First Report of Myrothecium roridum Causing Myrothecium Leaf Spot on Dieffenbachia picta 'Camilla' in Taiwan.

Dumb cane (Dieffenbachia picta (Lodd.) Schott 'Camilla'), family Araceae, is a popular houseplant in Taiwan. During the winter of 2012, dumb canes with dark brown concentric spots on leaves and bright yellow borders were found in a protected ornamental nursery in Wandan township, Pingtung County, Taiwan. On diseased leaves, fungal fruiting bodies were sometimes observed in the concentric lesions and a fungal isolate was consistently isolated from the lesions. A single spore isolate, myr 2-2, was maintained on potato dextrose agar (PDA) for further tests. To fulfill Koch's postulates, the spores of myr 2-2 were suspended in sterilized distilled water containing 0.05% of Tween 20, 1 × 105 conidia ml-1, and then sprayed on leaves of D. picta 'Camilla' growing in polypropylene plant pots (about 7 cm in diameter), three plants per treatment. For the control, three plants were sprayed with sterilized distilled water containing 0.05% of Tween 20. Both inoculated and non-inoculated plants were covered with plastic bags and incubated in a growth chamber at 26 ± 1°C. Nine to 12 days after inoculation, symptoms described above were observed on inoculated plants whereas the plants in control remained healthy. The same fungus was reisolated from inoculated plants but not from the controls. Furthermore, the fungal pathogen was identified using its physiological, morphological, and molecular characteristics. In the mycelial growth test, the diameter of the fungal colony reaches 58.2 mm on PDA at 25°C after 14 days. The colonies were floccose, white to buff, and sporulate in concentric zones with olivaceous black to black sporodochia bearing viscid masses of conidia. Conidia were narrowly ellipsoid with rounded ends. The average size of 100 conidia was 6.25 ± 0.04 × 1.63 ± 0.02 µm. For molecular identification, the rDNA internal transcribed spacer (ITS) of isolate myr 2-2 was PCR amplified using ITS1 (5'-TCCGTAGGTGAACCTGCGG-3') and ITS4 (5'- TCCTCCGCTTATTGATATGC-3') primer pairs (3) and sequenced. The rDNA sequence was deposited in GenBank (KC469695) and showed 100% identity to the Myrothecium roridum isolates BBA 71015 (AJ302001) and BBA 67679 (AJ301995) (4). According to the physiological, morphological (1,2), and molecular characteristics, the fungal isolate was identified as M. roridum Tode ex Fr. To the best of our knowledge, this is the first report of Myrothecium leaf spot caused by M. roridum on D. picta 'Camilla' in Taiwan. References: (1) D. F. Farr and A. Y. Rossman. Fungal Databases, Systematic Mycology and Microbiology Laboratory, ARS, USDA. Retrieved from http://nt.ars-grin.gov/fungaldatabases/ , January 31, 2013. (2) M. Tulloch. Mycol. Pap. 130: 1-42, 1972. (3) T. J. White et al. Page 315 in: PCR Protocols: A Guide to Methods and Applications. M. A. Innis et al., eds. Academic Press, New York, 1990. (4) Y. X. Zhang et al. Plant Dis. 95:1030, 2011.

Development of a Semiselective Medium for Detection of Nalanthamala psidii, Causal Agent of Wilt of Guava.

Guava wilt, caused by Nalanthamala psidii, has become an important disease of guava (Psidium guajava) in Taiwan since the 1970s. This study was conducted to develop a semiselective medium for detecting N. psidii in soil and in tissues of diseased guava trees. Among 9 carbon and 21 nitrogen compounds tested in a modified Czapek-Dox medium, the most effective carbon and nitrogen sources for mycelial growth of N. psidii were sucrose and glycine, respectively. Among eight fungicides tested, iprodione at 5 µg ml-1 and azoxystrobin at 1 µg ml-1 were the most effective fungicides for detection of N. psidii in artificially infested soil or in naturally infected guava debris. Based on the requirement for carbon and nitrogen sources and response to fungicides, a semiselective medium designated as modified sucrose-glycine semiselective medium (mSGSSM) was developed for isolation of N. psidii, using the modified Czapek-Dox medium containing 3% sucrose, 0.3% glycine, iprodione at 5 µg ml-1, azoxystrobin at 1 µg ml-1, streptomycin at 200 µg ml-1, and neomycin at 200 µg ml-1. Colonies of N. psidii on mSGSSM at 30°C for 5 to 10 days were white to orange with sparse aerial hyphae. N. psidii was detected more accurately and efficiently on mSGSSM than on other media, including potato dextrose agar, modified Nash-Snyder medium, and modified Czapek-Dox medium. This semiselective medium is effective in detection of N. psidii from various parts of diseased guava trees and in soil; therefore, it would be a useful medium for etiological, ecological, and epidemiological studies of guava wilt.

