ppt presentation of disease

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CH- 7. DISEASE AND INSECT PESTS OF PLANTATION CROPS

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Disease symptoms
CLR is found mostly on the leaves, first appearing on the underside
of the leaves as small circular orange-yellow to brown (orange red)
powdery spots.
The center's of the spot become dry and turn brownish, leaves fall
off prematurely.
The spots can be seen on the upper surface of the leaf, but the
powdery orange-spore are only seen on the under surface of the leaf.
Uredospore's present on lower surfaces of the leaf .
Premature shedding of leaves weakens the tree and results in
reduced yields, severe dieback of twigs and death of tree.
Coffee leaf rust (Hemileia vastratrix)
Diseases of coffee (coffea arabica l.)

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 In Ethiopia, the disease commonly occurs in areas having elevations
below 1800 m above area level.
 Continuous film of water is essential for spore germination so that
epidemic of this disease occurs in wet weather conditions.
 The leaf must remain wet for 24 hours for spore germination to take
place.
 If rain falls in late afternoon or in the evening, the coffee will remain
wet until the following morning favoring spore germination.
 Spore germination is influenced by temp (20-25, optimum 23 and 24
oC), age of the spores and age of leaves (more infection on younger
leaves than on older leaves).
Favorable conditions

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 Disease cycles of coffee leaf rust
Fungus exist as mycelium, uredia and uredospores in infected
leaves.
Uredospores are spread easily by wind, rain and perhaps by
insects.
Uredospores germinate only in the presence of free water and
enter leaves through the stomata of leaves.
 Management
Chemical sprays (Copper fungicides)
For seedbeds, afford adequate protection against the wind;
Thin out coffee tree carefully; tree pruning and weeding
Good site selection
Use of resistant varieties

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 Coffee berry disease (CBD) (Colletotrichum kahawae)
CBD chiefly attacks Coffee Arabica, the greatest damage
occurring due primarily to infection of berries, which result in fruit
(bean) rotting by active infection leading to total destruction of the
crop.
Small, dark-brown sunken spots or lesions with minute black dots,
on the green berries characterize CBD.
The majority of the diseased berries drop off or shed but a small
number remain on the branches as black mummies.
The pathogen frequently invades the branches especially those
with maturing bark changing from green into grayish cortex,
though the severity is low.

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 Survival mechanism
The pathogen survives on all infected plant parts including the
leaves, barks of branches, and mostly infected berries as
mummies.
In the absence of the infected berries, the bark constitutes the
main source of primary inoculum for the start of the disease on
the fruit berries.
Once some berries have become infected, very large numbers of
spores are produced and the disease starts very rapidly.

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 Dispersal mechanisms
Tools such as pruning shears, animals, birds, insect vectors and
human beings are suspected of transmitting the pathogen from plant
to plant.
The conidia are separated and dispersed slowly by water-splash over
comparatively short distances in water films and in splash droplets
cause by rainfall.
After dispersal of the spores by water into the healthy berries the
water droplets must remain on the berries for at least five hours to
enable the spores to germinate and to infect the berries.

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Favorable conditions
CBD is favored on areas above 1600 m above sea level.
The CBD incidence depends largely on climatic conditions
including high atmospheric humidity, fog, and low temperature
(15-28 oC, optimum 22 oC) favoring the spread of the pathogen.
It is also favored by shade and too close or narrow spacing.
During drought, it is dormant but commences to grow with the
onset of rains.

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1) Improvement of the coffee growing conditions in the orchards
through:
a) Extra dose of fertilizers or manure application,
b) Good crop husbandry,
c) Microclimate improvement by weed control
d) Microclimatic improvement by pruning coffee trees and shrubs,
e) Well balanced shade conditions to reduce inoculums potential,
and
f) Removal and burning of infected branches.
2. Spraying with fungicides
3. Use of resistant varieties

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 Disease of cotton (Gossypium hirsutum L.)
Angular leaf spot (Xanthomonas malvacearum)
Attacks all the plant parts above ground level at different stages of
plant growth.
The earliest symptoms of the disease is seen in the cotyledons of
germinating seeds.
Minute, water –soaked spots appear on the under-surface of the
cotyledons.
The disease spreads to new leaves formed and the seedling may
ultimately collapse and die.
On the leaves similar water-soaked spots appear or the under-surface
first and then on the upper surface.

