FUNGOID DISEASES OF PLANTS 137 



to use on soil that has produced tubers which have dry 

 rot. This fungus also attacks tomatoes, and the spores 

 will germinate o& one crop on to the other. Hence 

 neither should be put in on ground where in the case of 

 the other it has just occurred. 



Minor diseases of Potatoes include Skin Spot, little 

 round blotches on the tubers which are sometimes mis- 

 taken for the Blight itself. Leaf Curl, a curious affection, 

 is somewhat widely distributed. It has the effect, in 

 bad cases, of choldng the passages in stem and leaf 

 and so preventing the flow of nourishment from the soil. 

 Early hfting and dressings of kainit are recommended. 

 Silver Scurf is an affection of the outer skin caused by 

 Spondycladium atrovirens, and it may be kept in control 

 by using a little flowers of sulphur for storing purposes. 

 Rust, which produces the brown spots on the leaves of 

 both potatoes and tomatoes, is sometimes very active 

 as a fungoid disease, but its control may be achieved by 

 the timely use of Bordeaux as in the case of BHght. 



The curious ailment of Turnips and allied crops, which 

 has been named indiscriminately Fingers and Toes, 

 Club Root, Anbury, and Grub (which latter is an erroneous 

 confusion with the work of the Turnip Gall Weevil), 

 was once thought to be a physical trouble of the plant 

 itself, but has now been located as an internal fungus 

 called Plasmodiophora brassicce. I must apologize for 

 these long names, but they are the only ones which have 

 specific fixity. Fingers and Toes also attacks swedes, 

 cabbages, kohl rabi, radishes and common weeds of the 

 cruciferous tribe. The fungus is only visible under the 

 highest powers of the microscope. A turnip ceU is shown 

 in the illustration filled with the spores of this disease, 

 which causes the cells to expand and so distort the root 

 of the plant into all manner of grotesque shapes. The 

 spores have the power of lying dormant in the soil for 

 years if necessary, and as soon as they come in contact 

 with a suitable subject, to which they fasten themselves, 



