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Rubber tree or Hevea brasiliensis (H. brasiliensis), one of the important commodity crops in the world belongs to the family Euphorbiaceae. Hevea is exploited economically due to its milky latex, extracted from the tree which is commonly known as natural rubber (NR). Like any other crops, rubber tree also faced several diseases that influence rubber production. These diseases attacked four major parts of rubber tree which are the leaves, stem, panel and root area. Such diseases like Corynespora leaf fall, Southern American leaf blight (SALB) disease, abnormal leaf fall, Colletotrichum leaf disease, powdery mildew, leaf blight, brown bast, white rot disease, and brown rot disease are the major diseases that can affect global rubber productions. Hence, this review comprises the major diseases, causal agents and symptoms related to those diseases that attack the rubber tree.
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Pertanika Journal of Scholarly Research Reviews
http://www.pjsrr.upm.edu.my/
Major Diseases of Rubber (Hevea brasiliensis) in Malaysia
Safwan MAZLANa, Noraini Md JAAFARb, Aswad WAHABc, Zulkefly SULAIMANd,
Heraa RAJANDASe and Dzarifah ZULPERIf
a,c,fDepartment of Plant Protection, Faculty of Agriculture,
Universiti Putra Malaysia, 43400 Serdang, Selangor, Malaysia
bDepartment of Land Management, Faculty of Agriculture,
Universiti Putra Malaysia, 43400, Serdang, Selangor, Malaysia
dDepartment of Crop Science, Faculty of Agriculture,
Universiti Putra Malaysia, 43400, Serdang, Selangor, Malaysia
eDepartment of Biotechnology, Faculty of Applied Sciences,
AIMST University, 08100 Bedong, Kedah, Malaysia.
*safwanmazlan94@gmail.com
Abstract Rubber tree or Hevea brasiliensis (H. brasiliensis), one of the important commodity crops
in the world belongs to the family Euphorbiaceae. Hevea is exploited economically due to its milky
latex, extracted from the tree which is commonly known as natural rubber (NR). Like any other crops,
rubber tree also faced several diseases that influence rubber production. These diseases attacked four
major parts of rubber tree which are the leaves, stem, panel and root area. Such diseases like
Corynespora leaf fall, Southern American leaf blight (SALB) disease, abnormal leaf fall,
Colletotrichum leaf disease, powdery mildew, leaf blight, brown bast, white rot disease, and brown rot
disease are the major diseases that can affect global rubber productions. Hence, this review comprises
the major diseases, causal agents and symptoms related to those diseases that attack the rubber tree.
Keywords: Hevea brasiliensis, Rubber, Diseases, Causal agents, Symptoms.
Introduction
Hevea brasiliensis (H. brasiliensis) or commonly known as rubber tree is an essential commodity used
in manufacturing over 50,000 products worldwide (Nair, 2010). It belongs to the family Euphorbiaceae.
There are almost 2,500 plant species that produced rubber (Mooibroek and Cornish, 2000), but only the
genus Hevea is economically exploited for its production of natural rubber (NR). The tree is originated
from the Amazon basin and started to be commercially established outside of South America in the 19th
century (Rahman et al., 2013). Nowadays, rubber trees are mainly grown in tropical regions such as
Africa, Asia, and Latin America. The latex yield of rubber trees starts after reaching 5 to 7 years of
maturity, and the productive lifespan of 25 to 30 years. In Malaysia, rubber industries are important to
deliver RM230.9 billion of gross national income (GNI) by 2020 (Malaysian Rubber Board, 2009).
Natural rubber (cis-1,4-polyisoprene) is a latex polymer with high flexibility, resilience, elasticity,
efficient heat dispersion, and impact resistance (Mooibroek and Cornish, 2000). Due to these properties,
it makes the natural rubber differ from other synthetic rubber and it is difficult to be replaced. Natural
rubber is used to produce many kinds of rubber products such as condoms, medical gloves and even the
heavy-duty tires for aircraft and trucks. Consumption of the total natural rubber in the world is forecast
to grow in 2016 by 1.8% marginally above the 1.2% growth in 2015. Based on the International
Monetary Fund (IMF), natural rubber consumption is estimated rising at an accelerating rate of 2.9%
in 2017 and further at 3.3% in 2018 (Malaysian Rubber Board Digest, 2018).
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Like any other crops, rubber tree also suffers several kinds of diseases attacking the four major cross-
sections of H. brasiliensis which are leaf, stem, and panel and root areas. These plants suffer from
several diseases in different stages of its growth in nursery, immature and mature plantations. Among
the severe diseases of rubber tree are Corynespora leaf disease caused by Corynespora casiicola,
Southern American leaf blight caused by Microcyclus ulei, Phytophthora species causing abnormal leaf
fall, Colletotrichum leaf spot disease caused by Colletotrichum acutatum, powdery mildew caused by
Oidium heveae, leaf blight caused by Fusicoccum species, brown bast caused by physiological disorder,
white rot disease caused by Rigidosporus microsporus and brown rot disease caused by Phellinus noxius.
These diseases contribute to the fluctuation economic to the extent of tree desication.
Corynespora Leaf Fall Disease (CLFD)
Corynespora leaf fall disease (CFLD) is caused by the fungus Corynespora cassiicola, which is one of
the most serious threats to H. brasiliensis grown in African and Asia continents (Ismail and Jeyanayagi,
2003). The first case regarding this disease was reported in Malaysia (Newsam, 1960), and then in India
(Ramakirishnan and Pillai, 1961). The pathogen affecting young and old leaves which eventually
causing the reduction of leaves to whole year spend.
