18 G. MASSEE — PAEASITIC FUNGI. 



have in addition a strong? scent. The combination of scent and 

 colour attracts insects, which disperse the spores, but in other 

 groups wind is the chief agent of spore-dispersal. 



In concluding these remarks I may mention the great importance 

 of preventive measures, for, when once an attack gets established, 

 cure is almost impossible. The one general remedy which has 

 been used for whole groups of fungus-attacks is that which is 

 generally known as Bordeaux mixture. It contains two or three 

 per cent, of sulphate of copper in water, and is very often mixed 

 with a certain amount of quicklime. The great difficulty in 

 combating plant-diseases is in the thorough wetting of the leaves, 

 which should be sprayed with very fine spray both on their upper 

 and under surfaces. A small amount of soft soap mixed with the 

 solution causes it to adhere better to the foliage. 



The prevalent opinion that, owing to long-continued cultivation 

 and intercrossing of cultivated plants, the power of resisting fungoid 

 attacks is lowered, is not supported by facts. Botanists are well 

 aware that, in a wild state, almost every kind of plant is attacked 

 by one or more species of parasitic fungi. On the other hand, it is 

 only when almost every individual of a cultivated crop is injured 

 that the practical man considers the attack of these same fungi as 

 constituting a disease. Once upon a time the same ideas held good 

 in the case of cholera and scarlet-fever ; at the present time we 

 have learned the value of isolation and preventive measures in such 

 cases ; but, unfortunately, those most interested in the cultivation 

 of plants have yet to learn that the same rule holds good in the 

 case of plant-diseases. This condition of things can only be remedied 

 when the present ignorance or indifference is replaced by the 

 amount of sound knowledge which will result in unity of action. 

 It is practically useless on the part of one individual to carry 

 out the known methods for the prevention of fungoid and insect 

 pests, if his neighbours, through lack of the required knowledge, 

 unconsciously favour the spread of the same. 



