During a series of sampling in 2008 and 2009, stem rot disease was detected in Hylocereus polyrhizus plantations in Malaysia, with symptom appeared as circular, brown sunken lesion with orange sporodochia and white mycelium formation on the lesion surface. Eighty-three isolates of Fusarium were isolated from 20 plantations and were morphologically identified as F. proliferatum based on the variability of colony appearance, pigmentation, growth rate, length of chains, production of bluish sclerotia, concentric ring aerial mycelium and sporodochia. Three species-specific primers, namely ITS1/proITS-R, PRO1/2 and Fp3-F/4-R successfully produced PCR products and confirmed that the isolates from stem rot of H. polyrhizus were F. proliferatum isolates. From BLAST search of translation elongation factor 1-alpha (TEF1-α) sequences, the isolates showed 99-100% similarity with F. proliferatum deposited in GenBank which further confirmed that the isolates were F. proliferatum. The results from amplification of MAT-allele specific primers indicated that 14.5% of F. proliferatum isolates carried MAT-1 allele and 85.5% carried MAT-2. Crossing results showed that all 83 F. proliferatum isolates were male fertile showing positive crosses with the tester strains of MATD-1 and MATD-2. Perithecia oozing ascospore were produced. Forty isolates as representative were evaluated for pathogenicity test, produced rot symptoms similar to those observed in the fields which confirmed the isolates as the causal agent of stem rot of H. polyrhizus. To our knowledge, this is the first report of stem rot of H. polyrhizus caused by F. proliferatum in Malaysia.

White spider lily (Hymenocallis littoralis), locally known as Melong Kecil, is a herbaceous and bulbous perennial plant, commonly planted in Malaysia due to its medicinal and ornamental properties. Symptoms of leaf blight on H. littoralis were noticed in early September 2015 in Permatang Pauh, Penang with an incidence of up to 35%. The symptoms appeared as irregular reddish-brown lesion with black pycnidia scattered on the leaf (Fig. 1). When aged, the lesion enlarged and became darker.Small pieces of the infected leaves were surface sterilised, plated on potato dextrose agar (PDA) and incubated at 25 ±1°C for three days. A pure culture was obtained by single spore isolation. The fungus obtained was initially white with dense and hairy aerial mycelium and gradually turned dark grey to olive green (Fig. 2). Conidia formed in arthric chains, dark brown, ovoid to ellipsoid, round to rod-shaped with 0-to 1-septate conidia (Fig. 3). Abundant black pycnidia formed on carnation leaf agar with aseptate cylindrical conidia produced by conidiogenous cells. The fungus was identified as Neoscytalidium dimidiatum based on the description of its pycnidial and mycelial anamorphs (Crous et al., 2006). The identity of the isolated fungus was confirmed by PCR amplification of the internal transcribed spacer (ITS) region using the ITS1/ITS4 primers (White et al., 1990). Based on a BLAST search, the isolate showed 99% identity with an isolate of N. dimidiatum (GenBank Accession No. KP132486). DNA sequences were deposited in GenBank (KX290313).A pathogenicity test was done using the mycelial plug method. A healthy leaf of H. littoralis was surface sterilised with 70% ethanol prior to inoculation and four inoculation points were made using a sterile cork borer (6 mm). Fungal mycelial plugs were obtained from a seven-day-old PDA culture and transferred onto three inoculation points, whilst a PDA plug without mycelium was placed on the fourth inoculation point as a control. The test was repeated twice. The inoculated leaves were placed in surfacesterilised trays and incubated at 25 ±1°C with a relative humidity of 85%. Dark brown-reddish lesions appeared five days after inoculation (Fig. 4). As the disease progressed, the presence of black pycnidia was noticed on the lesion surface and the leaves began yellowing ten days after inoculation (Fig. 5). The symptoms produced were similar to those observed in the fields and the control remained symptomless. Neoscytalidium dimidiatum isolates were consistently recovered from symptomatic leaves of H. littoralis thus fulfilling Koch's postulates. This is the first report of N. dimidiatum causing leaf blight on white spider lily (H. littoralis). Previous studies showed N. dimidiatum was responsible for shoot blight, canker and gummosis on Citrus sinensis (Polizzi et al., 2009); collar and root rot of Jatropha curcas (Marchado et al., 2012); and stem canker on Hylocereus polyrhizus (Masratul Hawa et al., 2013). Information on the aetiology of white spider lily leaf blight can improve management p...

