Cashew Pests SEO

Introduction
• When cashew was introduced into Sri Lanka, it was considered as
a crop, which was not attacked by serious pests.
• Even though, later, it was found that it is susceptible to several
pests, the growers still consider it as a crop, which tolerates pests
and diseases, and also, which does not require serious attention
on pest management.
• Now it is confirmed that Cashew, too, faces serious threats from
pests and diseases, which can cause severe crop losses.

• Several higher animals, around 60 species of insects, some mites
and nematodes are known to be infesting cashew in Sri Lanka.
• But their damages could occur in different levels.
• Among higher animals, parrots bats and rabbits cause occasional
damages.
• Parrots and bats damage immature nuts and apples while rabbits
damage collar region of the plants, during 1" year.
• However, these damages are not economically significant.

• Some nematodes are found to infest roots of young seedlings but
their damage is not considered as important.
• When the severity of the damage is taken in to consideration only
few insect pests could be identified as serious pest.
• The two pests in particular can be considered as major pests.

Common insect pests of cashew
A. Pests of field planted cashew
1.Stem and root borer : Plocuederus ferrugineus L
2. Branch and twig borer : Apate submedia Pallas
3. Shoot tip borer : Hypatima haligramma Meyr
4. Apple and nut borer : Thylecoptila panrosema Myrich
5. Tea mosquito bug : Helopeltis antonii Sign
6. Leaf miner : Conopomorpha syngramma Meyr
7. Leaf and blossom Webber : Lamida moncusalis Walker
8. Defoliating caterpillar : Metanastria hyrtaca Cramer
9. Leaf caterpillar : Lymantria obfuscata Walker
10. Looper caterpillar : Oenospila flavifusata Walker
11. Flush worm : Cricula trifenestrata Helfer
12. Leaf twisting weevil : Apoderus tranquebaricus Fabricius,
13. Flower thrips : Rhyncothrips raonsis Gaer

B. Pests of cashew nurseries
1. Tea Mosquito Bug : Helopeltis antonii
2. Leaf caterpillar : Lymantria obfuscate

1. Stem and Root borer - Plocaederus ferrugineus L.
(Coleoptera: Cerambycidae)
• This coleopteran insect attacks stems and roots of the cashew tree.
• Usually they attack cashew plants of over 5 years of age and
common in old plantations and in poorly managed plantations.
• It occurs throughout the year, but more prevalent during the rainy
season and the damage symptoms become prominent during the
dry season.
• Females are generally attracted by the odour of the wounds and
lay eggs in crevices, cracks and wounds of bark on the trunk.

• Eggs are also laid on the exposed areas of the root above the
soil.

Damage Symptoms
• Appearance of holes of 2 - 4 mm in diameter on the stem at the
collar region, extrusion of gum and saw dust like frass from these
holes are common symptoms.
• Later leaves become yellow and shed.
• Serious could lead to dying of branches and ultimate death of
whole tree.

• Eggs are 2 x 4 mm in size and brown or pale white in colour.
• After 4 – 6 days, eggs hatch and young white grubs bore in to the
fresh tissues of the bark and feed on the sub epidermal and
sapwood tissues.
• They make irregular in the stem.
• At later stage some bore in to the wood.
• Reddish thick mass of chewed tissues excreta are thrown behind
the tunnels and extruded through the holes of entry.

• Gum oozes out of the damaged tissues and the
stem when the vascular tissues are damaged, sap
flow is weakened.
• At this stage leaves tum yellow and begin to fall.
• Larval stage lasts from 2 to 6 months.
• After completing the larval stage (Plate 4.2)
(growing to a length of 7 - 8 cm) it descends to
the root by making tunnels in the sapwood
towards the hardwood.
• It forms a chamber with tightly packed fibrous
tissues and frass about 15cm below ground level,
which provides protection to the calcareous
cocoon.

• Pupation lasts 20 - 60 days.
• Pupation in the trunk can also be observed specially in trees,
which are over 15 years of age.
Plate 4.1 Plate 4.2 Plate 4.3

Management
• As the borer is feeding on internal tissues of the tree, its presence
in the tree is difficult to identify.
• When the symptoms appear, the damage could be very serious.
• Therefore, use of prophylactic methods for prevention of the
damage is very important to protect the plants.
• As the adults (Plate 4.3) are attracted by the odour from the
wounds on the trunk, any kind of damage or a wound must be
avoided.

• When branches are removed with the purpose of pruning or
training of trees, the cut surfaces should be applied with Bordeaux
paste or covered by applying either liquid tar (LT), Cashew Nut
Shell Liquid (CNSL) or at least by application of waste lubricant oil
(WLO) from motor vehicles (engine oil).
• Inspection of the plantation for early detection of the attack need
to be done regularly.
• During the routine inspection, brushing of the main stem using a
brush with hard bristles for removal of possibly laid eggs must be
done.

• After brushing the stem, it should be painted up to a height of
about 1.5 m with CNSL or liquid tar (LT) or waste lubricant oil
(WLO) from motor vehicles.
• For better level of prevention by these prophylactic measures, the
cashew plant should be trained to get a single main stem at least
for a height up to about 1.5 m.
• Painting of multiple stems will be difficult, time consuming and
expensive.
• As the dead branches or trees may harbour live larvae or pupae,
they must be completely removed and burnt.

• After identifying the infested trees, the bark
should be peeled around the bored holes
towards the directions of bored tunnels and
grubs should be removed and destroyed.
• Area of the trunk with peeled bark must be
smeared with Bordeaux paste and
subsequently painted with either liquid tar (LT)
or waste lubricant oil (WLO).
• Excessive removal of the bark may lead to ring
barking causing the death of the tree. Hence
special care should be taken to avoid ring
barking.

• If the damage will not be severer, after scattering horizontal cuts
on the infested bark can be recommended to control the Root
and Stem borer in cashew.

