Grape fruit Physiological Didsorders A Lecture By Allah Dad Khan To FFS Trainee

2. Grape Fruit Physiological Disorders
A
Lecture To ToT trainees ( FFS)
By
Mr. Allah Dad Khan
Provincial Coordinator IPM KPK
MINFAL Pakistan

4. Frost
Identification tip: Frost dieback
 Brown dead leaves remain
attached to trees damaged
by cold weather, giving
plants a scorched
appearance. Certain other
leaf and twig diseases and
disorderscause similar
damage. With cold injury,
damage is most prevalent on
outer, exposed branches.
Young trees are especially
susceptible to cold.

5. Sunburn discoloring
Identification tip:
 Exposure to hot sun can kill
parts of leaves and fruit,
resulting in yellow-to-brown
blotches. Sunburn also
causes bark cankers (not
shown). Injury is most
prevalent on the south and
west sides of the tree if sun
exposure is the cause of
damage.

6. Fruit Splitting:
Identification tip:
 Rinds split at the bottom
of fruit after tree stress,
such as extreme weather,
inappropriate irrigation,
and potassium deficiency.
Decay fungi such as
Alternaria rot or blue and
green mold often invade
wounded fruit.

7. Puff and crease
Identification tip:
 An uneven appearance
develops on the outer
surface of rinds when the
outer rind has separated
from inner fruit. The
apparent cause is different
growth rates between the
inner fruit (endocarp) and
the white layer (albedo)
under the peel
Puff and crease

8. Peteca of lemon
Identification tip:
 This lemon malady causes
depressions in the rind,
which become discolored
or brownish

9. Rind disorder
Identification tip:
 Brown, water-soaked
blotches or dark, sunken
areas develop on the rind
after rainy weather and as
fruit matures and turns
orange. Secondary fungi
may colonize affected
areas as the fruit breaks
down. This physiological
problem (abiotic disorder)
is a problem in California
on Satsuma mandarins.

10. Hail damage
Identification tip:
 Hail impact causes
discolored scars on fruit
and twigs and tears or
shreds leaves. Damage
occurs on the exposed
side of fruit, including
locations not likely to
have been impacted by
equipment.

11. Wind scarring
Identification tip:
During persistent winds, fruit
may rub against twigs or
thorns and develop scars.
 Shallow, discolored scars
on the rind occur when
fruit rub against twigs or
thorns, especially on
lemon trees at exposed
locations

12. Chimera
Identification tip:
 A raised section in fruit,
typically in a wedge-
shape, is usually
from chimera. This
genetic mutation is of
minor importance.

13. Fruit Drop
Summer Drop
 During the late spring and
early summer, most citrus
trees will naturally drop tiny,
marble-sized fruit. Citrus trees
lose some of the developing
fruits to prevent the tree from
being weighed down by an
excessive amount of ripening
fruit. Unless your citrus tree
has another problem and you
are losing fruit in May, June or
July, the cause is likely natural
and unavoidable..

14. Pruning
Symptoms
 Too much pruning may cause
a loss of young fruit from your
tree. Citrus trees rarely need
heavy pruning. For the best
results from your tree, prune it
to remove branches that are
dead, diseased, decaying or in
danger of harming other
branches by contact. The best
time to prune is after the last
frost in the spring or during
the summer before August, to
prevent cold damage on any
new growth that appears after
pruning.

15. Drought Stress
Symptoms
 Inadequate watering of a
citrus tree tends to put the
tree under stress. A
drought-stressed tree may
jettison its fruit to ensure
the survival of the food-
making leaves, branches
and remaining fruit. Make
sure the tree is well
watered. Mulch around the
base of the tree to help
conserve water in the soil.

16. Temperature Changes
Symptoms
 Sudden, drastic temperature
swings, especially right after
fruit set, could cause the tree
to drop immature fruit. High
temperatures helps to sweeten
citrus fruit, but they should be
later in the summer, after the
young fruit has begun to grow.
During periods of high heat,
you will also need to pay
attention to the amount and
frequency of watering. If the
citrus trees are in pots, they
may need daily watering
during warm weather.

