LNSECTS, FUNGI, PLANT DISEASES, ETC. 169 



attack, and in the course of two or three years will die 

 entirely. 



The rosette is somewhat similar to yellows in its 

 methods of attack, but it is more decided in its appear- 

 ance. " It may first attack part of a tree and then the 

 remainder, the same as yellows, but it is more likely to 

 appear at once in the whole tree, and generally in early 

 spring. In trees attacked in this manner all of the leaf 

 buds grow into compact tufts or rosettes. These rosettes, 

 although seldom more than two or three inches long, 

 usually contain several hundred small leaves. A tree 

 thus attacked always dies the following autumn or win- 

 ter. The prevailing color of the foliage is yellowish green 

 or olivaceous." (Erwin F. Smith in Farmers' Bulletin 

 No. 17.) 



The only sure remedy is to dig up the infected trees 

 and carefully burn them, otherwise the disease will soon 

 spread throughout the entire orchard. 



Plowrightia morbosa (Sacc). The black knot of the plum. 

 This is an excrescence growing upon the bark and young 

 wood. The bark swells and bursts, and finally assumes 

 the appearance of a large, irregular lump, with a hard, 

 cracked, uneven surface. The flow of sap is obstructed 

 by this tumor, and the poison is gradually disseminated 

 over the whole tree. The Morello cherry is also subject 

 to the attacks of this disease. It made its appearance in 

 Athens, Georgia, for the first time in the year 1853 on a 

 tree from the North. The black, rough condition of the 

 knot is its last stage. When the tree is first infected the 

 trouble is not so clear to the ordinary observer, and the 

 disease obtains a strong foothold before one is aware of 

 its presence. The development is accomplished in the 

 following manner. If an examination is made of the 

 surface of one of the black knots small pimples will be 

 detected in which the spores, or so-called seeds, are 



