PLANT PROTECTION PROBLEM OF
DIFFERENT FRUIT CROPS AND CONTROL
MEASURE TAKEN IN NEPAL
Shankar Paudel
M.Sc.Ag. (Horticulture)
shankarpaudel23@gmail.com
Abstract
Fruits contribute important role in
Nepalese horticulture/agriculture and production of fruits offer opportunity of
high income per unit area of acute land scarcity with favorable income
generation. Fruits of Nepal can be classified in to 3 categories based on the
climatic requirement. Tropical fruits include Mango, Banana, Jackfruit,
Pineapple, Papaya etc. Subtropical fruits includes citrus, Guava, Pomegranate,
Litchi, Grapes etc. Similarly temperate fruits are Apple, Pear, Peach, Plum,
and Walnut etc. Production and productivity of fruits sector is not
satisfactory. This sector has many constraints. Generally, most fruit crops
take long gestation period before trees start giving economic yield and this is
one of the demotivational factor. Disease and pest cause huge loss in fruits
industries. Plant protection problems of fruit include insect pest, disease and
disorder of fruits. Very few researches are conducted in Nepal in fruit sectors
to solve the prevalent problem of fruit production. Various insect pests have
been reported in fruits in various locations. Among these, wooly aphid, scale,
oriental fruit fly, green stinkbug, mango stem borer, mango stone weevil,
banana stem weevil and banana rhizome weevils are considered to be key insect
pests in Nepal. Among the diseases prevalent in country citrus greening disease
and tristeza virus consider the major threats of citrus production of Nepal.
Similarly, Guava wilting of Guva; Rhizopus rot of Jack fruit; Panama wilt,
Bunchy top, Sigatoka disease of Banana; powdery mildew, anthracnose of mango;
Root rot, collar rot, papaya mosaic, Papaya ring spot virus of Papaya; powdery
mildew of apple are some important disease of fruits. In Nepal research is
focused in citrus. Government of Nepal has given priority to solve the problem
of citrus like citrus greening that cause citrus decline in western part of
Nepal. Wooly aphid is major problem in apple and researchers are focused to
reduce this problem. Similar focused should given to other problem of plant.
New technique and method indeed need to farmer level which can solve the
protection. Plant clinic may be one method to identify the disease and pest
found in farmer’s level. Researchers are needed to focus on the protection
issues.
Key word:
fruit, insect pest, disease, management
Nepal
has a great agro-ecological diversity and numbers of fruits are grown in
various region of country. Fruits
contribute important role in Nepalese horticulture/agriculture and production
of fruits offer opportunity of high income per unit area of acute land scarcity
with favorable income generation. Fruits have important nutritional value which
required about 67 g along with other in daily balance diet (Ranjit and Pun,
1990 as reviewed by Shrestha, 2010). Fruits and spice contributes about 13% in
AGDP. According to the statistical data of 2011/12 the production of fruits is 10,29,754
mt from 1,01,233 ha and productivity is 10.17 mt/ha (Krishi Diary, 2070). Fruits can be classified in to 3 groups based
on their climatic requirement they are Tropical, Sub-tropical and Temperate
fruits. Tropical fruits include Mango, Banana, Jackfruit, Pineapple, Papaya
etc. Subtropical fruits includes citrus, Guava, Pomegranate, Litchi, Grapes etc.
Similarly temperate fruits are Apple, Pear, Peach, Plum, and Walnut etc. Among
these, apple and pear are major temperate fruits grown in high mountains. Among
citrus, mandarin orange is one of the most important income generating crops
for farmer of middle hill of Nepal. Mango and banana are major tropical fruits
grown in Terai and inner Terai region of country.
Production
and productivity of fruits sector is not satisfactory. This sector has many
constraints. Generally, most fruit crops take long gestation period before
trees start giving economic yield and this is one of the demotivational factor.
Other factors are plant protection problem, irrigation and infrastructure
problem, lack of proper marketing facilities, lack of post harvest management
practice etc. Fruit species grown in our country have many problems like insect
pest infestation, disease infestation and improper management practices which
cause considerable loss in fruit production (Shrestha, 2010). Plant protection
problems of fruit include insect pest, disease and disorder of fruits. Very few
researches are conducted in Nepal in fruit sectors to solve the prevalent
problem of fruit production. Various insect pests have been reported in fruits
in various locations. Among these, wooly aphid, scale, oriental fruit fly,
green stinkbug, mango stem borer, mango stone weevil, banana stem weevil and
banana rhizome weevils are considered to be key insect pests in Nepal (Paneru
and Giri, 2011). Among the diseases prevalent in country citrus greening
disease and tristeza virus consider the major threats of citrus production of
Nepal. Similarly, Guava wilting of Guva; Rhizopus rot of Jack fruit; Panama
wilt, Bunchy top, Sigatoka disease of Banana; powdery mildew, anthracnose of
mango; Root rot, collar rot, papaya mosaic, Papaya ring spot virus of Papaya;
powdery mildew of apple are some important disease of fruits.
v To
identify the major insect pest of fruit grown in Nepal
v To
identify the major disease of fruits
v To
access with the control measure taken to manage disease and pest
For the
review of plant protection problem of fruit crop and control measure taken in
Nepal information were collected from different literature available. Journal,
Articles, Thesis, leaflet, booklet, proceeding available in library of NARC,
Annual Report of different fiscal year published in NARC and Fruit Development
Directorate (FDD) were mostly studied. Similarly, available materials in
different web/internet were consulted. Literatures available were thoroughly
read and important points were noted.
