Magarey, R.C., Suma, S., Irawan, Kuniata, L.S. and Allsopp, P.G. Proc. Aust. Soc. Sugar Cane Technol., Vol. 24, 2002

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1 SIK NA BINATANG BILONG SUKA DISEASES AND PESTS ENCOUNTERED DURING A SURVEY OF SACCHARUM GERMPLASM IN THE WILD IN PAPUA NEW GUINEA By R.C. MAGAREY 1, S. SUMA 2, IRAWAN 3, L.S. KUNIATA 4 and P.G. ALLSOPP 1 1 BSES, Tully and Bundaberg, 2 NAQIA, Pt Moresby, PNG, 3 ISRI, Pasuruan, Indonesia 4 Ramu Sugar, Gusap, PNG rmagarey@bses.org.au Abstract In May 2001, an international team of pathologists and entomologists undertook a Saccharum pest and disease survey around the perimeter of PNG. This paper reports on pest and disease observations in Saccharum officinarum, S. spontaneum, S. robustum, S. edule and in hybrid sugarcane. Ramu stunt was widespread. Other common diseases were chlorotic streak, orange rust, yellow spot, Fiji and Ramu streak. Specimens of Fiji disease with purple instead of pale green galls were found at Alotau; this is the first known report of purple Fiji disease galls. Downy mildew was only seen on the northern side of PNG. Leaf splitting disease, also caused by a Peronosclerospora species, was common in S. spontaneum around Popondetta. A number of minor uniquely PNG diseases was seen including veneer blotch and target spot. No sugarcane smut was observed at any location; ratoon stunting disease was not detected either. In relation to insects, of note was the widespread distribution of stem borers and planthoppers. The two planthopper genera, Perkinsiella and Eumetopina, account for the transmission of some very important sugarcane viral diseases and their broad distribution in PNG is of great significance. Eumetopina has been observed in the Torres Strait and on the northern end of Cape York. Rhabdoscelus obscurus (sugarcane weevil borer) had limited distribution. Some Chilo larvae collected were unrecognised and may be new species. There seemed to be a low awareness of sugarcane quarantine in PNG; movement of hybrid cane to remote villages around the country has been occurring for some time. This is of concern both for the spread of local and exotic pests and diseases and for the loss of S. officinarum germplasm. Actions are being planned in cooperation with PNG Government agencies to minimise the chance of sugarcane pest and disease spread. KEYWORDS: Diseases, Pests, Quarantine, Saccharum, Sugarcane. Introduction Papua New Guinea is the centre of diversity for Saccharum officinarum. This species is a major source of genes for high sucrose in commercial hybrid varieties around the world and is a unique source of genes for further variety improvement. In PNG, these canes are a source of sweetener for nationals and traditional PNG gardens usually contain S. officinarum. It is important that these canes are conserved, both for the maintenance of the traditional sweetener and for further commercial exploitation.

2 In 2000, the Australian Centre for International Agricultural Research (ACIAR) and AusAID funded a project led by BSES to assist in the conservation of this species in the region. ACIAR provides funding to Australian researchers and developing country partners for mutually beneficial outcomes. The focus of this project principally lies in determining the distribution of known pests and diseases in the region; quarantine strategies will then be developed to limit the spread of these organisms. The project also includes some specific research projects but these will not be reported here. In May 2001, a five member international team conducted a survey around the perimeter of PNG to determine the distribution of sugarcane pests and diseases in PNG. Three pathologists and two entomologists conducted the survey utilising a chartered Cessna 402; the survey occurred between May The chartered flight enabled the itinerary to be varied when necessary and allowed scientific equipment and supplies to be carried. Places visited included Daru Island, Morehead, Tabubil, Vanimo, Wewak, Manus Island, New Ireland, New, Lae, Ramu Sugar, Popondetta, Alotau and Port Moresby. Method The survey flight began in Cairns with approximately one day spent at each location enroute. PNG officers from the National Agricultural Quarantine Inspection Authority (NAQIA) or Department of Agriculture and Livestock (DAL), assisted with ground transport and inspection site selection. Local village gardens were the main focus, although in a number of locations other Saccharum species (S. robustum, S. edule and S. spontaneum) were examined in gardens or as wild cane growing along roadsides and riparian areas. Inspections for pests and diseases were supplemented by the collection of leaf and insect specimens for further identification. Insects Insect specimens were collected either as larvae or adults. Most were placed in >95% ethanol in labelled tubes while some beetles were mounted after killing. Some stem borers were kept alive and placed in tubes with a food source for rearing and identification at Ramu Sugar, Gusap. A range of insect types were brought back to Australia (under AQIS permit) for further identification. Two hundred and forty six specimens were collected. Some samples were duplicated and held by Ramu Sugar as reference for the PNG sugar industry. The full identity of many specimens will not be known for some time; identities will depend on the work of various taxonomists and the results from DNA assays. Specimens have been sent to appropriate experts. Diseases Photographs were taken of many leaf disease specimens and location determined by GPS and other information. Details were recorded on a paper-based record system. A computer database has since been developed and the data transferred. Where the disease was unknown, leaves were collected, pressed between sheets of newspaper in a plant press or cut into small (approx. 2 mm x 2 mm) squares and dried in sealed McCartney bottles containing calcium chloride (drying agent). Samples were passed through Australian quarantine systems (and fumigated where necessary) before being sent to identification laboratories. Pressed leaves were deposited in the mycological herbarium of the Queensland Department of Primary Industries (Meiers Road, Indooroopilly). Dried leaf samples were sent to the BSES DNPRC laboratory for assay for viruses and phytoplasmas. Assays are yet to be completed.

