254 



sumption, and southward for supplying the early demand of northern 

 markets, is subject to several diseases, of which only one appears com- 

 mon in Illinois. 



Leaf Blight 

 Caused by Septoria lactucac Pass. 



The blight of lettuce attacks the outer leaves, though rarely causing 

 much damage. It has been in Illiijois at least since 1S87 according to 

 Martin,^ and is now known in 19 counties, distributed as shown on 

 Map 115. Its range apparently extends from northern Illinois to the 

 southern tip of the state, and it is most general in the extreme south. 



Its control requires merely the practice of sanitary cultivation. 



Rhubarb 



Rhubarb is not subject to many diseases in Illinois, but at least one 

 of them is extremely serious. 



Crown and Stalk Rot 



Caused by Phytophthora sp. 



Crown and stalk rot is the most serious disease of rhubarb in Illi- 

 nois. How long it has been present in the state is not known, but it 

 certainly has been destructive since 1919. At present it seems to be 

 confined to southern Illinois. It is of especial concern in Union county 

 and has been found in Pulaski county also. 



Some idea of the seriousness of the disease may be conveyed by 

 two field notes made in 1923: Near Alto Pass, in Union county, a new 

 field of about 5 acres showed a large percentage of infected plants, and 

 along one side a third of the plants were already dead. In spots in a 

 half-acre field in Pulaski, from 10 per cent to 40 per cent were infected 

 and many were dead. 



This disease has not been studied, and control measures can not 

 be recommended. 



Leaf Spot 



Caused by Phyllosticta straniiiiclla Bres. 



Leaf spot of rhubarb is common in Illinois and at times destruc- 

 tive. Stevens reported the disease as injurious in 1918 in Kankakee and 

 Champaign counties. 



During 1923 it was found in IG counties as shown on ^fap 116. It 

 is evidently wide-spread and appears not to be limited to any one part 

 of the state. 



.lourn. Myc. 3 : 63. 18S7 