First Report of Chrysoporthe deuterocubensis Causing Canker on Syzygium samarangense in Taiwan.

Wax apple (Syzygium samarangense Merr. & Perry, syn. Eugenia javanica Lam.) belongs to the Myrtaceae family is an important economical tree fruit in Taiwan. The total production acreage of wax apple was 5,266 ha in which more than 77% were located in Pingtung County, southern Taiwan, in 2012. Since the winter of 2010, symptoms of withering leaves and cracking branches on wax apple trees were observed in some orchards in Nanjhou and Linbian Townships, Pingtung County. Diseased trees declined gradually and resulted in reduced fruit production. On the bark of diseased twigs and branches, black conidiamata with yellowish orange conidia were usually observed. For diagnosis, tissues from symptomatic branches were excised, surface sterilized with 0.5% sodium hypochlorite, and placed on 2% water agar in petri dishes. A total of four identical fungal isolates were obtained and maintained on potato dextrose agar (PDA). To fulfill Koch's postulates, three twigs of a wax apple tree were wounded with scalpel and inoculated with each of the four isolates, one tree per isolate. A 7-day-old hyphal mat (about 7 × 18 mm) of each fungal isolate was attached on the wound, wrapped with a wet absorbent cotton and Parafilm, and then covered with a layer of aluminum foil. For the control, the twigs of a wax apple tree were inoculated with PDA plugs. The pathogenicity test was repeated once. After 30 days, withering leaves and cracking twigs were observed on inoculated twigs and the same pathogen was reisolated. Conversely, all of the non-inoculated plants remained healthy. Identification of the pathogen was conducted using its morphological, physiological, and molecular characteristics. On malt extract agar, the colony was floccose and white with hazel hues. The optimal temperature for the mycelial growth was 30°C. Conidia were hyaline, and oblong, with the average size of 4.7 ± 0.6 × 2.7 ± 0.2 µm (100 conidia). Ascostromata were semi-immersed in the bark with fusoid asci, eight ascospores per ascus. Ascospores were hyaline, 2-celled, and tapered in both ends, with the average length of 6.8 ± 0.7 × 2.4 ± 0.3 µm (100 ascospores). For molecular identification, the internal transcribed spacer (ITS) of ribosomal DNA and ß-tubulin genes was amplified using the ITS1/ITS4 (3), Bt1a/Bt1b, and Bt2a/Bt2b (1) primer pairs. The gene sequences were deposited in GenBank (Accessions KC792616, KC792617, KC792618, and KC792619 for the ITS region; KC792620, KC792621, KC792622, and KC792623 for Bt1 region, and KC812732, KC812733, KC812734, and KC812735 for Bt2 region) and showed 99 to 100% identity to the Chrysoporthe deuterocubensis isolate CMW12745 (DQ368764 for ITS region; GQ290183 for Bt1 region, and DQ368781 for Bt2 region). In addition, the Bt1 region of the ß-tubulin gene consisted of two restriction sites for AvaI and one restriction site for HindIII. This is identical to the description of C. deuterocubensis, a cryptic species in C. cubensis, by Van Der Merwe et al. (2). According to these results, the pathogen was identified as C. deuterocubensis Gryzenh. & M. J. Wingf. To the best of our knowledge, this is the first report of canker disease caused by C. deuterocubensis on S. samarangense in Taiwan. References: (1) N. L. Glass and G. C. Donaldson. Appl. Environ. Microbiol. 61:1323, 1995. (2) N. A. Van Der Merwe et al. Fungal Biol. 114:966, 2010. (3) T. J. White et al. Page 315 in: PCR Protocols: A Guide to Methods and Applications. Academic Press, San Diego, 1990.