This disease might delay the maturation of rubber trees and resorting to plant death on the susceptible
clones. As CFLD causes some damages to the natural rubber industry, the International Rubber
Research and Development Board (IRRDB) has frequently warned all the rubber tree planters about the
danger that this disease brings to the trees and the risk of its outbreaks (IRRDB, 2000). The first CFLD
outbreak was reported on the clone RRIM 725 in 1975, where the rubber trees were planted in the main
field and subsequently, it also attacked a few rubber clones (Jacob, 2006).
The symptoms obtained from this disease are usually appeared to be a circular, rarely irregular
amphigynous lesions on the leaf lamina 1 to 8 mm in diameter (Figure 1a and Figure 1b). A spot of
white or light brown papery center with a dark brown ring at the margin of the leaf, surrounded by a
yellow halo can visibly see in each leaf. The disintegration of the central portion sometimes in shot hole
formation. Young leaves show the shivering at the leaf tips. Upper leaves are defoliated and drying of
the terminal portion consequent to the formation of several lesions are common during the dry weather
(Ramakrishnan and Pillay, 1961).
In bud woods nurseries, leaf spots are common, although blighting of leaves and defoliation are
occasionally seen. The infection on semi-mature leaves leads to a typical round or irregular lesions with
papery center brown margin and yellow halo. Even though mature leaves are affected but the size of
the lesions formed on mature leaves is very small; slightly larger than a pinhead (Jacob, 1955; Jinji et
al., 2007). Severe infection causes dieback on the shoot tips. The light green shoot tips also can be
affected but once the shoots turned dark green or brown and mature, infection is less and often limited
to spots (Figure 1c) (Jacob, 1955).
Figure 1: a) Yellow halo around spots; b) Railway track symptoms and c) Shoot tip infection (Manju,
2011).
(a)
(b)
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For the last two decades, only the large-scale infection of Corynespora can become a serious epidemic
to the more mature rubber trees. This sporadic of Corynespora leaf disease that infected the plantation
in Kodumon, Chittar, Shaliacary and Cheruvally in India also been reported in Johor, Malaysia (Tan,
1990; Chee, 1990).
Southern American Leaf Blight (SALB) Disease
Microcyclus ulei (M. ulei) causing Southern American Blight (SALB) is an endemic fungus originates
from Amazon area. At the beginning of rubber plantation, SALB were attempted all rubber trees in the
plantation at Central and South America (Lieberei, 2007). This occurrence happens because, till this
day, all control measures to withstanding this disease have been failed neither biological control nor
chemical protection measures in order to develop a healthy and productive plantation (Smith et al.,
1995).
The infection starts when conidiophores of M. ulei attached with young leaf of susceptible genotypes,
then the spores germinate on the wetted surface of the leaves and not washed away by rain as the germ
tube are strongly sticked to the cuticle of the leaves (Giesemann, 1986). Penetration of hyphae in three
epidermal cells is happened with or without formation appressoria. The formation of appressoria and
branched germ tubes is dependent on the interaction in the pre-penetration phase (Hashim et al., 1978;
Giesemann, 1986).
Germination of spore and formation of germ tube occurs instantly after conidiophores contact with the
leaf. The formation of the germ tube varies with the leaf surface structure of the young leaves. The
infection process was influenced by the formation of germ tube length, germ tube diameter, branching
and formation of appressoria (Blasquez and Owen, 1963; Hashim et al., 1978; Giesemann, 1986)..
After penetration of leaves surface, the colonization of hyphae at the underlying tissue by intercellular
growth. It will invade the tissue layers contiguous to the leaf vascular bundles and briskly along the
veins into the leaves (Lieberei, 2007). At this phase (biotrophic phase), the combination is not shown
cell death. In resistant clones, hyphae penetration are collapse due to the indirect contact of the cells.
At the initial observation, the infection of resistance plants resulting in a hypersensitive response in a
typical defensive reaction (Breton et al., 1997). This reaction as a sign for vertical or complete resistance,
but this concept is appropriate only to mature leaves of rubber (Lieberei, 2007).
Within 24 hours, branching of hyphae forming the conidiophores directly towards the lower epidermis
that break through the lower leaf surface and forming conidia and conidiophores (Figure 2a) (Garcia et
al., 1995a). The small lesion will form ring-like structures that can fuse laterally often lead to large
lesions (Figure 2b).
Figure 2: a) Conidial lesion and ascostromata on leaf surfaces; b)
close up of conidial lesions; c) and d) pycnidia and ascostromata
on mature and old leaves (FAO Regional Office for Asia and
Pacific, 2007).
(a)
(b)
(c)
(d)
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Abnormal Leaf Fall Disease
The abnormal leaf fall disease of H. brasiliensis is caused by Phytophthora palmivora (P. palmivora),
a universal fungal pathogen with a wide range of host including orange, papaya, tobacco, pineapple,
and rubber tree. This pathogen causes the root area, stem, and fruits of infected plants to rot. P.
palmivora and P. meadii are usually isolated and been described as a causal agent of the green pod rot,
shoot dieback, abnormal leaf fall, and black stripe diseases in rubber tree. It was also reported that
abnormal leaf fall phenomenon in Thailand and Malaysia are caused by P. palmivora and P. botryosa
(Erwin and Ribeiro, 1996).
At the beginning observation, the most susceptible rubber clones show the symptoms in the immature
green pods. Small lesions reveal the initial of black globules of latex, commonly at the basal end of the
pod, spread rapidly during continuous wet weather will turn into brown water soaked and the globules
of latex become larger and more severe. Then, white mass of sporangia soon will cover the pod surface
which is washed by rain down onto young shoots, petioles, leaves, and further in infection will be
happened at stems.
On petioles, infections are commonly found at the globule of latex which is the point of fungal entry
from grey-to-black lesion develops. Leaves will fall from the petioles at this stage, through leaflets often
turns to reddish-brown.