17. leocellosis:
leocellosis::
 It is caused by rind oil release
when oil cells get ruptured during
harvesting or during handling from
the field to the pack house. It is
more common in crop taken in
'Mrig' bahar and harvested during
February- March. Careful
harvesting and handling reduces
incidence of oleocellosis. Rind oil
from ruptured cells discolours the
skin making the fruit
unmarketable.
 Control : Best way to reduce its
incidence is to cure the fruit
overnight at a temperature of 18-
20 C for 12-24 hrs, before the fruit
is moved from the field to the pack
house

18. Nutrient Disorders
Identification tip:
Iron deficiency symptoms on
young citrus leaves.
 Leaf discoloring occurs
between distinctly greener
veins when nutrient
disorders such as a
deficiency of iron (shown
here), potassium, or zinc
are the cause

19. Nitrogen deficiency
Identification tip:
 Foliage is pale overall
when nitrogen is deficient.
The causes include a true
deficiency of nitrogen,
adverse soil conditions, or
unhealthy roots

20. Phosphorus Deficiency
Symptoms
Figure 4. Phosphorus
deficiency
[Click thumbnail to
enlarge.]
 Fruit are rather coarse with
thick rinds (Fig. 4) and have
lower juice content which is
higher in acid. Although rarely
observed, foliage may exhibit
a bronze appearance.
Phosphorus deficiency is
unlikely to occur in groves that
have received regular P
applications in the past.
However, new plantings on
previously uncropped land
usually require substantial
initial phosphorus applications

21. Potassium Deficiency
Symptoms
Figure 5. Potassium deficiency (3
levels of K deficiency with the
smallest fruit being the most
deficient.)
 Fruit are smaller, have
smoother, thinner rinds and
may be subject to splitting
and/or drop (Fig. 5).
Potassium deficiency is likely
to occur on calcareous soils
due to elemental antagonism,
and where large crops of fruit
are produced with high
nitrogen rates. A rarely
observed bronzing of foliage
may sometimes be observed,
particularly on lemons.

22. Manganese Deficiency
Symptoms
Figure 7. Manganese
deficiency
 Deficiency appears as dark green
bands along the midrib and main
veins surrounded by light green
interveinal areas giving a mottled
appearance (Fig. 7). As severity
increases, the light green interveinal
areas give way to a yellow-bronze
coloration. Both manganese and zinc
deficiencies may occur on calcareous
soil and may be more severe on trees
with highly pH-sensitive rootstocks.
Incipient manganese symptoms may
sometimes disappear as the season
progresses, so leaves should be
observed several times before
remedial action is taken. Soil and
foliar applications may be effective in
correction of manganese deficiency

23. Role of Soil pH
Symptoms
 Lemon trees perform best in a soil with a
pH level more acidic than many plants
require, between 5.5 and 6.2. Yellowing
among the veins on a leaf that signals an
iron deficiency may not arise because the
soil lacks iron. The true reason might be
that the soil tends toward the alkaline side
and cannot put the iron into a usable form
for the plant. A home soil test or a test sent
to a soil-testing laboratory will report your
soil's current pH level. If the soil tests too
high for a lemon's acidic preference, add
elemental sulfur. To lower the pH by one
point, for example, from 6.5 to 5.5, use 2
1/2 pounds per 100 square feet in loamy
soil. If your soil is sandy, reduce the
application by one-third. For clays, increase
the amount of sulfur added by 50 percent.
Work it thoroughly into the top 6 inches of
the soil.

24. Sunscald

25. Foliage Symptoms
Symptoms
 Since similar symptoms, such as yellowing of
leaves, can indicate too little of a number of
different nutrients or micronutrients, you should
submit or take a take home soil test before
supplementing. Insufficient water contributes to
nutrient deficiencies, as can soil pH imbalance.
Nitrogen inadequacy, the most common
deficiency, results in foliage turning yellow from
the lower leaves up. Iron, manganese and zinc
deficiencies often appear together as lighter
splotches between the veins of a leaf. If this
abnormality only shows up on the south side of
the tree, it may signal a shortage of zinc.
Occurring on the north side, a manganese
deficiency is the likeliest culprit. In
overwatered, poorly drained soil, yellow
splotches probably indicate that the tree does
not receive enough iron. A symptom of
magnesium deficiency is a yellow spot that
begins at a leaf's base and gradually spreads
over most of its surface.

26. Zinc Deficiency
Symptoms
Figure 8. Zinc
deficiency
 Early stages appear as small
blotches of yellow between
green veins on the leaf. With
severe deficiency, leaves may
become increasingly yellow
except for the green veinal
areas (Fig. 8). Under severe
deficiency conditions, leaves
will also be small with narrow
pointed tips on terminal
growth. Foliar fertilizer
applications are usually
recommended for correcting
zinc deficiency. Trees with
citrus blight will also show leaf
symptoms of zinc deficiency.

