»14 THE FARMERS' HANDBOOK. 



Of the Swedes, Champion Purple-top, Imperial Purple-top, and Garde» 

 Swede may be mentioned as good table sorts. 



For Stock Feed. — Green-top and Purple-top, Yellow Aberdeen, and White 

 Pomeranian Globe are fairly good croppers among tbe turnips. 



There are a number of good varieties of Swedes suitable for feeding to 

 etock. Imperial Purple-top, Champion Purple-top, and Skirving's Purple- 

 top may be mentioned as good, even croppers. 



Diseases and Pests of the Turnip. 



The turnip, like most cruciferous plants, is subject to several insect and' 

 fungus pests. It will scarcely pay to spray large areas of turnips, and the 

 best means of control is to stimulate the crop to such an extent by means 

 ©f good cultivation that tbe plants may resist the ravages. 



White Rust of the Turnip, Cabbage, &c. (Albugo (Cystopus) Candida, Pers.)- 



This fungus attacks nearly all plants belonging to the crucifer family, 

 in every part of the world. Among species of economic value may be enu- 

 merated cabbage, turnip, cress, horse-radish, and radish. Among crucifer- 

 ous weeds, Shepherd's Purse suffers most severely, and as this and other 

 related weeds may harbour the pest particular attention should be given to 

 their destruction. The fungus attacks the plants when they are seedlings, 

 entering into the tissues through the stomata (breathing pores) of the 

 tender young leaves. The fungus threads or mycelium grow up with the 

 plant, and at a later stage produce on the leaves, stem and flowers, small 

 white areas presenting the appearance of little blisters. 



These little blisters are due to the presence of the fungus beneath the 

 cuticle of the host, and when later the cuticle bursts, countless small spores, 

 which are borne in chains, the oldest being near the apex, are set free. Each 

 of these spores, after being for a short time in a film of water, sets free 

 several minute spores, which swim freely in the water, and thus make their 

 way to fresh spots, to again set up infection. 



A second kind of spore — the oospore (resting spore) — is sometimes pro- 

 duced, but this likewise eventually gives rise to minute spores, which swim 

 freely in a film of water, and thus spread infection. When it is bome in 

 mind that the infecting bodies are free swimming spores that can only 

 make their way about when a film of moisture is constantly present on the 

 host plant, and when it is remembered, further, that infection can only be 

 effected during the seedling stage of the host, it will be realised that seed- 

 beds should occupy a fairly dry, open situation. 



The effect of the fungus upon the different hosts are somewhat various. 

 In the case of the Shepherd's Purse, for example, the stems become enlarged 

 and distorted; usually no malformations of the flowers or leaves occur,, 

 though in the radish the flowers often become strikingly modified. 



Controls. — These may be briefly stated thus: — 



1. Rotation of crops. 



2. Destruction by burning of all diseased plants. 



3. Destruction of cruciferous weeds, such as mustard, Shepherd's 



Purse, &c, which harbour this fungus. 



4. Dust on the plants a mixture of equal parts of freshly-slaked lime 



and sulphur. 



