213 



Fly-speck 

 Caused by Lcplothyriuiii pond (Mont. &Fr.) Sacc. 



Fly-speck appears to be of common occurrence within the state. The 

 common name is descriptive of the disease, which appears as black 

 specks, usually smaller than a pin-head, on the fruit. It may also occur 

 on the twigs. 



No actual damage is caused by this disease. Its only efifect is, in 

 serious cases, to mar the appearance of the fruit, thereby impairing its 

 market value to a certain extent. 



Distribution within the state is shown on Map 53. 



According to Colby ,^ when infections are severe enough to mar the 

 fruit, the specks can be removed by the use of Javelle water. This prac- 

 tice is probably advisable only in preparing the very finest fruit for the 

 market. 



Crown-gall 



Caused by Pseiidomonas tumefacicns E. F. S. 



Crown-gall, known also under the names "crown knot," "hairy root," 

 and "root knot," is common not only on apples, but on many other plants. 



The disease is recognized in two common forms, as galls and as 

 hairy root. It is most common and most serious in nurseries; but the 

 rigid requirements of nursery inspection laws have prevented its serious 

 spread into orchards. 



Its known distribution in orchards is shown on Majj 53. A 

 very much wider distribution in nurseries would be evident were it pos- 

 sible to bring together proper re])orts. Distrilnition in orchards is ap- 

 parent as a rule only when trees die and crown-gall is demonstrated upon 

 their removal to have been the cause of death. 



Serious losses in nurseries from this disease and the doubtful serious- 

 ness of its efifects on older trees indicate a need for further investigation. 



Canker.s 



Bark cankers of apple are frec[uently met with in orchards. Among 

 those usually considered as diseases the following are known to occur in 

 Illinois: 



Valsa canker {Valsa ambicns Fr.) has been found in Pike and De- 

 Kalb counties. 



European canker (Ncclrui-dilissiina Tul.) is reported from Stci)hen- 

 son county. 



Myxosporium canker {My.vosporiiim corticohtm Edg.) has been 

 found in Champaign county. 



These cankers can be cut out with sterilized tools when seen, and 

 subsequent injury to the infected trees thereby avoided. 



•Polbv. A. S. Sooty blotch of pomaceous fruits. Tran.'<. III. St. Acail. Sci. 13 •. 

 139-175. 1920. 