27. Iron Deficiency
Symptoms
Figure 9. Iron
deficiency
 In mild cases, leaf veins are slightly
darker green than interveinal areas with
symptoms appearing first on new
foliage (Fig. 9). In severe cases,
interveinal areas become increasingly
yellow with entire area eventually
becoming ivory in color with emerging
foliage, which is smaller. Trees may
become partially defoliated with
eventual twig and canopy dieback. Iron
deficiency is usually an indication of
calcareous soil condition and is more
likely to be expressed on high pH-
sensitive rootstocks like Swingle
citrumelo. An early expression of
flooding damage to roots and of copper
toxicity may be iron deficiency
symptoms.

28. Copper Deficiency
Symptoms
Figure 10. Copper
deficiency (ammoniation)
 Mild copper deficiency is usually
associated with large, dark green leaves
on long soft angular shoots. Young
shoots may develop into branches which
appear curved or “S-shaped," referred
to as “ammoniation” usually resulting
from excessive nitrogen fertilization
(Fig. 10). Twigs can develop blister-like
pockets of clear gum at nodes (Fig. 11).
As twigs mature, reddish brown
eruptions may occur in the outer portion
of the wood. Severely affected twigs
commonly die back from the tip with
new growth appearing as multiple buds
or “witches broom”. Necrotic-corky
areas on the fruit surface may
sometimes occur in extreme situations.
Copper deficiency is more likely to occur
in new plantings on previously
uncropped soils, which are usually
deficient or totally lacking in copper

29. Boron Deficiency
Symptoms Figure 12. Boron deficiency
 Fruit symptoms most indicative of
boron deficiency include darkish-
colored spots in the white albedo
of fruit and sometimes in the
central core (Fig. 12). Fruit may be
somewhat misshapen with a lumpy
surface. Unlike other micronutrient
deficiencies, boron can impact fruit
quality and should therefore not be
allowed to occur. Slight excess can
cause toxicity, so maintenance or
correctional applications should
involve ground or foliage
applications, but not both.

30. Molybdenum Deficiency
Symptoms
Figure 14. Molybdenum
deficiency
 Rarely observed, it can
occur under acidic soil
conditions. The most
characteristic field
symptoms are large
yellow spots on the leaves
that appear first as less
defined water-soaked
areas in spring (Fig. 14),
later developing into
distinct larger interveinal
yellow spots.

31. Phytotoxicity from diuron
Identification tip:
When citrus roots take up too
much diuron, major leaf veins
turn yellow
 Leaf veins can turn yellow
or white (vein clearing)
after herbicide application
due to citrus root uptake
of bromacil or diuron.
After simazine exposure,
leaves yellow between
veins with the chlorosis
increasing in severity in
proportion to the amount
of herbicide exposure.

32. Phytotoxicity from simazine
Identification tip:
Range of damage from
simazine on citrus
 Pale blotches develop in
leaves after exposure to
simazine herbicide.
Interveinal chlorosis can
range from relatively mild
to severe depending on
the amount of herbicide
absorbed.

33. Mesophyll collapse
Identification tip:
Mesophyll collapse of leaves
caused by water stress.
 Soft tissue between leaf
veins becomes sunken
and translucent or pale
due to moisture stress
when trees are unable
to provide leaves with
enough water; affected
leaf tissue then
becomes tan-colored or
necrotic.

34. Salt Injury
Symptoms Figure 16. Salt injury
 Many salinity-induced symptoms are similar
to drought stress symptoms, including
reduced root growth, decreased flowering,
smaller leaf size, and impaired shoot growth.
These can occur prior to more easily
observed ion toxicity symptoms on foliage.
Chloride toxicity, consisting of burned
necrotic or dry appearing edges of leaves, is
one of the most common visible salt injury
symptoms. Actual sodium toxicity symptoms
can seldom be identified, but may be
associated with the overall leaf “bronzing”
(Fig. 16) and leaf drop characteristic of salt
injury. Slightly different symptomology may
occur depending on whether injury is due to
root uptake or foliage contact. Excessive
fertilizer applications, highly saline irrigation
water, and storm-driven ocean sprays can all
result in salinity-induced phytotoxic
symptoms.