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Lesions on stem, petioles, and fruiting branches are dark brown
to sooty black.
The affected stems show cracks and gummosis and are easily
broken by wind or there may be girdling and death of affected
organs.
Bolls or fruits the disease is characterized by the appearance of
water-soaked lesions on the surface.
Young infected bolls fall down prematurely.

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 Primary inoculum is the seed
 The infected seed lying dormant in the field and
germinating in the crop season.
 Leaves are infected mainly through the stomata.
 The secondary spread is through wind splashed rain and
dew.

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Favorable conditions
High humidity and moderate temperatures (28 oC).
 Soil temperature and moisture at the time of sowing.
 A temperature of 30 oC favours primary infection and secondary
infection is better AT 35 oC.
 Presence of moisture is very important for secondary infection
during the first 48 hours.
 Dry and hot weather retards development of the disease.

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Management
Removal and destruction of diseased plant debris.
Deep Ploughing after harvest buries the infected stalks and thus
reduces survival ability of the bacterium in soil.
Crop rotation, late sowing, early thinning, good tillage early
irrigation and addition of potash to soil help in reducing the
disease incidence.
Seed borne inoculums can be laminated by seed treatments.
Treating the seed with antibiotics like streptomycin eradicates the
internally seed-borne infection.
Regular spraying with copper fungicides can check the secondary
spread.

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Cotton fusarium wilts (Fusarium oxysporum f. sp. vasinfectum
Disease symptoms
Discoloration of tissues and plugging of vessels by hyphae.
Diseased plants are small with smaller leaves and bolls.
The fungus is soil borne surviving in the soil on stubbles of
diseased plants.
The disease is also seed borne.
Infection occurs through the root system, the fungus entering the
host when the plants are 1-3 weeks old and wilt symptoms
become visible when the plants are 5-6 weeks old.
The fungus also produces pectolytic enzymes to help in
breakdown of the cell wall components.

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Management of cotton fusarial wilt
Field sanitation, crop rotation, and mixed cropping are essential for
reducing the wilt disease of cotton.
Susceptible varieties of cotton should be replaced by resistant
varieties.
Proper application of micronutrients (such as zinc) and nitrogen
and potash fertilizers reduces incidence of cotton fusarium wilt.

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Symptoms
 Blackening of flower buds
 Fall of immature cherries
 Multiple branching
 Shortened internodes of terminal growth
Control method: pruning of coffee trees, shade tree regulation, hand
picking of bugs.
Biological control
Botanicals
A. Antestia bug (Antestiopsis intricata)
Insect pests of coffee

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One or more round holes
near the apex of ripe or dry
berries.
Blue-green staining on
damaged beans.
Different stages of the
borer can be found in
infested berries.
B. Coffee berry borer (Hypothenemus hampei)

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Cultural methods
 Reduce heavy shade
 Prune the coffee to keep the tree as open as possible
 Harvest at least once a week
 Pick all fallen cherries from the ground, under the tree during
picking to avoid missing fallen cherries.
 All infested cherries should be burned
 Before main flowering the tree should be completely stripped of
any remaining cherries

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 Brown irregular blotches on
the upper side of the leaf
(caused by leaf miner
caterpillars).
 Small white caterpillars is
observed when the upper
surface opens.
 Mined leaves are usually
shed.
C. Coffee leaf miner, Leucoptera caffeina
Symptom attack

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Biological methods
• Natural enemies play a key role to check coffee leaf miner.
• Blotch leaf miner is attacked by 8 species of parasitoids. The
most abundant species
•Aphidencyrtus aphidivorus,
•Pediobius caffeicola Ferr.
•Apanteles bordagei Gir
• Aphidencyrtus aphidivorus was the most abundant
species with 72% parasitization

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A. Pink Bollworm (Pectinophora gossypiella (Saunders))
Host: Though the pest attack other plants, cotton is the only
Malvaceae that can support a large infestation.
Damage: The entry of the caterpillar into a large green boll is
almost invisible, but if the boll is opened, the red & white caterpillar
can be found.
Damaged bolls fail to open completely & often have secondary
rots.

