INTERNATIONAL CONFERENCE OF INDONESIAN FORESTRY RESEARCHERS (INAFOR)

Invited Paper

Managing Ganoderma for Sustainable Plantation Forests in Indonesia

Abdul Gafur, Budi Tjahjono and Marthin Tarigan

RGE Fiber R&D, Pangkalan Kerinci 28300, Indonesia Corresponding author: Email: abdul_gafur@aprilasia.com; gafur@uwalumni.com

Paper prepared for The First International Conference of Indonesian Forestry Researchers (INAFOR)

Bogor, 5 – 7 December 2011

INAFOR SECRETARIAT Sub Division of Dissemination, Publication and Library

FORESTRY RESEARCH AND DEVELOPMENT AGENCY Jl. Gunung Batu 5, Bogor 16610

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Managing Ganoderma for Sustainable Plantation Forests in Indonesia

Abdul Gafur, Budi Tjahjono and Marthin Tarigan

RGE Fiber R&D, Pangkalan Kerinci 28300, Indonesia Corresponding author: Email: abdul_gafur@aprilasia.com; gafur@uwalumni.com

Abstract

The reforestation effort in Indonesia is aimed at sustaining the supply of forest products while

conserving the natural forests. This will maintain not only their economic importance, but

also environmental and social roles. The Ministry of Forestry has set a development of

plantation forests, both industrial and community-based plantation forests. In line with the

policy, industrial plantation forests of fast-growing species, especially acacias and eucalypts, are

being established on a large scale basis. A number of diseases have since been recorded.

Root-rot is the most economically significant disease of Acacia mangium Willd. Elucidation of

the identity of the causative organisms is very critical to develop its control strategies.

Morphological and molecular characterizations have identified Ganoderma philippii Karst. as the

fungal species most commonly found associated with the disease in A. mangium and eucalypt

plantations. Components of integrated disease management including cost-effective and

environmentally friendly biocontrol measures using Trichoderma and Gliocladium are also

discussed in this paper.

Introduction

The Government of Indonesia has developed forest plantation programs as an anticipation to

the ever increasing global wood demands. Since mid 1980s the area of both industrial and

community-based forest plantations in Indonesia, particularly those of short-rotation species,

has increased dramatically. Arisman and Hardiyanto (2006) stated that by 2006 industrial

forest plantations already covered nearly 2.5 million ha, with various tree species being planted

for wood and pulp production. This is aimed at providing the supply of forest products while

at the same time maintaining the natural forest. Dependence upon exploitation of natural

forest will eventually have to be terminated. Natural forests should be preserved and valued

for their ecological functions and benefits. To fulfill this requirement, development of new

plantation forests in responsible ways is very important. It is expected that through this

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program, not only the economic importance of the forests, but their environmental and social

roles will also be maintained.

As stated above, plantation forests of fast-growing species, especially acacias and eucalypts, are

being established on a large scale basis. One challenge has been to maintain high survival and

productivity of the trees. Disease is considered a limiting factor in plantation forest

production. Root rot (especially red root rot) is considered a major disease of acacias (Gafur

et al. 2007; Golani et al. 2007; Lee 2000; Old et al. 2000; Sankaran et al. 2005; Wingfield et al.

2010). Acacia mangium Willd. and A. crassicarpa Cunn. ex Benth are important species planted

primarily for fiber production in Indonesia and elsewhere in South East Asia. Ganoderma

root rot disease is also found on different species of eucalypts although at present it occurs in

lower magnitudes, (Coetzee et al. 2011; Francis et al. 2008; Gafur et al. 2010).

Disease Symptoms and Signs

Diseased acacia trees usually show a rapid decline, evidenced by off-color and sparse foliage

wilting, and death (Figure 1 top). Recently infected roots are covered with a red-coloured

rhizomorphs and white mycelium (Figure 1 bottom, left). Fruiting bodies are occasionally

observed at the bases of dead trees (Figure 1 bottom, right). Foliage yellowing and senescence

usually precede tree death. As infected woody materials (roots, stumps and other debris)

remaining in or on the soil continue to build-up, root rot incidence increases in the following

rotations. In the case of the Eucalyptus, roots have identical signs of infection including red

rhizomorphs and the typical mottled pattern of mycelial growth below the bark. Fruiting

bodies are sometimes also found on trees with roots having these symptoms. The current

level of damage and incidence of this disease requires that effective management be developed

to secure sustainable production of plantation forests in Indonesia. This is, however, not easy.

Effective control strategies for root rot disease are not simple once the disease infects plants.

Field management is complicated by the fact that its pathogen survives in the soil and on the

woody debris between rotations. The discussion focus of this paper is the pathogen

responsible for root rot disease in plantation forests with the emphasis on acacia and eucalypt

plantations and options for its control in the field based on currently available information.

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Figure 1. Symptoms and signs of Ganoderma root rot on Acacia mangium. Young trees

showing yellowing and wilting of leaves (top, left), dead trees (top, right), roots covered with

red-coloured rhizomorphs and white mycelium (bottom, left), and fruiting bodies of

Ganoderma philippii (bottom, right).