On leaves, the symptoms are brownish, circular water-soaked lesions occur on the lamina with the fine
droplets of coagulated latex in concentric rings. Lesions finally merge to form larger, asymmetrical
necrotic areas and leaflets are easily dropped on vigorous shaking. Infection of shoot leads the shoot
dieback. Infections on shoots result in depressed dark brown commonly found a white mat of sporangia
(Erwin and Ribeiro, 1996).
During the rainy season, the tapping wound will be infected when lesions on pods are actively
sporulating and develops the vertical parallel depressions. The removal of the infected bark will show
the vertical black lines on the wood that has external depressions (black thread or black stripe). At the
severe stages, the bark will burst, causing gaping wounds with smelly pads of coagulated latex between
the bark and wood (Erwin and Ribeiro, 1996).
Colletotrichum Leafspot Disease (CLD)
Colletotrichum leaf spot disease (CLD) is caused by Colletotrichum acutatum (C. acutatum),
ascomycete fungi which attacked leaves of the young plants and the leaves are developed toward the
latter part of the refoliation season. CLD can cause dieback at the weakened green shoots. This disease
can be are occur during the whole year and becomes dominant during the rainy season, causing major
defoliation in the most susceptible clones.
The symptoms start when tender leaves being produced right after the bud burst is susceptible to
infection. Once the infection is affected the immature leaves, it will start at the tip of the leave and
spreads towards the base of the leaf results the necrosis. When the symptoms become severe, the leaves
are distorted, dry and fall, leaving the petioles on the stem for a short period (Figure 3). The diseased
parts fall away and leaving the unaffected area of the lamina on the shoot. Natural resistance of the host
normally prevents extensive damage at the stage semi-mature and mature leaves. Infected leaves are
covered with spots having a yellow halo in the brown margin. The spots increased and become more
severe.
Defoliation of Colletotrichum causing dieback of succulent shoots of young buddings, and sometimes
the fungus affecting the bud patch and finally plant death. Due to the infection, it also can make plant
gradual death of the twigs and branches as well as kill the whole tree when it is highly susceptible to
the disease especially at higher elevation in that area when wet weather is experience continuously
(Figure 3) (Wastie, 1975).
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Powdery Mildew
Powdery mildew infection on the rubber trees are caused by Oidium heveae (O. heveae) and it is a vital
infection that happens in the rubber plantations worldwide. There are many reported outbreaks of
powdery mildew in India, Brazil, Malaysia, and Papua New Guinea (Beeley, 1933; Mitra and Mehta,
1938; Shaw, 1967). It might be that the distribution of this pathogen is transported from the planting
materials. Other reports also stated that the outbreaks in Papua New Guinea were spread by rubber
planting from one island to another (Shaw, 1967).
This disease causes discoloration, defoliation of young shoots, and even curling the margins on older
leaves. The powdery mass of fungus cover the whole upper and lower surfaces or appear in patches
only on the leaves and those been affected will left petioles attached to the twigs giving a broom-stick
appearance. After a few days, the petioles slowly will fall follows with the dieback of twigs. But to the
older leaves, these white patches may create necrotic spots and reduce the photosynthetic efficiency,
while the infected flowers and tender fruits will shed and affecting seed production.
The impacts of susceptibility infection are depending on the age of rubber leaves. Cultivated rubber tree
associated with Oidium heveae isolated from rubber leaves at three different maturity stages: bronze
coloured phase, light green phase and bronze phase. They discovered that the maximum number of
conidia produced by the leaves in the coloured phase, although at the light green phase, it took the
longest time for production of conidia, immature leaves colour indicates most susceptible to powdery
mildew causing fungus. Rubber flowers are most susceptible to Oidium hevea than the leaves, which
results in a poor fruit pod set.
The infection starts with germination of conidia, the formation of penetration tube then penetrate the
plant cuticle using both actions of enzymes and mechanical pressure. Haustoria will obtain the nutrients
from the tissues of the host after the leaf surface are fully colonized. Each epidermal cell commonly
consists of a single large ellipsoid haustorium, with the long axis oriented vertically to the plane leaves
in the lumen of the epidermal cell. A collar-like structure has been discovered with encircling the neck-
like area of the haustorium.
Figure 3: Infected leaf tips of Colletotrichum
leaf spot disease (Thomson, 2017)
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The most severe of powdery mildew results in major defoliation and reduced canopies. It will cause the
retardation of growth rate, yield loss as well as poor bark renewal. The continuous defoliation in the
areas where the disease is unsuccessful controlled, it will result in dieback of twigs and branches since
it also associated with secondary parasites, namely Botryodiploidia theobromae. Moreover, weather
conditions like cloudy rains, drizzle rain or misty nights with dew forming during refoliation can favor
this serious disease outbreak and even under shaded conditions and in high elevation, this disease is
very persistent all year round. When this powdery mildew infection achieves the conidial stage of
fungus, dusting some sulfur to the rubber trees at periodical intervals is the only method in treating this
disease when the infection is severe theobromae (Min et al., 2012).
Leaf Blight Disease
Leaf blight (LB) disease caused by Fusicoccum species (Fusicoccum spp.) is one of the diseases which
reduced the growth and performance of rubber trees. Fusicoccum spp. member of family
Botryosphaeriaceae is a common endophyte, parasites, and saprophytes of a large variety of plants
(Slippers and Wingfield, 2007; Begoude et al., 2010). The first report of Fusicoccum infection in
Malaysia was reported.
Fusicoccum infected large lesions with concentric brownish zone and rusty brown pinhead size spots
on the rubber leaves and within four months, the infected young leaves will fall (Nyaka et al., 2012).