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Damage: Damage in cotton often appears as clean round holes in
bolls of all sizes, but with plenty of frass in evidence.
Damaged flowers tend to be shed, leaving “flared” squares.
B. Cotton bollworm (Helicoverpa armigera)
Fully grown larva of H. armigera feeding on a
cotton boll
Boll weevil feeding injury on cotton
bolls

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 Clear the stubble of the previous crop, particularly the
infected bolls which remain spread on the field.
 Never gather tainted and infested cotton bolls in the
warehouse.
 Make sure to practice crop rotation so that you are
successful in breaking the life cycle of the pink
bollworm.
 Start the practice of early sowing and early harvesting.
 use of insecticides
Management

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Host range: The cotton aphid has a broad host: Fabaceae
(legumes, lucerne), Solanaceae etc.
Damage: Damage symptoms initially appear as crinkled and
curled leaves, with the margins of the leaves curling downwards.
Aphids cause damage to cotton in:
Reduces photosynthesis, secretion of honeydew, spread of the
disease
Colony of cotton aphid showing wide variation
in size and colour. Two large pale brown
parasitised aphids (‘mummies’) are at the top.
C. Cotton aphid (Aphis gossypii Glover)

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 Biological and chemical methods.
 Options for natural enemies include parasitic wasps, gall midges,
hover flies, ladybugs and lacewing larvae.
 Effective chemical plant protection products are broad acting
insecticides
Management

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Disease and insect pests of tea reading assignment

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Chapter - 9
Post harvest diseases and insect pests
 Post harvest diseases are diseases of crops which occur after harvesting.
 It is the damage of the harvested produce by microorganisms.
They may cause loss of quantity (weight) and quality of produce.
 Storage diseases are mostly caused by fungi in grains and fruits while
in vegetables mostly fungi and sometimes bacteria.
Postharvest diseases are generally caused by wound parasites.

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Classification of fungi associated with storage grains based on
ecological (moisture) requirement.
1. Field fungi: invade grains before harvest, while still developing or
after maturity.
2. Storage fungi: develop on the grain after harvest.
 Storage fungi have adapted to grow well under dry conditions.

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 Storage fungi enter in to gains trough:
 Existing opening: fissures, hilum and damages
 Direct penetration: invasions of cells of intact kernels by using
enzyme and mechanical pressure.

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Effects of field fungi
 Discoloration of seeds
 Kill ovules
 Weaken or kill the embryos
 Cause shriveling of seeds
 They may have produced mycotoxins

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Factors influencing grain spoilage
1. Intrinsic factors: inherent property of the grain. Grain quality
prior to storage is a major criterion for determining whether the
grain will maintain quality during long-term storage.
 Respiration
 Low heat conductivity
 Moisture content
 Pre-harvest grain diseases will reduce storability

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2. Extrinsic factors:
 Grain damage: Any breakdown in seed coat integrity allows easy
entry for storage fungi.
 Pre - harvest grain disease will reduce storability.
 Temperature: majority of storage fungi are mesophilic (20-40oc)
 Moisture: the most important single factor that influence grain
spoilage in storage
 Insect and mite infestation

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Effects of storage fungi
 Discoloration of grain
 Heating of seed bulk
 Decreased germination
 Increase in moisture content

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Grain Storage fungi
1. Aspergillus spp.
 A.glaucus
 A.restrictus
 A.flavus
 A.ochraceous
 They can germinate and grow under conditions of lower relative
humidity above 65%.
 Infection of stored grains with seed moisture content below 16%
is usually by Aspergillus species.