Important
tropical fruits are mango; banana, jackfruit, papaya, pineapple etc. are
important tropical fruits. Mango is
the most important tropical fruit grown in Nepal. Major insect pests and
disease found in Nepal are given in table.
Table:
insects of mango with major symptoms and general management
|
S.N.
|
INSECTS
|
SYMPTOMS
|
MANAGEMENT
|
|
1.
|
Mango hopper
Idioscopus niveosparsus
|
Suck the sap
and secrets honeydew and due to which sooty mold is develops and in sever
condition wilting of leaves takes place
|
Cultural
method: Use the light trap @ 1 trap/ha.
Biological
method: Use the entomopathogenic fungi: Metarhizium.
Chemical
method: Use of systematic fungicide every evening time.
|
|
2.
|
Mango
mealy bug
Drosicha
mangifera
|
Both nymph and adult suck the sap
from tender parts and secrets honey dew and which inturn develop sooty mold
in infected part
|
Cultural
method: Use the greasy band of about 10-15 cm wide in
the tree trunk to prevent the migration of the female into the soil.
Chemical
method: Use systemic type of pesticide. Use 250 gm per
tree of methyl parathion dust- 2%.
|
|
3.
|
Mango fruit fly
Bactrocera
dorsalis
|
The maggots consume the internal
tissue from where decaying takes place from which fruit drop takes place
|
-Complete
field sanitation.
-Collection of the fallen fruit
and destroying it.
-install the pheromone trap with
methyl eugenol bottle trap along with malathion to attract and kill male
fruit flies( 10 traps/ha). Replace methyl eugenol and malathion inside trap
in 2 week interval.
-apply the protein bait sprays on
the few spots @50 ml/plant in a field to kill the flies attracted to these
spots.
-use of neem fruits to repel
female flies, use of tobacco extracts and ginger extracts to kill fruit fly.
(Paneru and Giri., 2011)
|
|
4.
|
Mango stem borer
Batocerarufomaculata
|
Saw dust is seen just at the
mouth of hole made by borer
|
Chemical
method: Use kerosene oil in the hole. Use Dursban 20% EC
@2.5 ml/lt water to main trunk, branches and expose roots host trees.
Cultural
method: Jerking the hole with the help of long stem.
The larva is infected by a kind
of entomopathogenic fungi which is Metarrhizium
anisopliae.
|
|
5.
|
Mango stone
weevil
Sternochetus
mangiferae
|
Young grub
feed on pulp and stone and later cotyledon. No external symptoms of grub
attack appear on the fruits, while fruits are already damaged inside. The
infested fruits usually fall down.
|
-collect
destroy all fallen fruits and weevil damaged mangoes at weel;y intervals and
destroy all leftover in the orchard after harvest(Neupane, 2009)
-spray
chemical insecticides such as Dursban 20% EC @2.5 ml/lt on main trunk,
primary branches and junction of branches prior to flowering to manage
beetles hiding in the bark(Paneru and Giri, 2011)
|
|
5.
|
Mango shoot
gall maker
Apysylla
cistellata
|
It attack of
new twigs, and formed cone shaped galls which cause to stop leaf and flower
in new twigs
|
-destroy the
infected plant part
-use resistant
varieties like Alphanso, Himsagar, gulabkhas etc. (Neupane, 2009)
|
Table:
some disease of mango with their
major symptoms and general management practices
|
S.N.
|
Disease
|
Symptoms
|
Management
|
|
1.
|
Powdery mildew of mango
Oidium
mangiferae
(fungal
disease)
|
The powder
like substances is seen in the upper part of the leaves at the region of
around mid-rib which in sever condition shows the sporangial growth in the
lower portion of the leaf. Such leaves curl and are distorted.
|
Chemical
method: Dusting
the tree with sulfur can be done. A Karathane (0.05%) spray is found
effective against this disease.
|
|
2.
|
Leaf blight
Macrophoma
mangifera
|
Spots gradually enlarge
discoloring the surrounded tissue, which 1st become biscuit
colored, then brown and dark brown with slightly raised and broad dark
purplish margin.
|
Chemical
method: Dithane m-45 can be used to control this disease
|
|
3.
|
Die back
Botryodiplodia
theobromae
|
It is characterized by dying back
of twigs from top downwards particularly of the older trees followed by
complete defoliation which gives an appearance as it has been scorched by
fire.
|
Chemical
method: This can be controlled by spraying the trees by
copper oxychloride sulphate and applying the copperoxychloride paste at the
cut ends. Use of Bordeaux mixture(5:5:50) is found most effective to control
this disease
|
|
4.
|
Anthracnose of mango
Gloeosporium
raciborskii
Glomerella
cingulated
|
Numerous oval or irregular
vinaccous brown or dark brownish spots of variable sizes roundish or angular
scattered over the leaf surface are the characteristics symptoms. The spot
may begin from the apex of the leaf or any other portion of leaf.
|
Cultural
method: Diseased twigs and leaves which fall on the ground
are a potential source of infection. Such diseased material should be
collected and all infected twigs from the tree should be pruned away and such
refuse should be brunt.
Chemical
method: Spraying of Zineb, captan and Bordeaux mixture on
panicles results good control of anthracnose
|
|
5.
|
Pink disease
Pellicularias
almonicolor
|
Pinkish powdery coating on twigs
and branches is seen as first symptoms. Fungus invades inside tissue and
girdle the stem. It infers the transfer of nutrients, so leaf becomes yellow
and dry, shoot and branches of tree will wilt and ultimately dry up.
|
Cultural
method: The disease can be controlled by cutting and
burning the infected branches.
