The inability or Failure of two different plant Grafted together to produce a successful graft union is called Graft incompatibility. Some pear cultivars are successfully grafted on quince rootstock, whereas, the other may die soon. However the reverse combination i.e. the quince on pear rootstock is always a failure

2. Defination:-The inability or Failure of two different plant
Grafted together to produce a successful graft union is
called Graft incompatibility.
Example:-Some pear cultivars are successfully grafted
on quince rootstock, whereas, the other may die soon.
However the reverse combination i.e. the quince on pear
rootstock is always a failure
Plum grow well on peach rootstock but peach grafted on
plum is always a failure
Defination:-The inability or Failure of two different plant
Grafted together to produce a successful graft union is
called Graft incompatibility.
Example:-Some pear cultivars are successfully grafted
on quince rootstock, whereas, the other may die soon.
However the reverse combination i.e. the quince on pear
rootstock is always a failure
Plum grow well on peach rootstock but peach grafted on
plum is always a failure

3.  Complete failure to form succsessful graft or bud union
by some species, varieties or clones.
 Very low percentage of graft success.
 Union takes place and initial growth also occur but the
tree dies pre-maturelyeither in the nursery or in the field.
 Degeneration of the tissue at graft union ,decline in
vegetative growth and premature defoliation.
 Marked differences in the growth or vigour of the stock
and the scion.
 Appearance of deficiency symptom or nutrional disorder.
 The plant may have stunted growth.
 Complete failure to form succsessful graft or bud union
by some species, varieties or clones.
 Very low percentage of graft success.
 Union takes place and initial growth also occur but the
tree dies pre-maturelyeither in the nursery or in the field.
 Degeneration of the tissue at graft union ,decline in
vegetative growth and premature defoliation.
 Marked differences in the growth or vigour of the stock
and the scion.
 Appearance of deficiency symptom or nutrional disorder.
 The plant may have stunted growth.

4.  There may be yellowing of foliage in later part of the
season.
 Appearance of ougtgrowth at,above and below at graft
union.
 Excessive swelling at the graft join.
 Graft component break off cleanly at the graft union.
 Suckering of rootstock.
 Overgrowths at above, or below the graft union.
 There may be yellowing of foliage in later part of the
season.
 Appearance of ougtgrowth at,above and below at graft
union.
 Excessive swelling at the graft join.
 Graft component break off cleanly at the graft union.
 Suckering of rootstock.
 Overgrowths at above, or below the graft union.

5. Breakage at the graft union resultingBreakage at the graft union resulting
from incompatibility.from incompatibility.

6. Radial section through two fruit tree graft union. Left:Radial section through two fruit tree graft union. Left:--AA
strong, wellstrong, well--knit compatible graft unionknit compatible graft union
Right:Right:--A weak, poorly connected union, showingA weak, poorly connected union, showing incomaptibilityincomaptibility
symptom.symptom.

7. Physiological
incompatibility
between scion
androotstock. Scion
overgrowth caused
by blockage of
assimilates
ranslocating from
the scion to the
rootstock, causing a
weakroot system.
Physiological
incompatibility
between scion
androotstock. Scion
overgrowth caused
by blockage of
assimilates
ranslocating from
the scion to the
rootstock, causing a
weakroot system.

8. Undesirable suckering of rootstocks.Undesirable suckering of rootstocks.

9. Figure indicate scion too overgrow the rootstockFigure indicate scion too overgrow the rootstock
and yetand yet devlopdevlop into large, strong tree.into large, strong tree.

10. Graft failure can be
caused by
anatomical
mismatching, poor
craftsmanship,
adverse
environmental
conditions, disease,
and graft
incompatibility.
Graft failure can be
caused by
anatomical
mismatching, poor
craftsmanship,
adverse
environmental
conditions, disease,
and graft
incompatibility.

11.  Graft incompatibility
occurs because of:-
a)Adverse physiological
responses between the
grafting partners.
b)Virus or phytoplasma
transmission.
c)Anatomical
abnormalities of
vascular tissue in the
callus bridge.
 Graft incompatibility
occurs because of:-
a)Adverse physiological
responses between the
grafting partners.
b)Virus or phytoplasma
transmission.
c)Anatomical
abnormalities of
vascular tissue in the
callus bridge.

12.  The distinction between
a compatible and an
incompatible graft
union is not always
clear-cut. Incompatible
rootstock-scion
combinations can
completely fail to unite.
Frequently they unite
initially with apparent
success, but the graft
fails over time. This
process is referred to as
delayed incompatibility.
 The distinction between
a compatible and an
incompatible graft
union is not always
clear-cut. Incompatible
rootstock-scion
combinations can
completely fail to unite.
Frequently they unite
initially with apparent
success, but the graft
fails over time. This
process is referred to as
delayed incompatibility.

13.  Suckering of rootstock.
 Graft components
breaking apart cleanly
at the graft union.
 Suckering of rootstock.
 Graft components
breaking apart cleanly
at the graft union.

14.  Differences between
scion and rootstock in
the time at which
vegetative growth for
the season begins or
ends.
 Overgrowths at, above,
or below the graft
union.
 Differences between
scion and rootstock in
the time at which
vegetative growth for
the season begins or
ends.
 Overgrowths at, above,
or below the graft
union.