Stem rot was recorded as one of serious diseases of red-fleshed dragon fruit, (Hylocereus polyrhizus), in Malaysia. Fusarium fujikuroi was recovered from stem rot lesion of H. polyrhizus and the species was identified using TEF1sequence and mating study. From maximum likelihood phylogenetic tree using combined TEF1-and -tubulin sequences, the F. fujikuroi isolates from stem rot were grouped according to three geographical locations, namely Peninsular Malaysia, Sabah and Sarawak. Phylogenetic analysis indicated that F. fujikuroi isolates from stem rot of H. polyrhizus were clustered separately from F. fujikuroi isolates from rice because of intraspecific variation. From amplification of MAT allele-specific primers, 20% of the isolates carried MAT-1 allele while 80% carried MAT-2 allele. From isolates that carried MAT-1 allele, 65% crossed-fertile with MP-C (mating population of F. fujikuroi) tester strain while for MAT-2 allele, 56% crossed-fertile with MP-C. None of the isolates were identified as MP-D (mating population of F. proliferatum). Pathogenicity test conducted on 40 representative isolates showed that the stem rot symptoms were similar with the symptoms observed in the field, and can be categorized as low, moderate and high aggressiveness, which indicated variation in pathogenicity and virulence among the isolates. This study provides novel findings regarding Fusarium species associated with stem rot of H. polyrhizus and indicated that F. fujikuroi as a new causal pathogen of the disease.

Red-fleshed dragon fruit (Hylocereus polyrhizus [Weber] Britton & Rose) is a newly introduced and potential crop in the Malaysian fruit industry. Besides its nutritious value, the fruit is being promoted as a health crop throughout Southeast Asia. In April of 2007, a new disease was observed in major plantations of H. polyrhizus throughout five states (Kelantan, Melaka, Negeri Sembilan, Penang, and Perak) in Malaysia with 41 and 25% disease incidence and severity, respectively. Stems of H. polyrhizus showed spots or small, circular, faint pink-to-beige necrotic lesions that generally coalesced as symptoms progressed. Symptom margins of diseased stem samples were surface sterilized with a 70% alcohol swab, cut into small blocks (1.5 × 1.5 × 1.5 cm), soaked in 1% sodium hypochlorite (NaOCI) for 3 min, and rinsed in several changes of sterile distilled water (each 1 min). The surface-sterilized tissues were placed onto potato dextrose agar (PDA) and incubated under alternating 12-h daylight and black light for 7 days. A fungus was consistently isolated from the stems of symptomatic H. polyrhizus and identified as Curvularia lunata (Wakker) Beodijn (1–3) that showed pale brown multicelled conidia (phragmoconidia; three to five celled) that formed apically through a pore (poroconidia) in sympodially, elongating, geniculated conidiophores. Conidia are relatively fusiform, cylindrical, or slightly curved, with one of the central cells being larger and darker (26.15 ± 0.05 μm). All 25 isolates of C. lunata obtained from diseased H. polyrhizus are deposited at the Culture Collection Unit, Universiti Sains Malaysia and available on request. Isolates were tested for pathogenicity by injecting conidial suspensions (1 × 106 conidia/ml) and pricking colonized toothpicks on 25 healthy H. polyrhizus stems. Controls were treated with sterile distilled water and noncolonized toothpicks. All inoculated plants and controls were placed in a greenhouse with day and night temperatures of 30 to 35°C and 23 to 30°C, respectively. Development of external symptoms on inoculated plants was observed continuously every 2 days for 2 weeks. Two weeks after inoculation, all plants inoculated with all isolates of C. lunata developed stem lesions similar to those observed in the field. No symptoms were observed on the control plants and all remained healthy. C. lunata was reisolated from 88% of the inoculated stems, completing Koch's postulates. The pathogenicity test was repeated with the same results. To our knowledge, this is the first report of C. lunata causing a disease on H. polyrhizus. References: (1) M. B. Ellis. Dematiaceous Hyphomycetes. Commonwealth Mycological Institute, Kew, Surrey, England, 1971. (2) R. R. Nelson and F. A. Hassis. Mycologia 56:316, 1964. (3) C. V. Subramanian. Fungi Imperfecti from Madras V. Curvularia. Proc. Indian Acad. Sci. 38:27, 1955.