528 



THE PATHOGENIC SLIME-FUNGI. 



considered quite a safe interval, but seven years is, and with 

 good management the disease, though by no means uncommon, 

 only then attains serious dimensions in moist seasons. Massee 

 points out that the development of the fungus is favoured by 

 acids and checked by alkalis ; this explains the well-known 

 beneficial effects of dressings of lime or potash in keeping the 

 disease in cheek. With a six or seven-year rotation, and the 

 application of lime once in the rotation, the disease should 



C^^d^ 



Fig. 318. — Hypertrophied cells from a Cabbage-root attacked by Plasmodiophora 

 Several of the cells are filled with spores, (v. Tubeuf del.) 



never be very injurious. The direct application of farmyard 

 manure to the turnip crop should also be avoided, especially 

 if the stock which made the manure was fed on diseased turnips ; 

 this is necessary because it has been found that tlie spores are 

 not killed when eaten by animals.] (Edit.) 



Plasmodiophora vitis Viala et Sauv.^ This is said to 

 cause a Vine disease known as " Brunissure," which within 

 recent years has caused considerable loss in France, North 

 America, and Southern liussia.^ The early symptoms are light- 

 brown star-shaped spots on the upper surface of the leaves 

 between the ribs. The spots enlarge and cause a premature fall 

 of the leaf, whereby the grapes are prevented from maturing. 



1 Viala et Sauvageau, Conipt. 7-end., cxiv., 1892. 



-Cooke (Gardenpys Chrouirle, 1893) refers swellings found by him on roots of 

 the vine in England to the action of this fungus. (Edit.) 