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2. Pencillium spp.
They require a minimum relative humidity of 79-80% for
germination of conidia and a wide range of temperature, usually -4
to 48oc.
Generally they are considered to be more prevalent in cooler
climate than Aspergillus spp. Injury predisposes seeds to infection
by Pencillium sp.
They are more prolific pore producer than Aspergillus sp.

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3. Fusarium spp.
They are intermediate between field and storage fungi.
They are adapted to higher seed moisture content and higher
relative humidity.

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Management of Storage Diseases
 The control of storage diseases depends on certain precautions and
conditions that must be met before and during harvest and then
during storage.
Measures on the field
 Choice of variety/resistant variety
 Time of harvesting: crops should be harvested as quickly as
possible to avoid infestation of the grain in the field.
 Remove infested/infected material before storage
 Fungicides
 Reduction of grain damage

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Measures on the storage
 Drying: the grains must be stored at an optimum moisture
content level
 Modification of storage environment: the temperature and
moisture of stored grain is kept as low as possible.
 Sanitation, use clean storage container
 Controlled ventilation
 Fungicides like organic acid

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Chapter 10
Agricultural Pesticide and its Application
What are Pesticides?
 A pesticide is a substance intended to prevent, destroy, repel or
control any animal pest or disease caused by microorganisms, as
well as unwanted weeds.
 Pesticides are harmful to animals and microorganisms through
direct contact, feeding or other kinds of effective exposure during
their stages of growth.

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Types of pesticides
Pesticides can be classified according to type of pest or disease against which
they are effective.
 Bactericides for the control of bacteria
 Fungicides for the control of fungi & oomycetes
 Herbicides for the control of weeds
 Insecticides for the control of insects
 Miticides for the control of mites
 Nematicides for the control of nematodes
 Rodenticides for the control of rodents
 Virucides for the control of viruses

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Pesticides may also be classified according to the way they work
1. Contact pesticides The finer the spray mist, the better it will
penetrate the crop and thus kill the pests by contact. Contact
pesticides have to reach their target directly to be effective.
2. Systemic pesticides attach to and penetrate the plant surface, and
then disperse through the whole plant.
 Pesticides that persist for some time in the soil and subsequently
penetrate through contact with roots are also systemic.

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How Pesticides Work?
Pesticides must also be applied at the right time early in the life of the pest, in
order to be effective. Once it reaches the target pest, the chemical may act in
different ways:
 Blocking the cellular processes of target organisms
 Destroy or alter the pest’s metabolism
 Disrupt enzyme processes or denature proteins
 Simulate or otherwise interfere with hormones
 Nervous system disruptors
 Disrupt photosynthesis prevent the plant (weeds) from producing or storing
energy

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Side-Effects of Pesticide
Water pollution: Most pesticides do not breakdown in a short time. They
stay on the plant or end up in soil. During rains, these residual pesticides
wash into rivers and ponds.
Air pollution: drifts of pesticide during its application contaminate the air.
Effect on biodiversity: At a lower level, pesticides kill soil microbes and
other organisms that take part in nitrogen fixing and other important natural
cycles.
Effects on human: All pesticides affect humans to some extent. The effect
may range from short-lived to chronic, minor to serious and sometimes fatal
ailments.
Effects on consumer: Many of the foods we eat are grown using synthetic
fertilizers and chemicals. Pesticide residue occurs in food.

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Precautions of pesticides
 Do not store pesticides with foodstuff or animal feeds
 Apply the recommended pesticides early in the morning or late in the evening.
 Read the label carefully
 Check the safety precautions to be observed; select the dose rate, and note the
instructions for mixing on the product label.
 Always follow the recommended dose rates and dilutions.
 Always wear protective clothing
 Do not spray at windy and rainy time
 Dispose of containers and wastes by burning or burying them