3 Saccharum species During the survey, note was made of the distribution of Saccharum species and hybrid material around PNG. Meetings At the conclusion of the survey, a meeting was held with NAQIA administrative staff in Port Moresby to discuss survey findings. Strategies to progress the conservation of Saccharum germplasm in PNG were considered. Results Insects A wide range of insects was collected and general distribution records are summarised in Table 1. We did not attempt to collect soil-dwelling insects, as this would have meant digging up garden canes and potentially incurring the wrath of the owners. The most significant collections are detailed below.

4 Table 1 Sugarcane pests and their distribution around PNG in May Species Sesamia grisescens Sesamia inferens Chilo spp. Scirpophaga excerptalis Cosmopterix sp. Rhabdoscelus obscurus Trochorrhopalus strangulates Unidentified ceramycid 'Round' weevil 'Bicoloured' beetle Eumetopina spp. Perkinsiella spp. 'Black-white' bug Spittle bug Lophops spp. Phaenacantha sp. 'Long-winged' bug 'Green-white' leafhopper Ceratovacuna lanigera Aulacapsis sp. Saccharicoccus sacchari Neomaskiella bergii Psyllid 'Striped' leafhopper Western Sundaun East Sepik Manus New Ireland Province East New West New Northern Milne Bay Central Sesamia grisescens and S. inferens The stemborer Sesamia grisescens (Noctuidae) is the most serious insect pest at Ramu Sugar, where concerted control programs are in place (Kuniata et al., 2001). Eggs are laid under the leaf sheath and the newly hatched larvae feed on this tissue. Caterpillars then bore into the top of the stalk and feed together. When about half grown, the larvae move to adjacent plants and again bore into the stem (in the cabbage area). They pupate in the stem, after which they emerge as moths. The first symptoms usually noticed include death of the youngest (still rolled up) leaves in the shoot. This is described as a dead heart. This occurs because the insect larva eats through the base of the young leaves within the top of the shoot. As they grow, larvae move to other stalks and cause further damage by boring into the upper portions of the cane stalk. As they do, they destroy the inside of the stalk leaving, within the tunnels formed, a mass of chewed cane tissue and excreta (called frass). Severely affected cane crops will have many dead shoots and very little sugar in the

