CLUB ROOT.

Waipa Post, Volume IV, Issue 180, 17 January 1913, Page 4

CLUB ROOT.

A CABBAGE-PATCH TROUBLE. Most gardens have had some experience of club-root in their cabbages, and have found that plants which are affected by the disease seldom grow to maturity. It is an easy matter to detect plants which have the disease, as they have a wilted appearance during the day, although they recover at night. The disease is found to be worst on clay soils that are deficient in lime. In a soil in which sorrel flourishes the grower should be on the alert for the disease, as it is likely to develop rapidly. When a section of an infected root is examined under a microscope, it will be found that the larger cells are filled with a slimy substance. These are infested with the slime mould, and on account of the presence of this parasite, the cells undergo remarkable enlargement, and an influence is communicated to the outer neighbouring cells, so that the roots become much swollen and distorted. This fungus obtains entrance to the cells of the growing root, and there robs the infested tissue of its vital fluids, and, gathering new forces in itself, fills the cells with its own substance. This semi-fluid material then begins the process of spore formation, which results in the production of millions of minute bodies, each of which is capable of a new growth, when conditions are favourable. By the decay of the roots, which takes place rapidly, and with much offensive odour, the spores are set free in the soil. These spores there germinate by producing moving bodies capable of, penetrating, or being absorbed by the thin walls of the hair and other superficial cells oi the root. The soil becomes diseased in the sense that the germs formed in the swellings, and other distortions of the roots, are set free, and the earth holds them for an indefinite length of time. From a consideration of the nature of th'e club-root fungus, and a knowledge of the different kinds of plants infested by it, there may be some suggestions gathered as to preventive measures. When it is understood that the “clubroot, ”■ and all the injury to the crop accompanying it are due to an internal subterranean parasite, it becomes evident that no treatment to which the infested plant may be subjected can give promise of a cure. Preventive measures must be relied upon, and, in the first place, all the refuse of a cabbage, turnip, or other infected crop should be removed from the soil and burned. In view of the fact that the soil may become more or less impregnated with the germs during the growth of a crop susceptible to the disease, it is evident that a wise precaution consists in a judicious rotation of crops. Just what that rotation should be is a question for each grower to decide for himself, but, for the best results, cabbages or any allied crop should not be upon the soil oftener than once in three years. Cabbage, kale, rape, turnips, or radishes should not follow each otherjf “ club-root ” is prevalent. It is possible to get relief by the use of lime, and, by its constant use, at the rate of 75 bushels (2 tons) or so per acre each year, cabbages have been grown at frequent intervals —almost yearly, upon the same soil. It is likely that a soil naturally abounding in lime may be the best suited for cruciferous crops so far as “ club-root ” is concerned. Seedlings should be examined carefully, and, if they show signs of “ club-root,” consigned to the fire.