Chayote physiological disorders By Mr. Allah Dad Khan Provincial Coordinator IPM KPK MINFAL Islamabad

1. Cucumber Physiological
Disorders

2. Chayote Physiological
Disorders
ToT to FFS Staff
By Mr. Allah Dad Khan
Provincial Coordinator IPM KPK
MINFAL

3. Air Pollution
symptoms
• Another example of chemical
toxicity is damage from air
pollutants. Several gaseous air
pollutants can cause injury to
plants, including ozone and sulfur
dioxide. Ozone is produced when
components of
combustion/vehicle emissions
such as hydrocarbons and
nitrogen oxides react with oxygen
and sunlight to form ground level
ozone in the atmosphere. Its
effects on plants can be mistaken
for infectious diseases

4. Ozone Laayer
• Ozone can cause flecking
which could be mistaken for
mite injury. Ozone can also
cause bronzing, chlorosis , and
necrosis. Necrosis could be
mistaken for a leaf spot caused
by an infectious agent. In
conifers, injury can include
needle-banding and tip-burn
Air pollution levels are often
available from local

5. Soil Structure
• Soil structure determines the soil's ability to hold water,
nutrients, and oxygen and make them available to plants.
The most common issue related to soil structure is
compaction, which results in inadequate pore space for
root growth. Clay soils, with their smaller particle size, have
naturally smaller pore space and are at high risk for
becoming severely compacted. Compaction can occur from
a variety of sources including traffic (particularly heavy
farming or construction equipment) (Figure 1), raindrop
impact, tilling operations (plow layer), and minimal crop
rotation. Reduced water availability is an obvious
consequence of compaction as runoff occurs more
frequently in a compacted soil and available pore space to
hold water is limited
• symptoms

6. SoilpH
• Soil pH below 5.5 generally results in low
availability of calcium (Ca), magnesium (Mg), and
phosphorus (P), and increased solubility of
aluminum (Al), iron (Fe), and boron (B). High
levels of these three nutrients in low soil pH are
common, and can induce toxicity symptoms in
plants. Soils with pH levels above 7.8 have a high
availability of Ca and Mg at the expense of P, B,
Fe, manganese (Mn), zinc (Zn), and copper (Cu).
Plants grown in these alkaline soils often have
deficiency symptoms to these nutrients
• symptoms

7. Attrazine Pesticides

8. Calcium Deficiency
symptoms
• Calcium is important for the functioning
of cell membranes and the strength of
cell walls. Most calcium-related
disorders of crops are caused by
unfavourable growing conditions and
not by inadequate supply of calcium to
the roots. Rapidly growing crops in hot
windy conditions are most at risk.
Deficiencies can also develop when
cucumbers grow quickly under
continuously humid conditions, as in a
polyhouse. Other contributing factors
are waterlogging, soil salinity, high
potassium or ammonium supply, and
root disease

9. Boron Deficiency
symptoms
• Boron deficiency causes both leaf and fruit
symptoms. The main leaf symptoms are a
distortion of newer leaves (in severe cases
the growing point dies) and the appearance
of a broad yellow border at the margins of
the oldest leaves. Young fruit can die or
abort; abortion rates are high. The symptoms
of boron deficiency on mature fruit are
distinctive and include stunted development
and mottled yellow longitudinal streaks,
which develop into corky markings (scurfing)
along the skin. These symptoms are often
most severe near the blossom end of the
fruit. Similar symptoms can occur on fruit
grown in polyhouses with inadequate winter
heating. Developing and mature fruit can
taper and curve at the blossom end. The
proportion of pith to seed is often higher in
boron-deficient fruit.
Older leaves on boron deficient plants
develop a yellow border (top and left).
New leaves are distorted and appear
mottled

10. Chilling/frost injury

11. Excess Soil Moisture

12. The phosphorous deficient plant (on the left) is stunted and has small, dark green, dull
leaves.
A healthy plant is on the right.

13. The oldest leaf of this stunted plant is bright yellow, but the leaf above it remains dark
green.

14. Iron Deficiency
Iron deficiency
• Iron is needed to produce
chlorophyll and to activate
several enzymes, especially those
involved in photosynthesis and
respiration. Deficiencies of iron
are more likely in alkaline or
calcareous soils, and can be
induced by over-liming, poor
drainage, or high concentrations
of metallic ions in the soil or
nutrient solution. Iron availability
decreases at pHs above 7.
Manganese toxicity can induce an
iron deficiency

15. Magnesium deficiency
• Magnesium deficiency
causes yellowing of older
leaves. The symptom begins
between the major veins,
which retain a narrow green
border. A light tan burn will
develop in the yellow
regions if the deficiency is
severe. Fruit yields are
reduced.
Yellowing and light tan burn on older leaves
of magnesium deficient plant (left) compared with
a healthy plant (right).