5 stalks. Infested stalks are neither good for chewing nor for harvest for sugar production. The species is native to New Guinea, and appears common through the highlands and the northern mainland and islands of Papua New Guinea (Table 1; see also Szent-Ivany and Ardley, 1963). Sesamia inferens occurs from Pakistan through the Indian subcontinent and Southeast Asia to the Solomon Islands and north to Japan and Korea and infests a wide range of grasses and similar plants. Maize and rice are the preferred hosts (Allsopp and Sallam, 2001). On sugarcane, larvae feed in the spindle and cause characteristic shot-holing. Older larvae bore in the top section of stalks. We found it on many of the plants that we inspected (Table 1) but nowhere was damage severe. Chilo spp. Chilo borers (Pyralidae) are not as serious as S. grisescens borer at Ramu, but still may cause significant damage to cane stalks. The pest bores into cane stalks but does not leave frass inside the stalks as Sesamia borer does. We found Chilo spp. at many of the sites sampled (Table 1). The most common species in Papua New Guinea is C. terenellus, but identification of larvae and pupae, the stages that we found, is difficult and specimens are waiting comparison of DNA profiles with known species. Chandler and Croft (1986) recorded Chilo sp. (probably terenellus) from Saibai Island in the Torres Strait while Magarey (1997) observed the pest on Dauan Island, also in the northern Torres Strait. Scirpophaga excerptalis The top shoot-borer, Scirpophaga excerptalis (Pyralidae), was found in many of the northern sites (Table 1). The species is known only from PNG and Irian Jaya. Eggs are laid on the underside of sugarcane leaves. Young larvae bore cane (one larva per stalk) through the spindle bundle causing shot-holes as the leaves expand. The larva continues to feed downwards into the meristem (growing point) of the stalk, killing the shoot. Damaged stalks show stunted growth and produce excessive side-shoots or tillers. Cosmopterix sp. This midrib borer (Cosmopterigidae) was found only in Sundaun and Manus Provinces (Table 1). Larvae bore in the midribs of leaves leaving characteristic tunnels around which some reddening develops. Buzacott (1953) also recorded midrib borers from both lowland and highland localities, and, like us, realised that the symptoms were similar to those caused by C. dulcivora in Australia. Cosmopterix is a large genus in the Austro-Malayan area and a number of species have been recorded feeding on sugarcane. Weevil borers We found two species of weevil borers, Rhabdoscelus obscurus, the species introduced into Australia, and a morphologically similar species, Trochorrhopalus strangulatus (Curculionidae) (Table 1). The larvae of both bore into the base of shoots and feed within the stalk. Both species have previously been recorded on sugarcane in PNG (Buzacott, 1953; Szent-Ivany, 1963). Recent studies on DNA and morphology of adults indicate that there may be two species confused under the name R. obscurus (Giblin-Davis et al., 2000), and we have sent our specimens for DNA comparison. Eumetopina spp.

6 We found specimens of this genus (Delphacidae) at almost every site we visited (Table 1), and many of our collections include more than one species. There are at least 13 species described from PNG (FitzGibbon et al., 1998) and they vary considerably in colour. Eumetopina planthoppers are vectors of virus diseases of sugarcane and E. flavipes is known to transmit Ramu stunt disease (Kuniata et al., 1994). Both adults and nymphs are found in the leaf-spindle. Eumetopina also occur on cane in the Torres Strait and at Bamaga (Chandler and Croft, 1986; Allsopp, 1991; Magarey, 1997), but are not known from commercial cane in Australia. These planthoppers represent a considerable quarantine threat to Australia. Curiously, the genus is not recorded by Buzacott (1953) or Szent-Ivany and Ardley (1963). Perkinsiella spp. These insects (Delphacidae) are of importance as vectors of Fiji disease, although feeding by large numbers of nymphs and adults can cause excessive development of sooty mould. We found Perkinsiella at most sites sampled (Table 1) and colour and size differences indicate that a number of species are present. This is consistent with previous collections (Buzacott, 1953; Szent-Ivany and Ardley, 1963; FitzGibbon et al., 1998). Material collected has been added to material from Australia and other overseas areas being used in morphological and DNA studies on the genus. Lophops spp. These bugs (Lophopidae) are thought to be associated with Ramu scorch symptoms, caused through feeding on the leaves. We collected at least two species (Table 1). Phaenacantha sp. This species (Colobathristidae) was widespread through the northern areas in which we collected (Table 1). At least two species occur in Papua New Guinea (Buzacott, 1953) and our collections appear similar to the lowlands form that resembles P. australiae, the species present in eastern Australia. We saw no obvious symptoms caused by this bug, similar to Australian experience. Ceratovacuna lanigera This woolly aphid (Aphididae) is widespread in PNG (Szent-Ivany and Ardley, 1963), although we found it at only two sites (Table 1). It is widespread in southern Asia, but is not present in Australia (FitzGibbon et al., 1998), and so represents an important quarantine threat. Aulacaspis sp. We collected this scale (Diaspididae) at three sites (Table 1) on old canes. Two species of the genus occur on sugarcane, A. madiuensis and A. tegalensis (FitzGibbon et al., 1998). The first is common in eastern Australia, whilst the second, although widely distributed in Asia and recorded from the Torres Strait (Chandler and Croft, 1986; Allsopp, 1991), is not known from commercial cane in Australia. The second represents a quarantine threat to Australia. Saccharicoccus sacchari Pink sugarcane mealybug (Pseudococcidae) was collected in every area (Table 1) and is widely distributed in almost all sugar-growing countries (FitzGibbon et al., 1998). It is easily spread