• Prevention of further damage by the pest is possible by
application of
following insecticides:
1. Novaluron (30ml/10L)
2. Profenophos (30ml/10L)
3. Diazinon (30ml/10L)
• Therefore, it is necessary to emphasize that proper care should be
taken for prevention of the damage by Plocaederus ferrugineus at
the early stages of the attack

2. Tea Mosquito Bug - Helopeltis antonii
(Hemiptera: Miridae)
• This insect is occurring in most areas of cashew cultivation in the
world (Ohler, 1979) including Sri Lanka.
• It is a reddish brown mirid bug with a black head, red thorax and
black and white abdomen.
• A knobbed protrusion rises from the dorsal surface of the thorax.
• The female adult lays about 10-40 eggs deep inside the tender
shoots, inflorescence branches, leaf petioles and other soft
tissues of inflorescence branches.

• Presence of the egg inside the tissues can
be identified by a pair of tiny hair-like
filaments projecting outside the place
where it is laid.
• Eggs are creamy-white.
• After the incubation period of 6 - 7 days
eggs hatch and the nymphal period starts.
• It comprises of five instars and is
completed in 10 - 14 days.
• Longevity of adult bugs is around 10 days.
• The total life cycle is observed as 25 - 35
days.

• Helopeltis adults and nymphs prefer
high humidity and shade conditions.
• They suck the cell sap from the young
leaves, young shoots, inflorescences,
immature nuts and apples.
• Feeding activity is high at the temperatures between 25°C -30°C.
• Their active flying and feeding can be observed during 8.00 -10.00 hours
and 16.00 - 18.00 hours.
• During the other times of the day, Helopeltis bugs are almost inactive.

Damage Symptoms
• The saliva of the insects is very toxic to cashew plants and the place
of the puncture is surrounded by a slightly sunken, light brown
blistered lesion.
• After a day, these lesions turn brown and they become black in 3 - 4
days.
• Lesions on fruits start as brownish or black circular spots.
• Due to the damage by Helopeltis bug, immature nuts may drop off.
• When the tender tissues are pierced by the bug the site of the
puncture is marked by some exuded gum.

• When leaves are attacked, same type of
lesions can be seen on them.
• It may also cause reduction in growth,
wrinkling and even death of the affected
areas (Plate 4.7).
• Long black lesions appear on the affected shoots.
• Die back of the shoots can be observed when the attack is
severe.
• Attacked inflorescences usually turn black and die.

• Heavily infested plantations show scorched appearance of the new
flush and inflorescences.
• As a result of the damage to the shoot tip, extensive growth of
secondary branches is observed.
• Therefore, the trees which have been attacked in their early stage
of development may show a bushy appearance.
• Damage to the top branches and shoots of the young tree may
show sprouting of basal suckers and later developing into a multi-
stemmed tree.

• Helopeltis bug cause severe damages to the cashew plants at the
nursery stage too.
• When the seedlings are attacked, growth is stunted and sometimes
cause death.
• During vegetative propagation, attack on the developing tender
shoot of a graft may cause death of the graft.
• During the rainy season, Helopeltis populations increase and reach
their peak towards the end of rainy season or the beginning of the
dry season.

• This usually coincides with flowering
and flushing of the cashew trees.
• Damaged areas of the plant parts by
Helopeltis may subject to secondary
infections by pathogens such as
Colletotrichum gloeosporioides,
Botrydiplodia sp., and Phomopsis
anacardiae.
• When this occurs in inflorescences and shoots, blight and die back can be
observed.

• In addition to cashew, Helopeltis has alternate hosts such as tea,
mango, guava, grapes, neem, drum stick, mahogany, cocoa,
pigeon pea, black pepper, etc.
• There may be some more unidentified alternate hosts among
weeds in the cashew plantations.
• These alternate hosts are harbouring Helopeltis populations,
when cashew plants are not bearing new flushes and other
tender tissues.
• They act as breeding sites for the Helopeltis during this period.

Management
• As the Helopeltis bugs are migrating from alternate hosts to the
cashew plants when the new flush appears, it is essential to have
an efficient weed control of the cashew plantations to minimize
the initial population and reduce the rate of population build up.
• Further, clearing of the land under cashew trees and fumigation
of the new flush by burning of half dried weeds and other crop
residues will repel pests and also remove possible alternative
hosts of Helopeltis.

• Removal of non-productive and diseased branches from the trees
useful in reducing Helopeltis population.
• By practicing this operation air circulation and solar radiation within
the crop canopy can be improved and it will subsequently reduce
relative humidity within the crop canopy.
• These conditions may reduce the activity of Helopeltis and
subsequently reduce the damage caused by the pest.
• Pruning and training of cashew trees is an important measure to
reduce the pest populations.

• Modification of the tree canopy by this method improves the air
circulation and solar radiation within the crop canopy.
• This operation makes it easy to conduct inspection of the trees,
which is very much important for efficient management of
Helopeltis and also other pests.
• Further, clearing of the land under cashew trees and fumigation of
the new flush by burning of half dried weeds and other crop
residues will repel pests and also remove possible alternative hosts
of Helopeltis.

• In case of severe incidence of Helopeltis infestation, the population
of the pest can be reduced by three sprays of
Acetamiprid(10g/10L) at flushing, the onset of flowering, and
fruiting season.
• To avoid possible development of resistance to the pesticide by
Helopeltis, one of the following insectides can be suggested to
replace Acetamiprid in one of the above mentioned three sprays.
a) Diazinon 500g/1 EC (30m1/10L)
b) Carbosulfan 200g/1 EC (30ml/10L)
c) Pirimiphos-methyl 500g/ EC (25ml/10L)

• Applications of these insecticides must be justified by a careful
field inspection because they have no selectivity and can
exterminate the beneficial insects, including bees, other
pollinators and natural enemies of pests (Gruzdyev, 1988).
• Special attention must be paid to the second application at onset
of flowering to minimize the effect of insecticides on the
pollinators, otherwise it may cause a yield reduction.
• To reduce the effect on the pollinators, insecticide application can
be done when the 80% of the flowers on the inflorescence are not
opened or when the 80% of the flowers are already opened.