The symptoms on infected leaves are similar to anthracnose, except the infected parts were extensive
with sinuate to undulate margins with a concentric brownish zone standing out against uninfected
portions that remain green. If severe symptoms affected those rubber trees, embedded pycnidial
conidiomata were formed abundantly on the upper surface of the leaves (Figure 6). If been under
prolonged moist conditions, salmon-colored conidial tendrils oozed from the ostioles and the affected
leaves turned bronze then fell gradually (Radziah and Chee, 1989). However, this disease only
developed on fully expanded leaves in contrast to new leaves.
Figure 4: Powdery mildew on mature leaves of
rubber tree (Li et al., 2016).
Figure 5: Attached petioles after leaf material fall
off (Liyanage et al., 2016).
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Brown Bast
Brown bast attacked the panel part of the rubber tree. Known as tapping dryness, this disease imposes
an important threat to the rubber plantations in most of the rubber producing countries, resulting in
severe loss of latex yield. Brown bast obtained its name from the effect on the rubber tree which reduces
the latex harvest to be half-done and finally results in total dryness of the tapping zone. This case has
been reported in plantations from the early stages of rubber cultivation. The first report was in Brazil
on the wild rubber from the Amazon forest in 1887 (Rutgers and Dammerman, 1914). .
The first symptoms of brown bast syndrome appeared as small dry patches on the tapping zone. These
patches are clearly visible right after tapping and just before the latex begins to flow. The latex obtained
from tapping such trees is very low and if been harvest continuously, in the end, the whole tree would
be completely dry. The more severe symptoms are swelling and cracking on the bark right below the
tapping zone (Figure 7). This disease does not lead to the death of the rubber tree, the loss of latex been
harvest is a serious concern to the planters. The incidence of the bark dryness of the rubber trees has
long recognized as the first clear sign of brown bast symptom (Petch, 1921; Sanderson and Sutcliffe,
1921). The sign of the brown bast also presents even in untapped rubber trees has also been detected.
Other symptoms of brown bast are the apparent failure to spread from virgin bark to regenerated bark
and from one panel to another. The disorder of latex vessels is essential and results to no latex from
those vessels in diseased bark because the latex is coagulated as well as lead to the death of the vessels
(Paranjhothy et al., 1975).
In the plantation, the brown bast is occurred randomly, spread along the lines of the tree and ultimately
change the physiological characteristics (Lacrotte et al., 1997). At first, the symptoms displayed as
partial dryness with no browning on tapping cut. Later, the symptoms turn to brown and become thick
followed by the presence of deformation and cracking of the bark (Pakianathan et al., 1992; Gomez et
al., 1990). The disease spreads aggressively from the first tapping panel to the second tapping panel
which exhibits drying symptoms on the tapping cut (Murong et al., 1994).
On the basis of the tapping panel bark observation during tapping, the bark is able to dry with various
degrees which comprised of simple tendency dryness, typical dryness, more or less and complete
dryness (De Fay and Jacob, 1989). Therefore, the production of latex become less and swells on the
tapping cut. These characteristics are predicted as typical dryness symptoms caused by brown bast cut
(Rands, 1921; De Fay 1982).
The development of brown bast is promoted by water and nutrients stress during and after wintering
season where the availability of soil water is limited (Schwelzer, 1936; Vollema, 1949; Compagnon,
1953). Therefore, no water can be absorbed by root. Other research reported that the development of
brown bast could occur when a large of quantities of latex is removed repeatedly and caused water
available in the bark is fluctuate (Sharples and Lambourne, 1924). Based on the physiological
Figure 6: Brownish zone lesions of leaf blight disease on rubber leaves.
(Nyaka et al., 2012
).
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characteristics, infected and healthy trees are unable to differentiate. However, they can be distinguished
by the weakness of metabolism and lutoid (Sype, 1984).
White Rot Disease (WRD)
The white rot disease (WRD) is one of the serious disease infecting the H. brasiliensis all around the
world. White rot fungus or the Rigidosporus microsporus (R. microsporus) is an economically
important pathogen of the tropical rubber tree in the plantation (Oghenekaro et al., 2014). White root
disease usually infected several tropical crops species and was first discovered in 1904 as a pathogen
of rubber tree in the botanical garden in Singapore (Holiday, 1980). These pathogens produce
rhizomorphs associated with wood in the soil and capable of infecting adjacent tree roots.
White root disease has a widespread by attacking rubber plantations in Central, West and East Africa
and Southeast Asia. The epidemiology of the WRD including symptoms and development is different
between plantations located in Africa and Asia (Riggenbach, 1960). In Asia and Africa, R. microporus
also infect another plant hosts and it became parasitic on other perennial crops like Anana comosus
(Pineapple), Delonix regia (Flamboyant tree), Tectona grantis (Teak), Greenwayodendron suaveolens,
Cocos nucifera (coconut), and Triplochiton scleroxylon (Obeche) (Nandris et al., 1987 a; Begho and
Ekpo, 1987).
H. brasiliensis exhibits natural resistance to penetration of root pathogens. Colonization of living tissues
by pathogen on the rubber tree is to obtained nutrients from the host and caused the damaging and
weakening of the plant with releasing toxins or by preventing the plant's defense mechanism (Jayasuriya,
2004). The interaction of host-parasite will attacks by R. microporus on the taproot of the rubber tree.
Disease infection process occurs in three stages which are penetration, colonization, and degradation.
At the beginning of infection, the pathogen will penetrate the root system and colonize the living tissues
and the mycelium will degrade the host’s cell structures. R. microporus usually carry out penetration
and colonization of their host cell wall repeatedly and it carries out the disease infection activities either
by mechanical penetration through colonized opening wounds or enzymatic digestion (Nicole et al.