Chemical
method: Bordeaux mixture should be sprays and Bordeaux
paste should be applied to cut the ends.
|
|
6.
|
Alternaria leaf spot
Alternaria
alternate
|
Symptoms appear as small,
brownish circular spots on the surface of leaves and fruits and as black
patches on the twigs. Initially it becomes apparent on lower surface of the
leaf where it shows light brown coloration. After a few days the infection is
visible on the upper surface of the leaf also.
|
Chemical
method: Application of Bordeaux mixture is found to be
more effective for this disease. Mercurised Copper oxychloride also can be
used.
|
|
7.
|
Mango mal
formation
Fusarium
moniliformae
|
-the apical
end of shoot forms a crown of small leaves with greatly reduced internodes
between leaves(vegetative malformation)
-the diseased
inflorescence becomes clustered and rounded the flowers lack essential organs
and donot set fruits hanging on tree for month (floral malformation)
|
-affected plant
part should removed and exposed plant part should be posted with Bordeaux
-spraying 100
ppm NAA in October
-deblossoming
at bud brust stage
|
Banana
Table
: insects pest of banana and their
management
|
S.N.
|
INSECTS
|
SYMPTOMS
|
MANAGEMENT
|
|
1.
|
Banana pseudo-stem weevil
Odoiporus
longicollis
|
Tunnel is seen
from outside and even in small wind flow the pseudo-stem will fall
|
Cultural
method: Use resistant variety: Robusta, William Hybrid.
- remove water sucker regularly
-Cut down the spent -pseudo-stem
close to the ground as soon as the bunch harvested. Chop it into small pieces
up to 60 cm lengths and split each of them in the field. These cut pieces act
as egg laying traps, shelter and feeding stuff to the weevils. When the eggs
hatch, the newly emerged grub die from desiccation as the cut pieces dry
out(Neupane, 2009).
Chemical
method: Use of aluminum phosphide @1 tab/ stem.
-wash sucker and dip in a
solution of Dursban 20%EC (chlorophyriphos) @2.5 ml/liter before planting(Paneru
and Giri, 2011).
|
|
2.
|
Banana rhizome weevil
Cosmopolites sordidus
|
Grub makes the tunnel inside the
rhizome and rhizome starts to rot
|
Cultural
method: Crop rotation, clean cultivation, uproot and burn
all plants in the case of sever infestation. Grow healthy and vigorous plant
in good husbandry practices.
Chemical
method: Use Umet granules pesticide @ 1-2 per pit. Spray
Dursban 20% EC @ 2.5 ml/liter water
(Paneru and Giri, 2011)
|
|
3.
|
Leaf beetle
Nodostomasubcostatum
|
They chew the fruit and the
leaves seriously from August to September
|
Cultural
method: It can be controlled by clean cultivation
Chemical
method: spraying of BHC @ 0.1%.
|
Table:
some disease of banana with their
major symptoms with general management practices
|
S.N.
|
DISEASE
|
SYMPTOMS
|
MANAGEMENT
|
|
1.
|
Panama Wilt
Fusarium
oxysporium f. cubensis
|
Fungi remain
in soil and attack the roots of plant and plug the vascular bundles and
wilting occurs. In initial stage yellow spots are seen to bottom of old leaf
later on whole plant start to wilt.
|
-removing and
destroying effected plant
-do not grow
banana in effected area upto 3 years
-spray
Bavistin 2 ml/l water
-spray 1 part
lime and 3 part soil around the pit.
|
|
2.
|
Bunchy top
Banana virus 1
or Musa virus 1
(banana aphid
is a vector)
|
-leaves of
affected plant are yellow and stunted growth occurs, leaves are crowded.
|
-
destroy
the affected plant and plant’s part
-use virus
free tissue cultured plantlet.
-control
banana aphids
|
|
3.
|
Sigatoka
disease
Mycosphaerella
musicola
|
This fungal
disease enter the plant from stomata and attack the lower surface of leaves.
Yellow spots are seen in
|
-destroy the
affected plant and plant’s part
-good
provision of drainage as prone increase in water logged condition
-maintain some
distance between two plants(Ghimire and Aryal, 2010)
|
|
4.
|
Anthracnose
Cercospora
musae
(fungal
disease)
|
Dark blotchy areas appear on the skin of the
ripening fruit and enlarge rapidly
|
Chemical
method: Spraying with Bordeaux mixture 1%(10g lime, 10 g
CuSO4 in 1 lt water)(FDD, 2013), Dithane Z-78 or Difolaton (0.2%) gives good
control
|
|
5.
|
Moko disease
Pseudomonas
solanacearum
(bacterial disease)
|
Development of the yellowish
discoloration of the inner leaf lamina close to the petiole
|
-
Destroy all unnecessary pant in banana orchard
-
Remove inflorescence just after the fruiting(Ghimire
and Aryal, 2010).
|
Papaya:
papaya is one important nutritional fruits grown in Terai and inner Terai
region of Nepal. No such serious damage is caused by insects found in Nepal but
birds damage the fruit in ripening stage. Some insects found are scale insects
(Aspidiotus detructer), Root knot
nematode (Melodogyne incognita),
Renifarm nematode (Patylenchulus reniformis), red spider mites(Tetranchus spp.) etc. But viral and fungal diseases are the
serious problem of papaya. Which are given below in table.
|
S.N.
|
DISEASE
|
SYMPTOMS
|
MANAGEMETN
|
|
1.
|
Collar rot
disease
Pythiun
aphanidematum
(soil dwelling
fungal disease)
|
Water soaked
patches are seen on the stem which gradually enlarge and girdle the base of
the stem, the depleted area turn into black
|
-uprooting of
affected plant
-prevention of
water stagnation
-spray 1%
Bordeaux mixture or copper oxychloride at the rate of 2g/lt
|
|
2.
