Insect Pests a net Fungoid Diseases. 401 



the plants' requirements a soft unripened growth is made, 

 which is very liable to attack from fungi. 



Though a strict rotation is impossible and inadvisable in 

 gardening it is always better, when practicable, to arrange the 

 crops so that plants of the same families do not immediately 

 succeed each other, and under no circumstances should a 

 diseased crop.be followed with another of the same family, as 

 this would almost certainly be affected by the same disease, 

 and probably to a more serious extent than its predecessor. 



Acid soils i.e., those deficient in lime are favourable to the 

 development of certain pernicious soil fungi, such as that 

 causing " finger and toe" in turnips, and when superphosphates 

 or other acid manures are used on acid soils the crop becomes 

 still more liable to attack. All such soils should be dressed 

 with slaked lime before cropping, and a moderate dressing at 

 intervals of three or four years will do much to improve their 

 general condition and eradicate these objectionable fungi. 



Crops which are especially subject to disease, like potatoes 

 or tomatoes, should always receive one or more protective 

 sprayings with a suitable fungicide, whether disease is visible 

 or not. It is much easier to prevent serious infection than to 

 kill the disease when it is established in the tissues of the plant. 



The method of disposal of diseased plants, or parts of plants, 

 is of great importance. They should not be dug into the ground 

 or left lying about in rotting heaps, because even a small piece 

 of tissue in which the fungus is present may produce spores 

 and so act as a centre of infection for a future crop, whilst a 

 rotting heap would disseminate the spores in millions and so 

 endanger future crops over a large area. All such diseased 

 remains should be burnt, or if burning is not practicable; buried 

 after being covered with quicklime. Diseased plants or roots 

 should never be fed to pigs or other stock unless first boiled. 

 When this precaution is not observed the germs of the disease 

 frequently pass uninjured through the digestive tract of the 

 animals indeed, in some cases they benefit by the process. 

 Unconsumed pieces also become mixed with the manure and 

 are carried on to the land to infect future crops. 



Many weeds are able to act as hosts for the pests and diseases 

 of cultivated plants, and do so act in the absence of the usual 



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