92 Report of the Botanist of the 



experiments, the results of which indicated that the disease might 

 be controlled in this way. Russell'' says: 



On the horticultural grounds at the University, cauliflower was planted on soil 

 that had borne a similar crop the previous year, and one which was somewhat 

 affected with the rot. This field was allowed to develop in the usual manner until 

 September of this year. By the first of the month, the patch began to show evi- 

 dence that the disease was pretty generally distributed. At this date it was divided 

 into four sections and from alternate sections the attempt was made to stop the 

 disease by removing the affected leaves. The other two sections were left under 

 natural conditions and no attempt was made to check the spread of the malady. 

 The result of this experiment was that the disease was held completely in check. 

 Several plants became infected subsequent to the removal of the diseased leaves, 

 but by removing all of these later the further progress of the disease was brought 

 to a standstill. 



The continued spread of the disease in the uncontrolled sections showed that the 

 disease organism was being thoroughly distributed and therefore the failure to 

 spread was not due to absence of disease virus. 



Another experiment was also carried out on a larger scale under commercial con- 

 ditions. A field of about three acres of cabbage near Berry ville, Wis., was noted 

 that had been planted on new ground that had never had cabbage on it before. 

 When first observed on September ist, of this year, the cabbage rot was just 

 beginning to make its appearance. In some cases where the plants were small the 

 disease had established itself in the stem, but in the majority of cases only individual 

 leaves were affected. At our suggestion, the owner decided to remove all diseased 

 leaves and badly affected plants in order to see whether the progress of the trouble 

 might not be retarded. The result of this was that the repressive measures used 

 kept the disease well in check. The patch was only fifteen rods distant from 

 another field that was very severely affected, and of course the seeds of the disease 

 were continually being distributed liy means of the wind. The disease made but 

 slow headway as the season was unusually dry. Yet under the same atmospheric 

 and soil conditions, in another large patch in which no repressive measures were 

 attempted the disease developed severely. 



Smith"^ says: 

 This method was tried by the writer in August, 1897, on about four hundred 

 plants, with very satisfactory results, four-fifths of the heads being free from the 

 disease when harvested in November. The one-fifth may have been diseased in 

 the stem at the time the leaves were broken off, or may have subsequently con- 

 tracted the disease through other leaves. 



These experiments were all faulty in that no account was taken 

 of the all-important factor of yield. In Smith's experiment no 

 check is mentioned and Russell's cabbage experiment was also 

 without a proper check. 



« Russell, H. L. Loc. cit. 

 ' Smith, Erwin F. Loc. cit. 



