Nectria flute canker is a disease of Pinus radiata stems caused by the pathogen Neonectria fuckeliana occurring in the southern parts of New Zealand. In Northern Hemisphere countries where N. fuckeliana is endemic, it is commonly found in Picea and Abies spp. Open wounds, dead attached branches and branch stubs have been identified as the primary infection courts. Although in New Zealand the development of Nectria flute canker disease is associated with pruned branch stubs, recent studies suggest that this is not the only possible entry method as the fungus has been found in trees prior to pruning. Three field trials were established to examine the potential infection mechanisms for N. fuckeliana in P. radiata in New Zealand; including stem wounds and branch stubs. The difference between inoculations into the stem and into branch wood was clear. Inoculation of deep stem wounds resulted in the greatest fluting with 76% of trees inoculated developing cankers. Inoculation directly into stubs resulted in only small stem depressions that occurred in 17% of cases and the fungus was largely contained within the branch trace. Tree response to inoculation with either ascospores or conidia of the Acremonium anamorph gave similar results in terms of canker development and fungal spread within the stem. Tree response to inoculation was highly variable however: in one study 6% of trees did not respond to inoculation at all, while 26% produced severe cankers regardless of inoculation method. A more thorough understanding of the infection mechanisms of N. fuckeliana will contribute to the development of better disease management protocols to prevent infection and disease development in future plantation stock.

Neonectria fuckeliana (C. Booth) Castl. & Rossman is known to be associated with a stem canker disease of Pinus radiata D. Don in New Zealand plantation forests. Although N. fuckeliana has been previously recorded as a wound invader or weak pathogen of Picea and Abies species in the Northern Hemisphere, little is currently known about the basic biology of the fungus. This paper outlines early investigations into the spore production and dispersal of N. fuckeliana in New Zealand. Perithecia of N. fuckeliana occur frequently on pruned stubs and on the surface of cankers, and ascospores appear to be the primary means of dispersal for this fungus in New Zealand. Both field collections and spore trapping show that mature perithecia contain viable ascospores in all seasons, and spores are ejected and dispersed using moisture. The conidial phases are rarely found in the field. Optimum temperature for both growth of mycelium and ascospore germination was between 15 and 25 °C. Some spore germination occurred at temperatures as low as 5 °C, but above 25 °C spore germination was abnormal. Ascospores and perithecia favoured storage in lower temperatures: overall, ascospores from perithecia stored at room temperature gradually lost their viability, whereas those stored at 4 and –8 °C maintained their viability over an 18 month period.

Stem malformation associated with stained sapwood, typically developing after pruning, has become a problem in some Pinus radiata (Monterey pine) plantations in southern regions of New Zealand. Neonectria fuckeliana (syn. Nectria fuckeliana) is the most commonly isolated fungus from affected trees. In order to critically assess the pathogenicity of this fungus, Koch’s Postulates were conducted under controlled conditions in the glasshouse and under field conditions in the forest plantation. The pathogen was recovered from diseased tissue; however, there were marked differences in individual tree response to infection as some inoculated trees did not become diseased.

Inoculations showed that two previously described rust fungi (Basidiomycota: Pucciniales), Caeoma peltatum on Phyllocladus spp. and Uredo fuchsiae on Fuchsia spp., both endemic to New Zealand, are different stages of a single species. Uredinial and telial states formed on Fuchsia excorticata after inoculation with aeciospores from Phyllocladus trichomanoides. The oblong teliospores form directly from subepidermal hyphae, then divide to become metabasidia, each cell of which germinates to form a long suprastomatal sterigma and basidiospore. The rust closely resembles species in the family Mikronegeriaceae, and is named Mikronegeria fuchsiae sp. nov. This is the first record of a member of the Mikronegeriaceae in New Zealand.