|
Root rot
Phytophthora
palmivora
Rhizoctonia
solani
Fungal disease
|
Rotting of
root occurs
|
-seed
treatment with captan and caresan
-sterilization
of nursery by burning dry leaves
-spray
formaldehyde 2 week before sowing in nursery
|
|
3.
|
Papaya mosaic
Papaya mosaic
virus
(virus
disease)
|
Stunted growth
of plant, yellow motling, bending down of petiole, blister like patches on
leaves followed by death plant
|
-roughing of
infected plant
-controlling
insect vector by insecticide
|
|
4.
|
Papaya ring
spot virus (PRS)
Potyvirus
Transmitted by
aphid Myzus persicae
|
Yellowing ,
distortion and severe mosac. Oily or water soaked spots and streak appear on
the trunk and petioles, tisse necrosis
|
-use of
resistant varieties
-provision of
quarantine
-control of
aphids
-rouging of
infected plant and destroy them
-use of
healthy seedling
|
Rhizopus rot
caused by fungi Rhizopus artocarpi is
the most destructive disease of Jackfruit
(Shrestha, 2010). At first, soft
water soaked brown spots develop on the flowers and fruit subsequently which
later formed powdery, fuzzy looking mass of black spores and white fungal
mycelia covers the Jackfruit surface and make unsuitable for consumption. Some
of the control measures are given below,
·
Prune the tree to encourage good
ventilation and to reduce relative humidity in canopy
·
Remove and destroy diseased fruit from
trees and the ground
·
Field sanitation around the tree
·
Avoid water logging
·
Control of weed
·
Avoid wounding of fruit
·
Spray copper fungicide
(Agritech, 2011)
Citrus,
litchi, guava, pomegranate, and grapes are commercially important sub-tropical
fruits species of inner Terai to mid hills of Nepal. The citrus species occupy
largest area among all fruit crops in Nepal.
Protection problems and control
measures of citrus
Citrus is the highly profitable fruit in mid hills
than other traditional crops. Mandarin, sweet orange, limes and lemon dominate
in area and production. Among these mandarin and sweet orange are grown most
commercially. The production of this important fruit has been decline by
problem of disease, pest and disorders. Study of Dhakal et al., 2002, found that blossom and fruit drops due to a long
spell of drought and strong hailstorms during flowering and fruiting season as
well as citrus green stink bug, shoot borer, leaf miner, lemon butter fly and
citrus aphid are major problems. Similarly same study found that die back, citrus
canker, gummosis and tristeza virus are known as serious disease in country.
From the inspection of 17 commercial orchard for disease prevalence and lab
test of samples Shrestha, 2010 found that powdery mildew was major disease
followed by anthracnose, sooty mould and greasy spot. The frequency of citrus
tristeza virus was 7.7 %. All citrus orchards are affected by
various disease (powdery mildew, sooty mold, greening disease, gummosis,
canker) and pests (scale, citrus psylla, lemon butterfly, green stink bug and
borer) (Acharya et al., 2007).
Table 1: farmer’s perception on presence of
important disease and pest in survey conducted in Dailekh
|
Problem
|
Presence (%)
|
Absence (%)
|
|
Tip drying (citrus greening)
|
85
|
15
|
|
Powdery mildew
|
65
|
35
|
|
Sooty mold
|
65
|
35
|
|
Parasitic plant (Toranthes sps)
|
45
|
55
|
|
Green stink bugs
|
100
|
0
|
(Source: survey, 2008)
Main problems of citrus are fruit drop, granulation
and citrus decline/die back/frenching/chlorosis/neglectosis. Due to the lack of
pollination and fertilization, imbalance C:N ratio, hormonal imbalance, extreme
weather and disease and pest cause fruit drop. With the proper orchard
management, irrigation, disease pest management, application of PGR can reduces
this fruit drop problem.
Granulation is the physiological disorder of the
juice sacs of citrus fruits where in they become comparatively hard, assume a
greyish color and become somewhat enlarged. It is the serious problem affecting
the marketability of citrus and thus reducing the profits to grower. Several
factors such as high relative humidity, high temperature during spring, age and
vigour of plant, tree aspect, varieties are related with granulation problem.
Spray of lime @18-20 kg in 450 lt water, spraying of 2,4-D 12 ppm and micro
nutrients like Zn and Cu can minimize the granulation problem. Cracking and
splitting of fruits is also another common physiological disorder in lime and
lemons. This is also associated with the sudden changes in weather conditions,
heavy irrigation or rainfall after a prolonged drought and infection of
bacteria, hot winds. It can be minimize with the application of light and
frequent irrigation.
Citrus decline is not a specific disease but is a
symptomatic expression of many disorders in the plant. Two or more cause
contributed to the decline. Some of the insect pests and disease are tabulated
below.
Important insects pest found in Nepal are sever: Citrus Psylla(Diaphorina citri), Black aphid(Toxoptera citricida), Purple Scale(Lepidosaphes backii), Citrus leaf miner(Phylllocnistis citrella), Citrus Green
Stink bug(Rhynchocoris hymalera), moderate: Black Scale(Coccos herperidum), Soft scale (Icery spp.),Brown scale() , Citrus White fly(Alaurocanthus citrifolii), Citrus red mite(Paratetranchus citri), and citrus fruit fly(Dacus spp. ) and mild
Citrus mealy bug(Pseudococcus citricidus), citrus lemon caterpillar(Papiolio demoleus), citrus black fly (Alaurocanthys woglumi), Red scale (Aonidiella auranti) etc. (Ghos and
Singh, ?)
