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Plant protection
Vanilla plants are, in general, free from any major pests and disease incidence.
Among insect pests, a few small Lamellicorn beetles and ash gray weevil bite holes
in the flowers and often destroys the column. In addition, caterpillars, earwigs,
snails and slugs lives on tender parts of the plant such as shoot, flower buds,
immature beans etc. Grasshoppers and crab are also found to cut growing tip of plants
during the establishment stage of the plantation. Regular surveillance and removal
of pests can reduce their damage to a great extent.
Root rot, shoot tip rot, stem and bean rot as well as immature bean dropping are
the fungal diseases noticed. Phytosanitation measures are to be adopted in the plantation
for controlling the diseases. Application of organic manure in excess and heavy
mulching in plant base are to be avoided. Fungicides such as 1 % Bordeaux mixture
and 0.2% copper oxychloride may be applied as prophylactic measure. Application
of Pseudomonas @10-15 gms. per litre of water will also control spread of disease.
Conditions such as poor nutrient availability, excessive shade or the lack of it,
damage to roots and stems, over crowding of vines, excessive use of manures, excessive
moisture, water stagnation and poor drainage very often lead to pest and disease
problems.
Disease management
The major fungal diseases reported in vanilla are root rot, stem rot, stem blight,
fruit rot, shedding of beans and shoot tip rot. Pathogenic fungi like Phytophthora,
Fusarium and Sclerotium mainly cause these diseases. These are found in the soil
and atmosphere and multiply and become very active during favourable atmospheric
conditions.
Fusarium attack is mainly observed during August-September when there is high humidity
in the atmosphere. Phytophthora attack is found during heavy rainy season ie June-
July.
To prevent the chances of multiplication of these fungi and spread of these diseases,
the following should be adhered to.
- Avoid excessive use of manure, mulch and irrigation
- Cut and remove disease
affected plant parts and burn them
- Do not use planting materials procured from
infected gardens
- Avoid close planting of vines and over crowding. Follow the
recommended spacing
- Viral disease affected vines should be uprooted and burnt
- Do not use implements, which have been used on disease-affected
plants, on healthy plants without thoroughly washing and cleaning them
Bio control in fungal disease management
The use of beneficial organisms such as Trichoderma and Pseudomonas are recommended
to prevent and control the growth of the fungi. They also are reported to increase
the resistance power in the vanilla plant against the injurious fungi. In addition
some of them are growth promoters.
To prevent the occurrence of fungal diseases, the plants should be sprayed with
one per cent Bordeaux mixture. Simultaneously, 50 g of Trichoderma mixed with 2.5
kg of powdered cow dung should be deposited at the base of the plant. This should
be done before the onset of the monsoon in the first week of May.
About two weeks after the application of Bordeaux mixture [third week of May] Pseudomonas
should be sprayed on the plant.
The spray material should be prepared either using the Pseudomonas in powder form
@20 gm per liter of water or 10 ml of liquid Pseudomonas per litre of water.
Depending on the size of the plant, 100 to 500 ml of the preparation should be sprayed
on the plant.
Under no circumstances, both Bordeaux mixture and Pseudomonas should be sprayed
at the same time as Bordeaux mixture is injurious to Pseudomonas.
Since the initial deposit of Trichoderma will deplete due to rains, the application
of Trichoderma at the recommended dose should be repeated during September.
This should be followed by another round of Pseudomonas spray. It will be beneficial
if the application of both Trichoderma and Pseudomonas is repeated in November after
the cessation of rains.
The above recommendations relate to organic methods of prevention of fungal diseases.
There are also some chemical fungicides available in the market. However both chemical
fungicides and beneficial organisms should not be used simultaneously at short intervals.
If the fungal diseases are not brought under control even after following the above
cultural and management practices the following measures may be adopted in disease
control.
Other recommended practices for management of fungal
diseases
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Sl. No.
|
Disease
|
Symptoms
|
Causal Organism
|
Control Measures
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1
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Root rot
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Browning of roots leading to rooting and decay. Yellowing of leaves, stem and leaves
becoming flaccid, shrivelled and giving a drooping appearance
|
Fusarium, Sclerotium
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Cut and remove the affected roots, reduce mulch. Soil drench and spray the plant
with 0.2 percent COC (Baistin, Baenfil or Dorosan @ two or three litre per plant
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2
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Stem Blight
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Appearance of brown spots on leaves and stems follwed by yellowing of the leaves
and rotting of leaves and stem
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Phytophthora
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Spray 1 percent Bordeaux mixture or 0.4 percent Potassium phosphonate (Akomin, Phytophos)
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3
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Stem rot
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Water soaked lesions giving stem a brown coloured appearance resulting in rotting
of tissues, leaves turning yellowish and drying off
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Fusarium
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Cut and remove the affected portions. Spray 0.2 percent Carbendazim (2 gm/L). Repeat
spray after one month
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4
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Bean rot
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Rotting and shedding of beans
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Phytophthora
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Spray 0.2 percent Carbendazim and 1 percent Bordaeux mixture alternatively at weekily
intervals or spray 0.4 percent Potassium phosphonate
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5
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Immature bean shedding
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Yellowing of immature beans at tips, followed by splitting of the beans and shedding
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Fusarium
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Spray 0.2 percent Carbendazim at 15 days interval
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6
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Shoot tip rot
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Decaying of shoot tip and leaves at the tip
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Fusarium, Sclerotium
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Spray 0.2 percent Carbendazim at 15 days interval
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Important points to be remembered in disease management
- Never apply Bordeaux mixture or other fungicides and
bio control agents simultaneously or within fifteen days of the application of one
or the other
- Phytosanitation is essential for the
effective functioning of fungal bio-control agents and other beneficial microorganisms
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Disease affected plants should be destroyed immediately
- Do not take planting
materials from disease affected plants
Important prophylactic measures:
- Timely shade management
- Avoid excess moisture
- Allow free movement
of air
- Avoid overcrowding of vines by keeping adequate spacing
- Avoid
excessive mulching during rainy season and mulching with materials that are not
easily decomposed
- Avoid excessive manuring and use of fresh cow dung
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Apply recommended doses of bio agents like Trichoderma, Pseudomonas, Bacillus etc
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Collect and destroy the parts of plants showing disease symptoms
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