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 Manganese (Mn).Manganese deficiency is most
often observed on well-drained soils having a slightly acid
to alkaline pH range. However, soils abnormally high in
organic matter may exhibit the deficiency within a
slightly to moderately acid pH range. Manganese
deficiency in tree fruits is generally characterized by
interveinal chlorosis, which begins near the leaf margins
and extends toward the midrib, and finally only the veins
remain green. The deficiency symptoms are most
prominent in the older portions of the current season's
growth. One or more foliar applications of manganese
(Mn) as manganese sulfate (MnSO4) will usually correct
the deficiency in tree fruits. Apply at the rate of 1 pound of
Mn per 100 gallons of water per acre per application.
Manganese chelates used according to manufacturer's
recommendations may also be effective in correcting
manganese deficiencies in tree fruits.
Manganese Toxicity. commonly referred to as
'measles' is a physiological disorder brought on by
excessive uptake of maganese. The bark on fruit shoots
and laterals appears pitted. It is very common Red
Delicious strains but is seen in other cultivars as well.
Manganese toxicity is usually associated with very low
soil pH in subsoil and/or the topsoil. It is vital that the
pH range be adjusted to 6.5 in both layers of soil prior to
orchard establishment to prevent this condition.
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MM106.This rootstock is produced by stool beds,
layering, or semi-hardwood cuttings and is multiplied
from one clone. Vigorous scion varieties on MM106
rootstock produce trees 65 to 75 percent the size of those
on seedling rootstock. Spur-bearing and less vigorous
varieties will produce slightly smaller trees. Trees on
MM106 are fairly well anchored, sturdy, and efficient.
This rootstock's biggest advantage is the ability to
induce early and heavy production, particularly on slow-
bearing varieties. It also resists woolly aphids, and
suckers very little if planted with the bud union 2 inches
above the soil line.
MM106 cannot be recommended for New Jersey
because it is susceptible to the tomato ringspot virus,
which causes a necrosis and brown line at the bud union
that kills Red Delicious, Jerseymac, and Golden
Delicious. It is also sensitive to collar and root rot.
Because of its slow acclimation, early winter low
temperatures may injure trees on MM106.
M-7A. This rootstock is produced by stool beds and
layering and is multiplied from one clone of M-7 free of
chat fruit, apple mosaic, rubbery wood, and star-crack
viruses. Vigorous scion varieties on M-7A rootstock
produce trees 55 to 65 percent the size of those on
seedling rootstock. Spur-bearing and less vigorous
varieties may produce slightly smaller or full dwarf trees.
M-7A is reasonably vigorous, with most varieties
producing an open-spreading and heavily productive tree
reasonably early. M-7A is sensitive to some soil
conditions and responds very differently with scion
varieties. Red Delicious, Idared, and Rome on M-7A are
not well anchored and are smaller at maturity than well-
anchored Golden Delicious or McIntosh trees. M-7A trees
do very well on deep, fertile, loamy, and sandy loam
soils. M-7A is very responsive to irrigation, particularly
on sandy loam and loamy sand soils. M-7A is moderately
tolerant of crown and root rot but susceptible to woolly
aphids.
M-7A is recommended to growers with light-textured
soil willing to provide supplemental soil moisture.
Varieties on M-7A should be budded 12 to 18 inches on
the rootstock shank, so trees purchased can be planted
with the union 2 inches above the soil line. This will
improve anchorage and reduce suckering. If only low
budded trees can be purchased they should be planted
with the union at or just above the soil line.
M-26.This rootstock is produced by layering, stool
beds, or semi-hardwood cuttings and multiplied from one
clone. Vigorous scion varieties produce trees 50 to 60
percent the size of those on seedling rootstock. Spur-
bearing and less vigorous varieties on M-26 are smaller
and full dwarf in size. Spur Red Delicious with M-26 on
shallow sandy loam soils may be small, runty, and
poorly anchored and should not be planted. McIntosh
with M-26 on deep loamy soils in Central and North
Jersey may be reason-ably large, well anchored, and semi-
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Each rootstock has specific characteristics that should
be considered before planning or planting an apple
orchard. The most important traits to consider are growth
control, tolerance to soil and climatic variables, resistance
to insects and diseases, precocity and yield efficiency, and
tree anchorage.
Rootstocks and varieties that reduce tree size and
increase tree efficiency are recommended. Smaller trees are
easier to prune, spray and harvest. Clonal rootstocks
induce trees to bear fruit earlier and more efficiently.
The absolute size and performance of a mature tree on
a given rootstock are influenced by soil, climate, scion
variety,and, very importantly, by management and care.
The following general characteristics of each rootstock are
based on research observations in New Jersey and other
northeastern areas of the United States.
MM111.This rootstock is propagated by stool beds
or layering and is multiplied from one clone. Vigorous
varieties on MM111 produce trees semidwarf in size, or
70 to 80 percent the size of those on seedling rootstocks.
Spur-type trees on MM111 are slightly smaller. MM111
is semi-vigorous and well anchored, and it encourages
earlier production than seedling rootstocks. MM111 is
tolerant of drought high soil temperatures, and collar and
root rot. It is also resistant to woolly aphids and does not
sucker badly if planted with the bud union 2 inches above
the soil line. Because of its tolerance to collar rot, it does
better than other clonal stocks on clayey and poorly
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