TAXONVolume 55, Issue 3 p. 804-805 Proposals to Conserve or RejectsFree Access (1733–1735) Proposals to conserve the names Chrysomyxa empetri, C. piperiana, and C. ledicola (Uredinales) with teleomorph types against their anamorph homonyms Patricia E. Crane, Patricia E. Crane pacrane@shaw.ca Department of Renewable Resources, University of Alberta, Edmonton, Alberta T6G 2H1, Canada, and Northern Forestry Centre, Canadian Forest Service, 5320 - 122 Street, Edmonton, Alberta T6H 3S5, Canada; 14715 - 84 Avenue, Edmonton, Alberta T5R 3X1 CanadaSearch for more papers by this author Patricia E. Crane, Patricia E. Crane pacrane@shaw.ca Department of Renewable Resources, University of Alberta, Edmonton, Alberta T6G 2H1, Canada, and Northern Forestry Centre, Canadian Forest Service, 5320 - 122 Street, Edmonton, Alberta T6H 3S5, Canada; 14715 - 84 Avenue, Edmonton, Alberta T5R 3X1 CanadaSearch for more papers by this author First published: 01 August 2006 https://doi.org/10.2307/25065661AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat No abstract is available for this article. Volume55, Issue3August 2006Pages 804-805 RelatedInformation

Fusarium circinatum, the causal agent of pitch canker, attacks Pinus spp. in Mexico, Japan, South Africa, Chile, Spain and the United States.The pathogen was first recorded in conifer nurseries in South Africa and Chile.Pinus radiata is an economically important species in New Zealand and if F. circinatum were to establish here the impact could be severe.Therefore, the ability to identify F. circinatum in soil is essential for early detection and subsequent eradication of the pathogen.The object of this study was to ensure that F. circinatum could be readily isolated from soil using culturing and molecular techniques.Two samples of non-sterile commercial potting mix and two samples each of sterile and non-sterile nursery soil were inoculated separately and together with F. circinatum and F. oxysporum under strict quarantine conditions.Fusarium circinatum was re-isolated more frequently from the sterile soil than the non-sterile soil and very little F. circinatum was isolated from the potting mix.Molecular techniques were able to detect F. circinatum in soil and potting mix when the initial concentration of F. circinatum was high.Results suggest that F. circinatum is a poor competitor against other fungi in the soil environment.

Many rust fungi (Uredinales) that infect rhododendrons are difficult to identify because of similar spore size and overall morphology. As part of a morphological study of rusts in the genus Chrysomyxa, herbarium specimens of Asian rhododendron rusts were examined by light and scanning electron microscopy. They were compared with similar taxa from Europe and North America. Revised and illustrated descriptions are provided for the uredinia and telia of Chrysomyxa dietelii and Chrysomyxa succinea; details of the conspicuous uredinial peridium of both species are described for the first time. A new genus and species, Diaphanopellis forrestii, is proposed to accommodate a rust fungus with uredinia covered by a peridium of ornamented cells (Aecidium-type) and teliospores enclosed in transparent outer sheaths. This species includes the previously described anamorphs Aecidium rhododendri and A. sino-rhododendri. Three new anamorphic species with unique urediniospore morphology also are described: Caeoma clemensii from Philippines, Caeoma spinulospora from Tibet, and Caeoma yunnanensis from Yunnan, China. For morphological and nomenclatural reasons Uredo rhododendri ('rhododendronis') is renamed as Caeoma dumeticola and Uredo rhododendri-capitati is transferred to Caeoma. A key to Asian rhododendron rusts that form uredinia is provided. In general morphological groups of rhododendron rusts correlate with the subgenera of Rhododendron on which they occur, suggesting coevolution of these parasites with their hosts.

A rust fungus found in Japan on Rhododendron kaempferi, R. kiusianum, and R. dauricum has previously been identified as Chrysomyxa rhododendri. Light and scanning electron microscopy of fresh and herbarium materials of the rust fungus, however, show that the spore surface morphology differs from the urediniospores of C. rhododendri, and the spores are slightly smaller. Furthermore, the DNA sequence of the 5′-end of the large subunit of ribosomal DNA differs from that of C. rhododendri by 3%. Telia have not been found; therefore, it is redescribed as a new anamorphic species, Caeoma tsukubaense. Several specimens from North Korea, Tibet, and Nepal bearing a similar rust fungus are also included in the species.

Caeoma cassiopae sp. nov. (Uredinales) is described on the arctic-alpine shrub Cassiope tetragona. It was found in three locations in the Rocky Mountains of west-central Alberta, and is the first rust reported on the genus Cassiope. The sori resemble the uredinia of species in the genus Chrysomyxa. The host in the Ericaceae also suggests affinity with that genus. However, the spore morphology, studied by light and scanning electron microscopy, does not resemble known species of Chrysomyxa.

