Plant protection-Nursery
Pests
- Rhizome weevil ( Prodioctes haematicus )
- Shoot fly ( Formosina flavipes )
- Shoot/Capsule
borer (Conogether punctiferalis)
- Root grubs
(Basilepta fulvicorne)
- Spotted red spider mite
-
Cutworm ( Acrilasisa plagiata )
- Plant
parasitic nematodes(Meloidogyne sp.)
Diseases
- Nursery leaf spot
- Nursery leaf rot
- Damping off or seedling rot
- Clump rot (
Rhizome rot )
Rhizome weevil
( Prodioctes haematicus
)
This is a serious pest in the secondary nursery especially where seedlings are raised
continuously year after year. The grubs feed on the rhizome and basal portion of
the stem. This results in drying of leaves and breaking of stem at the base.
Management:
Drenching the nursery beds with chlorpyrifos at 0.04% can control the pest.
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Shoot fly
( Formosina flavipes )
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The pest is observed in the nursery during January to May. Dead-heart or decay of
the central spindle is the external symptom.
Management:
Spraying of quinalphos 0.025% is recommended for the control of the pest.
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Shoot/Capsule borer
( Conogethes punctiferalis )
The caterpillar bores into the stem and feeds on the internal contents. This results
in the decay of the central spindle and production of dead heart. Faecal matter
of the caterpillar can be seen coming out through the holes
Management:
Spraying with quinalphos 0.05%, carbaryl 0.1% or dimethoate at 0.05% is recommended
against the shoot borer.. For effective management of the pest, the insecticides have to be targeted
on the early stages of the larvae, which is usually present within 15-20 days after adult emergence in the field.
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Root grubs (Basilepta
fulvicorne)
The grubs of the insect cause damage. The grubs are small, 2-10 mm long, off-white
in colour and often assume a shape resembling 'C'. Grubs feed on cardamom roots
in patches. This reduces the uptake of nutrients and leads to yellowing of leaves.
Beetles are small greenish blue or blue or green and are found in large numbers
during May to July and October to February. A female beetle lays 124-393 eggs in
batches on dry grass, leaf sheath, mulch or dry cardamom leaves, during its life
span of nearly 85 days. Grubs drop down and enter into the soil and start feeding
on cardamom roots. Grub stage lasts for 45 to 60 days or 80 to 120 days depending
on season i.e., May to July or October to February respectively. They make earthen
cells and become pupae inside the cell. Adults come out from these earthen cells
as beetles.
Management:
Beetles may be collected and destroyed during March-April and August-
September.
Early stages of the grub which are usually present in soil during May-June
and September-October can be controlled either by drenching chlorpyrifos 0.04 %
@ 3-4 litres/clump. The granules may be spread up to 10 to 15 cm around the plant
base and incorporated in the soil.
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Spotted red spider mite
Spider mite at times assumes the status of a serious pest during summer. These mites
spin web and colonize behind it on under surface of leaves. They suck plant sap
from leaves resulting in the formation of grey blotches on leaves. The infected
portion of the leaf with its delicate silky threads, eggs and excreta look ashy
white and dusty. The affected leaves gradually dry up. These mites may also infest
tillers and panicles. About 15-20 days are required to complete its life cycle.
Management:
Spraying dicofol @ 200 ml/100 litre water or sulphur 80 WP 250 g/100
litre or dimethoate @ 167 ml/100 litre or phosalone 200 ml/100 litre on lower surface
of leaves is effective against this pest. Spraying may be repeated 2 or 3 times
at 15 days interval depending on severity of infestation.
As a precaution, use of organochlorine insecticides and pyrethroids
may be avoided in cardamom plantation.
Excess use of nitrogenous fertilizers may be curbed.
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Cutworm
( Acrilasisa plagiata
)
Cutworms feed on leaves of seedlings. Infestation is noticed usually during January-March.
The caterpillar is nocturnal in habit. It pupates in soil. Pupal period lasts for
17 days.
Management:
Collection and destruction of caterpillars and pupae.
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Plant parasitic nematodes
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Root-knot nematode Meloidogyne incognita is a serious problem in cardamom. They
are present both in the nurseries and plantations of the entire cardamom growing
tracts of South India. They feed on the roots; make the plants weak and vulnerable
to diseases. In their presence the nursery diseases like rhizome rot and damping
off due to Rhizoctonia solani get aggravated.
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Symptoms:
1. Poor germination of seeds in the primary nurseries.
2. Poor establishment after transplanting to secondary nurseries or main fields.
3. Yellowing and drying of leaf tips and margins.
4. Stunting and poor growth of the plants.
5. Shedding of immature capsules in the main field.
6. Heavy galling (root-knots) and abnormal branching of roots (Galling is prominent
in seedlings while in the mature plants the galls are small in size with abnormal
branching of roots which are devoid or rootlets).
Management:
The most important step is the production and distribution of healthy, nematode-free
seedlings. For this the following measures may be adopted.
1.
