72 Diseases of Economic Plants 



sulfur. Pt,epeated trials have shown that this is thoroughly 

 effective, increasing the value of the quince crop very mate- 

 rially both in size and quality of the fruit. The first applica- 

 tion should be made soon after the blossoms fall, and should 

 be followed at intervals of two or three weeks with two more 

 treatments. 



Black-rot (Physalospora cydonice, Sphceropsis) . — This 

 rot of wide distri'jution, and often amounting to a loss of 

 10 per cent, is due to the same fungus which causes black-rot 

 of the apple, and the treatments recommended for the apple 

 will prove efficient for the quince disease. It has not yet been 

 proved that this fungus causes cankers on the quince trees 

 such as have been described for the apple. The grower 

 should, however, watch carefully for the presence of canker, 

 as the relation between the canker and the rot in apple indi- 

 cates that the canker may possibly be found on the quince 

 also. 



Bitter-rot {Glomerella cingulata, Gloeosporium) . — This 

 disease is caused by a fungus identical with that causing 

 bitter-rot of the apple. The treatments already recom- 

 mended for other diseases will also prove efficient here. 



European canker (Nectria galligena Bres.). — This canker 

 is readily distinguished from the ordinary cankers pro- 

 duced by Physalospora or Glomerella by its brilliant red or 

 cinnamon-colored pustules scattered profusely over the 

 affected areas. While cankers due to this fungus have been 

 observed upon quince in America, no case of serious injury 

 is known. 



Pale-rot {Phoma cydonice S. & S.). — This is one of the 

 most prevalent decays of quince fruit in market. The 

 lesions usually appear in the region of bruises and are at first 

 pale blue or bluish-green in color and circular in outline. The 

 rot spreads rapidly, involving the entire fruit in a few days. 

 The surface becomes wrinkled and darker in color. Later 

 numerous white fruiting pustules stud the surface of the 

 decayed area. Care in handling the fruit to avoid external 

 injuries is the only control measure recommended. 