Caeoma cassiopae sp. nov. (Uredinales) is described on the arctic–alpine shrub Cassiope tetragona. It was found in three locations in the Rocky Mountains of west-central Alberta, and is the first rust reported on the genus Cassiope. The sori resemble the uredinia of species in the genus Chrysomyxa. The host in the Ericaceae also suggests affinity with that genus. However, the spore morphology, studied by light and scanning electron microscopy, does not resemble known species of Chrysomyxa.

Rust fungi in the genus Chrysomyxa Unger occur in boreal forests of the northern hemisphere on Pinaceae (mostly Picea A. Dietr.), and most species alternate to angiosperm hosts in the Ericaceae. About 30 species are known worldwide. Although several species are economically important pathogens of spruce and rhododendrons, knowledge about species delineations, relationships among species on different continents, and life cycles is lacking. A group of species with similar spore size, including the Chrysomyxa ledi de Bary complex, was re-examined using field observations, inoculation experiments, and light and scanning electron microscopy. In addition to host specificity, characters found useful in species delineation were urediniospore and aeciospore size and shape, and ornamentation of spores and the aecial peridium. Detailed descriptions are given for eight Chrysomyxa species, including synonyms, types, distribution, relationship to other species, and disease impact. The members of the C. ledi complex are considered separate species: Chrysomyxa ledi on Ledum palustre, Chrysomyxa nagodhii sp.nov. on Ledum groenlandicum and Ledum decumbens, Chrysomyxa neoglandulosi sp.nov. on Ledum glandulosum, Chrysomyxa cassandrae on Chamaedaphne calyculata, Chrysomyxa rhododendri on Rhododendron spp., and Chrysomyxa vaccinii comb.nov. on Vaccinium parvifolium. Chrysomyxa chiogenis, with similar spore size, is included for comparison. A previously unrecognized small-spored species, Chrysomyxa reticulata sp.nov., is described on Ledum spp. and Rhododendron spp. Evidence is presented that C. reticulata spreads from native Ledum spp. in North America to cultivated rhododendrons. A new anamorphic species, Peridermium zilleri, likely belonging in Chrysomyxa, is described on Picea sitchensis from coastal British Columbia.Key words: Uredinales, Rhododendron, needle rust, Ledum, systematics.

Chrysomyxa pirolata Wint., the cause of inland spruce cone rust, is a serious pathogen in natural spruce forests and seed orchards. Cone infection is caused by basidiospores produced by telia on alternate hosts in the genera Pyrola, Moneses, and Orthilia. The disease cycle of this rust and the influence of moisture on the differentiation of telia on Pyrola asarifolia Michx. were studied over two growing seasons at a wet site adjacent to a spruce seed orchard and a drier site adjacent to another orchard at Smoky Lake, Alberta, and at Edmonton and Hinton, Alberta. The proportion of uredinia to telia varied with microsite conditions, with more frequent production of telia in moist sites. The effect of moisture on formation of telia was tested by subjecting infected plants with immature sori to 90-100% relative humidity under various temperature and light conditions. Plants under high humidity, regardless of other conditions, formed mainly telia from immature sori, even if uredinia had already formed on parts of the leaves before the experiments. Telia formation, however, was much slower at 4-6°C than at 22°C. Cross-sections of sori showed that young uredinia could sometimes convert to telia. Results of a field experiment also suggested that increasing moisture increases the percentage of telia produced on plants. The production of undifferentiated sori that can become either uredinia or telia in response to environmental conditions may allow the fungus to maximize vegetative proliferation when conditions are unfavorable for sexual reproduction. It might also explain the large variation in cone rust levels from year to year in a given location.Key words: Picea, Pyrola, telia induction, seed orchard, Uredinales.

The rust fungus Chrysomyxa woroninii causes perennial witches’ brooms on several species of Ledum in northern and subalpine regions of Europe, North America and Asia. Spruce bud rust has been assumed to be the aecial state of C. woroninii because of the close proximity of infected Ledum plants and systemically infected buds on Picea. The lack of experimental evidence for this connection, however, and the presence of other species of Chrysomyxa on the same hosts has led to confusion about the life-cycle of C. woroninii. In this study, infections on both spruce and Ledum were studied in the field and in a greenhouse. The link between the two states was proven by inoculating spruce with basidiospores from Ledum groenlandicum. After infection of spruce in spring, probably through the needles, the fungus overwinters in the unopened buds until the next spring, when the infected shoots are distinguished by stunting and yellow or red discolouration. Microscopic examination of dormant Ledum shoots showed that C. woroninii overwinters in this host in the bracts and outer leaves of the vegetative buds, and in the pith and cortex of the stem. The telia of C. woroninii , on systemically infected Ledum leaves of the current season, are easily distinguished from the telia of other Chrysomyxa species on the same hosts. The latter produce localized telia and uredinia only on overwintered leaves, produce aecia on spruce needles in the same year as infection occurs, and are not systemic in spruce. The restricted habitat distribution of C. woroninii and the need for overwintering outdoors suggest that this rust fungus has specific environmental requirements for survival.

