was selected at East Malling from a group of traditional French
rootstocks known as Doucin. Much of the work on M.7 at East Malling was
carried out with clone M.7a which was free of the economically important
viruses, but known to contain a latent virus. A virus-indexed EMLA
introduced by East Malling Research Station in 1974 - 75.
Influence on Scion Habit
produces sturdy trees that are approximately twice the size of those on
M9, or about 60% the size of trees on seedling rootstocks. EMLA 7 has
been relatively little used in Europe but very widely used in North
America for its exceptional winter hardiness and good anchorage. Trees
on EMLA 7 are less precocious and have a lower cropping efficiency than
EMLA 9 or EMLA 26.
EMLA 7 is
moderately resistant to collar rot (Phytophthora cactorum).
EMLA 7 has excellent nursery habits. It is easy to propagate from
stoolbeds, and is compatible with a wide range of scion varieties. High
budding followed by deep planting with the graft union just above soil
level is recommended.
Commercially, EMLA 7 has been widely grown for decades. It appears to be
hardier than seedling varieties and under Washington conditions has
shown minimal susceptibility to collar rot (Phytophthora cactorum).
EMLA 7 performs better on deep fertile loam soils of a moderate to heavy
texture under a wide range of conditions. It does not perform well on
light sandy soils or under low fertility. It has been recommended for
soils with high lead arsenic residues and old orchard sites with replant
problems. EMLA 7 shows less suckering than M.7 and M.7a.