WRAPPING APPLE GRAFTS AND ITS RELATION TO CROWN-GALL. 19 



tory as rubber. The writers strongly advise against the wrapping of 

 grafts with thread and subsequently waxing the grafts. 



SUGGESTION TO NURSERYMEN. 



The results obtained from the experimental plats having shown that 

 the wrapping has materially reduced the number of crown-gall and other 

 types of rough trees, it will be very desirable to test these results on a 

 larger scale. The grafts in these experiments were all made with the 

 greatest care, and it would seem probable that the number of smooth 

 trees obtained was therefore larger than might be the case where com- 

 mercial grafts are made. The latter are usually not fitted with as much 

 care, either with respect to size of scion and root pieces or with regard 

 to an even and close union in the freshly made graft. It is therefore 

 urged that nurserymen generally test the wrapping of their grafts 

 this winter, either with rubber or cloth, after the manner previously 

 described. 



Care should be taken in setting out grafts with different kinds of 

 wrapping to treat them in the same manner, that is — 



(1) Use the same variety of scion. 



(2) Use the same stock of roots. 



(3) Make the grafts at the same time. 



(4) Plant the grafts on the same- date. 



(5) Plant in the same field or at least on similar soil. 



(6) Cultivate all grafts alike. 



Where such tests are made, it is requested that the Bureau of Plant 

 Industry be informed, so that all the experiments may be compared. 



It may prove of interest to estimate the total number of smooth and 

 rough trees to the acre which would result from the use of various 

 wrappings, estimating 18,000 grafts to the acre and using as a basis the 

 percentages of such trees obtained in the tests described in these pages. 

 By smooth trees are meant trees free from crown-gall and other dis- 

 eases; by rough trees, trees affected with true crown-gall, hairj^-root, 

 or manifestations of other diseases at or near the point of union. This 

 estimate has been attempted in the following table, which should be 

 regarded only as suggestive, however. The results are averaged from 

 five identical plats in four different States, containing about 9,000 grafts. 



Table III. — Estimate of the number of smooth trees and rough trees which can he raised 

 on an acre of land by using various methods of grafting. 



WraDDine- Smooth Rough Total 



VT rapping. . , . 



trees. 



trees. 



trees. 



Rubber ., 12, 600 



Cloth 12, 960 



Waxed paper 10, 260 



Plain thread i 9, 540 



Waxed thread 9, 360 



Plain thread with union waxed 3, 780 



Unwrapped 6, 660 



100—11 



1,980 



14, 580 



2, 340 



15,300 



4,320 



14, 580 



4, 320 



13, 860 



5,220 



14, 580 



4,860 



8,640 



5,580 



12, 240 