7 through infestations on planting material. Neomaskiella bergii This whitefly (Aleyrodidae) was widely distributed (Table 1) and occurs throughout southern Asia and into commercial sugarcane in Australia. They occur in well-defined colonies on the undersides of leaves and are attended by ants, but cause little apparent damage. Diseases The distribution of the recognised diseases in PNG is illustrated in Table 2. Table 2 Diseases and their distribution around PNG during the May 2001 survey. Disease \Province Fiji Ramu Stunt CSD Ramu Scorch Mosaic Orange Rust Yellow Spot Common Rust Veneer Blotch Target Spot Zonate Leaf Spot Downy mildew Leaf Splitting Red Leaf Spot Red Rot Eye Spot Ring Spot Small Ring Spot Banded Sclerotial Tar Spot Brown Stripe YLS Ramu Streak Western Sundaun East Sepik Manus New Ireland East New West New Northern Milne Bay Central Saccharum species distribution Fiji disease Fiji disease was widely distributed in PNG. As a major disease of sugarcane in Australia, there was considerable interest in its common occurrence, especially in areas close to the northern areas of Australia. Interestingly, an unusual symptom type was seen in pit pit at Alotau. The galls of these specimens were bright purple instead of the usual yellow-green. It is not known why the variant occurred but secondary infection could pose a mechanism for these symptoms. Not all galls

8 were purple. Ramu stunt A uniquely PNG disease which has caused great economic loss at Ramu Sugar, stunt was seen in all areas visited. Previously, stunt had only been observed near Ramu Sugar and close to Port Moresby. The disease is transmitted by the planthopper Eumetopina. The broad distribution of Eumetopina spp. suggests the disease could well be closer to Australia in areas where the planthopper occurs and perhaps on the tip of Cape York. Surveys in year 3 of the project will address this issue. Orange rust Causing large losses in Queensland in the 2000 crop, orange rust was seen in almost every garden in PNG. An unusual variant was seen where leaf lesions were common on the upper leaf surface. Leaf diseases Unusual leaf diseases were seen during the survey. Some of these were recognised and included veneer blotch, zonate leaf spot, target spot and eye spot. Unrecognised leaf diseases will be examined in association with a fungal taxonomist to help determine causal agents for previously unrecognised diseases. Chlorotic streak This disease is caused by an as yet unknown causal agent and had been seen in only limited distribution in PNG. During our survey, we confirmed that it has a much broader distribution. Chlorotic streak is an important disease in many cane-growing countries. Smut and RSD Neither of these diseases were seen in PNG which is fortunate for PNG and Australia since they have such an important effect on sugarcane yield. The distribution of various Saccharum species was also of interest during this survey. The centre of diversity of S officinarum is in PNG and Irian Jaya while the centre of diversity for S. spontaneum is in South Asia. It was of interest therefore to determine where each species was found. Table 3 outlines the observations made on Saccharum distribution. One of the most significant observations was the finding of commercial hybrid material in remote parts of PNG. This had been taken from Ramu Sugar sometime ago and was being referred to as Ramu Sugar. On several occasions, the material appeared to be the variety Ragnar.

9 Table 3 Saccharum species distribution in PNG. Saccharum species Western Sundaun East Sepik Province Manus New Ireland East New West New Northern Milne Bay Central officinarum edule robustum spontaneum hybrid? Meeting with PNG quarantine staff There was significant interest in the survey findings from PNG quarantine staff. Several strategies were developed during the meeting including the production of posters highlighting the need for sugarcane quarantine within the country to prevent pest and disease spread around the country. These posters will be displayed at border posts, airstrips and at government agencies in PNG. A decision was also made to hold a meeting with PNG government representatives to discuss the issue of germplasm preservation, Saccharum quarantine in PNG and further development of the sugarcane crop. One of the meeting aims will be to increase communication amongst those with interests in sugarcane. Discussion Identification of insects collected on this survey will be important for assessing incursion risks to Australia. Unrecognised species of Eumetopina, Perkinsiella, Chilo and several other genera were collected and each could be important as either pests in their own right or as vectors of important sugarcane diseases. Such a comprehensive survey of insect pests of sugarcane has not been undertaken before and the use of DNA technologies will greatly assist with determining the species collected. Pests remain one of the greatest threats to both the PNG and Australian sugar industries and there is an ongoing need to elucidate the distribution of those of greatest importance. The presence of many Saccharum officinarum varieties in PNG is of special interest to sugarcane plant breeders around the world. Perhaps never before has this resource been under such pest and disease pressure as it has in recent years. Major diseases including leaf scald have recently been introduced to PNG and these threaten the survival of many of the chewing canes. Movement of PNG nationals around the country and internationally is occurring and increasingly putting pressure on quarantine systems, as is happening in many other countries. In PNG, internal quarantine systems are almost non-existent. This has seen hybrid sugarcane move out into remote parts of the country potentially resulting in the dissemination of further pests and diseases. The funding of this project by ACIAR and AusAID is timely and provides a unique opportunity for scientists to learn more about the pest and disease status of the region. Detailed observations of sugarcane pests and diseases previously was focused on Ramu Sugar and its surrounds. On this survey, the focus was on the perimeter of the country. Diseases that were widespread included Ramu stunt, chlorotic streak, Ramu streak, Fiji disease, orange rust and yellow spot. It seems likely that chlorotic streak and Fiji disease originated in PNG. The widespread distribution of Ramu stunt and its vector (Eumetopina spp.), and the presence of the vector in a continuum through to the Torres Strait, strongly suggests Ramu stunt may already be in Australian