• In order to get maximum effect of Insecticide on Helopeltis, it
must be applied between 6.00hrs and 8.00 hrs or 16.00hrs and
19.00 hrs when Helopeltis bug is active (Ranaweera, 2000).
• To prevent the development of resistance to insecticides by pests,
continuous application of the same insecticide must be avoided.
• Rotation of above-mentioned insecticides can be done annually in
order to achieve better results.
• Preparation of spray solution according to the above mentioned
concentration is required to maximize the effect of insecticide on
Helopeltis.

• Application of insecticide to all levels of
crop canopy is also important.
• Therefore, a power sprayer or a mist
blower with an extended tube (lance) is
more suitable for spraying.
• Required amounts of the insecticide
solution per cashew tree are:
(a) Below 3 years age: 1-2 L
(b) Between 3 - 10 years: 2-5 L
(e) Above 10 years: 5-8 L

• If Helopeltis infestation is coincides with the rains, there is a high
possibility to get higher level of incidence of shoot and
inflorescence die back.
• Spray with a copper fungicide or Bordeaux mixture (1%) will be
required to control inflorescence and shoot die-back.
• Attention should be given to the fact that Diazinon is incompatible
with Bordeaux mixture and other copper containing compounds
(Anon, 1997).

Weaver Ants can be used to control Tea mosquito bugs

Minor insect pests of cashew
3. The apple and nut borer-Thylecoptila panrosema
(Lepidoptera : Pyralidae)
• The adult is a medium sized moth with dirty black forewings and
pale dark hind wings.
• The larvae are pink or red and move actively.
• The feed on the apples and nuts.
• The larval period extends for 15-30 days.

• When fully grown they drop on to the ground and pupate in the
earthen cocoons.
• The pupal period is 8-10 days.
• The larvae attack fruits at all stages of development.
• As a result apple becomes soft and
subjected to secondary infections.
• Attacked nut becomes shrivel and
sheds prematurely or dries up.

4. Defoliating caterpillars
• Many sporadic caterpillars attack the foliage of the cashew
causing damage to the tender foliage and rarely to mature
leaves.

a) Metanastria hyrtaca
(Lepidoptera: Lasiocampidae)
• This is a sporadic pest, which attacks isolated trees.
• The adult is a moth, which lays its eggs in clusters on the lower
surface of the leaves.
• Eggs are spherical and gray to black in colour.
• Incubation period is 9-12 days. The larval period lasts from 33-37
days.
• The pupal period
is 12-31 days.

• The early instar larvae are gregarious feeders of the slender
foliage.
• The mature larvae feed on voraciously on mature leaves as well.
• During the daytime they congregate on the trunk or branches,
there by escape notice.
• They feed actively in the night.
• Their attacks often lead to the complete defoliation of young
trees.

b) Cricular trifenstrata
(Lepidoptera : Saturniidae)
• The adult is medium sized reddish brown moth with three distinct
concentric spots on the wings.
• The body of the larvae bears fine hairs and spines.
• When fully grown it is stout, dark brown and measures 50- 65 mm
in length.
• The caterpillars are found in swarms in cashew trees and can cause
complete defoliation of trees.

• Pupation occurs inside the silken cocoons spun among the
leaves.

c) Lymantria obfuscata
(Lepidoptera: Lymantridae)
• It is a pest with high reproductive potential and can cause
considerable damage.
• The caterpillar with tuffs of hairs congregate in large numbers on
the ground under dry leaves, in crevices of the bark at the base of
the trunk and on the lower shaded parts of the branches during
the day time.
• In the night they crawl on the leaves.
• Pupae are reddish brown and life cycle is completed in 45-51 days.

Shoot tip borer- Hypatima haligramma
(Lepidoptera: Gelechiidae)
• The adult of Hypatima haligramma is a tiny dark brown moth.
• Tiny yellowish to greenish brown larvae feeds actively on the tips
and leaves of the new flush.
• The fully-grown larvae are 12mm long.
• Pupation takes place inside unopened leaves or in the small bore
holes on the apical shoot tips or floral branches.

• The pupae are yellowish red.
• The pupae period lasts for 7-8 days.
• The larvae mostly damage the tender shoots as they emerge during
the flush period.
• The emerging leaves remain folded with the caterpillars inside.
• Occasionally the larvae bore in to the tender shoot to a depth of
2cm feeding on internal tissues.

Leaf and blossom webber - Lamida moncusalis
(Lepidoptera: Pyralidae)
• Some times this pest can be serious in coastal cashew tracts.
• The males are dark and the females are olive green in colour.
• Eggs are laid singly or in groups of six, usually on the ventral side
of the leaves in the night.
• The newly laid eggs are yellowish green.
• Incubation period is 4-8 days.

The larval (5 instars) period 16-22 days and the pupae period 9-14
days.
Pupation takes place in cocoons inside the leaf webs or in the soil.
There is a pre-pupal period of 1-4 days.
The larvae web the terminal portions of new shoots and blossoms
and remain inside and feed on them.
Drying of apical webbed shoots and flower drop are the symptoms
of infestation.
The incidence is severe mostly in young trees

Leaf miner - Conopomorpha syngramma
(Lepidoptera: Lithocolletidae)
• Infestation by Conopomorpha syngramma is common in the post
monsoonal flush.
• Young plantations are more vulnerable to the damage.
• The adult is a silver grey moth, which lays its eggs on tender leaves.
• The larvae that they hatch out are pale white.
• When fully grown they turn reddish brown and 6mm long.

