52 HORTICULTURAL SOCIETY OF NEW YORK. 



it seems to be possible to obtain by selection alone disease resistant strains 

 of any quality desired, whether line or coarse, late or early. 

 Selection for Resistance to Other Diseases. 

 This comparatively unworked field in plant breeding offers great rewards 

 to coming investigators. There is every reason to think that strains of plants 

 can be developed which will resist many of our common and destructive dis- 

 eases. Many instances could be cited where the results of such work appear 

 promising. The production of disease resistant fruits, nuts and potatoes may 

 be looked for; but it should be remembered that results obtained with varie- 

 ties propagated by seed, like cotton, may not be duplicated with equal ease 

 in varieties propagated by grafting or buds. 



W. M. Hays: Is cotton generally open to cross fertilization? 



W. A. Orton: That is an uncertain point. Cotton fertilizes itself freely; that is, 

 flowers covered with a bag before opening are almost certain to set seed, and yet they 

 are freely visited by insects, and there is no question that abundant cross fertilization 

 takes place. But our results have been contradictory. Where different varieties have 

 been planted beside each other there has apparently been little crossing in some cases, 

 but in others a great deal. I think that cotton as a rule is not extensively crossed by 

 insects in the field. 



W. M. Hays: Have you used hybrids in large numbers; in anything like as large 

 numbers as your standard stocks? 



W. A. Orton: Hardly; hybrid coltons are very difficult to handle on account ot 

 ej^treme variation. 



The Chair: Have there been any experiments toward getting a variety of musk- 

 melon or cantaloupe resistant to wilt disease? That is a subject that appeals to all of us. 



W. A. Orton: The wilt of the muskmelon is due in the North usually to a form 

 of black rot. In the South there is a wilt of the cantaloupe which is due to a disease 

 very like the watermelon wilt, and I am working on that. So far as I know, no experi- 

 ments have been made on the Northern disease. 



W. M. Hays: I would like to ask the speaker if he knows of what this resistant 

 quality consists. 



W. A. Orton: The Department has just found that there are no anatomical feat- 

 ures that would explain the difference; and I believe the resistance is due to physiological 

 or chemical differences in the plant. The fungus seems to be unable to enter the roots, 

 or if it does obtain an entrance to the smaller roots it is unable to penetrate the water 

 passages, and I believe, although I have no definite proof of it, that the reason for the 

 difference is an enzyme of the plant. 



D. G. Fairchild: In 1899 I visited the experiment stations in Svalof, Sweeden, and 

 Dr. Nilsson called my attention to a patch of vetch which had been selected from a 

 single resistant plant which has resisted the attacks of Peronospora. The whole field 

 had been killed by this disease with the exception of this one plant. They had selected 

 it and raised plants from it and produced as beautiful a patch of vetch as I have ever 

 seen. My attention was recalled to this by Dr. Orton's remark that he believed there 

 was no limit to the possibilities of selection in plants for resistance to disease. 



H. H. Groff: Not long ago articles went the rounds of the horticultural press which 

 gave the impression that since all seed was produced free from disease, we might sow 

 with the expectation of securing strong and vigorous plants from the seed of diseased 

 parents. This, however, proves most conclusively, I think, that that must be an error. 

 Cotton is produced from seeds, is it not, Professor Orton? 



W. A. Orton: Well, in the case of these diseases, seed saved from diseased plants 

 is certain to become diseased if grown in infected soil. In a different kind of soil not 

 affected by this fungus, it is likely to grow and remain healthy, although, perhaps, not 

 as vigorous. 



S. Eraser: Is it necessary to grow the crop on diseased land in order to secure 

 immunity? 



