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planting. The yellow leaves are eventually shed, and the plant may die, 

 or, if it continues to live, it produces a long leafless stem capped by a 

 small and worthless head. 



How long this disease has been present in Illinois is not known. 

 Burrill reported it in Cook county in 1911, with the note that it was doing 

 considerable injury. In the following year he reported it from Madison 

 and St. Clair counties, as causing there a 50 per cent loss, estimated at 

 $35,000. 



It is at present known in 23 Illinois coimties as shown on Map 111, 

 which may be taken to indicate in a measure its abundance in the state. 

 It is commonest and most severe southward ; but toward the north, while 

 still extremely severe, it is confined rather noticeably to commercial or 

 local-garden plantings. Late crops appear to be most severely injured. 



Control of this disease requires either a soil not infected with its 

 fungus, or the use of resistant varieties, among which are certain selected 

 strains known as the Wisconsin Hollander. It may possibly be carried 

 by the seed, and seed disinfection is advisable to prevent its introduction. 

 Rotation is essential to check its injurious development after it has been 

 introduced. 



Black Rot 



Caused by Pscitdoinoiias cauipcstris (Pam.) E. F. S. 



Black rot is second in importance among cabbage diseases in Illi- 

 nois. Infection starts in the water pores at the leaf margin, travels down 

 the veins, killing the leaf tissue as it goes, and finally enters the stem, 

 where the bacteria clog the sap-carrying tissues and pass to other parts 

 of the plant. 



Black rot is widely prevalent in the state. It is known in 41 coun- 

 ties, as shown on Map 112. It seems to be most general in southeastern 

 Illinois, but its prevalence elsewhere is shown by the widely scattered 

 counties in which it occurs. Losses from this disease in Illinois have 

 been estimated to range from 1 to 4 per cent of the annual crop. 



Control consists in seed treatment, in crop rotation, and in avoiding 

 the replanting of land to related crops, such as radishes and cauliflower. 



Club-Root 



Caused by Plasmodiophora brassicac \\'or. 



Club-root, a malformation disease of the cabbage, produces large 

 knots or galls on the roots changing their structure so as to interfere 

 with their normal function, and the plant becomes sickly, grows slowly, 

 and often fails to head. 



The only reliable early record of club-root in Illinois is a report by 

 Burrill of its presence in 1911 in Cook county, where it was doing only 

 a small amount of damage. In 192.3 it was again found in Cook county, 

 on only a few ])lants in a 1-acre field. 



