Acacias are of considerable social and industrial importance for tropical reforestation, with about 2 million ha worldwide. The last few decades have seen a major expansion of plantations for industrial use, especially in South-East Asia. Both native and exotic species of Acacia are also widely grown in the Indian sub-continent. Turnbull et al. (1998) reviewed the status of tropical acacia plantations in Asia.

The species which have been most widely planted so far in industrial plantations in South-East Asia are Acacia mangium Willd. and A. auriculiformis Cunn. ex Benth. A. crassicarpa Cunn. ex Benth. and A. aulacocarpa Cunn. ex Benth....

The diseases can be grouped based on the part of the tree which is infected as summarised below.

The ‘leaves’ of the acacias dealt with here, with the exception of true leaves produced by young seedlings, are more properly referred to as phyllodes, and this term will be used throughout. Phyllodes often show a range of fungal spots, blotches and tip necrosis symptoms. Associated pathogens include species of Cercospora, Colletotrichum, Cylindrocladium, Pestalotiopsis, Phomopsis, Phaeotrichoconis, Phyllosticta and Pseudocercospora. In some situations a significant proportion of tree crowns, especially foliage borne on lower branches, can be affected but the impact on growth...

Phyllode rust, penyakit karat (Bahasa Malaysia), karat (Bahasa Indonesia)

Atelocauda digitata (G. Wint.) Cummins and Y. Hiratsuka syn. Uromyces digitatus Winter, Uromyces phyllodiorum (Berk. and Br.) McAlp.

A wide range of tropical and sub-tropical acacias including:

Acacia aulacocarpa, A. auriculiformis, A. crassicarpa, A. koa, A. leptocarpa, A. mearnsii, A. mangium, A. polystachya.

Australia (northern, eastern, south eastern and western), Papua New Guinea, China, Hawaii, Indonesia (including Java, Sumatra and Kalimantan), New Zealand. Although records have not been found for other countries the current distribution of this fungus is likely to include southern Sarawak as it was found in 1998 near...

Gall rust, karat puru (Bahasa Malaysia)

Uromycladium tepperianum (Sacc.) McAlpine, Uromycladium notabile (Ludw.) McAlpine

In Australia these rusts occur on a very wide range of Acacia spp. (Figs 13, 15). A survey of publications showed 57 species of acacias being recorded as hosts of U. tepperianum across Australia (McAlpine 1906; Warcup and Talbot 1981). A survey of the host range of the fungus in the south-west of Western Australia yielded a further 50 records on new hosts (Gathe 1971). The fungus also infects Paraserianthes lophantha ssp. lophantha (Willd.) Nielson in Australia and P. lophantha ssp. montana (Junghuhn.) Nielsen in Java...

Powdery mildew, kulapuk debu (Bahasa Malaysia), penyakit tepung (Bahasa Indonesia)

Oidium spp. are mitosporic fungi (the species of Oidium on these four tropical acacias and its perfect state have not yet been identified), indeed it is possible that more than one species is involved. A teleomorph, Erysiphe acaciae S. Blumer, has been observed on Acacia catechu in India (Bakshi 1976).

Oidium spp. are obligate parasites which attack many hosts. On acacias, powdery mildew is found on the phyllodes, mainly of plants in the nursery and also in the lower crown of young trees in the field. Species of Oidium have...

Black mildew, penyakit tepung gelap (Bahasa Indonesia)

The fungi causing black mildew, Meliola spp., belong to the family Meliolaceae, order Meliolales of the Ascomycota. The black mildews are often confused with the common sooty moulds which are superficial epiphytic saprophytes. The Meliolales, however, are obligate parasites which produce a variety of structures that penetrate host cells.

Species of Meliola are found on leaves and stems of a wide range of hosts in the tropics. Black mildew is common on acacias but there has been little study of the causal organisms. M. brisbanensis has been reported on Acacia auriculiformis and A....

Algal leaf spot, red rust

Cephaleuros virescens Kunze, a green alga of the family Trentepohliaceae, order Trentepohliales, division Chlorophyta.

This plant parasitic alga is found on an extremely wide range of hosts extending from dicotyledonous trees and shrubs to palms. It can infest both twigs and leaves.

Algal leaf spot has been reported worldwide between latitudes 32ºN and 32ºS on many hosts (Chase and Broschat 1992) including ornamental palms, perennial crops such as cocoa, citrus, cloves, tea, pepper, rubber, mango and other fruit trees. It has also been reported on forest trees such as mahogany and teak (Browne 1968) and...