• The young caterpillars start mining the epidermal layer on the upper
surface of the tender cashew leaves leaving tortuous markings.
• The larval period lasts for 14-16 days.
• At the end of the larval stage they make their way out of the mined
area and drop on to the soil where they pupate.
• Pupation takes 7-9 days.
• The epidermis overlying the mines swell in to blistered patches
these leaves open and expand the mined areas tear apart to
produce apart to produce holes the damage to young on the leaf
surface.

• The results of the injury is the damage to you leaves, which are
shriveled, dried and shed prematurely.

Leaf twisting weevils
a) Apoderus tranquebaricus
(Coleoptera:Curculionidae)
• This pest deposits its orange coloured eggs on leaf tips.
• It folds the leaves along the midrib after depositing eggs and it
twists the leaf into a compact roll.
• Characteristic leaf roll is the main symptom of damage.

b) Myllocerus curvicornis.
• This can cause heavy damages to tender leaves particularly in
nursery seedlings and young plantations during rainy season.

Flower thrips - Rhynchothrips raoensis
(Thysanoptera: Thripidae)
• The rasping and feeding injury made by thrips results in scabs on
Tora branches, apples and nuts.
• The infestation on developing nuts results the formation of
corky layers on the affected parts, malformation of nuts and
immature fruit drop (Ohler, 1979).

Management of minor pests
• All minor pests mentioned above are causing damage to the
tender parts of the cashew plant.
• Infestation by them is high under high humid and shade
conditions.
• Time of their damage coincide with the period of population
increase of Helopeltis.
• Recommended management methods to reduce the Helopeltis
population are equally effective in reducing populations of minor
insect pests of cashew.

• Usually the damage caused by these minor pests is not
economically significant.
• Therefore, no specific method of management is required to
apply in order to reduce their populations.
• When the leaf twisting weevils Apoderus tranquebaricus,
Myllocerus curvicornis.
• Leaf minor Conopomorpha syngramma, Shoot tip borer Hyparima
haligramma are damaging seedling, grafted plants and young
plants under 3 years of age, the growth of the plant may retarded.

• If heavy infestation occurs during this growth period foliar
application of following insecticides may be used to overcome
the damage:
1. Prfenophos (30ml/10L)
2. Carbaryl (25g/10L)

Disease management in cashew
• It was believed that cashew is not affected by serious diseases
and can tolerate pests and diseases.
• After the establishment of large plantations in the dry zone and
other areas where cashew is planted as a mono crop, strong
evidences do appear to say that there is a serious threat from
diseases.

Blight and die-back of shoots and inflorescences
• These disease conditions occur when the feeding punctures of
sucking insect pests are infected by the fungal pathogens such as
Colletotrichum gloeosporioides, Botrydiplodia sp., Phomopsis
anacardii and Pellicularia sp.

Symptoms
• The initial symptom is appearance of water soaked lesions on
the surfaces of inflorescence branches, shoots and also
immature nuts and apples.
• Gummy exudation may occur on lesions.
• After 2-3 days they become brown, and enlarge in size.
• The affected parts then dry up and become black, presenting
scorching appearance.
• When the shoots are damaged, they start drying up from tip
downwards and hence the name die-back.

• The pathogens usually attack cashew plants separately even
without an insect damage.
• These cause different disease symptoms according to the
pathogen present on the plant.
Eg. 1. Pellicularia sp. –Die- back
2. Colletotrichum gloeosporioides -Anthracnose
3. Phomopsis anacardii - Blight

• All these fungi are highly abundant in Sri Lanka on crop residues.
• When the rain coincides with the attack of sucking insects, a
complex of several fungi infects cashew plants simultaneously,
thus causing this disease syndrome.

Management
• Efficient management of sucking insects will prevent serious
damages caused by these disease conditions.
• If the disease incidence and severity are at a higher level,
Bordeaux mixture (1%) or other copper-based fungicides can be
recommended for the management.

• Fungicide application can be done simultaneously with the
spraying of insecticides against Helopeltis at flushing, onset of
flowering and fruiting season.
• It should also be noted that Diazinon is incompatible with
Bordeaux mixture and other copper containing compounds (Anon,
1997).
• These pathogens can continue their growth on the decaying parts
of cashew plants during unfavourable period.
• They become active and infect tender tissues when the
atmospheric humidity increases and the new flushes appear.

• Therefore, for successful management of the disease,
maintenance of phyto-sanitary conditions of the plantation
through the destruction of diseased plant parts, removal of
dead and non- productive branches from the trees, efficient
weed control etc. is important.

Yellow leaf spot
• This condition can be seen on leaves of mature trees and
sometimes of young plants.
• Yellow spots of various sizes appear on leaves.
• The number of spots on a leaf varies.
• Extent of the symptom is high on older leaves as these spots
enlarge as the leaves mature and become bright yellow colour.
• Reduction of chlorophyll in these spots lowers the photosynthetic
rate, resulting in yield reduction.

• The exact factor causing this disease is not yet clearly known.
• Microscopic examination and attempts to grow an isolated culture
of a causal organism did not reveal the presence of any fungi or
bacteria on the affected leaves.
• It is possible to suspect that molybdenum, manganese and iron
may involve in a physiological process that also interfere with the
functions of some other macro and micro nutrients ultimately
causing this disease condition.
• Therefore, an efficient nutrient management system may prevent
this malady on cashew plantations.

Diseases affecting cashew nurseries
• In the nurseries young cashew plants are provided with optimum
conditions to promote vigorous and healthy growth.
• As a result, there is a possibility of high incidences of pests and
diseases.
• The most destructive diseases affecting cashew nurseries in Sri
Lanka are root rot, damping off, die back and collar rot of grafted
plants.