1986). Affected tissues are colonized through pores penetration, by perforation and digestion of cell
walls and pits of the vascular tissues (Nandris et al., 1987).
Infected trees with WRD exhibited general foliage discoloration, then develops to premature flowering
and fruiting. Affected tree branches will cause dieback resulting destroyed the whole tree canopy and
later dies. R. microporus then forms extensive firm semi fleshy, often tiered brackets on the collar of
infected trees in the high severe stage of the disease. Commonly, formations of basidiocarps come up
and after the trees have been dead for a while. The appearance of basidiocarps (Figure 7b) are the upper
Figure 7: Brown bast of rubber tree (Correa, 2004).
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surface of concentric zones is brownish-orange with a bright yellow margin when fresh and the lower
surface is reddish-brown. When the infected roots are exposed, lavishly branched white rhizomorphs
are readily seen. Flattened mycelia (rhizomorphs) strands of 1-2 mm thick that grow strongly attached
to the surface of infected roots (Figure 7a).
At the infection point, R. microporus penetrates the taproot down the soil. Since the infection happens,
rhizomorphs are changed morphogenetically state into infectious hyphae that exhibiting degrading
extracellular enzymes capable of wood rotting (Nandris et al., 1987). Colonization of mycelia within
the taproot is developed towards the collar region and other parts of the root. The first infection on wood
is brownish then turns cream and soft. This infection may produce extracellular enzymes for the
degradation of lignin in the cell walls of the root system. Basidiocarps can be seen at the collar region
of the tree and produce a large number of basidiospores especially during rainy season, one of the most
prominent biology of R. microporus (Nandris et al., 1987).
Brown Rot Disease (BRD)
Brown rot disease (BRD) is one of the important diseases that infected the root parts of the rubber tree.
This disease is caused by a basidiomycete fungus, Phellinus noxius (P. noxius). P. noxius is a facultative
parasite that obtained its nutrients from dead and dying plant tissue. The enzyme secretion from P.
noxius breaking down the lamella and cell wall of the plant. The symptoms of the brown rot disease on
the rubber tree are typical as caused by many root rot pathogens, which are slowing the plant growth,
yellowing and wilting of leaves, branch dieback, and plant death. The above-ground symptoms are
caused by the root and butt rot that constraint the uptake and transport of water and nutrients from the
soil (Brooks, 2002). The visible rot at the fallen trees is another general sign that the tree is affected by
the disease. The deadwood is started to discolour reddish-brown and finally becomes crumbly, dry, and
white.
P. noxius pathogenic existence will exhibit a thick, medium brown adhere to the black crust of
mycelium as it found surrounding infected roots and formed around lower stems under humid
conditions. Even in the dark understory of the rainforest, the sign are noticeable as the edge of crust is
often creamy white, glistens with drops of clear, brownish exudate. A cluster of white mycelium can be
found between the sapwood and bark (Brooks, 2002).
Conclusion
Most of rubber tree diseases are infected by fungus and some of the diseases can be a serious problem
in the rubber plantation, such as SALB disease and white rot disease. Large-scale infection of fungus
can become a serious epidemic to the more mature rubber trees. Several issues require further researches,
for example, the causal agent of brown bast disorder is still failed to find the exact caused. Long-term
research is needed to find the best cure for disease outbreak while improving sustainable natural rubber
production nationwide. Effective management of all diseases is very important to have people
(b)
(a)
Figure 3: a) Rhizomorph strands on the collar of root; b) Basidiocarps of Ridigosporus lignosus
(Invasive Species Compendium, 2018).
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participation that can reduce the severity of infection as well as reducing disease outbreak for better
management of the plantations to boost productivity.
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... The Malaysian rubber plantations face a serious threat from pathogens. Several pathogens cause severe losses in latex yield and include Phellinus noxius (Nandris et al., 1996), Colletotrichum leaf spot disease (Mazlan et al., 2019), Rigidoporus microporus (Nandris et al., 1996), South American Leaf Blight (Onokpise and Louime, 2012), and powdery mildew (Liyanage et al., 2016). Rigidoporus microporus, one of the most destructive pathogens, causes white root rot disease, leading to substantial latex yield losses. ...
... Eq. (6) moves infected trees to treated, where they remain for the life of the model. Once the trees start showing symptoms such as leaves turning yellow and wilting (Fatin Farhana et al., 2017;Wattanasilakorn et al., 2012), the trees flower early and begin dying, while the fungus's rhizomorph forms along the root and trunk (Kaewchai and Soytong, 2010;Mazlan et al., 2019;Nandris et al., 1996). The plantation owners can utilise several methods to control and limit damage from Rigidoporus microporus, such as spraying the trunks with a fungicide. ...
... Once a state becomes infected with the pathogen, it stays infected for the life of the model. For example, Rigidoporus microporus forms rhizomorphs several meters long in the soil (Kaewchai and Soytong, 2010;Mazlan et al., 2019). The rhizomorphs grow in the soil and search and envelop healthy rubber trees' roots (Go et al., 2021). ...
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Research indicates that white root rot disease can inflict severe economic damage on the Malaysian rubber industry, which is caused by the fungus, Rigidoporus microporus. Accordingly, the economic impact of this disease is assessed by the partial equilibrium model, called the Malaysian Agriculture and Plantation Greenhouse Gas Model. The model represents the major commodities of the Malaysian agricultural markets and predicts market prices and quantities between 2023 and 2063. Although Malaysia has a million hectares of rubber plantations in 2018, the results indicate the rubber plantations could lose 400,000 ha to the oil palm plantations. Furthermore, a slow 5% fungal growth rate could infect half of the remaining stands of rubber trees. The oil palms help buffer the losses from the fungus since Rigidoporus microporus cannot infect oil palm trees. The loss of the rubber trees leads to rising natural rubber prices that decrease natural rubber exports and increase natural rubber imports. As the fungal infection growth rate increases, the natural rubber price rises further while the trade balance worsens. In addition, the rubber plantation owners can eradicate the fungus by paying an annual treatment cost per hectare. A higher treatment cost leads to the landowners treating fewer trees.