Table: insects
of citrus with major symptoms and management.
|
S.N.
1.
|
INSECTS’ NAME
Citrus
sting bug
Rhynchocoris
humeralis
|
MAJOR SYMPTOMS
Suck the juice from fruits so
juice less fruit is observed, brown ring can be found at the site of
infection
|
MANAGEMENT
Cultural
method: Hanging the carrion in citrus orchard attract
the citrus stink bug. Collect nymph and adult in insets sweep net in the morning
or evening hours and destroy them(Neupane, 2000)
Biologicalmethod
Big head ant, Pheidole megacephala and spiders are known to feed upon the young
nymphs of bugs. (Paneru, 2009)
|
|
2.
|
Citrus scale
Aonidiellaaurantii
|
Suck the sap, Show die back symptoms
at severity
|
Chemical
method:sulphur and lime sulphur are also used against
citrus snow (white louse) scale. Use of Agro-servo oil @500 ml/15 plants
Biological
method: lady bird beetle can be used as a predators.
Cultural
method: Over-fertilising with nitrogen should be avoided
as it is known to encourage higher levels of reproduction in some citrus
scales.
|
|
3.
|
Citrus aphid
Troxoptera
citricida
(this transmit citrus tristeza
virus)
|
Feed on plant part using their
sucking mouthparts, yellowing of leaves, sooty mold develops
|
-spray
roger 30% EC(dimethoate) @ 2ml/lt of water
-incorporate
Disiston 5% G(disulfoton) or Thimet 10% G(phorate) or Temik 10 %G(aldicarb) @
10 g, 40-50 g and 50-100 g per plant in trench around the root zone of small,
middle and big sized tree respectively and cover the soil with soil and then
irrigate immediately. (Neupane, 2009)
-plant
disease free plant
-remove or replace stunted plant
|
|
4.
|
Citrus stem borer
Stromatiumbarbatum
|
Releasing the saw dust excreta
outside the hole
|
Chemical
method: Use of kerosene oil inside the hole.
Physical
method: Plugging the hole.
|
|
5.
|
Citrus mealy bug
Planococcu citri
|
Suck sap, secrete honey dew which
inturn develop sooty mold
|
Biological
method: Use lady bird beetle and wasp as natural
predators.
Chemical
method: Use Agro-servo oil @ 5 ml/lit of water.
|
|
6.
|
Lemon butter
fly
Papilo
domeleus
|
Caterpillar
attack leaf and foliage and consume the plant part and make bare.
|
Chemical
method: spray
deltra methrin 2 ml/liter
|
|
7.
|
Citrus psylla
Diaphorina
citri
( vector of
citrus greening)
|
Suck the saps
of plant.
Sooty mould
fungus develop on excreta.
|
-apply neem
oil or petroleum oil @ 5ml per liter of water
-dip roots of
sapling in 0.1% solution of fenitrothion or dischlorvos just before
planting(Paneru et al., 2011)
- use the
method as in citrus aphids
|
|
8.
|
Oriental Fruit
fly
Bactocera
dorsalis
|
As in mango
fruit fly
|
As
in mango fruit fly given above
|
In
Nepal to control the insects pest IPM method is given priority in recent year.
Some
important disease of citrus are listed below in tabulated form
Different
virus, bacteria and fungi causes disease in citrus in Nepal. According to T. K.
Lama, 1999a, virus disease found in
Nepal are citrus greening disease, tristeza virus, exocortis, xyloporus wooly
gall and bud scion crease. Among these disease citrus greening disease and
tristeza virus are most cause of citrus decline in Nepal.
Citrus greening disease (Huanglonbing-HLB):
this disease first seen in china in 1870 in Huang Long Bing region and it is a
phloem limiting negative bacterium (Liberibacter
asiaticum)which was consider as virus in initial stage. It is the most
destructive disease and in Nepal it was entered with the infected sweet orange
planting material from Sharanpur, India reported in Pokhara. Later it was
believed to be spread to other part of country specially in western part with
planting material produce in Pokhara Station. Based on the visual observation
of 302 citrus orchard in Lamjung district, 232(72 %) were found suspected to be
HLB. Some of the control measure are given below,
v Established
citrus orchard and nursery above 700 m elevation and if possible surrounded the
nursery by thick forest trees(Lama, 2001)
v Raise
orchard under insect pest free condition and protect the orchard with
dimethoat, especially during spring flush when vtor is inactive.
v Biological
control by rearing and releasing natural enemies of Diaphorina citri
v Use
of quality sapling
v Rehabilitation
program should be initiated (for the rehabilitation program of HLB affected
area 1.5 years old seedling should use in3×3 m) planting distances
v Internal
and internal quarantine
(Annual report 2067-68 of NARC)
Citrus
tristeza virus: it is reported for the first time in
Pokhara valley in 1971. The virus is naturally transmitted by aphid Toxoptera
citricidus. This cause lime tree decline in orchard. It is found severe in
pokhara and dhading. The control measures are
·
Establish disease free citrus nursery
for distribution
·
Control vector with chemical spray and
with natural enemies.
·
This virus resistant root stock
Some
fungal disease of citrus reported by
Lama, 2001 in Pokhara are given below,
Phytophthora sp.
(blight or gummosis), Elsinue fawcettii (scab
dissease), Colletotrichum gloesporioides (antracnose), Capodium citri (sooty mold), Nectaria sp. (Pinkish disease), Olidium citri(powdery mildew), Penicilliun italicum and P. digitarium (blue and green mold on
fruit), Mycosphacrella karli(greay
spot on leaves and small twigs), Pesthaletia
sp(orange leaf spot), Alternaria citri(fruit rot of citrus)
etc..