• Disease incidence is usually high in large-scale nurseries, where
sometimes over 100.000 seedlings are produced annually.
• In these nurseries, generally most plants are kept for more than six
months.
• In a nursery with a high plant population, spread of diseases from
one planting stock to another is quite common if proper
maintenance and management practices are not taken care of.
• It is also found that use of poly bags, instruments, equipment and
irrigation water contaminated with pathogens also encourages
disease buildup and spread.

• Another factor that leads to cause diseases in seedlings is poor
drainage of poly bugs used in nurseries.

Root-rot disease
Symptoms
• Initially yellowing of lower leaves and stunted growth occur in the
seedlings.
• Further in these seedlings, rotting of the root system with initial
infection on roof tips can be found.
• Isolated culture tests of the pathogens show that disease is caused
due to an infection by Pythium sp.

Die-back of grafted plants
Symptoms
• Characteristic symptoms of the infection start with the necrotic
lesions the shoot tips.
• Later, colour of those lesions change to dark brown black and
coalesce.
• Shoots start dying from the tip downwards.
• Disease diagnosis tests show that the pathogen of this disease
condition is Colletotrichum spp.

• Pathogen penetration is possible in three way when the bud wood
is still on the mother plant, Colletotrichum spores can enter
through the feeding sites of sucking insects.
• Another mechanical of penetration is observed at the apex of the
bud wood.
• The mechanical damages or wounds of the apex and terminal part
of the bud wood caused by poor handling could enable pathogen
to penetrate.
• Infection by Colletotrichum through graft union has also been
recorded.

• When the graft union is infected the shoot starts dying from the
graft union and spreads towards the scion and root stock.

Damping-off
Symptoms
• This disease affects the collar region of seedlings.
• Affected seedling turn pale and show water soaked girdles of
darkened tissue around the stems.
• At late stages, affected seedlings topple and subsequently rot.
• A result of a severe infection, leaves also show water-soaked
areas, which enlarge and coalesce.
• Pathogenic tests show that Phytopthora spp. are the causal
organisms of this disease.

Management of the nursery diseases
• Almost all the reported causal organisms of the nursery diseases
are facultative saprophytes.
• Therefore, maintenance of good phytosanitary conditions is
essential in the nurseries to prevent occurance of the pathogens
and to destroy sources of infection to destroy sources of infection.
• Disease incidence is also high in poorly managed cashew nurseries
(Mubarak and Ranaweera, 2001).

• A good management system of cashew nurseries with following
measures will effectively manage the nursery diseases of cashew:
1. Regular weeding in the surrounding area of the nursery to destroy alternate
hosts of insect pests and pathogens.
2. Destruction of dead plants with media and polybags, and other plant debris
that play the role of major sources of infection.
3. Maintenance of optimum spacing and proper shading to provide good
ventilation and optimum humidity.
4. Provision of good drainage in polybags.

5. Use of healthy cashew seeds with high germination percentage and vigour
for planting. Avoid use of infected seeds.
6. Obtain bud wood from well-maintained healthy mother plants without pest
attacks.
7. Use of uncontaminated, clean water for irrigation.
8. Regular inspection of the nursery to find out presence of disease symptoms,
other pest damages, nutrient deficient etc.
9. If infestation of any above mentioned diseases is high and as Tebuconazole
(250g/EC, 3.5ml/10 1), Thiophenate methyl 50% + Thiram 30% (WP 18g/101)
should be applied separately from copper containing fungicides as they are
incompatible with copper containing compounds(Anon,1997 ).

10. Always use uncontaminated fresh potting media for filling of poly bags. If
potting media are re-used, proper measures should be taken to destroy all
disease carrying pathogens (eg.:- sterilization, fumigation etc.)

Management of insect pests in cashew nurseries
• Insect attacks are generally not serious in cashew nurseries in Sri
Lanka.
• Infestation of some insects have been recorded, but the damages
are not economically considerable.
• Gradual increase of the population of following insects and
subsequent higher levels of their damages have been observed
by the authors during the period of 1997 to 2002 Cashew
nurseries of Sri Lanka.

1. Shoot tip borer – Hypatima haligramma
2. Leaf Miner – Conopomorpha syngramma
3. Metanastria hyrtaca
• Although their populations have been increased with a considerable
rate: their damage is not economically considerable.
• Above mentioned phytosanitary measures for the management of
nursery diseases, if practiced, may destroy alternate hosts of these
insects thus reducing the populations.
• Application of following insecticides can be used to control these pests
if the level of damage is serious.

1. Carbaryl
2. Quinalphos
• Application should be done by using a knap-sack sprayer.
• If the infestation continues, repeated application after 14 days is
recommended.

Diseases affecting young cashew plants
• Among the young cashew plants under 5 years of age, several
disease conditions and maladies have been recorded, but only
two have found to be with a considerable incidence.
• They are collar rot and browning of leaves.

Collar Rot
• The first symptom is yellowing of all leaves and later become
brown.
• At this stage collar region shows black or dark brown colour and
starts rotting from the surface of the stem at collar region.
• Pathogenicity tests have shown that a Pythium sp. is the primary
cause of the disease.
• If the disease develops further the plant will wilt and die.
• This disease is usually observed under poor drainage and water
logo conditions.

• These conditions in the soil favour the pathogen as it prefer
anaerobic conditions.
• The disease condition can be avoided improving the soil physical
properties, drainage and by avoiding damages to the collar region
of the plant.
• Once the disease symptom occure, control of the disease using
fungicides is difficult.
• Therefore avoidance of the disease by adopting proper planting
techniques and cultural methods are recommended to overcome
this problem.

Browning of leaves
• The first symptoms are chlorotic, yellow, round spots on the leaves,
progressively turning to grayish brown.
• This may finally spread over the whole leaf area, causing the leaf to
wither and fall.
• This condition is observed only during the periods of heavy drought
that had seriously weakened the trees.
• There had been incidences where plants have been completely
destroyed due to this malady.

