THE ANNUAL MEETING. 135 



on the surface, we reach by exchisiou the probability of bacteria-like organisms, 

 and sufficiently account for their discovery now by investigators by their exceed- 

 ingly minute size. Further, such organisms have been found (by myself) in 

 great numbers in two different sets of specimens. Two lots of specimens ought 

 not to be allowed to decide a matter of so much consequence, and for myself, 

 these examinations would only be taken as strengthening a probability, did not 

 the published accounts strongly support the results reached. Nothing can be 

 clearer from practical experience than that the yellows is contagious, that the 

 malady may be spread with the pruning knife or that it does spread in some 

 way from diseased to healthy trees in the orchard. 



It is very doubtful as to the roots being in any special sense the chief seat of 

 the disease. In my specimens the roots were not infected at all, neither can 

 we suppose the organism believed to be the exciting cause lives in the ^arth. 

 The contagion is rather in the tops from which the roots as well may be infected. 



But the members of your society will surely ask, ''What preventive or 

 remedial measures can be adopted to eradicate the pest?" Perhaps some will 

 say, "To know the cause is nothing, the cure is the valuable thing." AVhile 

 you will not expect me to indorse the negative part of tlie last sentiment, it 

 does seem to me that there is sufficient support for the careful, vigilant 

 "stamping out" already in operation through the efforts of your society. To 

 do this effectively and economically, there is scarcely a doubt as to the value 

 of further scientific investigation. If, in pursuance of its good work, the 

 Michigan State Horticultural Society can bring this about, another laurel will 

 be added to its many splendid tokens of victory and success. 



BLIGHT. 



The announcements of last year upon the cause and character of the so- 

 called blight of the pear have been confirmed and verified during the past 

 season. Further inoculations have been followed by similar results, and the 

 disease in nature, studied under the light of its artificial production, is, I 

 venture to affirm, pretty well understood. Want of sufficient attention has 

 still left many questions unanswered, but there is certainly a reasonable pros- 

 pect that all these having important bearing can be solved. 



The most important result of some experiments and continual observations 

 during the last summer (so far as my own efforts are concerned) is the recog- 

 nition and demonstration that the disease known as fire-blight in the pear is a 

 common one in other plants. According to my observations, the so-called 

 twig-blight of the apple tree is much more prevalent and destructive in Illinois 

 than in Michigan. Of the identity of this and pear blight enough was ad- 

 vanced last year. The fact is our apple trees are, if not as much injured as 

 the pear, badly affected. Not only the twigs, but often larger limbs, and 

 great patches on the trunks, succumb to the destroyer. Whole trees, ten to 

 twenty, or more, years old, die in some, though not numerous, instances, in 

 one season. The Lombardy poplar is with us more liable to be taken off than 

 any fruit tree, and the disease in cause and consequence is assuredly the same 

 thing. It may be, for it has been, communicated from one to the other by 

 inoculation. Thus this worthless poplar is a dangerous neighbor for a pear 

 or apple tree, though how dangerous cannot now be told. A beetle (Agrilus) 

 bores the bark and outer layers of wood doing considerable injury itself to this 

 rapidly growing tree, but in most cases the wounds thus made speedily heal over 

 Avhen permitted to do so. The latter, however, is by no means always the case, for 

 the entrance wav through the outer coats having been made, the blight bacteria 



