- 15 



MMlll 



Strong points : 



1. Reported to be more tolerant of drought than other rootstocks. 



2. Rootstock is woolly apple aphid resistant. 



3. Good anchorage. 



4. Intermediate winter hardiness. 



5. More suitable when used with spur strains or as the understock for 

 interstem trees. 



Weak points : 



1. Large trees, perhaps only 10 to 30% smaller than seedling trees; thereby 

 requires wider spacings than trees on M7A or MM106. 



2. Late onset of fruiting. 



3. Quite susceptible to collar rot. 



M13 



Strong points : 



1. Tolerance to wet soils. 



2. May prove valuable as the understock on interstem trees. 



Weak points : 



1. Only about \0% dwarfing. 



2. Trees on M13 are in \jery short supply. 



3. Early studies in Massachusetts showed that yields of Mcintosh on M13 

 were low or only average. Therefore, the performance of interstem trees 

 with M13 as the rootstock needs testing. 



Virus-tested rootstocks (Based mainly on reports from other fruit growing 

 areas ). 



Strong points : 



1. Varieties on virus-tested rootstocks (EMLA) are more vigorous than those 

 on virus-infected rootstocks. 



2. Virus free M9's probably will produce larger yields than virus-infected 

 trees. 



3. Yield efficiency (pounds of fruit/unit of space occupied) may be higher. 



4. Fruit quality may be better. 



5. Virus-tested M9s, because they make stronger growth, may require less 

 "tender loving care" than M9s with virus. 



Weak points : 



1. Need further testing. (EMLA 27, EMLA 9, EMLA 26 and EMLA 27 currently 

 are under test at our Horticultural Research Station, Belchertown, MA. 

 EMLA 9 is producing slightly larger tree than M9. The trees are too 

 young for meaningful data comparing productiveness of trees on EMLA 9 

 and M9). 



