80 JOURNAL OF THE ROYAL HORTICULTURAL SOCIETY. 



where it finds an abundance of food, and soon spreads through 

 the entire leaf. When this has taken place, it is too late to 

 spray ; no solution can kill the mycelium present in the plant - 

 cells without also killing the leaf. The aim of the gardener 

 should be, by exercising the methods indicated above, to prevent 

 such inoculation from taking place, by a continuous warfare 

 against every form of fungus making its appearance. As a rule 

 a parasitic fungus attacks only one particular kind of plant, or 

 closely allied plants belonging to the same natural order ; con- 

 sequently, where numerous plants of the same kind are grown 

 in close proximity, it is necessary that a very sharp look-out 

 should be kept, and any plant showing symptoms of disease 

 should be promptly removed, and if of little value, be destroyed ; 

 or if too valuable it should be removed from the rest ; as, should 

 the disease prove to be of a fungoid nature, neglect may result 

 in disaster. Unfortunately the gardener's idea of a disease is 

 generally the simultaneous collapse of numerous plants, which 

 in most cases originates from a single individual being attacked 

 in the first instance ; therefore never delay doing all that can be 

 done, by promptly removing suspicious individuals, and after- 

 wards spray the entire batch of plants with some fungicide, so as 

 to destroy any spores that may possibly have spread from the 

 diseased plants before removal. It is not sufficient to pull up a 

 suspected plant and throw it down in a corner to die ; the plant 

 so treated would in all probability die, but if it was attacked by 

 a fungus, the latter would not perish also, but continue to grow 

 and produce spores just the same as if the plant had been 

 allowed to stand. For the same reason, diseased plants should 

 not be thrown on to a rubbish heap, but thoroughly destroyed 

 by burning. 



Most fungi differ very considerably from other plants in pro- 

 ducing two or more kinds of spores or reproductive bodies, which 

 serve different purposes. During the summer months most 

 parasitic fungi produce in rapid succession myriads of very 

 minute spores which aro capable of germination the moment 

 they arc ripe ; these spores are distributed wholesale by wind, 

 rain, &0., and those that happen to alight on the leaf or young 

 branch of the plant on which they are capable of growing, ger- 

 minate and enter the tissues at once. By this means a disease, 

 win n once present, spreads rapidly. A single mildewed apple 



