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Pometia pinnata (family Sapindaceae), locally known as 'Kasai', is a tropical hardwood and fruit tree species grown in Malaysia. The decoction of the bark is used for the treatment of fever, sores and colds, while the fruits are edible (Adema et al. 1996). In May 2021, irregular brown spots and necrotic lesions were observed on 'Kasai' with an incidence and severity of approximately 60% and 10% on 10 plants in a nursery (5°55'30.7"N 116°04'36.2"E) in Penampang, Sabah province. When the disease progressed, the spots coalesced into extended patches, blightening the leaves and, gradually, the entire foliage. Small pieces (5 x 5 mm) of infected leaves were excised from the infected margin, and then surface sterilized according to Khoo et al. (2022b), and plated on potato dextrose agar (PDA), and cultured at 25 °C. for 6 days. Colonies were dark brown in color initially whitish on the PDA. The color of fungal colony was dark as the culture aged. Semi-appressed mycelia were observed on the plates with abundant micrrols. M. phaseolina has been reported to cause leaf blight on Jasminium multiflorum in India (Mahadevakumar and Janardhana, 2016), and Crinum asiaticum and Hymenocallis littoralis in Malaysia (Abd Rahim et al. 2019). To our knowledge, this is the first report of M. phaseolina causing leaf blight on 'Kasai' in Malaysia and worldwide. Our findings serve as a warning for the authorities and farmers that the disease threat has appeared for 'Kasai' in Malaysia.Philodendron bipinnatifidum Schott ex Endl (Araceae) is native to South America. It was introduced in Guangdong around the 1980s, and then gradually promoted for use as a landscape ornamental in South China (You et al. 2013). Previous studies showed that an extract of P. bipinnatifidum displayed antinociceptive and anti-inflammatory activities (Scapinello et al. 2019). In August 2019 and June 2020, leaf spot disease was observed on P. bipinnatifidum leaves in Qingxiushan Park, Nanning, Guangxi province, China, with approximately 80% disease incidence. Symptoms began as small brown spots that extended into large, irregular, dark brown, necrotic, sunken lesions. The leaves eventually became yellow and then withered and died. The symptomatic leaves were sampled from three different places in the park. Leaf pieces (5× 5 mm) of three samples were cut from the junction of diseased and healthy leaf tissue, disinfected in 75% (v/v) alcohol for 10 sec, 2% (v/v) sodium hypochlorite for 1 min, and then rinsed three timeeaves. C. karsti and C. endophytica were consistently re-isolated from the inoculated leaves which was confirmed by morphology and sequencing, fulfilling Koch's postulates. C. siamense was previously reported as a pathogen on P. bipinnatifidum in China (Ning et al. 2021). To our knowledge, this is the first report of leaf spot caused by C. karsti and C. endophytica on P. bipinnatifidum worldwide. This research may accelerate the development of future epidemiological studies and management strategies for anthracnose caused by C. karsti and C. endophytica on P. bipinnatifidum.Disease incidence and metrics of disease severity are relevant parameters for decision making in plant protection and plant breeding. To develop automated and sensor-based routines, a sugar beet variety trial was inoculated with Cercospora beticola and monitored with a multispectral camera system mounted to an unmanned aerial vehicle (UAV) over the vegetation period. A pipeline based on machine learning methods was established for image data analysis and extraction of disease-relevant parameters. Features based on the digital surface model (DSM), vegetation indices, shadow condition and image resolution improved classification performance in comparison to using single multispectral channels in 12% and 6% of diseased and soil regions, respectively. With a post-processing step, area-related parameters were computed after classification. Results of this pipeline also included extraction of disease incidence (DI) and disease severity (DS) from UAV data. The calculated area under