Ginger is a subtropical shade loving plant.
The economic part of the plant namely the underground rhizome is often
attacked by scale insect, Aspidiella hartii, both in field and in
storage condition.
The minute crawling nymphs infest near the growing buds and suck the
sap. It results in shrivelling and drying of the rhizomes. The plants
are devitalized and get withered. The rhizomes fail to germinate.
Pest biology
The adult scale insect is circular in shape, light brownish to grey in
colour and about 1mm in diameter.
It reproduces without fertilization laying its young ones directly.
About one hundred nymphs are laid by a single female. The life span is
around one month. The insect multiplies rapidly on stored ginger.
Selection of healthy rhizomes free from scale infestation prevents the
insect spreading to new areas. Avoid water stagnation in the field.
Severely infested rhizomes are to be discarded before storage of
rhizomes.
Soak the rhizome seeds in 0.075 per cent quinalphos for 20-30 minutes
before storing and sowing. Drench the soil with a systemic insecticide
such as dimethoate 30 EC at 2ml/lit of water.
Rhizome treatment
To ensure seed material free from scale infestation, the rhizomes must
be treated with 0.05 per cent phosalone, methamidophos, dichlorvos or
monocrotophos.
The treated rhizomes must be kept at least for a week before planting
to get the maximum effect of the toxicants.
The scale infested rhizomes are to be dipped in the insecticidal
solution for 15 minutes, air dried and can be stored on sand.
Storing method
Storing of rhizomes in dried leaves of Strychnos nux-vomica also helps
in keeping the rhizomes free of scale infestation.
Two species of parasitic wasps and one species of a predatory mite
keep the population of ginger scale insect under biological control.
J. JAYARAJ & M. ANANTHAN
HORTICULTURAL RESEARCH STATION, THADIYANKUDISAI PERUMPARAI, DINDIGUL,
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