears." therefore, the only wise course to pursue is to treat the paddock as a plague-spot so far as turnips, rape, kale or chou-mollier are concerned. Mangels, carrots, lucerne, maize, millet or cereals can be grown, but probably the best plan is to sow the paddock down to grass for at least five years. This removes all risk of infection through implements, etc. In growing future crops of crucifers (turnips, rape, etc.). it is then necessary to select grouud that is absolutely free from suspicion of taint. No stock should have used it that have had access to an infected crop, and all implements should be carefully cleaned, and disinfected by being exposed for some days to strong sunshine. Where the disease has become very prevalent it is perhaps best to go out of turnipgrowing altogether; even rape and chou-mollier are risky, though to a less extent than turnips. The place of turnips must be taken by hay and silage, and by non-cruciferous crop 9.