Fusarium head blight (FHB) of wheat caused by Fusarium graminearum species complex (FGSC) is a devastating disease worldwide. The pathogens not only reduce the yield of wheat, but also impact the quality of wheat by contamination with trichothecene mycotoxins. A systematic investigation on the pathogens of FHB in Taiwan is lacking. Here, molecular and morphological approaches were used to identify species of the Taiwanese FGSC isolates and determine their trichothecene genotypes. In this study, a total of 195 isolates of FGSC from diseased wheat were collected from 8 areas of northern and central Taiwan. All isolates were subjected to seedling inoculation for verification of pathogenicity. The pathogenic isolates were genetically characterized by sequence characterized amplified region (SCAR), PCR- restriction fragment length polymorphism (RFLP), phylogenetic analysis and fixed nucleotides to clarify their phylogenetic species, and by PCR assays of TRI genes to determine trichothecene genotypes. They were identified as F. asiaticum, F. graminearum sensu stricto, F. meridionale and an unknown species. Isolates of F. asiaticum were the major causal agents (98%) in this investigated population and were comprised of SCAR type 5 (75%), SCAR type 4 (21%) and SCAR type 3 (2%). Their trichothecene genotypes were either 15-acetyl-deoxynivalenol (15-ADON) (83%) or nivalenol (NIV) genotype (17%). These genetic characterizations indicated that F. asiaticum (15-ADON SCAR type 5) accounts for 60% of this Taiwanese population. Virulence assay on wheat heads indicated virulence of F. asiaticum isolates in subpopulations divided by SCAR types or trichothecene genotypes were comparable, suggesting other factors influence the unequal subpopulation sizes. This is the first study that FGSC isolates in Taiwan were systematically collected and characterized. In addition to F. graminearum sensu stricto and F. meridionale, F. asiaticum with 15-ADON genotype was identified as the predominate species in Taiwan. In contrast to Chinese and Japanese populations that F. asiaticum isolates were typically of 3-ADON or NIV genotype, the predominate 15-ADON genotype in Taiwanese population was unique among F. asiaticum populations and represented the southernmost 15-ADON genotype population in East Asia.

Eucalyptus robusta commonly known as swamp mahogany or robusta eucalyptus was introduced into Taiwan around 1896 for forestation. Due to its adaptability to the low elevation climate, it was planted as shade trees in many parks and public open spaces. Since August 2014 severe defoliation and shoot blight of E. robusta were noticed in Taichung city of central Taiwan (E120°40'35.7" N24°07'20.9"). The same symptoms were observed at Taipei city of northern Taiwan (E121°32'03.2" N25°01'00.8") in the following year. Necrotic leaf spots were associated with most fallen leaves. Leaf spots were sub-circular to irregular with smooth or irregular edges, and were cream brown in color with a dark brown margin and frequently an internally concentric dark ring. Infected leaves from the two locations were surface sterilized and incubated on potato dextrose agar (PDA). The colonies of purified isolates on PDA gradually developed yellow brown mycelia from the center to the edge, and turned grey with increasing age. Pale yellow conidia mass produced on PDA or induced on a piece of autoclaved leaf of E. robusta placed on PDA. Conidia were produced from cylindrical, discrete, and phialidic conidiogenous cells in conidiomata embedded in leaves. Conidia were hyaline, ellipsoid, slightly curved, thick wall, with an obtuse apex and a flat protruding scar at the base, and were (15)16-20(22) x (7)7.4-8.6(10) μm with average 2.2 : 1 ratio (length : width). Conidia were aseptate, but developed 1-3 septa before germination. Detached leaf assays were conducted by inoculating 5 ul of a conidia suspension (10^5 spores/ml) on host leaves that were either intact or wounded with a sterilized needle. Necrotic leaf spots resembling the described symptoms developed on both treatments at 7 days post-inoculation, but not on water control treatment. Fungi re-isolated from these diseased leaves were identical to the inoculated fungus. The pathogen was identified as Pseudoplagiostoma eucalypti based on the morphological characteristics and symptoms (Cheewangkoon et al. 2010; Old et al. 2003). To further confirm the identification, the ITS and β-tubulin genes were amplified from extracted genomic DNA of isolate PE1 with primers pairs ITS4/V9G and T1/Bt-2b, respectively (Cheewangkoon et al. 2010). The obtained ITS sequence (accession number: KT831771) was 100% identical to that of P. eucalypti type strain CBS124807 while the partial β-tubulin sequence (accession number: KT831772) was 99% identical. A phylogenetic analysis of the concatenate sequences of ITS and β-tubulin genes of three Pseudoplagiostoma species and two Plagiostoma species was performed with a maximum likelihood method. The result indicated that isolate PE1 was clustered with the P. eucalypti type strain in the same clade with a 100% bootstrap value, which agrees with the morphological identification. Pseudoplagiostoma eucalypti Cheewangkoon, M.J. Wingf. & Crous (formerly known as Cryptosporiopsis eucalypti Sankaran & B. Sutton) is widely distributed in tropic and temperate countries (Cheewangkoon et al. 2010; Sankaran et al. 1995). The leaf spot of E. robusta caused by P. eucalypti was reported in Hawaii (Sankaran et al. 1995). To our knowledge, this is the first report of the fungus and its disease on E. robusta in Taiwan. Due to the recorded host range of C. eucalypti, the presence of the pathogen may be a potential threat to other Eucalyptus spp. in the country. References: Cheewangkoon, R. et al. Fungal Divers. 44: 89, 2010. Old, K. M. et al. Page 10 in: A manual of diseases of eucalypts in South-East Asia. Center for International Forestry Research, Bogor, Indonesia, 2003. Sankaran, K. V. et al. Mycol. Res. 99: 827, 1995.