• However, with the rainy season most plants recover.
• Probably, this malady is not a disease by itself, but a symptom
caused by due to several factors such as physiological disorders,
nutrient deficiency or even by pathogens attacking plants under
weak conditions.
• Therefore, managing the plantation with recommended cultural
practices would help to overcome this problem.

Weed management in cashew plantations
• Weed management of weed populations is equally important as
other pests and Diseases.
• Presence of weeds in cashew plantations of may cause serious
damages to cashew production If proper weed management is not
practiced in the young cashew plantations, weeds can totally
suppress the growth of cashew.
• This damage is high especially if the cashew plants are less than
five years old.
• Growth suppression occurs due to the competition of weeds with
cashew and covering of cashew plants by weeds.

• Presence of weeds in mature cashew plantations too can cause
several problems.
• Weeds are the major source of infection.
• Among the weeds there are plants that act as alternate hosts of
several pests.
• They harbor pests and contribute to develop a higher initial
population of pests that makes pest management difficult.
• Weeds become a physical barrier for most of the important cultural
practices such as fertilizer application, pruning, harvesting, pest
management etc.

• Therefore, an efficient weed management system is a must to
achieve a higher productivity level in cashew plantations.
• Presence of representatives from various weed groups in cashew
plantations makes weed management a complicated task.
• Action for the weed man for the weed management should be
started with the establishment of plantations.
• During land clearance it is necessary to remove all parts of the
perennial weed plants, trees, bushes etc.
• This will help to remove all possible propagules of vegetatively
propagated weed plants.

• For long-term management of weeds, following measures can be
taken during field planting of cashew.
1. Establishment of a suitable intercrop: Use of an intercrop will be
economically viable only up the fifth year after planting of cashew.
2. Cultivation of a cover crop selected according to the prevailing
climatic conditions in the area: Successful establishment of Pureria
and Centrosema pubescence was recorded in some plantations of
Puttalam district. Pureria can be established easily in the mature
plantations (over five years of age due to the shade and relatively low
temperature provided by the canopy of cashew plants. Cover crops
are useful not only for the weed management, also for moisture
conservation, nutrient management and protection from soil erosion.

• During the harvesting period, area under the canopy of cashew
plants should be cleared from cover crops by slashing or application
of contact weedicide like Paraquat.
• Action should also be taken to prepare the fertilizer circle.
• Establishment of a cover crop in an existing plantation should be
done after removal of the weed plants.
• For better results, slashing and subsequent uprooting of shrubs is
essential.
• Cover crops will establish well after ploughing and le sow the cover
crop seeds during the rainy season.

• Instead of maintaining a cover crop or an intercrop, an efficient
systemic weedicide can be used to suppress the weed populations
in cashew plantations.
• Glyphosate can be successfully used for this purpose.
• For best results, shrubs and herbaceous plants among the weeds
must be moved before the application of Glyphosate.
• If slashing is done leaving roots and trumps of large weed plants
behind, new lateral shoots are developed from the remaining
parts.

• In such situation, weedicide should be applied only after giving time
(30 - 40 days), to get the sap flow of new weed plants started to
descend to the roots.
• Otherwise the active ingredients of weedicides may not reach the
roots of the plant.
• Weed control using weedicides in cashew plantations will give best
results, when it is applied in rotation with other manual and
mechanical weed control methods such as slashing, uprooting of
weeds using mammoties grass cutters, slashers etc.

Storage pests of cashew
• Cashew nuts are attacked by common storage pests after shelling.
• However, the losses are not economically significant when
compared to yield losses due to pests under field conditions.
• Damage due to storage pests are generally high when post-
harvest management is poor.
• No specific pests that cause damage only to cashew nuts, but
most of the storage pests which are common in other food crops,
are too capable of causing damage to the stored cashew nuts.

• Among the storage pests of cashew, following are the most
important
a) Ware House Moths - Ephestia spp.
b) Meal Moth - Plodia interpunctella

• Flour beetles Tribolium castaneum, T. confusum and Grain Weevile
Sitophilus spp. have also been found infesting cashew during the
storage.
• If drying of raw cashew and processing of shelled cashew nuts are not
done properly, growth of saprophytic fungi such as Mucor sp.,
Aspergillus spp. can be observed on the kernels.
• Although the Grain Weevils and Moths cause damage only during
their larval stage, the control of adult population is important to check
the population build up.

Warehouse Moths - Ephestia spp.
• This moth may cause a serious damage to cashew nuts during
storage as the adults may lay eggs on stored cashew nuts even after
the processing, is done.
• A female can lay about 250 eggs.
• Larvae are about 20 mm in length and grayish-white in colour with
dark head.

• Two dark patches can be observed on prothorax.
• They on the nuts and usually produce webbing and cocoon
between ad nuts.
• Pupation takes place inside a silken cocoon made between nuts.
• Adult moths are grayish with about 10 - 15 mm long body. At rest
the wings are folded along the body.
• Wingspan is about 15 - 18 mm. In storage. breeding of this moth
is continuous (Hill and Waller, 1990).

Meal Moth - Plodia interpunctella
• This moth can also be a serious pest that can damage cashew nuts
during the storage.
• Adult female lays about 200-400 eggs that are stuck on to nuts.
• Eggs hatch usually after 4-6 days.
• Larvae are small pale caterpillars that feed on nuts and grow
rapidly reaching 8-10 mm in length, in about 12-20 days.

• The adult is of distinctive appearance with the distal parts of the
fore wings in coppery red and basal parts in cream colour; body
length is about 6-7 mm and wingspan is 14-16 mm (Hill and Waller, 1990).