... The Malaysian rubber plantations face a serious threat from pathogens. Several pathogens cause severe losses in latex yield and include Phellinus noxius (Nandris et al., 1996), Colletotrichum leaf spot disease (Mazlan et al., 2019), Rigidoporus microporus (Nandris et al., 1996), South American Leaf Blight (Onokpise and Louime, 2012), and powdery mildew (Liyanage et al., 2016). Rigidoporus microporus, one of the most destructive pathogens, causes white root rot disease, leading to substantial latex yield losses. ...
... Eq. (6) moves infected trees to treated, where they remain for the life of the model. Once the trees start showing symptoms such as leaves turning yellow and wilting (Fatin Farhana et al., 2017;Wattanasilakorn et al., 2012), the trees flower early and begin dying, while the fungus's rhizomorph forms along the root and trunk (Kaewchai and Soytong, 2010;Mazlan et al., 2019;Nandris et al., 1996). The plantation owners can utilise several methods to control and limit damage from Rigidoporus microporus, such as spraying the trunks with a fungicide. ...
... Once a state becomes infected with the pathogen, it stays infected for the life of the model. For example, Rigidoporus microporus forms rhizomorphs several meters long in the soil (Kaewchai and Soytong, 2010;Mazlan et al., 2019). The rhizomorphs grow in the soil and search and envelop healthy rubber trees' roots (Go et al., 2021). ...
... Di daerah asal tanaman karet seperti Brazil dan negaranegara Amerika Selatan, SALB merupakan penyakit utama yang menyerang hampir semua klon sehingga budidaya karet tidak terlalu berkembang di daerah tersebut. Di Asia Tenggara yang merupakan sentra produksi karet alam dunia, SALB juga tidak berkembang, namun PGD Corynespora, Colletotrichum, Oidium, dan JAP menjadi ancaman utama terhadap penurunan produksi (Situmorang et al., 2007;Manju et al., 2015;Mazlan et al., 2019). Kondisi tersebut diperparah oleh terjadinya outbreak PGD baru pada tahun 2018 yang menyerang semua klon karet yang mengakibatkan penurunan produksi lateks mencapai 45% (Febbiyanti & Fairuzah, 2019). ...
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The development of plant resistance selection methods against major diseases needs to be done, one of which is selection assisted by molecular markers. The aim of the study was to evaluate the resistance of rubber plants to the main diseases that attack rubber plants, namely Corynespora, Colletotrichum, and Oidium leaf fall disease, as well as white root disease (WRD), furthermore, to identify QTLs associated with these diseases. Analyzed population were 201 F1 progenies obtained from crosses of PB 260 x SP 217 clones. Observation of symptomps each disease carried out every three months until immature period 2. The genetic link maps of population were compiled by using 263 of selected SSR markers. QTLs identification were done by joint the disease observation data on two years old of plant and genetic linkage map using Map QTL software. The observations showed that there were variations of resistance level of F1 progenies to attack of each pathogen. Resistance of F1 to Corynespora and Colletotrichum leaf fall disease as well as to white root disease had a normal distribution with disease severity level of 0-9%, 0-22.5%, and 0-7% respectively. Otherwise to Oidium leaf fall disease, all of F1 progenies had a high resistance level which the disease severity less than 1.5%. Three QTLs related to Corynespora leaf fall disease resistance were identified in LG 10, 14, and 15 with LOD range 3.1 to 5.19 and the highest QTL effect was 17.7%. Four QTLs related to Colletotrichum leaf fall disease resistance were found in LG 1, 3, 10, and 16 with LOD 3 to 4.44 and the highest QTL effect was 11.2%. On LG 8 LOD 2.9, there was a putative QTL related to WRD resistance, while a QTL related to Oidium leaf fall disease had not been identified. QTLs that have been identified with LOD above 3 are expected to be stable and will be analyzed periodically so that they can be used as a tool for resistance selection. Abstrak Pengembangan metode seleksi ketahanan tanaman terhadap penyakit utama perlu dilakukan, salah satunya adalah seleksi dengan bantuan marka m o l e k u l e r. P e n e l i t i a n b e r t u j u a n mengindenfikasi evaluasi ketahanan tanaman karet terhadap penyakit utama yang menyerang tanaman karet yaitu penyakit gugur daun Corynespora, Colletotrichum, dan Oidium, serta penyakit jamur akar putih (JAP) dan identifikasi QTL yang terpaut dengan penyakit tersebut. Populasi yang digunakan adalah 201 progeni F1 hasil persilangan klon PB 260 x SP 217. Pengamatan gejala setiap penyakit dilakukan setiap tiga bulan sekali sampai TBM 2. Peta pautan genetik yang digunakan adalah peta yang dihasilkan dari penelitian sebelumnya dengan menggunakan 263 marka SSR terseleksi. Identifikasi QTL dilakukan dengan menggabungkan data pengamatan penyakit tanaman umur dua tahun dengan peta pautan genetik m e n g g u n a k a n p r o g r a m M a p Q T L. Pengamatan menunjukkan bahwa terdapat
... Rubber plantations constitute 22.14% of landcover in Xishuangbanna (Yunnan) and the spread continues (Xu et al. 2014). This perennial crop has been associated with several fungal lifestyles including endomycorrhizae, endophytes, saprotrophs and pathogens (Jinji et al. 2007, Seephueak et al. 2010, Priyadarshan 2011, Rocha et al. 2011, Mazlan et al. 2019, Chaiwan et al. 2021. Only a few studies have been conducted to explore fungal communities associated with rubber plants in China (Jinji et al. 2007, Dai et al. 2010, Tu et al. 2012, Liang et al. 2021, Xu et al. 2022. ...
