Colletotrichum caladii sp. nov. causing anthracnose leaf spot of Caladium × hortulanum (Araceae) in Florida, USA.

Caladium (Caladium × hortulanum) is an ornamental plant popular for its variable and colorful foliage. In 2020, plants showing leaf spots and blight, typical of anthracnose, were found in a field trial at the University of Florida's Gulf Coast Research and Education Center (UF/GCREC) in Wimauma, FL, USA. Leaf samples consistently yielded a Colletotrichum-like species with curved conidia and abundant setae production in the acervuli. The internal transcribed spacer (ITS), partial sequences of the glyceraldehyde-3-phosphate dehydrogenase gene (gapdh), actin gene (act), chitin synthase 1 gene (chs-1), beta-tubulin gene (tub2), and histone3 gene (his3) were amplified and sequenced. Blastn searches in the NCBI GenBank database revealed similarities to species of the Colletotrichum truncatum species complex. Phylogenetic analyses using multi-locus sequence data supports a distinct species within this complex, with the closest related species being C. curcumae. Based on morphological and phylogenetic analyses, a new species of Colletotrichum, named C. caladii, is reported. Pathogenicity assays and subsequent isolation confirmed that this species was the causal agent of the disease.

Pseudocercospora pancratii Causing Leaf Spots on Commercial Blackberry (Rubus sp.) in Florida.

Blackberry (Rubus L. subgenus Rubus Watson) is a deciduous berry crop that is the fourth most economically important berry crop, and its production is expanding in the southeastern United States. However, since most commercially available cultivars were bred under temperate conditions, they are not always well adapted and could be threatened by new pathogen populations inhabiting subtropical areas. In 2017, plants showing purple or brown leaf spots and angular-to-irregular lesions on both leaf surfaces, with clusters of black conidiophores at the center, were observed in a field trial at the University of Florida's Gulf Coast Research and Education Center (UF/GCREC) in Wimauma, FL. A fungus resembling Cercospora/Pseudocercospora was isolated from the lesions. The ribosomal DNA internal transcribed spacers, the translation elongation factor 1-alpha, and the actin genes were amplified and sequenced. Based on the phylogenetic analysis, the closest related species was Pseudocercospora pancratii. Pathogenicity assays and subsequent reisolation confirmed that this species is the causal agent of the disease. Among eight cultivars screened, no complete resistance was found. However, 'Osage' was the least susceptible, and 'Kiowa' was the most susceptible. This study is the first report of P. pancratii causing leaf spots on blackberry worldwide, and it may help shape future research into disease epidemiology and management for a crop that is rapidly expanding but has very limited disease information currently available for Florida growers.

The Identification of a New Species, Diaporthe humulicola, a Pathogen Causing Diaporthe Leaf Spot on Common Hop.

Common hop, Humulus lupulus, is a commercially important crop in the United States, with an increasing number of hop yards being established in the Northeast. In 2018, a new fungal disease was observed at two research hop yards in Connecticut. This new pathogen affected all hop cultivars being grown and caused leaf spots and browning of cones. The causal organism was isolated and Koch's postulates were performed to confirm pathogenicity. The disease symptoms were similar to the previously described Phoma wilt; however, morphological and phylogenetic analyses placed the causal organism as a new species of Diaporthe. We propose the name Diaporthe humulicola. The disease increased under hot, humid conditions (around 24°C and 90% relative humidity), which prevail during the summer in the northeastern United States as well as other parts of the country. An in vitro preliminary assessment of fungicide sensitivity revealed that pyraclostrobin and boscalid inhibited D. humulicola growth in culture and should be further assessed for field efficacy against this new disease of hop. The proper identification and monitoring of this pathogen will be important to inform hop growers of this new threat.

First report of postharvest stem end rot disease on MD2 pineapple fruits caused by Neoscytalidium dimidiatum in Malaysia.