Table:
some other important disease of
citrus
|
S.N.
|
DISEASE
|
SYMPTOMS
|
MANAGEMENT
|
|
1.
|
Citrus canker
Xanthomonas
axonopodis
Transmitted by
citrus leaf miner
|
Characteristics
lesion on leaf, fruit, and stem with raised, brown, water soaked margins,
usually with yellow halo or ring effect around the lesion.
|
-prune and
burn the affected plant part
-spray
bordeaux mixture or blitox 1%
-control leaf
minor by spraying metasystox @ 0.1 %
at regular interval
|
|
2.
|
Gummosis
Phytophthora
spp.
|
Gum formation
on the trunk. Sapoozing from small crack, giving the tree a bleeding
appearance
|
-preventive
method should be follow to control this method
-disease free
planting material should be use.
|
|
3.
|
Pink disease
|
Pathogen
attack the branches causing wilting and premature drying during the post
monsoon
|
-remove all
the affected plant part
-apply
Bordeaux paste on cut ends.
-spray
Bordeaux mixture in January, February, June and September(Subedi et al., 1996 )
|
|
4.
|
Powdery mildew
Oidium
citri
|
-white powdery
spots appear on upper leaf surface
-young leaves turn
a pale whitish green
|
-use disease
free plant
-use karathane
0.01 % (Mishra, 1985)
-corrective
pruning and use Bordeaux paste
|
Guava
Guava
is another important sub-tropical fruits of Nepal. Guava whitefly, guava moth
and carobbean fruit fly are the major problems in guava in different
agro-ecological zones. Mealy bugs, scale, common white flies and thrips are the
minor problems. Use of systematic insecticide can control the major insects. In
some country the fruit is covered when small with paper sacks to protect it and
assure prime quality fruits for markets.
Foliage
disease, such as anthracnose, can be a problem in humid climates. They can be
controlled with regular fungicide application. Where present root-knot nematode
will reduces plant vigor. Disease attacking to the guava are guava wilt,
anthracnose, stem canker, seedling blight, and scab disease. Among them guava
wilt is the most important disease of guava destroying the whole guava orchard.
Guava wilt
is most serious disease causing decline of guava orchard spread out throughout
the country and especially in Terai region of Nepal. This wilting is cause by
the fungus Fusarium
oxysporium f. psidi Sources of infection are soil. The symptoms
are yellowing of leaves followed by drying of leaves and twig from the tip and
complete wilting of trees within 10-15 days. This disease spread rapidly during
the rainy season and occurs severally in acid soils. Cultural practices
includes removing the infected plant, avoiding water stagnate, use of certified
saplings, use of resistant varieties, use of Chinese guava as a root stock etc.
and chemical control include use of lime along with irrigation water, around
the infected tree, soil drenching around the tree with 0.8% Bordeaux mixture
(4:4:50) at the early stage, soil drenching with brassicol and , soil drenching
around the tree with 0.8% Bordeaux mixture (4:4:50) at the early stage at the
early stages of infection etc. are the control measure of guava wilt.
Litchi
Litchi
has the high value in markets so its commercializing is taking up in
sub-tropical region of Nepal. But the production of this fruit is decline due
to various problems. Some problems like fruit cracking, fruit drop, seediness,
low pulp etc. Shrestha, 1981 indicated that ethephon was effective in reducing
the problem.
Table:
insects of litchi
|
S.N.
|
INSECTS
|
SYMPTOMS
|
MANAGEMENT
|
|
1.
|
Litchi bug
Tessaratoma papillosa
|
Suck the fluid
from the tender parts and in sever condition premature fruiting and fruit drop
take place
|
Chemical
method: Use chloropyrivus @ 2ml/lit of water.
Biological
method: Protection
of hymenopteron parasitoids in nature because the bug is easily parasitoids
by it.
|
|
2.
|
Lichi leaf curl mite
Aceria
litchi or
Erisone
mite
|
Attack the young leaves causing
hairy blister like gall on the upper side of the leaves: the leaves become
thickened, wrinkled and distorted
|
Chemical
method: Spray with sulphur or kerathane 0.12@ of 1-2
ml/lit of water.
Spray malathion 50% 20 ml/ 10 lt
water.
Spray monocrotophos @ 1.25
lit/1250 liter water/ha.
Cultural
method: practice field sanitation; collect and burn all
the infected leaves and maintain optimum planting density.
|
Disease
of litchi are given below
|
S.N.
|
DISESASE
|
SYMPTOMS
|
MANAGEMENT
|
|
1.
|
Litchi leaf spots
Colletotrichum
gloeosporioides
(fungal
disease)
|
The symptoms
of the disease start from the tip of the lamina and extend towards the base.
These spots are irregular in outline and are brown in color with prominent
brown margin encircling them.
|
Cultural
method: Destruction of infected leaves is recommended for
the control of these leaf spot as economic control.
Chemical
method: Zineb
and maneb also provide effective control of the leaf spots under laboratory
as well as field conditions.
|
|
2.
|
Red
rust/Algal leaf spots
Cephaleuros
virescens
(algal disease)
|
The disease is characterized by
red round misty spots mostly on the leaves and sometimes also on the tender
stems. Orange yellow to pink velvety coating is formed on the spots which are
sporangia of the alga.
|
Chemical
method: Spray copperoxychloride @ 0.3% .