10 territory. This will be examined in a follow up survey of the Torres Strait in the final year of the project. If this distribution of Ramu stunt is confirmed, the Australian sugar industry will need to refine quarantine strategies. Fortunately for both Australia and PNG, no sugarcane smut or ratoon stunting disease was identified during the survey. Both diseases would have great consequences on the germplasm in PNG. Smut would lead to the loss of many varieties of Saccharum officinarum, and consequently many genes for high sucrose and yield would be lost. Some considered it likely that ratoon stunting disease (RSD) could have originated in the same place as S officinarum, but this survey suggested that RSD is unlikely to be present in PNG. The disease may have originated in another Saccharum species in South Asia or spread to the Saccharum genus from another host. The disease can now be found in all other commercial cane growing countries, with the transport of infected material through unsatisfactory quarantine systems. If the disease was introduced to PNG, either through the introduction of infected hybrid cane or on infected knives and cane introduced through Irian Jaya, there is little doubt the disease would spread very quickly in PNG. PNG nationals frequently use bush knives for cutting grass and cane. Without any awareness of sterilisation techniques, RSD spread would occur rapidly into chewing canes (S officinarum) and pit pit (S edule). Spread into S. robustum and S. spontaneum may be slower but would probably occur. Acknowledgments We thank Charles O Brien, Jon Martin, Doug Williams and Murray Fletcher for insect identifications and ACIAR for providing funds for this project. We also thank staff of Ramu Sugar and Bernard Maladina (ACIAR, Port Moresby) for assistance with PNG arrangements. Funding provided by both ACIAR and AusAID is gratefully acknowledged. REFERENCES Allsopp, P.G. (1991). Quarantine survey of sugarcane pests and diseases on the Torres Strait islands Proc. Aust. Soc. Sugar Cane Technol., 13: Allsopp, P.G. and Sallam, M.S. (2001). Sesamia incursion management plan. Version 1. BSES Project Report PR Buzacott, J.H. (1952). The sugar cane varieties of New Guinea. Cane Growers Quarterly Bulletin, 16: Buzacott, J.H. (1953). Insects associated with sugar cane in New Guinea. Tech. Comm., Bur. Sugar Exp. Stns, 1953(2): Buzacott, J.H. and Hughes, C.G. (1951). The 1951 cane collecting expedition to New Guinea. Cane Growers Quarterly Bulletin, 15: Chandler, K.J. and Croft, B.J. (1986). Quarantine significance of pests and diseases of sugarcane on the Torres Strait islands. Proc. Aust. Soc. Sugar Cane Technol., 8: FitzGibbon, F., Allsopp, P.G. and De Barro, P.J. (1998). Sugarcane exotic pests - pest risk analysis database. CD BSES, Brisbane. Giblin-Davis, R.M., Gries, R., Crespi, B., Robertson, L.N., Hara, A.H., Gries, G., O Brien, C.W. and Pierce, H.D. (2000). Aggregation pheromones of two geographical isolates of the New Guinea sugarcane weevil, Rhabdoscelus obscurus. J. Chem. Ecol., 26: Hughes, C.G. (1952). Diseases of cane in New Guinea. Cane Growers Quarterly Bulletin, 16: Kuniata, L.S., Chandler, K.J. and Korowi, K.T. (2001). Management of sugarcane pests at Ramu, Papua New Guinea. Proc. Int. Soc. Sugar Cane Technol., 24(2): Kuniata, L.S., Young, G.R., Pais, E., Jones, P. and Nagaraja, H. (1994). Preliminary

11 observations on Eumetopina sp (Hemiptera: Delphacidae) as a vector of Ramu stunt disease of sugarcane in Papua New Guinea. J. Aust. Entomol. Soc., 33: Magarey, R.C. (1997). Quarantine survey of some Torres Strait islands in Proc. Aust. Soc. Sugar Cane Technol., 19: Szent-Ivany, J.J.H. and Ardley, J.H. (1963). Insects of Saccharum spp. in the Territory of Papua and New Guinea. Proc. Int. Soc. Sugar Cane Technol., 11: