1. PaDIL Species Factsheet Scientific Name: Didymella bryoniae (Fuckel) Rehm (Ascomycota: Dothideomycetes: Capnodiales: Mycosphaerellaceae) Common Name Didymella bryoniae Live link: http://www.padil.gov.au/maf-border/Pest/Main/143022 Image Library New Zealand Biosecurity Live link: http://www.padil.gov.au/maf-border/ Partners for New Zealand Biosecurity image library Landcare Research — Manaaki Whenua http://www.landcareresearch.co.nz/ MPI (Ministry for Primary Industries) http://www.biosecurity.govt.nz/ 2. Species Information 2.1. Details Specimen Contact: Eric McKenzie - [email protected] Author: McKenzie, E. Citation: McKenzie, E. (2013) Didymella bryoniae(Didymella bryoniae)Updated on 3/23/2014 Available online: PaDIL - http://www.padil.gov.au Image Use: Free for use under the Creative Commons Attribution-NonCommercial 4.0 International (CC BY- NC 4.0) 2.2. URL Live link: http://www.padil.gov.au/maf-border/Pest/Main/143022 2.3. Facets Commodity Overview: Field Crops and Pastures Commodity Type: Cucurbitaceous produce Distribution: Oceania, Afrotropic, Antarctic, Australasia, Indo-Malaya, Nearctic, Neotropic, Palearctic Groups: Fungi & Mushrooms Host Family: Cucurbitaceae Pest Status: 2 NZ - Regulated pest Status: NZ - Exotic 2.4. Other Names Ascochyta cucumis Fautrey & Roum. Mycosphaerella melonis (Pass.) W.F. Chiu & J.C. Walker Phoma cucurbitacearum (Fr.) Sacc. Sphaeria bryoniae Fuckel Stagonosporopsis cucurbitacearum (Fr.) Aveskamp, Gruyter & Verkley 2.5. Diagnostic Notes **Disease** Gummy stem blight. Causes leaf spot, stem canker, black leaf and fruit rot; common name refers to the characteristic gummy exudate on stem lesions. Water soaked lesions may spread rapidly to involve whole leaf or fruit in a black rot, and waxy water soaked cankers can girdle stems causing vine wilt. Fruit may rot following damage after harvest. The teleomorph may form on stems and fruit. **Morphology** _Asci_ cylindrical to subclavate, 8-spored, 60–90 × 10–15 µm. _Ascospores_ arranged in overlapping rows, ellipsoid, tapering towards each rounded end, hyaline, 1-septate, slightly constricted at septum, guttulate, 14–18 × 4–7 µm. _Conidiomata_ pycnidia, immersed, becoming more exposed with time, dark brown; conidia may be exuded in a white ooze. _Conidia_ variable in shape, size and septation, straight or slightly curved, subglobose to ellipsoidal, hyaline, with several small guttules, (0–)1(–2)-septate. In culture conidia mainly aseptate, 4–8 × 2–3 µm, but some larger 1-septate conidia may be present. On plant material conidia usually 1(–2)-septate, (6–)8–10(–13) × 3–4(–5) µm. _Chlamydospores_ not formed. 2.6. References - Boerema, G.H., de Gruyter, J., Noordeloos, M.E. & Hamers, M.E.C. (2004). _Phoma Identification Manual_. CABI Publishing, UK, pp. 236–238. - Ellis, M.B. & Ellis, J.P. (1985). _Microfungi on Land Plants. An Identification Handbook_. Macmillan Publishing Company, p. 322, plate 134. - Gerlach, W.W.P. (1988). _Plant Diseases of Western Samoa_. Samoan German Crop Protection Project, Apia, Western Samoa, 94–95. - Punithalingam, E. & Holliday, P. (1972). _Didymella bryoniae. CMI Descriptions of Pathogenic Fungi and Bacteria 332_, 1–2. 3. Diagnostic Images Didymella bryoniae conidia Didymella bryoniae early symptoms on Conidia: Paul Bachi University of Kentucky watermelon Research and Education Centre In Life: E. McKenzie Landcare Research Didymella bryoniae early symptoms on Didymella bryoniae early symptoms on watermelon watermelon In Life: E. McKenzie Landcare Research In Life: E. McKenzie Landcare Research Didymella bryoniae symptoms on Didymella bryoniae symptoms on watermelon leaves and petioles watermelon leaves and petioles In Life: Jason Brock University of Georgia In Life: Clemson University - USDA Cooperative Extension Slide Collection Clemson University Didymella bryoniae symptoms on Didymella bryoniae fruiting bodies on watermelon leaves and petioles watermelon vine In Life: E. McKenzie Landcare Research In Life: Jason Brock University of Georgia Results Generated: Wednesday, September 29, 2021 .