Pest categorisation of Lasiodiplodia pseudotheobromae

Abstract

The EFSA Plant Health Panel performed a pest categorisation of Lasiodiplodia pseudotheobromae, a clearly defined fungus of the family Botryosphaeriaceae, which was first described in 2008 as a cryptic species within the L. theobromae complex. The pathogen affects a wide range of woody perennial crops and ornamental plants causing root rot, damping-off, leaf spots, twig blight, cankers, stem-end rot, gummosis, branch dieback and pre- and post-harvest fruit rots. Lasiodiplodia pseudotheobromae is present in Africa, Asia, North and South America and Oceania and has also been reported from Spain with a restricted distribution. However, there is uncertainty on the status of the pathogen worldwide and in the EU because in the past, when molecular tools (particularly multigene phylogenetic analysis) were not available, the pathogen might have been misidentified as L. theobromae. Lasiodiplodia pseudotheobromae is not included in Commission Implementing Regulation (EU) 2019/2072 and there are no interceptions in the EU. Because of the very wide host range of the pathogen, this pest categorisation focused on those hosts for which there is robust evidence that the pathogen was formally identified by a combination of morphology, pathogenicity and multilocus sequence analysis. Plants for planting, including seeds, fresh fruits and bark and wood of host plants as well as soil and other plant-growing media are the main pathways for the further entry of the pathogen into the EU. Host availability and climate suitability factors occurring in parts of the EU are favourable for the further establishment of the pathogen. In the area of its present distribution, including Spain, the pathogen has a direct impact on cultivated hosts. multilocus measures are available to prevent the further introduction and spread of the pathogen into the EU. Lasiodiplodia pseudotheobromae satisfies the criteria that are within the remit of EFSA to assess for this species to be regarded as potential Union quarantine pest.

Keywords: Botryosphaeriaceae; Lasiodiplodia theobromae; pest risk; plant health; plant pest; quarantine.

Figure 1

Life cycle of Lasiodiplodia theobromae on Theobroma cacao (adapted from Moreira‐Morrillo et al., , https://doi.org/10.17268/sci.agropecu.2021.068). Lasiodiplodia pseudotheobromae has a similar life cycle

Figure 2

Lasiodiplodia pseudotheobromae. (a, b) Conidiomata and conidia on surface of dead twig of Tectona grandis (teak). (c) Section through conidioma. (d) Conidioma wall. (e) Conidia attached to conidiogenous cells with paraphyses. (f, g) Immature conidia. (h–j) Mature conidia in two different focal planes showing longitudinal striations. (k, l) Germinated mature conidia. Note (e, g) stained with lactophenol cotton blue. Scale bars: (a) = 300 μm. (b) = 200 μm. (c) = 100 μm. (d, f) = 20 μm. (e, g–l) = 10 μm (from Doilom et al., ; https://doi.org/10.11646/phytotaxa.233.1.1)

Figure 3

Global distribution of Lasiodiplodia pseudotheobromae [Data Source: CABI CPC (online; last accessed on 12/10/2022), Farr and Rossman (2022; last accessed on 12/10/2022) and other literature sources]

Figure 4

Distribution of 10 Köppen–Geiger climate types, i.e. BSh, BSk, Cfa, Cfb, Cfc, Csa, Csb, Dfb and Dfc that occur in the EU and in third countries where Lasiodiplodia pseudotheobromae has been reported. The legend shows the list of Köppen–Geiger climates