Chrysomyxa weirii (Uredinales) is the only autoecious, microcyclic species of Chrysomyxa occurring in North America. The telia form on second-year needles of spruce, causing premature needle loss. The morphology of the telia was studied in herbarium specimens from diverse locations, and the teliospore germination, nuclear condition, and reproductive biology of fresh collections were studied on microscope slides and on artificially and naturally infected host tissue using light and scanning electron microscopy. Basidiospore production was infrequent in mature sori, but teliospores dispersed readily in water and germinated to produce a two-celled basidium and two basidiospores. The two cells of the basidium could also separate to form two sporelike cells that could produce germ tubes, or the teliospore produced a long hyphalike promycelium. The type of germination was influenced by temperature. The ready dispersal of teliospores in water and their presence on the surface of current-year needles confirms that they function as diaspores. The distribution pattern of this rust and the elongated, smooth, thin-walled spores that are held rigidly together until wet suggest a water-dispersal mechanism. A cytological study showed that the vegetative hyphae are mostly monokaryotic. Dikaryotization and karyogamy occur in the cells at the base of the telium and result in teliospores with one large nucleus. During germination, the teliospore nucleus migrates into the basidium, where it divides once before a septum forms. A second nuclear division occurs in each cell during basidiospore formation. Both nuclei move into the basidiospore, and subsequently divide one or more times. The two-celled basidium, the fragmenting basidium and other unusual forms of germination, and teliospore dispersal have not been previously reported in the genus Chrysomyxa.

Twenty-two microfungi (Ascomycota and Deuteromycota) isolated from Populus tremuloides were tested for their ability to degrade wood of this species. They were inoculated onto preweighed, sterile aspen wood blocks and allowed to grow for 6 months. These fungi varied greatly in their ability to degrade aspen wood, with Phialemonium curvatum causing the highest weight loss (25.7%) and Dothiora sphaerioides the least (2.3%) over a 6-month period. Most of these fungi cause a soft rot type of decay, based on localized cavity formation in the S-2 layer of the cell wall. The more generalized degradation caused by Hypoxylon mammatum more closely resembled a white rot; other fungi, such as Lecythophora lignicola were largely confined to ray cells. All fungi caused decay near the wood surface, where pockets of totally degraded wood cells occurred. Many fungi occurring in apparently healthy or sound wood of standing aspen have the ability to cause significant wood degradation under certain environmental conditions.

Large black stem galls occur sporadically on trembling aspen (Populus tremuloides) in western Canada. Although little is known about their cause or structure, trees having these galls are less likely than surrounding aspen to have advanced decay caused by the fungus Phellinus tremulae. The anatomy and histochemistry of black galls and associated branch galls were studied and compared with normal wood and bark. Light microscopy showed that the cambium of black galls produces greater numbers of cells per growth ring and that growth rings are two to three times wider than normal. Vessel elements and fibers are unusually small and misshapen. Gall xylem has characteristics associated with wounding or infection: ray cells filled with phenolic deposits, and vessel elements occluded by tyloses and granular material. Frequent radial strands of undifferentiated callus tissue surrounded by necrophylactic periderms indicate sites of cambial damage of unknown cause. White areas within dark-colored gall xylem of some samples were free of most of these abnormalities, suggesting that a persistent agent is required for continuing tumor growth. Thickened outer bark harbored a variety of saprophytic fungi, especially hyphomycetes. Surface and internal morphology of black galls was also compared with similar stem galls caused by poplar budgall mites (Aceria parapopuli) and was found to be different. Bacteria, fungi, or mites were not obvious within living tissue, and further studies are necessary to determine the etiology of black galls. Key words: Populus tremuloides, poplar, black gall, wood anatomy.