The fungicide captafol (0.2%) and
ziram (0.25%) were also effective.
|
|
3.
|
Fruit rots
Aspergillus
variecolor
(Fungal disease)
|
Diseased portions on the fruits
are somewhat in circular patches but subsequently they coalesce and become
irregular. Gradually the diseased surface turns velvety and finally brownish
green color.
|
Chemical
method: Pre-treatment of fruits with 500 ppm of
aureofungin is effective against fruit rots.
|
In
Nepal red rust of litchi is a serious problem among these diseases.
Grapes
Though
the grapes is not commercially in Nepal it has some problems
Table:
Insect pest of grapes
|
S.N.
|
INSECTS
|
SYMPTOMS
|
CONTROL
MEASURES
|
|
1.
|
Grape vine flea beetle
Sceledonta
strigicollis
|
The adult consumes the fresh
leaves after pruning.
|
Chemical
method: Spray with parathion 0.025 %
|
|
2.
|
Ground beetle
Gonocephalum
depressum
|
They suck the fruit juice from
the grape fruit
|
Chemical
method: spray with 0.25 % BHC is recommended to control
|
|
3.
|
Leaf roller
Syleptatunalis
|
They feed on green tissue in the
early stage and eat up a large portion of leaf as they grow
|
Chemical
method: Spray of endrin 0.02% /parathion 0.025%/
monocrotophos 0.04%
|
Table
: disease of grapes with major symptoms and general management practices
|
S.N
|
DISEASE
|
SYMPTOMS
|
MANAGEMENT
|
|
1.
|
Downy mildew of grape
Plasmopara
viticola
|
Disease
appears on any succulent parts of the vines on leaves; small-greenish yellow
spots develop on the upper surface and downy growth consisting of conidia and
conidiophore appear on lower leaf surface.
|
Chemical
method: Use Bordeaux mixture.
Spray
blitox-50 (0.3%), zineb, maneb, mancozeb (0.2%), captan (0.2-0.5%)
|
|
2.
|
Powdery mildew of grape-vine
Uncinula
necator
|
It infects the plants at any
stage of the growth, attacking all the aerial parts, especially the young
leaves and fruits. Leaves show white patches on both the surfaces. Diseased
vines give a sickly look and show restricted growth.
|
Cultural
practices is important.
Chemical
method: Spraying vine with sulfex (0.2%) or bavistin
(0.1%) gives effective control.
|
|
3.
|
Anthracnose
Gloeosporium
ampelophagum
|
Leaves produce dark brown spots
during July-August and November-December. Depressed canker are produced at
the stem and twigs. On the berries, circular brown sunken spots with
dark-brown margins develop leading to their shriveling and drying.
|
Cultural
method: Removal of diseased twigs.
Destruction of pruned materials.
Chemical
method: Spraying with Bordeaux mixture (5:5:50)
|
|
4.
|
Rust of grapes
Phakospora
ampelophagum
|
The symptoms are numerous orange
colored sori mostly on the lower surface of the leaves. Severely infected
older leaves show upward curling, distortion and drying up.
|
Chemical
method: Spraying with sulfex (0.2%) or sulphur dusting
during morning hours is helpful in controlling it.
|
|
5.
|
Black rot
Phyllosticta
ampelicida
|
On leaves, red-brown irregularly
shaped spots develop in which black fruiting structures of the fungus are
produced in concentric rings. Small dark elliptical cankers are produced on
shoots, tendrils, cluster stems and petioles. First symptoms on berries are
light brown soft circular spots, as
these enlarge the entire berries become discolored.
|
Cultural
method: Destruction of the infected vine material by
burning or by deep burial helps to reduce inoculum levels.
Chemical
method: Pre-bloom and post-bloom treatments are done with
fungicides like Bordeaux mixture.
|
Temperate
fruits are Apple, pear, peach, plum, walnut etc. Although there are lots of
potentiality of different temperate fruits species in Nepal the apple is the
most important species in the country. Apple has many problems like fruit drop,
biennial bearing, physiological problem includes bitter pit, cork spot, scald,
jonathan spot, water core etc.and insects pest and diseases.
|
S.N.
|
INSECTS
|
SYMPTOMS
|
MANAGEMENT
|
|
1
|
Wooly
aphid
Eriosoma lanigerum
|
They are fruit sucker.
Produce honey dew like substances
where sooty mold develops.
In severe
infestation, the affected branches show knots like structure.
|
Chemical
method: Agroservo oil can be used @ 10-15ml/lit of water
as a foliar spray. Spray Biomite or Ramban
@ 0.66ml/lt foliar spray 3 times in 7day
duration.
(GC et al., 2011)
Biological
method: Aphilinus
mali- a hymenopteron parasite also can be used to
control. (ARS, Jumla, 2011)
-use of wooly aphid resistant
rootstocks MM series
Physical
method: Banding
with the help of greasy substance above 50 cm from the ground level restrict
the nymph to climb the tree.
|
|
2
|
San
jose scale
Quadraspidiotus perniciosus
|
Suck the sap from new succulent
plant parts and plant shows yellowing coloration.
Develop honey dew and sooty mold
in turn.
|
Cultural
method:Use healthy saplings.
Cutting the affected branches.
Chemical
method: Use of Agro-servo oil @10-15 ml/lit in May- April.
Apply ATSO@ 10 ml/lt(ARS, Jumla, 2011)
Biological
method: encourage building of ladybird beetle.(Paneru, et al.,2011)
|
|
3
|
Apple
stem borer
Zeuzera
spp
|
Bore the stem of apple by larva.
Release of saw dust where it has
affected.
|
Chemical
method: Use of 1-2 drops of the kerosene oil in each hole.
Cultural
method: Plugging the hole.
