226 



boundary of the state — Jo Daviess, Stephenson, and Winnebago. The 

 DeSoto variety appears to be most often diseased. 



Bacterial Shot-hole 

 Caused by Pscudomonas primi E. F. S. 



This disease, which is the same as the bacterial shot-hole of peach, 

 causes serious damage to both the leaves and the fruit, and produces 

 cankers on the twigs. On the whole the disease appears to produce more 

 serious effects on the plum than on the peach. It is not. however, so 

 common or abundant on the plum, possibly because the more immune 

 varieties, the Americana and Wild Goose, are among those most com- 

 monly grown. Japanese varieties are very susceptible. 



The distribution of this disease appears at the present time to be 

 limited to southern Illinois. It is known to occur in 13 counties as 

 shown on Map 7;5. 



Control measures are the same as for peach shot-hole (p. 222). 



Leaf-curl 

 Caused by Exoasciis mirabilis Atk. 



Recently there has appeared in Illinois a disease of plum not pre- 

 viously known in the state, best described under the name of leaf-curl. 

 Infection, which appears to take place in the bud or when the branch is 

 still very young, results in a marked distortion of leaves, dwarfing and 

 distortion of the twig, and eventual death, of the part diseased. 



The known occurrence of this disease in the state is shown on Map 

 74. It is not yet commonly distributed, but it has a wide range and the 

 damage it causes is often serious. So far as observations go it appears 

 to be rather definitely limited to the Wild Goose group of plums. 



It can be controlled in some measure by means of the usual sprays, 

 but their use should be supplemented by pruning out diseased parts, 

 taking particular care to cut a considerable distance below the manifest 

 injury and to have the tools thoroughly disinfected. 



Cherry 



Cherries like plums are not extensively cultivated in the state on a 

 commercial scale but they are grown almost everywhere to su]iply home 

 tables and local markets in season. On this account diseases of the cherry 

 are the more common and serious for isolated trees or small orchards 

 usually receive less care than commercial plantings. 



Powdery Mh.df.w 



Caused by Podox/'iMcra oxyacaiillmc (DC.) De Bary 



Cherry is the only one of the Illinois fruits that is commonly sub- 

 ject to attack by a jxiwdcrv mildew. Iv'irly in June, wiiite, powdery 



