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ROOTSTOCK EVALUATION IN MASSACHUSETTS 



(Editors note: Massachusetts is involved in a multistate apple 

 rootstock evaluation project (NC-140). Two groups of rootstocks are being 

 evaluated at the Horticultural Research Center in Belchertown, Massachusetts 

 along with approximately 30 other locations in the U.S. and Canada. The 

 first group was planted in I98O and the second was planted in 1984. The 

 descriptions presented here were supplied by Dr. David Ferree, Ohio State 

 University, and a later Frui t Notes article will discuss observations in 

 Massachusetts. ) 



Rootstocks in I98O NC-TtO Planting 



1. Ottawa 3 - Originated as a cross of Robin x M.9. (Robin is a hardy 

 crabapple). It produces trees of M.9 size or slightly larger, but better 

 anchored than M.9. It is reported to be resistant to crown rot, but 

 susceptible to fireblight and to wooly aphids. Suckering is rare. 



2. EMLA 7 - This is the original M.7 with known viruses removed. According 

 to early reports, it produces a tree only slightly larger than the 

 original M.7, which would be 50 to 60^ the size of standard. 



3. EMLA 9 - In providing this stock with EMLA virus status, apparently a 

 sub-clone was selected and trees on the EMLA 9 may be 25-50^ larger than 

 the original M.9. It is reported to result in less russet on Golden 

 Delicious and have greater productive efficiency than M.9. 



4. EMLA 26 - Early reports indicate only a slightly larger tree than the 

 original M.26. 



5. EMLA 27 - This stock has not been widely tested, but produces a tree 

 smaller than M.9 (15-20^ the size of standard), is very precocious, not 

 well anchored, and generally free of root suckers. Originally it was 

 produced from a cross of M.13 x M.9. Northern Spy and Granny Smith have 

 shown some incompatibility (broken off union) with EMLA 27. Compared to 

 M.9, M.27 is similarly resistant to crown rot and susceptible to fire 

 blight and wooly aphid. Its hardiness is unknown. 



6. M.9 - This rootstock produces trees 20-35% the size of standard trees, 

 is very precocious and fruitful, and poorly anchored with a tendency to 

 sucker. It has a long history in both the U.S. and Europe and is used 

 as the standard in this trial. 



7. MAC 9 (MARK) - Introduced in I98O by Michigan State University. Dr. 

 Robert Carlson selected it as an open-pollinated seedling of M.9. It 

 produces trees about the same size as M.9 or slightly larger, is very 

 precocious and fruitful, and is non-suckering. 