Cutting the affected branches and
pasting with Bordeaux mixture(Neupane, 2009).
|
|
4.
|
Tent caterpillar
Malacoxoma indica
|
Makes tent like webby structure
in twig and leaves.
Defoliation of leaves take place.
|
Chemical
method: Use neem based pesticide. Use Sumicidin 20% 1
ml/lt.
(Neupane, 2009)
Cultural
method: Pruning and removing of small twigs that hold egg
masses, before egg hatch.
Biological
method: Bacillus thuringiensis var. kurstaki (Bt) is
effective in controlling early instar caterpillars
|
|
5.
|
Slug caterpillar
Caina
spp.
|
It eats the tender leaves
voraciously and remain only the vein structure and appear like the net.
|
Chemical
method: Use contact poison @2 ml per lit.
Cultural
method: Collection of larva and pupa and destroy them.()
|
According
to Paudel, 1986, of the four insecticides such as, Metasystox, Dimecron, Rogor
and Sumithion, the last one controlled wooly aphid as much as 100 %. Various
other insects namely, San Jose scale,
tent caterpillar, apple leaf roller are also controlled by Meatacid,
Metasystox, sevin, Thidoan alone or combination in Marpha (Gurung, 1985)
Table:
disease of apple prevalent in Nepal
|
S.N.
|
DISEASE
|
SYMPTOMS
|
MANAGEMENT
|
|
1.
|
Scab
Venturia
inequalis
(fungal
disease)
|
Olive green
irregular spots are seen underside of
the leaves. Later these spots become metallic black in color and
appear on both side of the leaf surface giving rise to “sheet scab”. These
symptoms appear in both foliage and leaf and rearly in twigs.
|
Chemical
method: Spray the mancozeb
or captan @300 gm/100 lit of water or bavistin 0.2%
Cultural
method: Physical
removal and burning of infected leaves also can be done in small garden.
|
|
2.
|
Powdery mildew
Podosphaera leucotricha
(fungal disease)
|
Powdery growth of fungus appears
on young leaves, shoots, bloosm and fruits of the commercial cultivars.
Greyish or white patches of mycelium develop on the under surface of the
affected leaves then after leaves become crinkled, curled, hard and brittle
and soon dry up.
|
Chemical
method: Powdery mildews are best controlled with the
application of sulphur fungicide. Spray carbendazim (0.05%).
Cultural
method: Removal of affected twigs, branches and leaves.
|
|
3.
|
Crown gall
Agrobacterium
radiobacter pv tumefaciens and A. rhizogenes
(bacterial disease)
|
Globular, elongated or irregular galls are
produced at or near the graft union. First evidence of the disease is a
convoluted tumour production composed of light colored frostly masses of
tissues. The roots are thick which gives woody appearance, characteristics of
this disease.
|
Chemical method: Entire roots system of healthy grafted plants
should be dipped in 1 % copper sulphate soln. for 1.5 hrs.prior to transplanting.
Physical method: Destruction of infected plant material by
uprooting and burning.
|
|
4.
|
Pink disease
Pellicularia
salmonicolor
|
In initial stage water soaked area formed which
is change into pink color
|
Cultural method: removal of infected plant
Chemical methods: use of blitox 50.
Paint the cutting surface with the bordo paste.
|
Some
previous research in Nepal shows that bavistin (0.2%) is more effective than
80W 0.2%. similarly Bordeaux mixture and Dithane M-45(0.2%) are effective to
reduce the intensity of the apple scab disease. The spray of urea (5g/l) before
leaf fall and then with bavistin (0.2%) to reduce the intensity of apple scab disease in Marpha condition.
(Gurung, 1985). Powdery mildew of
apple in Marpha is control by spray Karathane 0.5ml/l and Bavistin (2ml/l) at
15 days intervals when its symptoms appear on leaves and flower. For the control
of papery bark in apple, Bordeaux
mixture (6:6:50) at 20 days intervals were good in Marpha condition.
Anthracnose
(Gnomonia leptostla) a fungal disease
and bacterial disease (Xanthomonas
camestris pv. juglandis) are important disease of walnut. Application of benomyl,
chlorothalonil, cubric hydroxide, dodine and maneb to control anthracnose and
spray streptocyclin 250 PPM + 0.3 cupper oxychloride for bacterial blight are
used to control. Walnut caterpillar is the major insects of walnut. In plum Shot Hole (Stigmina earpophila) and rust(Tranzschelia
discolor) are important fungal disease. Bordeaux mixture is used to control
these diseases. Peach leaf curl aphid is the important of insect peach which is green in color and both
nymph and adult suck the plant saps from twigs and leaves. This cause curling
of leaves. Similarly, peach leaf curl( Taprina
deformans) is important fungal disease of peach which is control/manage by
spraying captan 0.2% and benlate 0.075 %.
Fruits are important part of horticulture contribute
important role in AGDP. Most of the fruits found in world are found in Nepal
due to its high agro-ecological diversity. The production and productivity is
not satisfactory due to various problems. Very few researches are conducted in
Nepal to solve the fruit related problem. Plant protection is most important
issue of in production, processing and marketing of fruit. In Nepal there are
much devastative diseases and insect pests like Citrus greening, Tristeza
virus, wooly aphid, guava wilting, banana bunchy top, panama wilt, Rhizopus
rot, fruit fly etc are found. These cause huge loss of fruit production. Integrated disease and pest management should
follow to minimize the loss from the disease and pest. Research related fruit
crops and plant protection problem are not satisfactory. New technique and
method indeed need to farmer level which can solve the protection. Plant clinic
may be one method to identify the disease and pest found in farmer’s level. Researcher
are need to focus on the protection issues.
