2. ENVIRONMENTAL
FACTORS THAT CAUSE
PLANT DISEASES
Temperature, moisture, oxygen, light, air
pollution, nutricial deficiencies in plants,
soil mineral toxic to plant, herbicide
injury, hail injury, lighting, other
improper agricultural practices
3. GENERAL CHARACTERISTICS
• Non infectious diseases of plants, is that are
caused by the lack or excess of something that
supports life
• Non infectious diseases occur in the absence of
pathogens and cannot, therefore, be transmitted
from diseased plant to healthy plants
• Non infectious diseases may affect plant in all
stages of their lives (e.g., seed, seedling, mature
plant, or fruit), and they may cause damage in
the field, in storage, or at the market
• The symptoms caused by non infectious
diseases vary in kind and severity
• Symptoms may range from slight to severe, and
affected plants may even die
4. DIAGNOSIS
• Sometimes made easy by the presence of
characteristic symptoms
• Carefully examining and analyzing several
factors: the weather conditions prevailing before
and during the symptoms; recent changes in the
atmospheric and soil contaminants; and the
cultural practices
• Often, the symptoms are closely resemble those
caused by pathogens
• By growing plants under conditions in which the
degree of suspected environmental factors has
been adjusted to normal
5. CONTROL
Non infectious diseases can be controlled
by ensuring that plants are not exposed to
the extreme environmental conditions
responsible for such diseases or by
supplying the plants with protection or
substances that would bring these
conditions to level favorable for plant
growth
7. A. HIGH-TEMPERATURE EFFECT
• Seems to cause its effects on the plant in
conjunction with the effects of other
environmental factors, particularly excessive
light, drought, lack of oxygen, or high winds
accompanied by low relative humidity
• Sunscald injury, appearing on the sun-exposed
sides of fleshy fruits and vegetables, such as
peppers, apples, tomatoes, onion bulbs, and
potato tubers
• Kill young seedlings, causes cankers at the
crown on the stem of older plants
11. B. LOW-TEMPERATURE EFFECT
• Far greater damage to crops is caused by low
than high temperatures
• Excessive sweetening and on frying, undesirable
caramelization of potatoes
• late frosts to young leaves and meristematic
tips
• The frost killing of buds of peach, cherry, and
the killing of flowers, young fruit, and sometimes
succulent twigs of most trees
• Kill the young roots of trees or cause bark
splitting and cancer development
• Discolored corky tissue on surface of apple or
pear fruit
15. C. LOW SOIL MOISTURE
EFFECTS
• Moisture disturbances in the soil are
probably for more plants growing poorly
and being unproductive annually, over
large areas than any other single
environmental factor
• Plants usually remain stunted, are pale
green to light yellow, have few, small and
drooping leaves, and wilt and die
• Plants are also more susceptible to
certain pathogens and insects
16. • Water stress in the rice paddy. The lack of water
in the soil reduces the ability of the plant to
extract essential nutrients from the soil
17. • Corn with rolled leaves, indicative of water
stress.
19. D. HIGH SOIL MOISTURE
EFFECTS
• Excessive soil moisture occurs much less
often than drought, may result in more
serious and quicker damage or death
• Plants have lack vigor, wilt frequently,
leaves are pale green or yellowish green,
and plant die
• Edema or oedema (swelling)
23. E. INADEQUATE OXYGEN
• Lack oxygen may cause desiccation of
roots of different kind of plants in
waterlogged soil
• A combination with high air temperature
causes root collapse in plants
• Blackheart of potato
24. F. LIGHT
• Lack of sufficient light retards chlorophyll
formation and promote slender growth
with long internodes, thus leading to pale
green leaves, spindly growth, and
premature drop of leaves and flowers
(etiolation)
• Etiolated plants are usually thin and tall
and are susceptible to lodging