First Report of Lasiodiplodia theobromae Causing Dieback of Aquilaria sinensis in Taiwan.

Incense trees (Aquilaria sinensis (Lour.) Gilg) belong to a plant family used for alternative medicine in China and the production of wood. In the summer of 2012, at a nursery in Niaosong district, Kaohsiung City, Taiwan, more than 30% of a total of 400 incense trees had dieback symptoms on twigs with leaves attached, leading to eventual death of the entire plant. Symptomatic twigs and trunk pieces from six trees were collected and discolored tissues were excised, surface sterilized in 0.5% sodium hypochlorite solution, rinsed in sterilized distilled water, dried on sterilized filter paper, and then placed in petri dishes containing 2% water agar (WA). The dishes were incubated at room temperature for 1 to 2 days to obtain fungal strains from diseased tissues. The hyphal tips from developing fungal colonies were transferred to potato dextrose agar (PDA, Difco) dishes and placed under UV light (12 h/day) at 30°C. The purified colonies were used as inoculum in the pathogenicity tests. Pathogenicity tests were performed on 2-month-old A. sinensis seedlings, each treatment had three plants. Each plant was wounded by removing bark of the twigs with a disinfected scalpel enough to place a mycelium plug (about 5 × 10 mm2) of 7-day-old fungal isolate on the wound. The inoculated area was wrapped with a wet paper towel and Parafilm. Control plants were treated with PDA plugs. The symptoms described above were observed on inoculated plants 4 to 8 days after inoculation whereas control plants did not show symptoms. Diseased twigs were cut and placed in a moist chamber 21 days after inoculation and conidia oozing from pycnidia were observed. The same fungal pathogen was reisolated from inoculated plants, but not from the control. To identify the pathogen, the fungus was cultured as described above. The colonies were initially white with green to gray aerial mycelium after 5 to 6 days and eventually turned darker. Immature conidia were hyaline and one-celled, but mature conidia were dark brown, two-celled, thin-walled, and oval-shaped with longitudinal striations. The average size of 100 conidia was 25.23 ± 1.97 × 13.09 ± 0.99 µm with a length/width ratio of 1.92. For the molecular identification, the internal transcribed spacer (ITS) region of ribosomal DNA was PCR amplified with primers ITS1 and ITS4 (2) and sequenced. The sequences were deposited in GenBank (Accession No. JX945583) and showed 99% identity to Lasiodiplodia theobromae (HM346871, GQ469929, and HQ315840). Hence, both morphological and molecular characteristics confirmed the pathogen as L. theobromae (Pat.) Griffon & Maubl (1). To the best of our knowledge, this is the first report of L. theobromae causing dieback on Incense tree. This disease threatens tree survival and may decrease the income of growers. References: (1) W. H. Ko et al. Plant Dis. 88:1383, 2004. (2) T. J. White et al. Page 315 in: PCR Protocols: A Guide to Methods and Applications. M. A. Innis et al., eds. Academic Press, New York, 1990.

Emphysematous gastritis secondary to acute gastric dilatation.

Emphysematous gastritis is a life-threatening disease. Although rare in incidence, it has a fulminating course with a high mortality rate. A case of a 58 year old male with emphysematous gastritis is reported. Initially, he presented with acute gastric dilatation secondary to anorexia/bulimia-like behaviour. Later, emphysematous gastritis developed. The abdominal sonographic findings, which have not been previously described in the literature, showed intramural gas and gastric wall thickening. After receiving a total gastrectomy, he had a satisfactory outcome. The present report discusses the possible aetiologic relationship between acute gastric dilatation and emphysematous gastritis, and suggests abdominal sonography to be the first choice of diagnostic measure for patients and the intramural gas in the gastric wall. This is the first case of emphysematous gastritis diagnosed by abdominal sonography.