Classification of the guava wilt fungus Myxosporium psidii, the palm pathogen Gliocladium vermoesenii and the persimmon wilt fungus Acremonium diospyri in Nalanthamala

Abstract

Psidium guajava wilt is known from South Africa, Malaysia and Taiwan. The fungus causing this disease, Myxosporium psidii, forms dry chains of conidia on surfaces of pseudoparenchymatous sporodochia, which develop in blisters on bark. Similar sporodochia are characteristic of Nalanthamala madreeya, the type species of Nalanthamala. Nalanthamala, therefore, is the appropriate anamorph genus for Myxosporium psidii, while Myxosporium is a nomen nudum (based on M. croceum). For M. psidii the combination Nalanthamala psidii is proposed. Nalanthamala psidii, the palm pathogen Gliocladium (Penicillium) vermoesenii, another undescribed anamorphic species from palm, two species of Rubrinectria and the persimmon pathogen Acremonium diospyri are monophyletic and belong to the Nectriaceae (Hypocreales) based on partial nuclear large subunit ribosomal DNA (LSU rDNA) analyses. Rubrinectria, therefore, is the teleomorph of Nalanthamala, in which the anamorphs are classified as N. vermoesenii, N. diospyri or Nalanthamala sp. Nalanthamala squamicola, the only other Nalanthamala species, has affinities with the Bionectriaceae and is excluded from this group. Rubrinectria/Nalanthamala species form dimorphic conidiophores and conidia in culture. Fusiform, cylindrical, or allantoid conidia arise in colorless liquid heads on acremonium-like conidiophores; ovoidal conidia with somewhat truncated ends arise in long, persistent, dry chains on penicillate conidiophores. No penicillate but irregularly branched conidiophores were observed in N. diospyri. Conidia of N. psidii that are held in chains are shorter than those of N. madreeya, of which no living material is available. Nalanthamala psidii and N. diospyri are pathogenic specifically to their hosts. They form pale yellow to pale orange or brownish orange colonies, respectively, and more or less white conidial masses. Most strains of Rubrinectria sp., Nalanthamala sp. and N. vermoesenii originate from palm hosts, form mostly greenish or olive-brown colonies and white-to-salmon conidial masses. They form a monophyletic clade to which Nalanthamala psidii and N. diospyri are related based on analyses of the internal transcribed spacer regions and 5.8S rDNA (ITS rDNA), LSU rDNA, and partial beta-tubulin gene. Few polymorphic sites in the ITS rDNA and beta-tubulin gene indicate that Nalanthamala psidii comprises two lineages, one of which has been detected only in South Africa.

Verrucostoma, a new genus in the Bionectriaceae from the Bonin Islands, Japan

“…Beyma, Leucosphaerina Arx and Mycoarachis Malloch & Cain as well as the anamorphic genera Acremonium Link, Geosmithia Pitt and Stanjemonium W. Gams et al These fungi form a distinct clade within the Bionectriaceae (Rossman et al 2001, Schroers et al 2005 and are represented by Emericellopsis glabra and Mycoarachis inversa in this study (FIG. 1).…”

“…C. coccinea, C. vilior, C. viliuscula and C. wegeliniana) form a monophyletic group within the Nectriaceae. The type species of Acremonium, A. alternatum, belongs in the Bionectriaceae, most closely related to the anamorphic genus Geosmithia, for which no teleomorph is known, and the cleistothecial genera Emericellopsis and Mycoarachis (Rossman et al 2001, Schroers et al 2005.…”

Efficacy of fungicides, plant resistance activators and biological control agents against guava wilt disease caused by Nalanthamala psidii

“…Schroers & M.J. Wingf. (Schroers et al 2005) was first reported from the Malelane area (Mpumalanga Province of South Africa), in 1981 (Grech 1985;Grech 1990). At that stage the guava industry relied solely on the Fan Retief (FR) cultivar.…”

Preliminary evaluation of guava selections for guava wilt disease resistance in South Africa

“…Guava wilt, caused by Nalanthamala psidii (Schroers et al 2005) is a serious disease of guava in the guava-producing areas of the Mpumalanga and Limpopo Provinces. Guava wilt disease was first reported in Taiwan by Kurosawa (1926), but is now also present elsewhere in South-East Asia.…”