Application of cartap hydrochloride 4G @ 1 kg ai/ha before monsoon and use of Neem cake 2 kg/plant
before monsoon or Bacillus macerans (1 x 107 cfu) 30 g/plant or Pseudomonas fluorescens
(1 x 108 cfu) 30 g/plant before monsoon.
2. Do not use the same site repeatedly for raising the seedlings. If possible, rake
the soil of the site and expose to sunlight before taking up sowing. The roots should
be pruned prior to distribution or transplanting.
Diseases
Nursery leaf spot
Leaf spot caused by the fungus Phyllosticta elettariae is a destructive
disease especially in nurseries of Karnataka area. In other areas it is a minor
disease. It appears mostly during February-April months with the receipt of summer
rains. Disease appears as small round or oval spots, which are dull white in colour.
These spots later become necrotic and leave a hole (shot hole) in the centre. The
spots may be surrounded by water soaked area. High intensity of disease is noticed
in open nurseries exposed to direct sunlight. In such cases, numerous spots develop
on the leaves and ultimately the leaves dry off and the young seedlings may perish.
Young leaves are more susceptible to leaf spot incidence. Seedlings develop tolerance,
as they grow old.
Management:
Prophylactic spraying with fungicides such as Dithane M-45 (mancozeb) or Indofil
M 45 0.3% may be given on the leaves. First spray is to be given during March-April
depending on the receipt of summer showers and subsequent sprays at fortnightly
intervals. Two to three rounds of spraying may be given. Clipping and destruction
of severely affected leaves after spraying is to be done.
In addition to fungicidal sprays, the following supplementary measures also may
be followed:
a) Sow the seeds in August-September, to ensure sufficient growth of seedlings,
so that they may develop sufficient tolerance.
b) Avoid exposure to direct sunlight from top or sides. Use coir matting or coconut
fronds for shade. When jungle leaves are used for thatching, sloppy roofing may
be provided.
c) Do not raise the nursery continuously in the same site.
In grown up seedlings of the secondary nursery, another type of leaf spot is of
common occurrence. Symptoms are yellowish to reddish brown rectangular patches seen
on the lamina. These will be almost parallel to the side veins. The mature lesions
show a muddy red colour. Following heavy infection, the leaves dry off. The disease
is caused by the fungus Cercospora sp. The fungicides listed above can
be used for controlling the disease.
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Nursery leaf rot
This disease is seen in young seedlings of 3-4 months old. It is not wide spread
in occurrence; but seen only in a few nurseries. The symptom is development of water
soaked lesions on the leaves, which later become necrotic patches leading to decay
of affected areas. Usually the leaf tip and distal portion is damaged. In severe
cases, rotting extends to petiole and leaf sheaths. It is caused by fungi such as
Fusarium sp. Alternaria sp. etc.
Management:
To control this disease avoid excessive watering of seedlings. Spray 0.3% Dithane
M45 (mancozeb) twice at 15 days interval after destroying the infected leaf portions.
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Damping off or seedling
rot
The disease appears usually in the germination nursery (primary nursery) during
rainy season when there is excessive soil moisture due to improper drainage. Leaves
turn pale and their tips become yellow. Gradually, these symptoms spread over the
entire leaf extending to leaf sheath resulting in wilting of seedlings. The collar
portion decays and the entire seedlings die. Infection spreads in the nursery beds
resulting in death of seedlings in small patches. In grown up seedlings, rotting
extends from the collar region to the rhizomes resulting in their decay and ultimate
death of the plant. Disease is caused by soil borne fungi such as Pythium vexans
and Rhizoctonia solani . Fusarium oxysporum also causes similar
seedling rot resulting in the wilting of the entire seedlings.
Management :
a) In the primary nursery, practise thin sowing for avoiding overcrowding of seedlings.
b) Provide adequate drainage facilities.
c) Remove affected seedlings early and maintain proper phytosanitary measures in
the nursery.
d) Treat the nursery beds with formalin (formaldehyde 2%) for three days at the
rate of 15 litres per square metre at least 15 days prior to sowing.
e) When infection is noticed, drench the nursery beds with copper oxychloride 0.3%
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Clump rot
(Rhizome rot)
This disease occurs in mature seedlings (6 to 18 months old) of the secondary nursery.
It is seen during the monsoon season when soil moisture is in excess due to improper
drainage.
Early symptoms on leaves appear as pale yellow colour, partial rolling of leaf margins
and withering of seedlings. Rotting or decay starts at the collar region and it
spreads to rhizomes and roots. In severe cases, the collar region breaks off and
the seedling collapses. The disease is caused by the soil-borne fungi Pythium vexans
and Rhizoctonia solani . Rotting of roots due to Fusarium
sp. is also observed.
Management:
a) Uproot and destroy all the affected seedlings in a nursery.
b) Stop irrigation of nursery beds.
c) Remove mulch materials from nursery beds and rake the soil gently.
d) Drench the nursery beds with copper oxychloride (COC) 0.3% at the rate of 3 to
5 litres per square metre. Two to three rounds may be applied at 15 days interval.
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