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A total of approximately 104,000 fungal species can be expected in Yunnan. However, approximately 6000 fungal species have been reported from the province leaving much to be described. This study introduces a new species, Fitzroyomyces xishuangbannaensis sp. nov and a new collection of Fit. cyperacearum from Yunnan province, China. The taxa were characterized based on morphological characteristics and combined multi-gene phylogenetic analyses. Both maximum likelihood (ML) and Bayesian inference posterior probabilities (PP) were conducted for combined LSU, ITS and mtSSU sequences data. The new Fitzroyomyces species formed a distinct clade among the extant species of Fitzroyomyces with high statistical supports in the phylogenetic analyses while our new isolate nested together with the corresponding strains of Fit. cyperacearum. A key to Fitzroyomyces species and a synopsis table of morphological characteristics for Fitzroyomyces are provided to support the taxonomic placement.
... However, the clone RRII 105 with low K content was found as susceptible to more leaf drying to drought stress also support the role of high K in drought tolerance of clones. As far as the leaf diseases are considered, abnormal leaf fall and powdery mildew caused by Phytophthora palmivora and Oidium hevea steinm, respectively, are the major crop loss resulting diseases in India (Mazlan et al., 2019). Among the clones studied, the clone RRII 105 and GT1 were reported as resistant clones to phytophthora leaf fall on prophylactic spraying (Edathil et al., 2000). ...
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Natural rubber (Hevea brasiliensis Wild. Ex A. Juss.) Müell. Arg. is an important commodity crop grown in world over for industrial raw material rubber latex for various products, mainly tyre manufacturing. Hevea propagation is through clones evolved by breeding as cultivars with desired characters. This article presented the biomass and nutrient accumulation of four important Hevea clones viz. RRII 105, RRII 118, RRII 203 and GT1 at 30 years age. Biomass and nutrient concentration of tree components viz. trunk, branches, leaf and root were assessed by uprooting the trees in the field and standing trees using allometric equation. Among the different clones, RRII 118 and GT1 recorded higher biomass compared to RRII 105 and RRII 203. Above-ground biomass (88-93 per cent) varied more than below-ground biomass (7-11 per cent). The high yielding clones had higher leaf and root biomass. Drought tolerant and timber clones viz. RRII 118 and RRII 203 recorded higher K and high yielding clone RRII 105 had higher Ca accumulation. Biomass removal of these clones may lead to deficiency of K and Ca in soil and hence needs the external supplements. The relation of high Ca content and leaf disease of fungal origin is promising for further studies. The higher accumulation of iron and manganese indicated the tolerance of Hevea to these elements and possibility of phytoremediation. The per cent contribution of nutrients to total biomass varied less between clones and was below 3 percent at the age of 30 years and this is evidence of adjustments in proportions of nutrients in Hevea irrespective of clonal variations.
... In addition, they can easily react to any changes and diseases that threaten the tree. The rubber tree is risky in obtaining the disease during the growth through four ways which are via the stem, leaf, panel, and also root (Mazlan, Sulaiman, Wahab, & Zulperi, 2019). Good agricultural practice (GAP) can be one of the solutions to the problem. ...
... (Situmorang et al., 2007). Hingga saat ini PGDC masih merupakan salah satu penyakit utama yang menyerang perkebunan karet di India (Manju et al., 2015) dan Malaysia (Mazlan et al., 2019) dan negara-negara penghasil karet lainnya termasuk Indonesia. Meskipun outbreak penyakit gugur daun Pestalotiopsis terjadi di Indonesia pada tahun 2018, pengamatan di lapangan menunjukkan bahwa intensitas serangan PGDC masih terlihat tinggi. ...
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Serangan penyakit gugur daun Corynespora (PGDC) masih menjadi salah satu permasalahan utama dalam budidaya tanaman karet. Berbagai upaya pengendalian sudah dilakukan salah satunya adalah dengan penggunaan klon-klon karet unggul yang resisten sebagai bahan tanam. Penelitian bertujuan untuk mengidentifikasi tingkat ketahanan 30 progeni F1 calon klon-klon unggul baru yang merupakan hasil persilangan BPM 1 x RRIM 600 terhadap PGDC. Penelitian dilakukan menggunakan Rancangan Acak Lengkap dengan tiga ulangan. Tingkat resistensi ditentukan berdasarkan intensitas kelayuan daun akibat sensitivitas daun tanaman terhadap filtrat toksin empat isolat C. cassiicola yang mengakibatkan terjadinya kehilangan cairan pada daun. Hasil penelitian menunjukkan bahwa intensitas kelayuan daun setiap progeni berbeda nyata terhadap setiap isolat C. cassiicola. Terdapat interaksi antara genotipe progeni dengan jenis isolat yang digunakan dalam pengujian. Isolat CC-GT 1 memiliki tingkat virulensi yang paling tinggi diantara 4 isolat yang digunakan dalam pengujian. Isolat yang tergolong haplotipe 1 (CC-GT 1 dan CC-IRR 104) memiliki tingkat virulensi yang lebih tinggi dari haplotipe 2 (CC-RRIM 600 dan CC-IRR112). Ketahanan progeni F1 terhadap PGDC sangat beragam dimana 4 progeni tergolong sangat tahan, 14 progeni tahan, 7 progeni rantan dan 5 progeni tergolong sangat rentan teradap PGDC. Progeni yang memiliki ketahanan yang tinggi berpeluang menjadi klon-klon unggul di masa yang akan datang.
