Orchids
Scales
Symptoms of damage
Nymphs and adults suck the sap from leaves
It damages both leaves and pseudobulbs
Honey dew excretion causes development of sooty mould fungus
Yellowing of leaves
Wither and dry up
It is the common armoured scale found on cattleya andcymbidium.
Management
The root extract of plant Derris is recommended.
Spraying of fish oil rosin soap at 15 gms per lit of water.
Field release of green lace wing larvae Chrysoperla carnea
Conserve the predatory Lady bird beetles Cryptolaemus montrouzieri ,Scymnus sp.
Spraying of malathion 50 EC or phosalone 35 EC or methyl demeton 25 EC @ 1 ml/l
Mealy bugs
Symptoms of damage
Mealy bugs cover the stem and leaf, suck the sap, secrete honeydew and attract ants.
In severe infestation, sooty mould may develop on the leaves.
Affected plants lose their vigour.
Management
Lady bird beetles Cryptolaemus montrouzieri and Scymnus sp. are known to feed mealy bugs.
Spray malathion 50 EC @ 1 ml/l of water.
Mites
Symptoms of damage
Red spider mite suck the sap from cells of leaves – causing white specks.
In heavy infestation webbing on the plants.
This is a serious pest on orchids during warm and dry season.
Management
The predatory phytoseiid mites, Amblyseius sp. and Phytoseiulus persimilis are found to feed on spider mite.
Spray dicofol 18.5 EC or dimethoate 30 EC or methyl demeton 25 EC @ 2 ml/l of water.
Giant African Snail
Symptoms of damage
They feed on the young leaves, roots, flower buds and even open flowers.
Slugs usually hide during day and become active during night
Presence of slimy fluid on foliage
Management
Apply 15% metaldehyde dust or 20% metaldehyde liquid.
Sprinkle 5% metaldehyde pellets around the infested plant.
If the population is low, collect and destroy.
Source: https://agritech.tnau.ac.in/