16. Manganese Deficiency
symptoms
• The function of manganese in the
plant is closely associated with
the function of iron, copper and
zinc as enzyme catalysts.
Manganese is needed for
photosynthesis, respiration and
nitrate assimilation. Deficiencies
are more likely in calcareous or
alkaline soils, or over-limed soils;
availability is high in acidic soils.
• The veins of middle to upper
leaves of manganese-deficient
plants appear green against the
mottled pale green to yellow of
the blade.

17. Molybdenum Deficiency

18. Nitrogen Deficiency
Symptoms
• Most plants need nitrogen in
large amounts. It is generally
considered to drive plant
growth, probably because its
supply is often limiting. A
shortage of nitrogen reduces
the plant's capacity to trap
energy through
photosynthesis. Nitrogen is
required in the production of
chlorophyll (the green pigment
in leaves), which is responsible
for converting sunlight to
usable plant energy

19. Phosphorus Deficiency
symptoms
• Phosphorus-deficient plants have
weak roots, are stunted, and
produce small, dark, dull, grey-
green leaves. The oldest leaf, at
the base of the shoot, turns
bright yellow. However, unlike
nitrogen deficiency, the leaf
directly above this leaf remains
dark green. Brown patches
appear between the veins on
mature leaves. These become
scorched and spread until the leaf
dies prematurely. Fruit set is
reduced and so production is
impaired.
The phosphorous deficient plant
(on the left) is stunted and has
small, dark green, dull leaves.
A healthy plant is on the right.

20. Phosphorus Toxicicty
• Phosphorus toxicity Phosphorus toxicity is
uncommon in soil-grown crops but can occur
in hydroponic

21. Zinc Toxicity
symptoms
• Zinc toxicity causes a pale
green chlorosis of newer
leaves. If toxicity is severe,
pinhead-sized light-brown
spots may appear between
the veins. Older leaves may
wilt and appear dull. All
leaves are a lighter green
than is normal
Where there is excess zinc, the older leaf (on
the left) appears dull. The younger leaf is pale
green with pinhole-sized light brown spots
between the veins

22. Potassium Deficiency
symptoms
• Potassium deficiency causes yellowing
and scorching of older leaves. These
symptoms begin at the margins of the
leaf and spread between the veins
towards its centre. Large areas of tissue
around the major veins remain green
until the disorder is well advanced. A
brown scorch develops in the yellow
areas and spreads until the leaf is dry
and papery. As each leaf dies, others
further up the shoot develop the same
symptoms. These symptoms can
develop rapidly in hot weather. Fruit
may not expand fully at the stem end,
although they look swollen at the tip
end, a symptom that is also caused by
water stress.

23. Salt Injury
symptoms
• Plants grown under saline conditions,
where the soil or growing medium has
high electrical conductivity (EC), are
stunted and produce dark green, dull,
leathery leaves that are prone to
wilting. A narrow band of yellow
necrotic tissue is often present on leaf
edges. This can affect leaf expansion,
causing a slight downward cupping of
the leaf. After a serious water stress,
the oldest leaves may develop a
uniform pale green chlorosis and small
necrotic areas within the leaf. If water
supply is maintained, leaves may only
develop a band of pale green tissue
around their edges. Plants are likely to
wilt in warm weather

24. Wind and Sand Injury

25. Chloride Toxicity
symptoms
• Cucumbers are moderately
sensitive to chloride. Chloride
salts are common in the soil or
groundwater in areas on
Wianamatta Shale (for example,
around Glenorie and Blacktown in
NSW). Chloride is also present in
fertilisers, such as muriate of
potash (potassium chloride). Do
not use these fertilisers if salt is a
problem. Chloride toxicity
reduces plant vigour and causes
yellowing and scorching of leaf
margins, and premature leaf fall
Band of pale green tissue around the leaf
margin with some edge scorching associated
with 3% chloride in tissue

26. 2,4-d Pesticide Injury

27. Blossom End Rot

28. Drought Stress

29. Flood Damage

30. Hollow Heart