257 



It may be controlled by the application of ammoniacal copper car- 

 bonate, lime-sulfur, or Bordeaux. 



Leaf Si'ot 

 Caused by Phyllosticta rosac Desm. 



Leaf spot of rose is of less common occurrence than black spot and 

 is not often serious. 



It is known to occur in 18 counties, as shown on Map 121. With 

 this, as with the black-spot disease, there appear to be two regions of 

 most common occurrence, one in the southern tip of the state, and one 

 in the extreme northwest. 



It may be controlled, when necessary, by application of any of the 

 standard fungicides. 



Lilac 



The lilac, with its several cultivated varieties, is of large import- 

 ance in the decorative plantings of the state, and is also of considerable 

 value to the nurseryman. In Illinois it is subject to only one serious 

 disease. 



Powdery Mildew 



Caused by Microsphacra alni (Wall.) Salm. 



Powdery mildew of lilac appears, as a rule, late in summer, cover- 

 ing the leaves with a whitish powder, which presently becomes gray and 

 dirty. When the season favors, it may cause severe and early defolia- 

 tion. 



This very common disease has the distinction of being the first 

 one definitely recorded in Illinois. It was collected in McLean county 

 in 1873 and again in 1879 by Seymour. Further collections were made 

 in 1881 and 1882 in 9 counties — Jo Daviess, McHenry, Lake, Cook, 

 Rock Island, La Salle, McLean, Jackson, and Union — indicating a wide- 

 spread occurrence over the state at that time. 



At present, powdery mildew is known in 59 counties, the distribu- 

 tion of which is shown on Map 182. The commonness of the disease 

 where it has been found may be illustrated by the fact that there are 

 in the Survey herbarium 190 specimens of this mildew. 



Carnation 



The carnation, grown in greenhouses for cut flowers and in many 

 varieties in gardens for decoration and for flowers, suffers from a single 

 common disease, the "carnation rust." 



