First report of Calonectria tunisiana causing crown and root rot on Eucalyptus globulus

Abstract

Calonectria tunisiana. Crown and root rot. Eucalyptus globulus During autumn 2019, a widespread crown and root rot was observed in a commercial nursery in Catania province, Italy, on about 5000 potted 10-12 month-old plants of Eucalyptus globulus Labill. More than 15% of plants obtained from cutting showed brown to black necrotic lesions on crown, and root were decayed. Discolouration was observed under the bark. Diseased tissues of twenty plants were surface disinfected for 1 min in 1.5% sodium hypochlorite solution, rinsed in sterile water, placed on potato dextrose agar (PDA) amended with 100 mg/l of streptomycin sulfate, and then incubated at 25°C for seven days. Calonectria sp. was consistently isolated. Colonies surface and reverse sienna, developed sparse aerial mycelium with abundant cylindrical conidia, rounded at ends, 1-septate, 47 to 51 × 4 to 6 μm. Conidiophores were stipe septate, hyaline, smooth, 42-95 × 7-11 μm and phialides were doliiform to reniform, hyaline, aseptate, 8-13 × 3-5 μm. Chlamydospores were present. These morphological characteristics were consistent with the original description of C. tunisiana L. Lombard, G. Polizzi & Crous (Lombard et al. 2011). Part of tef1 gene of CAL-EU1 and CAL-EU2 isolates was amplified using EF1-728F and EF1-986R primers. The sequence data were deposited in GenBank (accession Nos. MT365928 and MT365929). The obtained tef sequences showed 100% identity with the tester isolate DISTEF-TME1 of C. tunisiana (JN607286). Pathogenicity test was conducted on 6-month-old cuttings of E. globulus. The inoculum consisted of mycelial plug inserted Publisher's note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Morphological and Molecular Characterization of Calonectria foliicola Associated with Leaf Blight on Rubber Tree (Hevea brasiliensis) in Thailand

“…C . metrosideri causes leaf blight on E. benthamii in Brazil [ 55 ], whereas C. tunisiana causes crown and root rot of Eucalyptus globulus in Italy [ 56 ]. However, C. foliicola , which belongs to the C .…”

Calonectria leaf blight of Eucalyptus: A global review

“…Disease symptoms induced by different Calonectria species on Eucalyptus include cutting rot, crown rot, root rot, damping‐off, leaf blight, seedling rot, shoot blight and stem canker (Aiello et al, 2020; Brown & Ferreira, 2000; Crous, 2002; Crous et al, 1991; Li et al, 2017; Liu & Chen, 2017; Lombard et al, 2010a, 2015; Pham et al, 2019). The pathogen forms chlamydospores and microsclerotia in plant debris and soil and their germination during favourable conditions results in root infection that ultimately leads to shoot and foliar blight.…”