Rbode 



New York AgricVjltural Experiment Station. 525 



Tio. 



II. PHEVENTION OF CABBAGE CLUB-ROOT. 



The disease of cabbage, cauliflower, etc., known asclnb-root,is too 

 well known to need any description. In all parts of the world 

 where cabbage is grown this disease is troublesome, and probably it 

 is nowhere worse than in the market-garden region of southeastern 

 New York. In ditferent countries it passes under different names. 

 Club-root, club-foot and clump-foot are some of the names used in 

 America. 



So far as known, it attacks only plants which belong to the 

 mustard family, Cruciferae. The cabbage and its varieties (cauli- 

 flower, kale, Brussels sprouts and kohl-rabi) and the turnip {Brassica 

 rapa) suffer most. In Russia the candytuft {Iheris umlellata) and 

 stock {Matthiola incana) are attacked. Dr. Halsted has recently 

 shown that the disease sometimes occurs on the radish {Rajphamis 

 sativus) and the two common weeds, shepherd's purse {Capsella 

 Bursa-pastoris) and hedge mustard {Sisymhriuni vulgare). Further 

 investigations will probably show that it infests other cruciferous 

 plants. 



While everyone is familiar with the appearance of club-root there 

 may be some who do not know its cause. Formerly various theories 

 were set forth to account for it. Some claimed that it was due to 

 insects, and there are farmers at the present time who believe in the 

 insect theory. The true nature of the disease was discovered about 

 twenty years ago by a botanist named Woronin. He proved con- 

 clusively that the disease is due to a microscopic organism of simple 

 organization, which lives within the cells of the cabbage root. This 

 minute parasite feeds upon the starch in the root, and by irritating 

 the tissues produces the characteristic distortions. Woronin named 

 it Plastnodiopliora Brassicae^ It belongs to a group of organisms 

 called Myxomycetes or slime moulds, very few of which are para- 

 sites. Most of the speciet inhabit decaying wood. 



As for remedies, it is obvious that no spray or powder or other 

 treatment applied to the leaves can do any good whatever. The 

 seat of the difficulty is below ground, and no fungicide applied to 

 the parts above ground can reach the disease. Of the various sub- 

 stances applied to the soil, lime has given the best results, and we 

 may consider it established that lime is a preventive of this trouble- 



1 For figures and description see Journal of Mycology, Vol. VII, pp. 79-88. Also, New Jersey 

 Agr'l Exp. Sta. Report for 1S93, pp. 332-345. 



