CLUB-ROOT.

Otago Witness, Issue 2558, 25 March 1903, Page 10

CLUB-ROOT.

This disease appears to be common among cabbages this season, and a plant sent fiom the- north allows a most virulent form of the disease known as ambury and peculiar io the cabbage worts. The plant becomes infected in the reed bed, and the infection aprears as a gall or wart on the stem near to the roots. This wart contains a small white matrgot, the larva of 1 little insect called the weevil. Cutting off tho gall with its tenant nnd replacing the plant in the soil, the wound soon iieak, and the plant is little retarded in growth. Care mu»t be taken to remove the gall with its tenant completely, and cause no injury to the tap root, or the result will be a failure. Ambury is worse where cabbages or turnips are grown in successive years, md the remedies recommended are gasworks lime, scot, etc. A fiome authority ays the disease ia now almost beyond the power of remedies.

The most recent investigation into the cause of the disease gives a different re-port, saying that at one time it was thought the disease was due to die irritation set up by a species of beetle. Modern research xs, however, against the beetle theory, .hough it must bo confesfed that, wherever clubbing appears, the gall weevil is present in largo numbers. The Board of Agriculture and the Kew authorities have made known the result of their investigations, agreeing that it is caused by a fungus. At one time it was thought not safe- to cultivate cabbagu for several year 3in soil where -he dieease had existed. To-day, however, by a process of sterilisation, suoh ground may bo rendered fit foi the reception of cabbage planta. According to the Tvew Bulletin the practical treatment of these " lime fungi " resolves Itse'.f into the following: — (1) In addition to cultivated plants, several common weeds belonging to Crucifer? are attacked by this fungus, and should be removed from fields and hedge banks. (2) The ■ germs of disease are present in soil that has produced a disea33d >rop, and they retain fcbeir vitality for at least two years. (3) The develop ment of the fungus is favoured by the presence of acids, and checked by the presence of alkalies, agreeing in this respeot with tho fungi rather than with bacteria. (4) For the purpose of sterilising infected soil, experiments prove that either ft dxeiauvg oj

lime or a manure containing" potash salts is effective, the latter being more valuable as it not only destroys the germs in the soil, but also arrests the disease in seedling plante, and at the same time supplies one of the ingredients necessary for the healthy growth of turnips. I<; may be added that the same disease, as manifested in the turnips, gets the name of finger and toe, and alsc that the weed which, from its earliness, is most attractive to the weevil or beetle, is charlock, generally known as wild mustard, which is now pretty freely established in our midst. I. M. I.