Repeated sampling conducted from December 2019 to March 2020, and fruit of pineapple (Ananas comosus) var MD2 showing early stem end rot symptoms including brown and rotten fruit skin near the stem end region (Fig.1Aa) or darker skin with black discoloration (Fig.1Ab) indicated a consistent fungal infection. The samples (30 fruits from each location) were collected from store houses in three farmer fields with 60% disease incidence in Serdang, (3.0220oN,101.7055oE), Selangor, West Malaysia. The pulp of infected fruits appeared watery with characteristic spoilage odour. Symptomatic necrotic tissues from stem end region and skin were cut in to pieces (1x1cm), surface sterilized and plated onto potato dextrose agar amended aseptically with 0.5 g L-1 streptomycin sulphate. The plates were incubated at room temperature (28±2oC) in natural light conditions. Five days old cultures were light grey in colour and gradually turned dark brown to black with dense deeply tufted, mycelium as the culture aged (Fig.1B, C). Conidial morphology was observed using compound microscope (Olympus model BX-50F4, Tokyo, Japan) equipped with Dino-Eye. Branched mycelia with 0-1 septate arthospores were evident in 14 days old cultures (Fig.1D). Measured arthroconidia (5 to10x3 to 4.5µm) were ellipsoid to ovoid or round shaped, hyaline with an acutely rounded apex, truncate base, initially aseptate (Fig.1E) and arranged as chain at maturity (Fig.1F). The pathogen was identified through PCR amplification of the internal transcribed spacer (ITS) region using ITS1 and ITS4 primers (White et al., 1990) and BLASTn homology search as Neoscytalidium dimidiatum based on 100% similarity to a reference sequence (accession number KJ648577) that was previously deposited (Mohd et al.,2013). The sequence was deposited in Gen Bank ( accession number MW082810). Pathogenicity test was performed using the mycelial plug inoculation method and repeated twice with five replicates. Healthy MD2 pineapple fruits were surface sterilized with 1% NaOCl solution for15 min. followed by washing with sterilized distilled water. One centimeter diameter PDA plug at the margin of actively growing seven days old cultures were inserted in each of two inoculation wounds made on the skin and stem end of each fruit then the wounds were wrapped with moist cotton wool. Non-colonized PDA plugs were used to inoculate the control fruits. Fruits were incubated under 85% RH at room temperature. Five days after inoculation, the fruits showed similar dark necrotic discoloration and confirmed as N.dimidiatum by PCR (Fig.1G). The Koch postulates were fulfilled by inoculation and re-isolation of the fungal pathogen. This pathogen has also been reported previously to cause economic losses on a number of other hosts, such as pitayah fruits in Israel and Malaysia (Erza et al., 2013; Mohd et al., 2013)) and almond in California (Mohomed et al., 2018). To our knowledge this is the first report of N. dimidiatum causing postharvest stem end rot on MD2 pineapple in Malaysia. It may have the possibility to develop postharvest economic losses to pineapple industry, if severely affected fruits with high population of the pathogen left unattended in store houses.

Successive new-pathogen prosthetic joint reinfections: Observational cohort study on 61 patients.

OBJECTIVES: Prosthetic joint infection (PJI) treatment failure may be due to relapsing infection (same microorganism) or new-pathogen reinfection (npPJI). The aim was to describe npPJI epidemiological, clinical and microbiological characteristics, their treatments and outcomes, and identify their risk factors. METHODS: This observational, single-center, cohort study was conducted in a French Referral Center for Bone-and-Joint Infections between September 2004 and December 2015. Patients treated for at least two successive hip or knee PJIs in the same joint with a different pathogen were identified in the prospective database. We compared each patient's first PJI and subsequent npPJI(s) to analyze the type and microbiological characteristics of npPJIs. To search for npPJI risk factors, we compared those cases to a random selection of 122 "unique-episode" PJIs treated during the study period. RESULTS: Among 990 PJIs, 79 (8%) npPJIs occurring in 61 patients were included. New-pathogen prosthetic joint infections (npPJIs) developed more frequently in knee (14%) than hip prostheses (5%). Median interval from the first PJI to the npPJI was 26 months. New-pathogen prosthetic joint reinfections (npPJIs) more frequently spread hematogenously (60% vs 33%) and were predominantly caused by Staphylococcus (36%) or Streptococcus (33%) species. Multivariate analysis identified two risk factors: chronic dermatitis (odds ratio: 6.23; P<0.05) and cardiovascular diseases (odds ratio: 2.71; P<0.01). A curative strategy was applied to 70%: DAIR (29%), one-stage (28%), two-stage exchange arthroplasty (7%) or other strategies (7%). The others received prolonged suppressive antibiotic therapy (30%). CONCLUSIONS: New-pathogen prosthetic joint infections (npPJIs) are complex infections requiring management by multidisciplinary teams that should be adapted to each clinical situation.

