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Parasitic and non-parasitic maladies
Tapping panel dryness (TPD)
TPD leads to approximately 15-20% decrease in yield.
Symptoms: Excessive late dripping
of latex occurs simultaneous with a reduction in the dry rubber content of the latex
in the initial phase. Total inhibition of rubber biosynthesis occurs and no latex
is produced towards the final phase.
Management: Giving tapping rest
and changing the tapping panel are the generally followed plantation practices.
As a curative measure, resting the trees without tapping for a considerable period
is advised. Therefore, tapping can be resumed changing the tapping panel and following
a low intensity tapping system.
Phanerogamic parasites
Phanerogamic parasites, Loranthus and Cuscuta (Dodder) attack both
rubber and cover crop Purearia phaseoloids and Mucuna bracteate.
Management: The best remedy is to
destroy them in the initial stage itself along with the host by cutting, removal
and burning of attacked parts.
Lightning injury
Symptoms: In the affected portions,
exudation of latex is observed and the bark separates from the wood. The damaged
bark is colonized by borer beetles in large numbers. A characteristic feature is
that cambium is the tissue that gets damaged first and as a result, cambium and
the inner bark are coloured scarlet to dark violet. Dying of tissues starts from
the cambium extending through the bark in an outward direction. Soon after lightning
strikes, incidence of patch canker also increases.
Management: In the case of partially
affected plants, the damaged bark is scraped out, the exposed area washed, cleaned
with Dithane (Indofil) M45, 0.75 per cent solution and after drying, a wound dressing
compound applied. If exposed to hot sun, the treated portions may be whitewashed.
Sun-scorch
Symptoms: The bark at the collar
region dries up resulting in a girdling effect and affected seedlings dry subsequently.
Management: In plants where the
damage is not deep and extensive, the affected region may be scraped and washed
with fungicide Dithane (Indofil) M45, 0.75 per cent solution and a thin coating
of wound dressing compound applied. Above the treated surface, whitewashing of the
stem from the collar upwards on the brown bark may be carried out using lime, during
hot weather and this may be continued till the canopy closes.
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