LOSSES DUE TO CROWN-GALL. 183 



the colonies thus obtamed proved to be actively virulent. When 

 these were inoculated into the control daisies tumors soon appeared 

 and are now growing rapidly. Numerous "resistant" plants were 

 inoculated at the same time. All of these have developed small 

 hyperplasias; but it is too early for comparative statements, and 

 furthermore a correcter test, and one we have not yet been able to 

 make (o^\^ng to the failure mentioned above) , would be to inoculate 

 checks and resistant plants with a virulent organism taken from a 

 tumor on some iplant which had never before home tumors. This would 

 remove the possibility of a heightened virulence in the organism used. 



LOSSES DUE TO CROWN-GALL. 



In consideration of the slow progress of this disease on many 

 inoculated plants, the question has arisen whether crown-gall is really 

 a serious disease or only to be regarded in the light of a minor dis- 

 turbance, i. e., something comparable to warts or benign tumors in 

 the higher animals. 



Inasmuch as our exact experiments have not continued in all cases 

 for a long enough period of years to give comprehensive results the 

 most that can be done here in many instances is to summarize the 

 opinions of growers and others who have given most attention to the 

 disease as it prevails in the field, supporting these as best we may 

 with our own observations, already detailed, in great part. 



THE DAISY. 



The plants are dwarfed and disfigured but only rarely killed out- 

 right or at least not for a long time. They are more or less stunted 

 according to the size and rapidity of growth of the gall. Cuttings are 

 injured worse than old plants. The New Jersey grower mentioned 

 earUer is the only one who has made complaint to us. 



THE ALMOND, THE PEACH, AND OTHER STONE FRUITS. 



Toumey described tliis disease as serious on the almond in Arizona, 

 and showed photographs of a 40-acre orchard ruined by it. Speaking 

 of this orchard, he says: 



In the Glendale orchard some of the trees were diseased when planted. The actual 

 number, however, that had galls upon them was very small . After the expiration of 

 eight years, less than 1 per cent remained unaffected. * * * 



With each succeeding year a greater number of trees died outright or broke off at 

 or just beneath the surface of the ground, where developing galls had gradually 

 weakened the stem. A very conservative estimate would place the losses in this 

 one orchard at at least ten thousand dollars. Probably the losses to the deciduous 

 fruit and grape growers of Arizona from this disease amounts in the aggregate to from 

 forty to seventy- five thousand dollars annually. 

 213 



