290 THE FRUIT GARDEN 



of air, insects, clothing, &c., or by spraying ; and if the leaf surface is moist 

 such conidia germinate, and the germ tubes enter the tissues of the leaf 

 directly. Very frequently a leaf becomes quite dry, and crumbles to the ground 

 within twenty-four hours of the first infection. Such dead fallen leaves are 

 much more responsible for the rapid spread of the epidemic than are the conidia 

 which pass directly from one leaf to another. When the dry fragments of a 

 diseased leaf fall on damp earth, the mycelium present in the tissues quickly 

 commences growth and forms an exceedingly delicate cobweb-like mycelium, 

 which runs on the surface of the soil and produces myriads of very minute 

 conidia, which are dispersed by currents of air, and infect the leaves in a 

 manner similar to that of the larger conidia borne on the leaves. 



The Mycelium in the soil originating from diseased fallen leaves continues 

 to extend and produces conidia so long as the requisite conditions as to moisture 

 and temperature are present. When these conditions fail the mycelium passes 

 into a resting condition, but readily assumes renewed activity when stimulated 

 by returning moisture and heat. By this means the fungus survives from one 

 season to another in the soil, and the disease is almost certain to recur year after 

 year in a house that is once infected unless the soil is thoroughly sterilized. It 

 is important to remember that the disease under consideration can only assume 

 the proportions of a destructive epidemic when attacking plants grown under 

 glass, and when a high temperature and an excess of moisture are present. 

 Such conditions, accompanied by a deficiency of light, result in the production 

 of " soft " foliage, and it is only such soft foliage that the fungus can attack. 



Preventive Measures. — If the foliage is fairly hard the disease cannot 

 assume the dimensions of an epidemic, and even if it appears it can be kept well 

 in hand by spraying. To accomplish this end a fair supply of air should be 

 admitted, so that the atmosphere is not constantly saturated with moisture. It 

 is wise to spray in anticipation of the disease, using a solution of potassium 

 sulphide (liver of sulphur), 2 oz. to 3 gallons of water, adding 2 oz. of soft 

 soap. It is important that the under surfaces of the leaves be thoroughly wetted 

 with the solution. If the disease be present the soil should also be drenched 

 with it. Diseased leaves should be gathered and burned before they decay and 

 fall to the ground. After a diseased crop has been removed, the soil should be 

 thoroughly drenched with a solution of " Jeyes' Fluid," in the proportion of 

 one ounce to a gallon of water. 



SPRAYING CROPS 

 By WILLIAM CRUMP 



Growing plants are liable to serious injury from two classes of organisms, viz. 

 noxious insects and parasitic fungi. Where either of these is allowed to flourish 

 it is impossible to practise successful fruit cultivation, therefore we must deal 

 promptly and thoroughly with these enemies. Generally speaking, this can 

 best be accomplished by spraying with an insecticide, the thorough application 



