- 14 - 



4. Suckers from rootstock. 



5. Trees require support in many orchards. 



6. Frequently tree growth is quite variable within blocks of trees. 



7. It is difficult to develop strong central leaders on trees of some 

 varieties and spur strains. Thus, leader support may be necessary. 



8. Some cultivars and spur-types on some soils may have weak growth, for 

 example Cortland, Macspur and Sturdeespur Delicious. 



9. "^ery sensitive to "wet feet." 



Because of these weaknesses, M26 is generally not recommended in 

 Massachusetts. 



M7A 



Strong points : 



1. Excellent commercially proven rootstock for most varieties. 



2. 55 to 75% dwarfing of seedling trees. 



3. Above average resistance to collar rot. 



4. Above average tolerance to drought. 



Weak points : 



1. Severe suckering. 



2. Delicious trees on this rootstock may have poor anchorage. 



3. Susceptible to woolly apple aphids (Sec.)^ 



MM 106 



Strong points : 



1. Induces early bearing. 



2. Varieties productive on this rootstock. 



3. Above average tolerance to drought and low temperature. 



4. Good anchorage. 



5. Sucker free. 



5. The rootstock is woolly apple aphid resistant. 

 7. Excellent rootstock on well-drained soils. 



Weak points : 



1. Susceptible to collar rot. 



2. Susceptible to Tomato Ring Spot Virus. 



3. Sensitive to "wet feet." 



4. Trees on MM106 tend to grow late in the fall and therefore may be 

 susceptible to winter injury. 



5. Excessive vigor particularly on standard- type Delicious because trees 

 may not bear early. 



5. 75 to 90% dwarfing of seedling tree. 