disease progress curve (AUDPC) of DS was 2810.4 to 7058.8 %.days for human visual scoring and 1400.5 to 4343.2 %.days for UAV-based scoring. Moreover, a sharper differentiation of varieties compared to visual scoring was observed in area-related parameters, like area of complete foliage (AF), area of healthy foliage (AH) and mean area of CLS lesion by unit of foliage (Ac/F). These advantages provide the option to replace the laborious work of visual disease assessments in the field with a more precise non-destructive assessment via multispectral data acquired by UAV flights.Photinia × fraseri is a well-known evergreeen ornamental tree. Owing to its flower-like red leaves and its ability to tolerate stressful environments, P. fraseri is widely cultured as a fast-growing hedge in southern China. From July to September in 2021, a disease with symptoms similar to leaf spot was extensively observed on P. fraseri in Daozhen county (28° 51 'N, 107° 57 'E), Zunyi, Guizhou province, China. About 500 plants were surveyed and the incidence of leaf spot on P. fraseri leaves was 35% to 70%, significantly reducing the ornamental and economic value. The symptomatic leaves displayed irregular, watery dark brown lesions with black conidiomata in gray centers, and 10 symptomatic leaves were collected from 10 trees. After surface sterilization (0.5 min in 75% ethanol and 2 min in 3% NaOCl, washed three times with sterilized distilled water) (Fang 2007), small pieces of symptomatic leaf tissue (0.2 × 0.2 cm) were plated on potato dextrose agar (PDA) and incubated at 25°C for about 7 days. Three sinn GenBank with accession numbers OK563071 (ITS), OK584020 (TUB) and OK663023 (TEF). BLAST searches of the obtained sequences revealed 100% (482/482 nucleotides), 99.05% (419/421 nucleotides), and 99.33% (891/897 nucleotides) homology with those of N. asiatica in GenBank (JX398983, JX399018 and JX399049, respectively). Phylogenetic analysis (MEGA 6.0) using the maximum likelihood method placed the isolate GZAAS 21-0328 in a well-supported cluster with N. asiatica. The pathogen was thus identified as N. asiatica based on the morphological characterization and molecular analyses. To our knowledge, this is the first report of leaf spot on P. fraseri caused by N. asiatica in China. This study provides valuable information for the identification and control of the leaf spot on Photinia × fraseri.Controlled environment experiments were conducted to evaluate the effects of temperature on Calonectria pseudonaviculata mycelial growth and the effects of temperature and infection period on boxwood blight severity. In experiment 1, 15 Oregon isolates (representing five genotypes) were grown on potato dextrose agar (PDA) and malt extract agar (MEA) at six temperatures from 5 to 30°C. Growth (culture diameter) was measured after 2 weeks. Optimal growth occurred at 25°C on PDA and 20°C on MEA. Isolates of genotype G1 also grew faster than genotype G2, but only on MEA at 25°C. In experiment 2, Buxus cultivars Green Velvet (GV, more susceptible) and Winter Gem (WG, more resistant) were inoculated and incubated in moist chambers for 9 or 24 h at 22°C (infection period), then moved into growth chambers at 15 or 25°C. After 4 weeks, chamber temperatures were switched, and plants were incubated for 4 more weeks. Disease severity was evaluated weekly. During the first 4 weeks, disease was generally more severe on GV than WG, on plants with a 24-h versus a 9-h infection period, and on plants incubated at 15°C versus 25°C. However, disease was just as severe on WG as GV when the 24-h infection period was followed by incubation at 15°C. After the temperatures were switched, disease increased only on WG that were cooled from 25 to 15°C. Results show that Oregon isolates of C. pseudonaviculata are capable of growing faster and causing more severe disease at temperatures cooler than those reported previously.Photinia × fraseri Dress is a hybrid species of Rosaceae and Photinia genus which is widely cultivated in China. During 2020 and 2021, approximately 80% of plants growing in Xuanwu district of