$62 THE FRUIT INDUSTRY ix NEW YORK STATE 



rust, insect punctures, bruises made by the orchardist, and so on. 

 Once the organism is assisted in its entrance, the effects of its 

 work are soon evident. On the bark, the first signs of the disease 

 consist of a slight brown area, which slowly becomes darker and 

 more extended, the spot taking on an oval shape, the longer 

 diameter being parallel to that of the main axis of the cankered 

 limb. Very soon the surface is depressed and the margin shows 

 a crevice; before many weeks the infected area exhibits a great 

 many small dome-shaped fruiting bodies of the pathogene, which 

 are known as pycnidia, and contain the spores of the fungus. 

 Under proper conditions of moisture these spores ooze out of the 

 pycnidia and are washed to the leaves and fruits below, resulting 

 in the production of leaf spot and black rot. These forms of the 

 disease, however, are of relatively little importance in New York 

 State. 



The fungus in the above described condition passes the winter 

 in these cankers. In the spring the fungus usually starts its activi- 

 ties again by its spread at the margin of the old canker and by the 

 dissemination of its spores. The fungus in some of the cankers 

 dies out at the end of the year ; in others it spreads for several 

 years in succession, there being produced eventually a large canker 

 sometimes several feet in length. 



Control 



In the control of this disease there are several things to be 

 borne in mind : (1) The fungus cannot be eradicated by the use of 

 sprays; its vegetative parts are buried in the host tissues and are 

 not reached by any known fungicide. (2) The prevention of 

 wounds and the protection of injured surface by means of fungi- 

 cides are logical measures to practice. (3) Cankers furnish a 

 hibernating place for the fungus, and dead wood may also hold 

 the parasite for several months. 



With these points as a basis, the following means of control are 

 to be followed: Remove cankers from the larger and more valu- 

 able limbs, wherever it seems desirable and profitable to save such 

 limbs. Cut out all diseased parts, bark or wood, pointing the upper 

 and lower ends of the cut and making the edge of the wound per- 

 pendicular to the surface, and dress the wound with coal-tar. In 



