I? - 



A BRIEF -SUMMARY OF ROOTSTOCKS AND INTERSTEM TREES 



Wil 1 iam J. Lord • 

 Department of Plant and Soil Sciences 



The following information cites the strong points and weak points of 

 rootstocks and of interstem trees currently found in Massachusetts orchards 

 and describes some of the newer rootstocks. The comments are based on 

 observations in Massachusetts and other fruit growing areas. Some of the 

 newer rootstocks such as M''7 and Mark are now available from nurseries. 

 Virus-tested rootstocks, Alnarp 2 (used as the understock for interstem 

 trees), the Polish Series, and the Budogovsky Series are currently being 

 tested in the United States. 



M?7 



Strong point s: 



1. Very dwarfing (smaller than M°). 

 ?. Resistant to collar rot. 



3. May be useful as stempiece on interstem trees. A "^ or R inch stempiece 

 of M''7 grafted on MMlOf or MMlll produces a tree approximately the size 

 of M?F. 



4. Easy to prune and harvest. 

 ^. Relatively sucker free. 



Weak points : 



1. Probably less suitable than MQ for growers with small holdings and/or U- 



Pick blocks. 

 ■'. Poor anchorage because brittleness of roots thereby requires support. 



3. Susceptible to fire blight where a problem. fSec.1^ 



4. Requires deep, well-drained soils and detailed tree management. 



Because of weak points listed above, not recommended for commercial 

 orchards in Massachusetts. Probably best suited for home orchards. 



M2 



Strong points : 



1. Easy to prune and harvest. 



'. Early bearing. 



''. High early yields/acre particularly if trellised. 



4. Valuable as stempiece on interstem trees. A 7 or R inch stempiece of M9 

 grafted on MMin*^ or MMlll produces a tree approximately the size of M26. 



5. Well suited for trellising or training to a post. 

 ^. Resistant to collar rot. 



^Sec = secondary problem in Massachusetts 