Nanjing, China, exhibited disease symptoms including blight, necrosis, and dieback of crowns and roots. Symptomatic root tissues collected from 2-year-old plants were rinsed with water, cut into 2-mm tissues which were surface-sterilized in 70% ethanol for 60 s, and plated onto 10% V8 PARP agar and incubated in the dark at 26°C for 3 days. Hyphae emerged from 70% of the samples. Two representative isolates (PF-he2, PF-he3) were obtained and deposited. Ten agar plugs (2×2 mm2) of each isolate were transferred into 10 mL of 10% V8 juice to produce mycelial mats. To stimulate sporangial production, 3-5 drops of soil extract solution (soil collected from healthy fields, immersed in sterile water, and filtered) were added to each plate. Sporangia were terminal, ovoid to globose or papillate. The zoospores were 7.1-9.3 µm in Controls were treated with ddH2O. Three seedlings/isolate were used for each treatment including controls. All plants were repotted using the original sterilized potting mix and pots. After inoculation, the plants were covered with plastic bags, and sterilized H2O was sprayed into the bags twice per day to maintain humidity and kept in a greenhouse at the day/night temperatures at 25/16 °C. All the inoculated plants showed lesions similar to those observed in the field after 23 days , whereas controls were asymptomatic. The isolates were reisolated from the lesions and sequenced as P. helicoides which has found causing root rot on Nelumbo nucifera, Rhododendron pulchrum, Zea mays in China, and also on Fragaria × ananassa in America, Peach Rootstock in California. Globally, this is the first report of P. helicoides causing crown blight and root rot of P. × fraseri. Management programs are under development to contain the spread of P. helicoides and treat diseased plants.Carica papaya Linn, belonging to the Caricaceae family, is an economic and medicinal plant, which is widely cultivated in tropical and subtropical countries (Soib et al., 2020). Beginning in 2021, abnormal symptoms of Carica papaya exhibiting leaf yellow, crinkle and leaflet were found in Wanning city of Hainan Province, China. The diseased symptoms of the plant, with about 20 % incidence in the sampling regions, were suspected to be induced by phytoplasma, a phloem-limited and could not be cultured in vitro prokaryotic pathogen. Total DNAs were extracted from 0.10 g fresh leaves of symptomatic or asymptomatic Carica papaya using CTAB DNA extraction method (Doyle and Doyle, 1990). PCR reactions were performed using primers R16mF2/R16mR1 (Gundersen and Lee, 1996), secAfor1/secArev3 (Hodgetts et al., 2008) and AYgroelF/AYgroelR (Mitrović et al., 2011) specific for phytoplasma 16S rRNA, secA and groEL gene fragments. PCR products of the 16S rRNA, secA and groEL gene target fragments of phytoplasma were obtained 41-48. Soib, H.H., et al. 2020. Molecules, 25 517. Yang, Y., et al. 2016. Int. J. Syst. Evol. Microbiol. find more 66 3485-3491. Zhao, Y., et al. 2009. Int. J. Syst. Evol. Microbiol. 59 2582-2593.First Report of Didymella rhei causing leaf spot on rhubarb in New York E. J. Indermaur1, C. T. C. Day1, and C. D. Smart1† 1School of Integrative Plant Science, Section of Plant Pathology and Plant-Microbe Biology, Cornell University, Geneva NY 14456 †Corresponding author C. D. Smart; Email [email protected] Rhubarb (Rheum spp.) is a perennial grown across the northern United States for petiole production (Foust & Marshall 1991). In August 2021, leaf spots were observed on rhubarb growing in a two-acre field in Erie Co., NY (Fig. S1). Approximately 30% of the plants in the field had leaf spot with disease severity of 5%. Initial symptoms on leaves were light brown, circular lesions with red margins that later coalesced into irregular spots. Lesion centers were dry with concentric rings, often perforating as they enlarged. Lesions on petioles were light brown, fusiform, and sunken with red margins. To identify the causal agent(s), symptomatic leaves and petioles from 50 plants (cultivar unknown) were collected with a W-shape sampling scheme.
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