The Causal Agent

In the past studies on fungal identification were based heavily, if not solely, on morphology of

reproductive structures such as fruiting bodies or spores, whose presence in nature is

unfortunately not always observed (Gafur et al. 2011a). Recent advancements in molecular

biology, however, have enabled researchers to integrate morphological and molecular

characteristics for identification purposes. While morphology has long been used extensively

in taxonomy, the more recently developed molecular approaches provide excellent ways of

identifying the vegetative stages of fungi (Coetzee et al. 2011; Gafur et al. 2011c).

The causal agent of red root rot disease in acacia plantations had been linked to different

fungal genera. Recent reports, however, indicated that in tropical areas the disease is caused

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by Ganoderma spp. (Gafur et al. 2007; Glen et al. 2009; Golani et al. 2007; Lee 2000;

Mohammed et al. 2006; Old et al. 2000). Ganoderma root rot is also known to affect

Eucalyptus (Francis et al. 2008; Gafur et al. 2010) although the causal agent of the disease has

not been exactly identified (Old et al. 2003). In this paper discussion on the pathogen

responsible for root rot disease in acacia and eucalypt plantations is primarily based on the

work done by Coetzee et al. (2011) who employed both morphological and molecular

approaches. During the study they examined a total of 189 isolates obtained from the newly

infected roots of A. mangium trees, 6 from Eucalyptus roots and 2 from fruiting bodies formed

at the base of trees associated with infected roots. This represented one of the largest single

collections of isolates from newly infected A. mangium roots in root rot centres in Indonesia to

the authors‘ knowledge.

Based on their investigation Coetzee et al. (2011) revealed that Ganoderma philippii Karst. is the

fungal species most commonly found associated with root rot disease in A. mangium

plantations in Riau. DNA-based identification of the collected isolates showed that 97

percent of them represented a single species, G. philippii. Some other basidiomycete species

such as G. mastoporum, Phellinus noxius, and Tinctoporellus epimiltinus are also isolated from

infected roots. The researchers also reported that DNA sequence comparisons and

phylogenetic analyses showed that G. philippii is also the causal agent of the disease on

eucalypts. This has been the first report of G. philippii causing root rot on Eucalyptus in

Indonesia so far.

Disease Management Options

As mentioned earlier there has not been any single effective control of Ganoderma in the

plantation forests. Controlling root rot disease is also difficult because the pathogen survives

on the woody debris and/or in the soil. Thus, it is suggested that compatible components of

integrated disease management be implemented to manage the disease in plantation forests.

As chemical treatments are economically inefficient and environmentally not preferable

(Gafur et al. 2011b; 2011d), silvicultural practices and limiting the growth and spread of the

pathogen are potential options. Similarly, cost-effective and environmentally friendly

biocontrol measures employing consortium of different functional groups of synergistic

microorganisms have been considered as an important component of root rot disease

management in plantation forests (Gafur et al. 2011b; 2011d).

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In one of their experiments Gafur et al. (2011b; 2011d) indicated that Ganoderma incidence in

naturally regenerated A. mangium plots is lower than that in planted plots of the same rotation.

Differences in root architectures are considered to be one of the determining factors in this

case. Early space competition may have forced the roots of naturally grown stands to

penetrate deeper. Also, naturally regenerated stands seem to have a more differentiated

structure of tap roots compared to nursery-raised seedlings. Stands with more vertical and

reduced lateral roots have a higher chance to escape the disease in the field.

Trials in two different locations in Riau (Baserah and Logas) reveal that de-stumping in

general reduces incidence of Ganoderma root rot in plantation forests (Figure 2). This has

been proven particularly in A. auriculiformis, Eucalyptus pellita, and hybrid eucalypt plots. In A.

mangium sites, however, de-stumping fails to decrease disease incidence (Gafur et al. 2011b;

2011d). This might have been due to the fact that in the experiments only big sized roots

were removed (partial de-stumping), whereas smaller wood debris remained in the field as

food base for the pathogen. Another option for field control of Ganoderma disease is the

implementation of the cost-effective and environmentally sound management of biological

control measures using consortium of synergistic microorganisms. For example, in a trial site

it was revealed that Trichoderma reduces Ganoderma incidence by 4.9%, whereas in another

location Gliocladium decreases Ganoderma incidence by 6.7% (Gafur et al. 2011b; 2011d).

Figure2. Partial de-stumping in general reduces incidence of root rot disease.

"Partial" Destumping

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Non Destumping Destumping

Treatment

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Baserah Logas

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Conclusions

Ganoderma root rot in plantation forests, especially A. mangium and eucalypts, is primarily

caused by G. philippii. The disease represents the major disease in plantation forests. There

are, however, options for field management of the disease employing silvicultural practices

and consortium of different functional groups of synergistic microorganisms as biocontrol

agents. These are considered as the key components of root rot disease management in

plantation forests in Indonesia.

References

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Coetzee MPA, Golani GD, Tjahjono B, Gafur A, Wingfield BD, Wingfield MJ. 2011. A single dominant Ganoderma species is responsible for root rot of Acacia mangium and Eucalyptus in Sumatra. Southern Forests. In press.

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