Tadeusz Kowalski

Differentiation of Ophiostoma piceae and Ophiostoma quercus by Morphology and RAPD Analysis.

Summary Ophiostoma piceae (Munch) H. and G. Sydow was found to comprise two distinct species by means of morphological investigation on synnematal size as well as by RAPD technique for genomic analysis. The two species are separated undoubtedly by the means of morphological investigations on synnematal size, the onset of a respective yeast stage, and genomic analysis by the PCR based RAPD technique. Different mean values of synnematal size were corroborated statistically by the Kolmogorov — Smirnov Test. RAPD analysis is ensured by phylogenetic computation of the discrete state matrix arising from the arbitrary PCR fragment patterns. The two Ophiostoma species separated harbour isolates predominantly grown on spruce on the one hand ( O. piceae ) and gathered isolates from oak and probably other hardwoods on the other hand ( O. quercus ). For the latter species the name O. quercus (Georgev.) Nannf. must be reinstated.

Fungal assemblages in stem and twig lesions of Quercus robur in Switzerland

Fungal assemblages present in necrotic tissues of Quercus robur were determined at two sites in Switzerland. Fungi were identified by examination of fruitbodies or by isolation. Assemblages differed with location (stem or twig), tissue source (xylem or bark), method of detection (isolation or inspection), stage of damage, and between sites. Dominant fungi in stem lesions were Amphiporthe leiphaemia, Pezicula cinnamomea, Phomopsis quercella, Fusarium sp., and Dichomera saubinetii . In diseased twig tissues A. leiphaemia and Colpoma quercinum, Fusarium sp., and P. cinnamomea were the most common. It is suggested that the lesions were induced by drought followed by a high frost incidence but that fungi may have been contributory.

Cryptosporiopsis radicicola sp. nov. from roots of Quercus robur

A new species of the coelomycete genus Cryptosporiopsis is described. The fungus is one of the most frequent species on roots of Quercus robur in Poland.

Virulence of Hymenoscyphus albidus and H. fraxineus on Fraxinus excelsior and F. pennsylvanica.

European ash (Fraxinus excelsior) is currently battling an onslaught of ash dieback, a disease emerging in the greater part of its native area, brought about by the introduction of the ascomycete Hymenoscyphus fraxineus (= Hymenoscyphus pseudoalbidus). The closely-related fungus Hymenoscyphus albidus, which is indigenous to Europe, is non-pathogenic when in contact with F. excelsior, but could pose a potential risk to exotic Fraxinus species. The North American green ash (Fraxinus pennsylvanica) is planted widely throughout Europe and regenerates naturally within this environment but little is known about the susceptibility of this species to ash dieback. We performed wound inoculations with both fungi (nine strains of H. fraxineus and three strains of H. albidus) on rachises and stems of F. excelsior and F. pennsylvanica under field conditions in Southern Poland. Necrosis formation was evaluated after two months on the rachises and after 12 months on the stems. After inoculation of H. albidus, only small lesions (of up to 1.3 cm in length) developed on the F. excelsior and F. pennsylvanica rachises, but with no significant distinction from the controls. Hymenoscyphus albidus did not cause necrotic lesions on the stems of either Fraxinus species. In contrast, H. fraxineus induced necroses on all inoculated rachises of both ash species with mean lengths of 8.4 cm (F. excelsior) and 1.9 cm (F. pennsylvanica). Necroses also developed on all of the inoculated F. excelsior stems (mean length 18.0 cm), whereas on F. pennsylvanica such lesions only occurred on about 5% of the stems (mean length 1.9 cm). The differences between strains were negligible. No necroses were observed on the control plants. Reisolations of H. albidus were only successful in around 8–11% of the cases, while H. fraxineus was reisolated from 50–70% of the inoculated organs showing necrotic lesions. None of the Hymenoscyphus species were isolated from the control plants. Our data confirm H. fraxineus’ high virulence with regards to F. excelsior and demonstrate a low virulence in relation to F. pennsylvanica under field conditions in Poland. Hymenoscyphus albidus did not express any perceivable pathogenicity on both host species.

Cryptosporiopsis melanigena sp. nov., a root-inhabiting fungus of Quercus robur and Q. petraea

A new species of Cryptosporiopsis is described. It was isolated frequently from roots of healthy-looking and declining oaks (Quercus robur and Q. petraea). The relationship to C. radicicola, a similar species also occurring on oak roots, is discussed. The new species is separated from C. radicicola by means of morphological and physiological characters, genomic analysis by the PCR-based RAPD technique as well as by the production of metabolites.

Chalara angustata sp. nov. from roots of Quercus petraea and Quercus robur

A new species of the hyphomycete genus Chalara is described. This fungus was isolated several times from roots of healthy and declining oaks (Quercus petraea and Q. robur). It differs from previously described species of Chalara by its septate conidia, the morphology of the phialophores and by colony characteristics.

Sporothrix inflata, a root-inhabiting fungus of Quercus robur and Q. petraea.

The anamorphic fungus Sporothrix inflata, known as a soil-borne fungus with worldwide distribution, was isolated for the first time from the cortex and central cylinder of living and dead roots of healthy and diseased oak trees (Quercus robur and Q. petraea). Isolation frequencies of S. inflata from oak roots varied according to the health status of trees, oak species, study sites, soil depth and root diameter. Colony morphology and growth rate of isolates are influenced by colony age and type of culture medium.

Pycnidial formation and pathogenicity in Tubakia dryina

Tubakia dryina produces pycnidial conidiomata on twigs of Quercus robur , whereas on the leaves rhizothyrial conidiomata are formed. Inoculation experiments did not result in the formation of necroses.

THE ANAMORPHS OF GROVESIELLA ABIETICOLA

An ascomycete associated with the recently described coelomycete Pitostroma abietinum on dead twigs of Abies alba in Poland was identified as Grovesiella abieticola. Two characteristics of the G. abieticola from Poland differed from those of collections from North America. The ascospores of G. abieticola collected in North America were wider [(3.2-)3.5-4.2(-4.8) nm] than those from Europe [2.2-3.5(-4) nm], and the European populations do not produce cankers while the North American populations do. Single ascospore isolates of G. abieticola and single conidia isolates of P. abietinum produced identical colony morphologies and in single ascospore isolates the Pitostroma-state was formed in addition to the microconidial state. Thus, P. abietinum is the macroconidial state of G. abieticola. A description of the morphology of the micro- and macroconidial state of G. abieticola in culture is

Pitostroma abietinum gen. et sp.nov., a new coelomycete on twigs of Abies alba.

Pitostroma , a new genus, is erected to accommodate P. abietinum , a new coelomycete species from twigs of Abies alba from Poland. The genus and species are described and morphological differences from known genera and species are discussed.