Lasiodiplodia syzygii sp. nov. (Botryosphaeriaceae) causing post-harvest water-soaked brown lesions on Syzygium samarangense in Chiang Rai, Thailand.

BACKGROUND: Syzygium samarangense (Wax apple) is an important tropical fruit tree with high economic and nutrient value and is widely planted in the tropics or subtropics of Asia. Post-harvest water-soaked brown lesions were observed on mature fruits of ornamental wax apples in Chiang Rai Province, Thailand. A fungus with morphological characters, similar to Lasiodiplodia, was consistently isolated from symptomatic fruits. Phylogenetic analyses, based on ITS, LSU, TEF1-a and tub2, revealed that our isolates were closely related to, but phylogenetically distinct from, Lasiodiplodia rubropurpurea. NEW INFORMATION: Morphological comparisons indicated that pycnidia and conidiogenous cells of our strains were significantly larger than L. rubropurpurea. Comparisons of base-pair differences in the four loci confirmed that the species from wax apple was distinct from L. rubropurpurea and a new species, L. syzygii sp. nov., is introduced to accommodate it. Pathogenicity tests confirmed the newly-introduced species as the pathogen of this post-harvest water-soaked brown lesion disease on wax apples.

The Prevention and Treatment of Pulmonary Nodules “Nodule-cancer Transformation” Based on the View of “Disease with Latent Pathogen Induced by a New Pathogen” / 中医杂志

As one of the pathogenic mechanisms contained in The Inner Canon of Yellow Emperor （《黄帝内经》）， “disease with latent pathogen induced by a new pathogen” means that the induced new pathogen resulted to a combination of the latent previous pathogen and the new pathogen， which caused the disease. Based on this， it is believed that the change of “nodule-cancer transformation” of pulmonary nodules is actually based on the deficiency of original qi， and the new pathogen induces the latent pathogens like phlegm coagulation， qi stagnation， blood stasis， toxicity， so healthy qi can not drive the pathogens out， and the long-time detention generated into cancerous turbidity， and deve-loped into cancerous tumour at the end. Therefore， based on the three-stage treatment of unformed cancer， dense cancerous toxin， and developed cancer， the clinical practice applied six methods of clearing， expelling， dissipating， tonifying， harmonizing， and transforming， taking into account both the manifestation and root cause， moving the treatment window of pulmonary nodules forward， attacking the pathogens when the toxin was not yet overbearing， supporting the healthy qi before declining， delaying the process of nodules-cancer transformation， and providing ideas for the prevention and treatment of pulmonary nodules “nodule-cancer transformation” in traditional Chinese medicine.

Characterization of Sclerotinia sclerotiorum, an Emerging Fungal Pathogen Causing Blight in Hyacinth Bean (Lablab purpureus).

Stems and pods of hyacinth bean cultivated in a farmer's field in Gazipur District, Bangladesh, were found rotted in nearly 5% hyacinth bean plants. A fungus having fluffy mycelium and large sclerotia was isolated from affected tissues. Combined results of morphological, molecular and pathological analyses identified the fungus as Sclerotinia sclerotiorum (Lib) de Bary. Inoculating the fungus on healthy hyacinth bean plants and pods reproduced the symptoms previously observed in the field. The three isolates obtained from naturally infected plants were cross inoculated in hyacinth bean, okra and African-American marigold and they were pathogenic to these hosts. The optimum temperature and pH for its growth were 20°C and pH 5.0, respectively. Sclerotial development was favored at pH 5.0. Sucrose and mannitol were the best carbon sources to support hyphal growth, while glucose was the most favourable for sclerotial development. The hyacinth bean genotypes, HB-82 (Rupban Sheem) and HB-102 were found highly resistant, while HB-94 (Ashina) was moderate resistant to the fungus. Finally, S. sclerotiorum was sensitive to Bavistin, Dithane M-45 and Rovral fungicides and Ca in the form of CaCl2. This observation could possibly aid in eliminating field loss in hyacinth bean caused by an emerging pathogenic fungus S. sclerotiorum.