losses resulting from diseases in rubber plantations are substantial.
Timely plant protection operations ensure healthy growth and economic
production. The major diseases of rubber are as follows
- Abnormal Leaf Fall
- Shoot Rot
- Powdery Mildew
- Secondary Leaf Fall
- Bird's Eye Spot
- Leaf Spot
- Pink Disease
- Patch Canker or Bark Canker
- Black Stripe, Black Thread or Black Rot
- Dry Rot, Stump Rot Collar Rot or Charcoal Rot . Brown Root Disease
- Poria Root Disease
- Scale Insect
- Mealy Bug
- Termite (White Ant)
- Cockchafer Grub
- Bark Feeding Caterpillar
- Slug and Snail
- Porcupines and Wild Pigs
- Cover Crop Pests
- Parasitic and Non-Parasitic Maladies
disease is a disease that affects the stems and branches. It is
primarily a disease of the bark, in advanced stages the infection
spreads from the bark into the underlying wood.
characteristic symptom of pink disease is the appearance of a salmon
pink incrustation produced by the growth of the fungus found on the
surface of the bark.
symptoms of Pink Disease are; Wilting and subsequent death of the
leaves, which turn brown and remain attached to the infected branch for
some time. Bleeding of the branches or stem, forming black streaks of
coagulated latex. Green lateral shoots arising dormant buds. Open
wounds or cankers resulting from the death and shedding of limited
areas of bark.
RED ROOT DISEASE
root disease is common ailment to a rubber tree. As the disease is slow
growing it may not be noticed until the tree is ready for tapping
Symptoms The symptoms must be sought by examining the root system of the tree.
The fructifications are hard woody brackets with a dark red brown
wrinkled upper surface, smooth gray white under surface, and a swollen
creamy white margin.
Infected roots are covered
with a red skin of mycelium to which soil adheres, but the red color
may not be apparent in a fresh specimen until it is washed. The growing
margin of the fungus is creamy white; the characteristic red color is
formed some inches behind the limit of advance.
the early stages the rot is pale brown and hard. In the later
stages it is pale buff, wet and spongy unless the soil is dry. It
is unlikely, the rot produced by the other two parasites affect
the annular layers of wood.
WHITE ROOT DISEASE
root disease is the most serious of all diseases found in Malaya. Not
only does it damage the tree, but it involves heavy expenditure
for its control.
symptoms begin to appear in the aerial parts it is too late to save
the tree. Likewise fructifications of the fungus forms much too late in
the history of an attack. Therefore it is late in diagnosing and then
curing the disease. One must rely on symptoms appearing on the roots
themselves in order to recognize the disease.
symptoms on the tree as a whole are exactly those to be expected if
the roots were to be progressively cut away. The leaves go yellow and
die. Frequently a diseased tree blows over before the foliage has been
visibly affected. Fructifications may be found, especially during wet
weather, at the collars of infected trees and on large exposed roots or
stumps that are in advanced decay. The brackets are firm, fleshy, and
usually tiered. The rhizomorphs are white flattened strands, usually
sparsely branched. Old rhizomorphs become rounded and pale orange red.
The wood of a root which is newly killed is brown and hard; in the
later stages it is white or cream and usually firm.
STINKING ROOT ROT
This disease is not very common but has striking symptoms that are easily recognized.
Characteristic smell is not a symptom of the disease as it is produced
not by the usual parasite, but by fungi and bacteria which grow in
association with it. The smell may be sufficiently strong to be
discernible to persons walking through affected fields.
characteristic rhizomorphs by means of which the disease can be
recognised do not appear on the outside surface of an infected root.
When the bark is stripped off the pattern is seen: dark brown flat
strands on the surface of the wood, and a white impression on the inner
surface of the dark. The dead wood has no characteristic rot. The tree
dies after showing the foliage symptoms displayed after attack by any
This disease is probably more common and responsible for more damage than is generally recognized.
superficial symptoms may be confused with mould rot or tapping wounds.
Careful examination shows small areas of sunken discoloured bark just
above the tapping cut. On scraping away the bark, vertical black lines
are seen to underlie these areas and to extend a short distance below
the tapping cut.The black lines are wood vessels that a pathogen has
invaded. Growing under the renewing tapping panel, producing splits and
cankers in the overlying bark. Splitting and latex exudation from the
older renewed bark may be unassociated with streaks on the surface of
the recently tapped bark. Some clones are more susceptible to infection
than others; in Malaya PB 86 is found to be particularly susceptible.
is a progressive death of the branches starting at the extremities and
extending towards the main stem until the whole tree may die. The
dieback described here is different from branch death due to poor
nutrition, disease, or any injury affecting the tree as a whole, and
from parasitic invasion of the branches.
is indicated by dead leafless branches in the upper part of the
canopy. These should be distinguished from living branches that have
merely lost their leaves.
In cases only a few months old
the young shoots that have died remain as shriveled, curved brown
twigs. There is a well defined boundary between dead wood and living
wood of an affected branch; this may be discerned from a changed
appearance of the bark but is more obvious when the branch is cut into.
On larger branches the boundary often extends much further down one
side than the other, giving the characteristic spearhead effect.
Vigorous shoots may grow from one side while the opposite side is
BARK - BURSTS - BURRS
Short vertical splits in the bark
from which latex exudes are not uncommonly seen on young high yielding
trees, but they lead to no other effects. Sometimes there is internal
bleeding and a pad of coagulum forms against the wood; the overlying
bark then dies.
growth surrounding the wound may heal right over it, but often renewed
bursting occurs at the same place, giving rise to a large burr
comprising successive layers of rubber, wood and bark tissues. Bursts
and burrs may occur anywhere on the stem and branches.
post-war development of chemical weed control on rubber estates there
has been a great increase in the number of cases of accidental
poisoning. So long as only the leaves are affected little damage is
likely to happen, but it is important to know the effects so that stem
damage can be recognized.
Direct contact with a herbicidal
spray leads to large patches of whitened dead tissue which are rapidly
invaded by saprophytes. Absorption of poison on a scale insufficient to
kill the tree produces a pattern of dead bleached tissue, which
eventually becomes invaded by saprophytes.
Malformation is normally encountered
in the most actively growing parts – the leaves and young shoots – of
young plants. It may take various forms and have several causes.
plant is distorted from its normal shape by unequal growth, some parts
becoming disproportionately long or broad, curved to one side or fused