48 THE COXNECTICUT POMOLOGICAL SOCIETY. 



reveal the presence of the disease, so that careful inspection of 

 the young trees for one or two years after they are set out 

 in the orchard is very desirable. 2nd, that the best way to 

 combat yellows in the orchard is the prompt removal of a 

 tree and its destruction as soon as it shows any signs of the 

 disease. When we definitely know the cause of the trouble 

 this precaution may be shown to be unwarranted, but certain- 

 ly custom and apparent results favor the procedure at pres- 

 ent. 3rd, that trees reset in place of the old ones are not 

 more subject to disease than the surrounding ones in the same 

 orchard. 



(C). Neither experimentation nor practice has proven: 

 1st, that yellows is positively contagious in the ordinary sense 

 of germ diseases. The nearest we come to proof are the ob- 

 servations made in orchards where the disease, first appearing 

 in single trees, seems to spread to the adjacent ones. 2nd, 

 that it is spread by the pollen. Smith's work, so far as it 

 goes, is against the theory of its spread by this means. 3rd, 

 that it is carried by the tools in pruning or by the leaves, etc. 

 In Waite's report last year he states that he failed to repro- 

 duce the disease by injection of juices from diseased trees, 

 but he did succeed in producing it by "budding in pieces of 

 the bark without the bud." 4th, the exact cause of the yel- 

 lows remains unproven. 



Concerning the nature of yellows there seem to be two 

 general views, viz. : 1st', that it is a germ disease, apparently 

 of bacterial origin ; and 2nd, that it is a physiological disease, 

 whose active constituent or virus is a chemical substance be- 

 longing to the enzymes or the toxins. So far all effort to 

 prove the bacterial character of the disease has been unsuc- 

 cessful. In a recent talk with Erwin F. Smith, he expressed 

 the belief that the cause of the disease might suddenly be dis- 

 covered. He apparently was inclined to the bacterial theory, 

 and seemed to think that th presence of the germs on the roots 

 might explain the problem. This idea, however, certainly 

 does not coincide with the apparently successful practice of 

 resetting young trees where diseased ones have been removed. 

 Waite, also, in his address, seemed inclined to the germ the- 