Cylindrocladium foliar blight

Cylindrocladium spp. are widespread and damaging pathogens of a very wide range of plant hosts including acacias. Many Cylindrocladium spp. are known to have perfect stages in the genus Calonectria de Not. Those species of Cylindrocladium known to be associated with foliar infections of Acacia spp. include C. crotalariae (Loos) Bell & Sobers, C. ilicicola (Hawley) Boedijn & Reitsma, C. quinqueseptatum Boedijn & Reitsma (Calonectria quinqueseptata Figueiredo & Namekata), C. scoparium Morgan and C. theae (Petch) Subramanian (Calonectria theae Loos).

C. scoparium causes foliar infection, and stem and root rot of Acacia spp. in Australia (Bertus 1976), foliar spots of A....

Cercospora and Pseudocercospora foliar disease

Two as yet un-named foliar pathogens in the genera Cercospora and Pseudocercospora.

Cercospora sp. infected seedlings of Acacia mangium and A. auriculiformis raised in a nursery at Ingham, Queensland in 1990 and subsequently planted out at several locations in northern Queensland (Old et al. 1996). The pathogenicity of this fungus to other tropical acacias has not been tested. During surveys to determine the extent and occurrence of Cercospora sp. on acacias in plantations and native acacias in northern Australia, a similar fungus was found on A. crassicarpa. At first it was thought that this was...

Leaf spot, bintik daun (Bahasa Malaysia), bercak daun (Bahasa Indonesia)

Phaeotrichoconis crotalariae (Salam & Rao) Subram. A similar and closely related fungus, Helminthosporium (Exserohilum) rostratum (Drechs.) Leonard & Suggs, was reported by Mohanan and Sharma (1988) to cause a leaf spot on Acacia auriculiformis.

This is a pan-tropical fungus with a very wide host range including A. crassicarpa (Old et al. 1996), A. auriculiformis identified as E. rostratum (Mohanan and Sharma 1988), coconut (Miller 1997) and other palms (Chase 1982), cardamom (Dhanalakshmi and Leelavathy 1976), Cyperus iria (Mishra et al. 1972), ornamentals such as Alternanthera sessilis (Ramakrishnan et al. 1972) and vegetable...

Colletotrichum foliar spot, anthracnose.

Colletotrichum gloeosporioides (Penz.) Sacc., teleomorph Glomerella cingulata (Stonem.) Spauld. & Schrenk.

Colletotrichum gloeosporioides is worldwide in distribution, affecting a large number of cultivated as well as wild plants, especially in the warm-humid tropics. It is known to cause die-back, leafspots, seedling blight, and leaf blight of several hosts including tropical acacias (Mordue 1971). The leaf spots incited by this pathogen are often called anthracnose, being limited in extent with necrotic areas bounded by brown, black or discoloured margins.

Anthracnose disease of Acacia phyllodes is reported from various tropical countries. In India, C. gloeosporioides and Colletotrichum sp. cause...

Leaf spot, leaf necrosis

Pestalotiopsis spp. Identification of this group of fungi is based on the characteristic five-celled spores. The three central cells are pigmented in various shades of brown and the terminal cells are free of pigment. The basal cell is typically conical with a short simple appendage whereas the apical cell bears two or three appendages reminiscent of a mediaeval jester’s cap. Species identified on tropical acacias include P. acaciae and P. neglecta (Fig. 48).

Pestalotiopsis spp. are found on scattered spots or more extensive necrotic areas on Acacia aulacocarpa, A. auriculiformis, A. crassicarpa and A. mangium. Fungi...

Phomopsis foliar spot

Phomopsis spp. These fungi are imperfect states of the genus Diaporthe which includes many pathogenic species attacking woody plants and other hosts. Phomopsis is the most commonly found state of these fungi, including those associated with diseases of acacias (Sharma et al. 1985).

Phomopsis spp. are found on a wide range of host plants, including acacias and other tropical plantation species. They are commonly associated with leaf spots and stem cankers of woody hosts. Diaporthe eres Nitschke, a fungus with a very wide host range on woody species, was found by Kobayashi and de Guzman (1988) associated...

Phyllosticta foliar blotch

Phyllosticta sp. and its teleomorph Guignardia sp.

Guignardia spp. are well known foliar pathogens of broad-leaved trees e.g. G. aesculi (Peck) V. B. Stewart (Punithalingam 1993), conifers (Bissett and Palm 1989; Kobayashi and Sasaki 1975), and herbaceous plants. Although there are records on several tree species grown in the tropics, e.g. Gmelina arborea (Kobayashi and de Guzman 1988) and Castanopsis (Hsieh et al. 1997), the surveys undertaken in northern Australia and Indonesia in 1996 (Old et al. 1997) provided the first records of this pathogen on plantation acacias. Cannon et al. (1997) examined the specimens from Australia...

Pink disease, cendawan angin (Bahasa Malaysia), jamur upas (Bahasa Indonesia)

Corticium salmonicolor Berk. & Br. (syn. Pellicularia salmonicolor (Berk. & Br.) Dastur).