Management of moths and other storage insect pests
• For the protection of nuts from storage pests, proper maintenance
of the stores is very important. Following aspects must be given
high priority to minimize damages:
1. Storage buildings without holes or cracks in the walls and with the
doors and windows that can be closed tightly. This is essential to
prevent the entrance of adult pest species.
2. Use of sealable containers.

3. Maintenance of store hygiene such as, removal, burring or
destroying of, old packing materials, spoiled nuts and all other
debris. General cleaning of storage premises must be done with
removal of insects and their eggs. This can be better achieved by
vacuum cleaning than ordinary sweeping.
4. Nuts should be inspected properly prior to store to avoid
introduction of infested material to the stores.
5. Adoption of proper processing techniques is necessary for
destruction of possible eggs on the nuts.
6. Treatment of buildings and containers with recommended
pesticides by spraying or fumigation.

• If the moisture content of nuts is higher than 13%, moulds can
cause qualitative losses by producing changes in colour, odour and
flavour of kernel.
• Some fungi may produce myco-toxins when they grow on the nuts.
• Cashew spotting during storage is also suspected as a disease
condition caused by some fungi.
• To overcome the damages caused by the microorganisms during
storage, above recommendations are equally effective.
• Keeping the moisture levels of the seed below 10% would prevent
attacks from many storage pests and diseases.

Approaches for integrated pest management in cashew
plantations
• The Integrated Pest Management (IPM) System includes management
all kinds and groups of pests including insects, plant pathogens,
weeds other pests encountered by cashew Management of any group
of pests is a major component of an IPM system.
• An effective IPM system aims at minimizing crop losses due to pests,
through efficient management of soil, water, nutrient and crop by
integrating cultural and agronomic practices, pesticide application,
host-plant resistance, natural enemies (biological agents), legislative
methods and other mechanical and physical methods of pest
management.

• The existing methods for pest management in cashew mainly aim
for the management of individual pests through different practices.
• Among these, pesticide application is the most widely used
method.
• Even though, the pesticide application on a tree crop like cashew,
with a high and large canopy, is highly hazardous to the
environment and workers of the plantation, the most of the
cashew growers still consider it as the only worked out method of
pest management with considerable success methods so as to
develop integrated pest management systems to combat with the
multiple pest encounters.

Cultural approaches
• Cultural practices that may form an integrated part of the pest
management systems have not gained proper attention of the
cashew growers as an important tool of pest management.
• Most of the cashew growers still adopt traditional cultivation
practices, without an aim of pest management through appropriate
cultivation methods.

Some examples of important cultural practices in pest management
are given below.
1. When the cashew varieties with resistance to major pests become
available to the growers, seeds or bud-wood for grafting should be
obtained from the mother plants of resistant varieties. During
selection of mother plants, health and vigour of mother plants is an
essential criteria because a diseased and weakened mother plant may
disseminate propagules of pests through seeds or bud wood obtained
from it.
2. Proper management of the nursery will be effective in controlling
the nursery diseases.

3. Planting of cashew at recommended spacing to get optimum plant
density thus maintaining good ventilation within the crop canopies.
Pruning and training of cashew trees and removal of unproductive
branches also improve the ventilation. Helopeltis bug and some other
minor pests prefer high humidity conditions. By improving ventilation,
humidity within canopy can be controlled and make it desirable for
most of the major insect pests and pathogens of cashew.
4. Maintaining cashew plantations with good phytosanitary
conditions is not only an important cultural practice also an essential
practice that must be adopted to reduce sources of infection of most
pathogens and to remove possible alternate hosts of pests. Removal,
and destruction of plant debris may also eliminate different stages of
some insect pests.

5. Majority of the diseases affecting young cashew plants under 5
years of age, are influenced by cultural practices such as irrigation, soil
preparation, fertilizer application and other soil amendment
applications. Therefore, these practices must be applied according to
the conditions prevailing in the plantation and they will reduce the
incidences and severity of the prevalent local diseases.
6. Regular inspection of the plantation is an essential practice required
for the efficient management of the plantation During these
inspections, special attention must be given for the identification of
nutrient deficiencies and disorders, observations on sanitation, early
detection of pests and diseases and identification of any other
shortcomings in the plantation

• Therefore, regular inspection of the plantation, throughout the
year should be an essential practice.
• Ideal sequence of the inspection would be once a week but
during the periods of flushing, flowering, fruit setting and
harvesting it should be increased to twice a week.

Use of pesticides
• Although pesticides application causes some serious negative
effects on the environment and personnel of the cashew
plantations, it is the most commonly used method.
• The reasons for this situation are:
1. Higher rate of mortality of pests can be achieved by using
pesticides.
2. When compared to other methods of pest management,
pesticides give quick results.

3. As a result of the continuous use of polytoxic pesticides in cashew
plantations, natural enemies and other factors of population control
of the pests have been disappeared from the environment.
• Therefore, sudden outbreaks of pest populations are frequently
occurring.
• In such situations, pesticide application is the most effective
method.

• Therefore, pesticides will continue to be, in the near future, as an
important tool in cashew pest management because they provide
a dependable, rapid, effective and economical means of managing
whole complex of cashew pests.
• Considering above facts it is possible to say that pesticides may be
an essential component of an IPM system in cashew.
• In IPM systems, pesticides can be applied as a preventive
treatment to protect plants from infection by pathogens or
infestation by animal pests, or as a curative treatment to limit
population development of a pest or a group of pests.

• The reasons for using pesticides and the consequences of misusing
them must be carefully analyzed in order to obtain maximum
benefit from their application.
• At the same time, actions should be taken to prevent and remedy
the possible hazardous effects on non-target organisms and the
environment.
• A major objective of an IPM system must be proper, restrained and
further refined use of pesticides in order to avoid development of
resistance to pesticides by nests and to avoid harmful interactions
with natural enemies and the environment.