Mango (Mangifera indica L.) is an economically important tropical fruit in southern Taiwan. In February 2019, new leaf blotches distinct from anthracnose lesions were noticed on mango leaves in Meinong, Kaohsiung (N22°54'43.7" E120°32'59.3"). Symptoms were circular to irregular lesions with easily torn centers and were cream to light brown with dark brown margin on both leaf surfaces. Similar symptoms were observed on mango leaves in Yujing, Tainan (N23°07'31.3" E120°27'18.2") in July of the same year. We surveyed the disease incidence on 60 mango trees consisting of three cultivars, 'Irwin', 'Yu-win No.6' and a native cultivar in a commercial farm by randomly examining five shoots of each tree. The disease incidences of 'Irwin', the native cultivar and 'Yu-win No.6' were 25%, 37% and 73%, respectively. Diseased tissues from the two locations were surface sterilized and incubated on potato dextrose agar (PDA) for pathogen isolation. Seven isolates (Mgk3, TMg2-2.2, TMg3-1.2, TMg3-2.1, TMg4-1, TMg6-3, and TMg8-1.1) from different locations and cultivars were selected for further study. Pycnidia were produced on 7-day-old PDA cultures. Conidiogenous cells were hyaline and short cylindrical phialides. Conidia were hyaline, aseptate, thick-walled, 20-24 × 11-16 μm, and subcircular to ellipsoid with 1-2 large oil droplets and a markedly flat protruding hilum at the base. These morphological features presenting in the seven isolates were identified as a member of Pseudoplagiostoma (Cheewangkoon et al. 2010). Pathogenicity assays were conducted by the point inoculation method on 10 intact young leaves growing on 'Irwin' mango plants in a greenhouse at 20-25℃. Each leaf was inoculated at six points on the abaxial surface with point inoculation. Each point was inoculated with a 10 μl conidial suspension (106 conidia/ml) of isolate TMg 8-1.1. Sterilized water was used as control. Shoots with inoculated leaves were covered with translucent plastic bags for 2 days. At 7 days post-inoculation (dpi), 70% of conidia inoculated points (n = 60) displayed symptoms resembling the field symptoms, but sterilized water inoculated points (n = 60) did not. The six other isolates were inoculated on detached leaves by the point inoculation method. All inoculated leaves were maintained in humid containers at 25℃ with 12 h light/dark regime, and displayed similar lesions at 7 dpi. Fungi re-isolated from the symptomatic leaves showed the same morphological characteristics observed in the Pseudoplagiostoma originally isolated from diseased tissues. Internal transcribed spacer (ITS), TUB2 and LSU gene sequences of the seven isolates (ITS accession nos.: MN818659 to MN818665; TUB2 accession nos.: MW415921 to MW415927; LSU accession nos.: MN876849 to MN876855) were amplified with primer sets ITS4/V9G, T1/Bt-2b and LSU1Fd/LR5, respectively, and used for molecular identification (Cheewangkoon et al. 2010). The seven isolate were 95.8%, 99-100% and 99.8% identical to Pseudoplagiostoma mangiferae Dayarathne, Phookamsak & K. D. Hyde KUMCC 18-0179 (the ex-type strain) for the ITS gene (MK084824), TUB2 gene (MK084823) and LSU gene (MK084825), respectively. Phylogenetic analysis based on concatenated sequences of ITS and LSU genes was performed by the Maximum Likelihood method. All seven isolates were clustered in a well-supported clade with P. mangiferae KUMCC 18-0179 with 100% bootstrap value. Based on the pathogenicity and morphological characteristics, the pathogen was identified as P. mangiferae which was reported as a new species associated with mango leaf blight in Yunnan, China (Bezerra et al. 2019; Cheewangkoon et al. 2010; Crous et al. 2012; Crous et al. 2018; Phookamsak et al. 2019; Suwannarach et al. 2016). The newly emerging leaf blotch may become a prevalent disease of mango in future.

In this paper, an alternative randomized response procedure is given that allows us to estimate the population proportion in addition to the probability of providing a truthful answer. It overcomes a difficulty associated with traditional randomized response techniques. Properties of the proposed estimators as well as sample size allocations are studied. In addition, an efficiency comparison is carried out to investigate the performance of the proposed technique.