528 Report of the Mycologist of the 



small roots, seldom on the main root ; while on Plot C the main 

 root was generally affected. 



From a practical standpoint the experiment may be summed np 

 as follows : On soil treated with 90 bushels of shell-lime per acre 

 an excellent crop of cabbage w^as grown while on soil not limed, 

 472 plants produced only 60 marketable heads. 



It is 23robably best to apply the lime two or three montbs befoi-e 

 planting, and where lime is applied two or more years in succession 

 it is likely that a smaller quantity will be required with still greater 

 success in preventing club-root. 



While experiments sbow that by the application of lime cabbages 

 can be grown year after year on the same ground without serious 

 injury from club-root, the practice is not to be recommended. By 

 a proper system of crop rotation the same end may be attained 

 without the expense of applying lime. The system of rotation 

 should be such that neither cabbage nor other cruciferous crops are 

 grown on the same ground oftener than once in three years. 



As far as possible all cabbage refuse should be destroyed. Upon 

 the decay of the infested cabbage plant there are set free myriads 

 of spores which are capable of living in the soil until the following 

 spring when they will germinate and attack the next crop of cab- 

 bage plants. If cabbage refuse is fed to animals the spores of the 

 disease will be carried back to the field in the manure if it is not 

 thoroughly rotted. There is a popular belief that hog manure 

 causes club-root. Such is not possible, except in cases where the 

 hogs have been fed on the refuse of infested plants. 



In this connection I wish to record an observation which indi- 

 cates that even the leaves of cabbage may contain tbe disease in 

 considerable quantity. In July, 1894, Mr. Forbell planted a certain 

 field of late cabbage. The following winter the trimmings (con- 

 sisting of leaves only) of tliese cabbages were spread over the field 

 on which they grew. In the spring of 1895, the field was planted 

 to potatoes, and these were followed by Siberian kale or " sprouts." 

 When examined in November 1895, the kale was so badly 

 ('clubbed" that it was nearly worthless. Mr. Forbell thinks that 

 the cabbage leaves are responsible for the severity of the disease. 

 He assures me that he has practiced this rotation (cabbage, potatoes, 

 kale — applying lime before the cabbage) for several years and has 

 never had the kale badly " clubbed" except in this case where cab- 

 bage leaves were spread over the ground. The idea that the 



