SECTION XIX 

 Diseases of Fruit caused by Fungi; &c. 



i. GENERAL 



It may be stated at the outset that the various preventive or remedial 

 measures suggested in this article are only intended for use against 

 parasitic fungi, and would not answer for insects, or in many instances 

 might be diametrically opposed to the most approved means by which 

 insects are successfully controlled. There is a very marked difference in 

 the mode of procedure of the person who undertakes to destroy insects 

 and the one who attempts to hold fungi in check ; and I think that perhaps 

 the chances of success are greater with the former, for the following 

 reasons. The majority of insects are superficial; for example, hordes of 

 caterpillars, &c. such can be readily reached and killed. There is no 

 such parallel in the case of the fungi. When an epidemic due to fungi 

 is present, in the great majority the fungus is safely located in the tissues 

 of the leaf, or other part of the plant, and absolutely free from treatment 

 of any kind; hence a case of a cure against a fungus parasite that has 

 once entered the tissues of a plant is unknown, whereas an epidemic 

 resulting from insects may be, and is often, cured. 



Coming to preventive methods, or in other words checking the exten- 

 sion of an outbreak, or in preventing its commencement, conditions still 

 favour the destroyer of insects. It is a well-known fact that in the field, 

 as spraying is done on a large scale, it is a very difficult matter to cover 

 every portion of every leaf with the fungicide used. Well, this point is 

 not of such vital importance in the case of dealing with insects as with 

 fungi. The caterpillar, in obtaining its food, moves at a comparatively 

 rapid rate, and sooner or later is certain to eat a portion of the leaf coated 

 with the insecticide, which seals its doom. On the other hand, if the spore 

 of a fungus alights on a portion of the leaf not protected by the fungicide, 

 under favourable conditions it germinates and enters the tissues, and an 

 infection which may spread is set up. If the spore alights on a portion 

 of the leaf covered with the fungicide, of course it is killed at the moment 

 of germination. 



A point of great practical importance to cultivators of plants is a clear 



