Page 4 



BETTER FRUIT 



January, 1921 



parently there is a beneficial inter- 

 change of vital substances in at least the 

 cases of certain congenial grafts, caus- 

 ing a stimulation and increase of activ- 

 ity of the scion. In this respect botani- 

 cal relationship seems to play a lesser 

 part than similarity of habitat of thp 

 two consorts. 



A decreased vigor as a direct result 

 of top grafting can just as easily take 

 place, as was considered above. 



3. An increased vigor may carry in 

 its trail a number of benefits which are 

 directly dependent upon vigor. The 

 most important of these is most prob- 

 ably the general health of the tree. The 

 comparative resistance of the stock and 

 scion to parasites and injurious organ- 

 isms, especially many fungus diseases, 

 may make a variety more immune or 

 resistant to certain diseases when top 

 grafted on particular stocks. To what 

 extent this is a direct acquirement or a 

 secondary result due to a general in- 

 crease in vigor is still an open question. 

 A general improvement of the tree's 

 health by top working because of a sub- 

 stitution of the roots, stem and even 

 parts of the scaffold branches by a 

 variety of known hardiness of immu- 

 nity to particular troubles has been con- 

 sidered previously. 



A desired stock may, however, trans- 

 mit or impart a disease to the scion. 

 This is said to lake place, for instance, 

 when stocks infected with peach yel- 

 lows or little peach is budded with 

 healthy buds; so also when blight in- 

 fected stocks of the apple or pear are 

 used. 



4. In many sections of the upper Mis- 

 sissippi Valley the practice has become 

 well established. Horticultural litera- 

 ture of the prairie states abounds with 

 information on observations where 

 hardiness has been increased by top 

 grafting. 



In almost all of these cases under 

 hardiness has been meant the resistance 

 of the variety to low temperatures. 



Fig. 2. A close view of ux 

 scion of a top-grafted tree. 



3f stock and 



The question as to the degree and 

 amount the scion may be influenced by 

 the stock is, however, not known. 

 There is much information on hand, 

 however, which shows most clearly 

 that the top of a tree has been affected 

 by the hardy stock; that trees have 

 been saved from being killed by low 

 temperatures because of the hardiness 

 of their roots. Of course, a very ex- 

 treme frost, such as frequently occurs 

 in the northern-most states and in Can- 

 ada, will kill a tree in spite of the in- 

 creased resistance to cold. 



5. Top worked trees are commonly 

 more productive and usually more pre- 

 cocious. A top worked tree will come 

 into bearing two to four years earlier 

 than when the variety is grown on its 

 own roots. This is natural, because of 

 the supply of an already well developed 

 root system and frame work to the 

 scion, which then makes a more rapid 

 growth and reaches the bearing age 

 much sooner. Not only early bearing, 

 but also fruitfulness is increased by 

 top working. Weak growing varieties 

 will be made more fruitful because of 

 the increased vigor as a result of the 

 use of a more vigorous stock. Varieties 

 that make a rapid and luxurious wood 

 growth, especially during the first few 

 years, will be made more productive 

 when top worked on less vigorous stock 

 or on one with which a more or less 

 imperfect union is made. In both cases 

 a diminished supply of sap from the 

 stock will tend somewhat to weaken the 

 top and make it more productive. This 

 can be set down as a general rule not 

 (inly, in cases of top grafted apples, but 

 also with those of most other fruits. 

 After many years of experimenting 

 with top grafting of grapes, Hedrick 

 found that grafted grapes have larger 

 yields than those on their own roots. 



fi. That the time of blossoming and 

 maturing of fruit is often altered as a 

 result of top grafting, has been fre- 

 quently observed by fruit growers. 



After much observation and exper- 

 ience with many varieties of apples, 

 Budd of Iowa concluded that "there is 

 much evidence that winter sorts of 

 apples ripen prematurely when top 

 grafted on Oldenburg or Whitney. 



Again, the blossoming time of the 

 scion is frequently affected by the 

 stock. The differences in this respect 

 have been noted to be from a few days 

 to a week or more. 



Hedrick reports of a case that has 

 come to his observation, where a whole 

 orchard of Mcintosh top grafted on 

 Oldenburg matured fruit two weeks 

 earlier than Mcintosh on standard 

 stocks. 



As in the case of maturing of the 

 crop, so with time of blossoming, hast- 

 ening or retarding in either case will 

 depend mainly upon the difference in 

 length of the growing season with dif- 

 ferent varieties used for stock. 



7. In respect to longevity of top 

 grafted trees, observation seems to be 

 cpiite at variance as to whether top 

 grafting in general increases the lon- 

 gevity of the tree. Hedrick believes 



that it is almost a rule that weak grow- 

 ing varieties when grafted on vigorous 

 stock will result in short lived trees. 

 The use of a hardy variety for stock 

 will in most cases insure a longer lived 

 tree. This would be especially true if 

 top working is done on the branches 

 instead of the main trunk, for this 

 would insure hardiness and health to 

 the most vital part of the tree. Varie- 

 ties that are especially subject to var- 

 ious root troubles and to diseases of the 

 crown, trunk or crotches would be 

 insured a longer life. 



In the case of many congenial varie- 

 ties there seems to be a direct benefit 

 derived from top grafting as a result of 

 the differences of physiological changes 

 in the stock and scion, which may act 

 in a beneficial and stimulating way and 

 thus increase the longevity of the top 

 grafted tree. In what specific way this 

 is brought about is still an unsolved 

 question. The common information on 

 this and many other influences of the 

 stock on the scion are largely of an 

 empirical nature. In order to learn 

 what are the present opinions of ex- 

 perienced horticulturists regarding the 

 beneficial influence exerted by the stock 

 on the scion, the writer, while a staff 

 member of the pomology section of the 

 Iowa Agricultural Experiment Station, 

 solicited in 1918 the opinions of a large 

 number of the most prominent growers 

 and nurserymen of the United States 

 and Canada. It was asked in a ques- 

 tionnaire as to whether observations 

 and experience have led to the belief 

 that top grafting the apple on hardy and 

 disease resistant stock has influenced 

 the vigor, hardiness, productivity, 

 health and longevity of the tree. The 

 following answers were received from 

 a total of close to a thousand solicited: 



Scion has been made Yes No 



More hardy 55 12 



More disease resistant 48 10 



More vigorous 51 10 



More productive 52 12 



Longer lived 48 11 



Total 254 55 



From the above answers it is evident 

 that while 82.2% of the total replies 

 asserted that the scion has been bene- 

 fitted in all of the above respects, only 

 17.8% are of the contrary opinion. This 

 is especially true in respect to hardi- 

 ness and an increase in vigor and pro- 

 ductivity of the top worked trees. This 

 cumulative evidence is self-assertive 

 and extensive enough to give additional 

 emphasis to the benefits derived from 

 top working. 



Influence of the Stock on Fruit. 

 The indirect influence of the stock on 

 the scion, expressed in changes of char- 

 acter of the fruit, may be in respect to — 



1. Modification of color of the fruit. 



2. Changes in size. 



3. Changes in respect to eating and 

 keeping qualities of the fruit. 



As in many instances it is almost next 

 to impossible to ascertain in what re- 

 spect and to what extent the above 



Continued on page 34. 