• While using the present recommendations of pesticides, further
research is needed to improve pesticide recommendations by
finding pesticides which have more specific and systemic action,
shorter residual activity and less harmful to natural enemies.
• Further attention must also be given on using improved
formulations such as granules and bites.
• Improved methods of application such as spot treatments, padding,
pheromones or repellents, that are relatively safe for natural
enemies and thus fit better in an integrated management approach.
• Considering the above facts and pest damages in cashew, following
pesticide applications can be included in IPM of cashew:

1. In case of severe incidence of Helopeltis infestation, Carbaryi or
other recommended pesticide application as described earlier.
2. If rains or high humidity conditions coincide with Helopeltis
infestation, there is a higher probability of high incidence of
inflorescence blight or die back. Therefore, when such environmental
conditions prevail with Helopeltis infestation Bordeaux mixture or other
recommended application is required as described earlier.

3. Observation of the damage of Plocaederus ferrugineus on a cashew
tree gives the signal to remove the grubs an application of insecticides
such as Oxydemeton- methyl Fenthion or Chlorpyriphos. In this case
padding method is more efficient and also suits the IPM as it is
relatively safe for other organisms in the environment and has an
efficient action on target organism.
4. Application of Tebuconazole, Thiophenate methyl + Thiram or
copper containing fungicides is recommended if higher incidences of
nursery diseases such as root rot, die-back, damping-off, are
observed.

• To make a correct decision on application of a pesticide,
background information, if available are useful.
• Some of them are, growth stage of the tree, availability of
nutrients to the plants, information on the pests damaging cashew
in the area, life cycle of the pest, damaging stage of the pest.
• Information on pest damages in the previous year’s meteorological
data, weather forecast, population density of the pest growth rate
of pest population, forecast of pest epidemics / outbreaks etc.

• Some of the required information can be collected by the cashew
growers themselves through available information sources.
• However for certain information such as weather forecasts,
forecast of pest epidemics, outbreaks etc. institutional help may
be obtained.
• To collect correct information from the plantations, field or from
nurseries, regular inspection must be practiced.
• When all above mentioned facts are considered, necessity of the
inclusion of regular inspection as a component of IPM is obvious.

Host-plant resistance
•
Cashew breeding and selection will be an important element in
the development of IPM systems.
• The choice of a variety is an important management decision
that the grower makes in an integrated crop management
system.
• The variety decides the level of susceptibility to pests, the tactics
needed to manage the crop and pests, and production costs.
• Resistant varieties can make the foundation for a successful IPM
system.

• Varieties, even with low to moderate levels of resistance, are highly
compatible with all other pest management methods and
contribute stability and offer advantage to IPM.
• A resistant variety may not require as many treatments or as high
rates of pesticide application to achieve successful pest
management.
• Subsequently the production cost and risk will be reduced and the
profit may be increased.
• Therefor use of resistance will be the most effective, economical
and reliable method of maintaining healthy plants reducing pest
damages.

• It must be used in IPM system of cashew in a combination of other
pest management methods that includes cultural, biological and
chemical approaches.

Biological Method
• One of the most successful, non-chemical approaches to pest
management is biological management that indicates the use of
population control agents in which the active principle is living
organism or virus for regulating the incidence of pest.
• The development of IPM system in cashew it is essential to search
for effective biological control agents in order to reduce the pest
populations below the economic injury level.

• In Australia use of the green ant, Oecophylla samaragdina (Fabricius)
(Hymenoptera: Formicidae), was successful in controlling populations
of Helopeltis bug (Peng et. al. 2000).
• The preliminary studies carried out at Achchigewatta and
Kamandoluwa plantations of Sri Lanka Cashew Corporation, it was
found that the green ant Oecophylla samaragdina (popularly known
in Sri Lanka as red-ant, red weaver ant are Dimbiya) occurred in large
numbers on cashew trees and also on other native plants.
• These ants will be very useful in IPM system of cashew as biological
agents, as they are very active and prey on a large range of
arthropods, and mainly on insects including Helopeltis bug.

Use of bio-pesticides on pest management
• In an IPM system an important role can be played by bio- pesticides
as they will have minimum effect on natural enemies, environment
and no residual toxicity on the products.
• A relatively higher level of selectivity can also be achieved by using
bio- pesticides.
• During a preliminary study carried out at Kamandoluwa Plantation
of SLCC on the effect of some botanicals on Helopeltis, Neem Seed
Extract that contains Azadirachtin as active ingredient showed an
efficient control of Helopeltis population.

• Use of neem seed extract will be a valuable contribution to the
IPM of cashew and also to the production of organic cashew
that has a high demand and value in the world trade.

Quarantine and regulatory control
• The introduction of new pests from sources of infestation within
or outside the country will be a serious threat to cashew
cultivation as with any other crop.
• Introduction of new pests is often caused by movement of
cashew plants, planting material (seeds or bud wood), nuts,
apples, people, other commodities and equipment carrying the
contaminant.
• This can be overcome by imposing quarantine and contaminant
laws or regulations and other legislations within the country and
also internationally.

• Considering the above facts, it is possible to say that to meet
the challenges and achieve the future prospects in developing
IPM system for cashew, following strategies must be adopted.
1. Development of pesticides those are effective at lower doses,
more specific for the target organisms, less toxic to the user,
consumer, flora and fauna of the ecosystem, natural enemies of
pests and less persistent in the ecosystem
2. Selection and development of varieties having pest resistance.
This can be facilitated by preserving land races with better resistant
gene pool as sources of resistance.

3. Use of Biological control methods and Bio-rational pesticides for
pest management.
4. Creating awareness among growers on integrating improved pest
management methods. Pesticides must be integrated with other
pest control methods including resistant varieties, cultural practices,
biological and legislative methods. Pest management methods must
be integrated with cashew production techniques.
5. Development of IPM system must be based on the research work
conducted on cashew.

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