90 



BLACK KNOT. 



mention all the known species of fungi that are injurious to vegetation, 

 but merely a few of those that are best known and most troublesome to 

 fruit-growers. Some of these are more or less cosmopolitan in attacking 

 various fruits, others again confine themselves to single kinds or 

 families. These latter will be dealt with in the special articles upon the 

 different kinds of fruits, and those only are noticed, in this part of the 

 work, that are troublesome to various families. But though the list 

 named may not be so complete as some would wish, yet cultivators must 

 bear in mind that the treatment recommended for those mentioned is 

 also applicable to many others. 



Black Knot. This is a peculiar and con 

 spicuous excrescence sometimes found on stone 

 fruit trees, and more especially the Plum and 

 Cherry. It is rather troublesome to fruit- 

 growers in Europe and America, but is but 

 little known in this part of the world. There 

 is some uncertainty as to what causes the 

 disease, as authorities are divided in opinion as 

 to whether it is brought about by insects or 

 fungi. But the weight of authority is in 

 favour of the fungoid theory. The knots vary 

 in size, ranging from half-an-inch to twelve 

 inches, or more, in length. The excrescence is 

 generally on one side only of the branch, which 

 it usually kills in time. The name is derived 

 from the fact that the knots assume a dark 

 colour in the winter, and the outer surface 

 hardens. Remedy : The only effective way 

 of dealing with the evil is to cut the 

 excrescences away with a sharp knife, taking 

 care to burn them, so that the fungus germs 

 are effectively destroyed, or otherwise the 

 disease will again make its appearance very 

 quickly. The cut parts of the branches should 

 be painted over with a composition of lime and 

 sulphur in equal proportions, with a small 

 quantity of kerosene added. 



Fusicladiums. These are a very common 

 and troublesome class of fungi, embracing 

 several species, which cause serious injury to 

 many fruits, and more especially Apples and 

 Pears. Commonly the fungus is known as 

 "Scab." They make their appearance on the 

 leaves of the trees in the spring in the form of 

 little dark dots. These afterwards appear upon 

 the young fruit, of ten in patches, which have the 



appearance of scabs. The fungus grows upon the fruit, which is conse- 

 quently rendered more or less worthless. "Remedies : Soap and sulphur, 

 biuestone and ammonia, green vitriol. 