The fungus is an obligate parasite of numerous woody plants ranging from forest to fruit trees. It has also been recorded on many tropical crops such as cacao, coffee, tea, ramie, rubber (Fig. 60) and many forest plantation trees (Browne 1968).

The fungus is widely distributed in the tropics, sub-tropics and warmer parts of the temperate region. Pink disease is primarily a disease of the stem and branches. The pathogen infects and kills living bark tissue. Trees of almost any...

Stem and branch canker, kanker batang dan dahan (Bahasa Malaysia, Bahasa Indonesia)

Botryosphaeria spp. and their anamorphs; Lasiodiplodia theobromae (Pat.) Griff. & Maubl and Dothiorella spp.

Valsa Fr., anamorph Cytospora spp.

Nattrassia mangiferae (H. & P. Syd.) Sutton & Dyko (syn. Hendersonula toruloidea Nattrass)

Macrovalsaria megalospora (Mont.)

A wide range of trees and woody shrubs, in plantations and native vegetation.

Botryosphaeria spp. and Valsa spp. are distributed worldwide in tropical and temperate regions (Old et al. 1991; Lenné 1992; Roux and Wingfield 1997), whereas N. mangiferae (Punithalingam and Waterston 1970) and M. megalospora (Sivanesan 1975) are mainly found in the tropics and sub-tropics....

Heart rot, reput teras (Bahasa Malaysia), busuk hati, busuk umbut (Bahasa Indonesia)

A range of hymenomycetes are known to be associated with heart rot of acacias, but the fungi associated with Acacia mangium have only recently been identified. Phellinus pachyphloeus and Trametes palustris were reported from India (Mehrotra et al. 1996) while P. noxius, Tinctoporellus epimiltinus and Rigidoporus hypobrunneus were found to be associated with heart rot of A. mangium in Peninsular Malaysia and East Kalimantan (Lee and Noraini Sikin 1999). P. noxius was associated with heart rot of A. crassicarpa in Vanuatu. Oxyporus cf. latemarginatus was also associated with...

Root rot, reput akar (Bahasa Malaysia), busuk akar (Bahasa Indonesia)

The fungi associated with root rot diseases found in tropical Acacia plantations are mainly members of the basidiomycetes, e.g. Ganoderma spp., Phellinus noxius and Rigidoporus lignosus. Root pathogens of other acacia species are discussed in Gibson (1975). In the nursery a different group of fungi, mainly members of the mitosporic fungi, are associated with root rot diseases such as damping-off and dieback of seedlings. Recently, G. philippii, P. noxius, Tinctoporellus epimiltinus and Amauroderma cf. parasiticum were also found to be associated with root rot of A. mangium trees in Peninsular...

Planting stock for large-scale plantation programs is raised in forest nurseries for several months before field planting. Location and management of the nursery are crucial in producing healthy and vigorous seedlings. Important requirements for a successful nursery operation are light-textured, fertile soil, use of a balanced potting medium with moderate pH, an open area without any shade from trees or buildings and a good water supply.

Conventionally, in most tropical countries acacia seeds are sown in seed beds or trays after scarification or hot water treatment. Seedlings are later transferred to polythene containers and maintained in the nursery until field...

Damping-off, lecuh pangkal (Bahasa Malaysia), penyakit semai, rebah semai (Bahasa Indonesia)

Pythium spp., Phytophthora spp., Fusarium oxysporum Schlecht. and Rhizoctonia solani Kuhn.

Damping-off affects many host species including Acacia spp. and is caused by F. solani, Phytophthora spp., Pythium spp. and Rhizoctonia solani (Lee 1985; Liang 1987; Maziah 1990). Damping-off of A. mangium caused by Fusarium sp. is quite common in Indonesia (Soeyamto and Mardji 1986). In Sarawak, A. auriculiformis damping-off has been caused by concurrent infection by Pythium spp. and Fusarium spp. (Chin 1995). In India, post-emergence damping-off of A. holosericea, caused by F. oxysporum, has also been reported...

Web blight

Rhizoctonia solani Kuhn, teleomorph Thanatephorus cucumeris (Frank) Donk.

The genus Rhizoctonia represents a morphological group, being the mycelial state of several basidiomycete fungal genera such as Thanatephorus and Ceratobasidium (Mordue 1974). Rhizoctonia spp. are characterised by sterile mycelia with rather wide hyphae and wide-angled branching. The lateral branches are narrowed and septa occur near the junctions with the main axis of the hyphae. Isolates identified as R. solani are pathogenic to plants, have brown or yellow pigmented hyphae and often form discrete rounded aggregations of hyphae known as sclerotia. The teleomorphs of individual isolates are often not known...