Experiments in the Treatment of Fungous 

 Diseases of Fruit and Potatoes 



BY H. H. LAMSON 



The diseases with which this Bulletin is concerned are those 

 known as fungous diseases. They are not due to insects, 

 which belong to the animal kingdom, but to members of the 

 vegetable kingdom — that is to say, plants. These disease-pro- 

 ducing plants belong to the class known as fungi, and as they 

 grow upon other plants, they are called parasitic fungi. They 

 are so small that their nature cannot be made out by the naked 

 eye, so that it is not strange that they are not so well under- 

 stood by the majority of people as are insects. The parasitic 

 fungi grow at the expense of the plant on which they live, and 

 cause, in many cases, serious damage; and in the case of cul- 

 tivated plants, great pecuniary loss. It has been found that 

 many of these diseases may be largely prevented by spraying 

 with some substance which is harmless to the cultivated, but 

 .poisonous to the fungous, plant. 



DISEASES OF THE APPLE AND PEAR 



The most serious fungous disease of the apple and pear is 

 usually the scab. This disease appears on both the fruit and 

 the foliage. On the fruit it appeals as dark gteen or almost 

 black spots, with a velvety surface. The spots are circular in 

 outline, and occur separately or run together in irregular 

 patches, often covering a large portion of the surface. The 

 spots are thickened, and slightly raised above the surface, so 

 that the term scab is very applicable to the disease. 



A fruit which is badly affected with the scab is usually 

 deformed or one-sided, and frequently cracked so as to be 

 worthless. Certain varieties of both apples and pears are more 