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This study focuses on ascomycetes associated with Para rubber trees, collected from plantations in Thailand. We provide descriptions and phylogenies for one new genus, seven new species, two asexual-sexual morph connections, 20 new host records, and one reference specimen. Dothideomycetes are dominant among ascomycetes on Para rubber. Only three species from our collection have previously been reported from Para rubber in the Amazon Forest, where Para rubber originates. Most taxa found on rubber trees in this study have previously been recorded in Thailand, either on Para rubber or different hosts. It is apparent that the taxa jumped from unrelated hosts to colonize rubber. A checklist of fungi and fungus-like organisms associated with Para rubber is also provided. The checklist includes references for each taxon, life mode information, and distribution. The checklist comprises 785 species and 180 taxa identified only to genus from 59 countries. The taxa in the checklist belong in 67 orders, 168 families, and 513 genera
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Latexes of different plants contain a mixture of molecules which exhibit diverse activities against invaders. Among many other functions, they protect plants against herbivores, insects, fungi, parasites, bacteria and viruses. Due to the presence of pharmacologically active substances, mankind for centuries have applied latices and their preparations for their beneficial effect on human health. Most of these substances exert analgesic, wound healing, anti-pathogenic (antiviral and antimicrobial), anti-parasitic, anti-diabetic and other activities, which have been broadly exploited in traditional medicine. Following volume 93, this review presents popular latex applications and discusses perspectives for their use in medicine, agriculture and industry.
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Powdery mildew disease of rubber trees affects young rubber leaves, buds, inflorescences and other immature tissues reducing rubber latex yields by up to 45%. The disease is present in all rubber-growing regions, with a high incidence rate in subtropical environments. The causal agent of powdery mildew disease of rubber trees was first described as Oidium heveae, but later research on the morphological characteristics suggests that O. heveae was in the past confused with Erysiphe quercicola. However, the most appropriate classification is still under debate between the genera Golovinomyces or Podosphaera. Molecular and phylogenetic analyses have established some relationships between rubber powdery mildew fungus and other powdery mildew species, but the generic sexual state of rubber powdery mildew fungus has not yet been established. Rubber powdery mildew conidia are wind-spread spores that are produced in great numbers when growth conditions of the disease are favourable. The optimum conditions for conidial germination are 97–100% relative humidity and temperatures between 25 and 28°C. While some newly bred rubber clones have shown resistance to the disease, it can also be controlled with a number of fungicides and biological control agents. It is clear from recent knowledge about climate–fungus relationships that changes in weather strongly influence disease incidence and severity. The aim of this review is to highlight the classification conflicts, main causes and influencing factors behind the disease spreading, as well as draw attention to the impact of weather changes on the outbreaks of the disease. The information in this review will be helpful to adopt better control measures of the powdery mildew disease of rubber, especially in higher humidity areas, thereby minimizing the loss of rubber yields due to this disease.
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Powdery mildew is an important disease of rubber trees caused by Oidium heveae B. A. Steinmann. As far as we know, none of the resistance genes related to powdery mildew have been isolated from the rubber tree. There is little information available at the molecular level regarding how a rubber tree develops defense mechanisms against this pathogen. We have studied rubber tree mRNA transcripts from the resistant RRIC52 cultivar by differential display analysis. Leaves inoculated with the spores of O. heveae were collected from 0 to 120 hpi in order to identify pathogen-regulated genes at different infection stages. We identified 78 rubber tree genes that were differentially expressed during the plant-pathogen interaction. BLAST analysis for these 78 ESTs classified them into seven functional groups: cell wall and membrane pathways, transcription factor and regulatory proteins, transporters, signal transduction, phytoalexin biosynthesis, other metabolism functions, and unknown functions. The gene expression for eight of these genes was validated by qRT-PCR in both RRIC52 and the partially susceptible Reyan 7-33-97 cultivars, revealing the similar or differential changes of gene expressions between these two cultivars. This study has improved our overall understanding of the molecular mechanisms of rubber tree resistance to powdery mildew.
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Major tree crops contribute substantially to the economy of many developing countries on the Asian, African and Latin American continents. For example, coffee is the main revenue earner for Kenya. This book provides a comprehensive review of the agronomy, botany, taxonomy, genetics, chemistry, economics, and future global prospects of a range of crops that have great food, industrial and economic value such as cocoa, coffee, cashew, oil palm and natural rubber. Discusses the major tree crops of great economic value to the developing world The author is an eminent scientist who has won numerous awards for his work in this area.
Article
A method for culturing powdery mildew (Oidium heveae) from isolated leaves of Hevea brasiliensis was evaluated, which included three steps: Leaves and fungi selection, nutrient solution and culture dish preparation, fungi inoculation and culture. The culture time and produced conidia number were considered as decision index. We tested the influence of micro components of nutrient solution including 6-benzylaminopurine (6-BA), salicylic acid (SA) and vitamin C (VC) and evaluated the culture difference of various leaf phenological phases and rubber tree clones. The results show that the longest culture time of isolated leaves emerged on modified Murashige and Skoog (MS) macro elements with 4 mg/L 6-BA, 20 mg/L SA, 1 mg/L VC. The colour phase leaf was the preferable choice for culturing average 15 to 16 days and producing 3.2222 × 10 6 mL -1 conidia. The culture effects of using various rubber clones were different and higher resistance clones cultured less conidia. The method leading to mass production of powdery mildew was simple using a climate incubator to resolve problems linked to season and space limitation and preservation of powdery mildew. This method could improve rubber resistance breeding process. Key words : Hevea brasiliensis, Oidium heveae, in vitro culture, nutrient solution, phenological phase.