15.  Anatomical Flaws
 Nontranslocatable (Localized) Incompatibility
 Translocatable Incompatibility
 Pathogen-induced Incompatibility (Virus, Phytoplasma)

16.  Grafts may fail because
there is poor anatomical
cell differentiation in the
union.
1. Callus initiates but no
subsequent vascular tissue
forms.
2.Poor phloem
development.
3.Xylem interrupted by
parenchyma tissue.
 Grafts may fail because
there is poor anatomical
cell differentiation in the
union.
1. Callus initiates but no
subsequent vascular tissue
forms.
2.Poor phloem
development.
3.Xylem interrupted by
parenchyma tissue.
Arrows indicate interrupted
vascular tissue in an apple graft.

17. Compatible apricot scion on plum
rootstock showing regularly shaped cells
in the callus bridge after 10 days
Incompatible apricot scion on
plum rootstock showing
irregularly shaped cells in the
callus bridge after 10 days.

18.  This is a type of localized
incompatibility where
contact cells from the two
partners fail to recognize
each other and do not
initiate callus formation.
A mutually compatible
interstock overcomes
translocatable
incompatibility between
the scion and rootstock.
 This is a type of localized
incompatibility where
contact cells from the two
partners fail to recognize
each other and do not
initiate callus formation.
A mutually compatible
interstock overcomes
translocatable
incompatibility between
the scion and rootstock.
Bartlett‟ pear grafted directly onto
a quince rootstock is
incompatible, but when mutually
compatible „Old Home‟ is used as
an interstock, the three-graft
combination is completely
compatible.

19. Translocatable incompatibility includes certain graft/rootstock
combinations in which the insertion of a mutually compatible
interstock does not overcome incompatibility. Apparently, some
biochemical influence moves across the interstock and causes
phloem degeneration. This may be the case with translocation of
prunasin from a quince rootstock to a pear scion where it is
metabolized into hydrogen cyanide that poisons the graft union.
TranslocatableTranslocatable incompatibilityincompatibility
Translocatable incompatibility includes certain graft/rootstock
combinations in which the insertion of a mutually compatible
interstock does not overcome incompatibility. Apparently, some
biochemical influence moves across the interstock and causes
phloem degeneration. This may be the case with translocation of
prunasin from a quince rootstock to a pear scion where it is
metabolized into hydrogen cyanide that poisons the graft union.

20.  Viruses and phytoplasmas
(mycoplasma-like
organisms) cause
pathogen-induced
incompatibility.
 Cases of this type of
incompatibility are
widespread, and more are
continually being found.
 Testing graft partners for
disease becomes an
important part of
commercial propagation.
 Viruses and phytoplasmas
(mycoplasma-like
organisms) cause
pathogen-induced
incompatibility.
 Cases of this type of
incompatibility are
widespread, and more are
continually being found.
 Testing graft partners for
disease becomes an
important part of
commercial propagation.
Latent viruses tolerated by the
scion can cause symptoms to
appear in a susceptible
rootstock following grafting.
Here “stempitting” virus
symptoms (arrow) have
developed in the sensitive
„Virginia Crab‟ apple rootstock.

21.  Examples of pathogen-induced Incompatibility
 Citrus quick decline or Tristeza
 Pear decline
 Walnut blackline
 Apple union necrosis and decline (AUND)
 Prune brownline
 Graft Incompatibility Pathogen-induced incompatibility
 Examples of pathogen-induced Incompatibility
 Citrus quick decline or Tristeza
 Pear decline
 Walnut blackline
 Apple union necrosis and decline (AUND)
 Prune brownline
 Graft Incompatibility Pathogen-induced incompatibility

22.  It has been postulated
that the critical event
deciding compatible and
incompatible grafts may
occur when the callus
cells first touch. There
may be a positive
cellular recognition
event that must occur for
a successful graft union
formation. Graft
Incompatibility
 Cell Recognition of the
Grafting Partners
 It has been postulated
that the critical event
deciding compatible and
incompatible grafts may
occur when the callus
cells first touch. There
may be a positive
cellular recognition
event that must occur for
a successful graft union
formation. Graft
Incompatibility
 Cell Recognition of the
Grafting Partners

23.  In a compatible graft,
shared plasmodesmata
form between cells of
the graft partners. This
forms a potential
communication
pathway among cells in
the graft bridge, which
may be important in cell
recognition and
compatibility/incompati
bility responses.
 In a compatible graft,
shared plasmodesmata
form between cells of
the graft partners. This
forms a potential
communication
pathway among cells in
the graft bridge, which
may be important in cell
recognition and
compatibility/incompati
bility responses.

24.  A model for graft
compatibility.
Important events
following callus
formation include:
adhesion of partners,
auxin flux, and
vascular differentiation.
 A model for graft
compatibility.
Important events
following callus
formation include:
adhesion of partners,
auxin flux, and
vascular differentiation.

25.  To be able to predict in
advance of grafting whether or
not the components of the
proposed scion-stock
combination are compatible
would be of tremendous value.
An electrophoresis test was
used for testing cambial
peroxidase banding patterns
of the scion and rootstock of
chestnut, oak, and maple. With
electrophoresis, if the
peroxidase bands match, the
combination may be
compatible; if they do not,
incompatibility may be
predicted.
 To be able to predict in
advance of grafting whether or
not the components of the
proposed scion-stock
combination are compatible
would be of tremendous value.
An electrophoresis test was
used for testing cambial
peroxidase banding patterns
of the scion and rootstock of
chestnut, oak, and maple. With
electrophoresis, if the
peroxidase bands match, the
combination may be
compatible; if they do not,
incompatibility may be
predicted.