Vol 2 (2007)

Table of Contents

Articles

Powdery Mildews on Weeds in the Pacific Northwest: A Miscellany of New Records PDF
Frank M. Dugan, Dean A. Glawe 1-7
Erysiphe polygoni on Rumex crispus, documented previously in California, is reported for the first time in the Pacific Northwest. Podosphaera (Sphaerotheca) fusca is reported in the Pacific Northwest for the first time on Taraxacum laevigatum, a host record documented previously in Europe. New host records for Idaho are Golovinomyces sordidus on Plantago majorErysiphe convolvuli on Convolulus arvensus, and Podosphaera Sphaerotheca) aphanis on Geum macrophyllumGolovinomyces (Erysiphe) cichoracearum on Cirsium arvense is reported for the first time in Washington.


Succession and community gradients of arctic macrolichens and their relation to substrate, topography, and rockiness PDF
Emily A. Holt, Bruce McCune, Peter Neitlich 1-21
We describe lichen community structure and its relation to environment in the Bering Land Bridge National Preserve in northwestern Alaska. We used a stratified random sample to estimate macrolichen abundance and several environmental variables from 78 0.38-ha plots within lichen-dominated areas of the Preserve. We found a total of 140 macrolichen taxa. Two primary gradients in lichen species composition were related to habitat rockiness and a substrate-topographic gradient. The strongest gradient, rockiness, correlates with lichen succession. Rocky habitats have less competition from vascular plants and may be more resistant to soil disturbance. The substrate-topography gradient is largely driven by the presence of Sphagnum moss contrasting with calcareous parent rock material. To uncover additional underlying patterns in lichen community composition, we deleted rocky and calcareous plots and strictly saxicolous species from the analyses. Although we found similar patterns from the original analysis in this subset, diversity and community composition also varied with differing microtopography. These gradients of lichen community composition can also be divided into three major groups; rocky non-calcareous sites, calcareous areas, and the remaining plots form the alluvial lowland communities. We used two-way cluster analysis which combines independent clustering of sample units and species into a single diagram. This technique linked individual species and species assemblages with these major trends.


Lichens in relation to management issues in the Sierra Nevada national parks PDF
Bruce McCune, Jill Grenon, Linda S. Mutch, Erin P. Martin 1-39

The central and southern Sierra Nevada are subjected to high levels of ozone, high and increasing nitrogen deposition, and unknown quantities of pesticides such as organophosphates from agricultural emissions in the Central Valley. Fire regimes have changed greatly over time, from relatively frequent fire historically, to fire exclusion, to its reintroduction as prescribed fire. Parts of the Sierra parks have been grazed by livestock, and some of this persists today. On top of these factors, climate is likely to change rapidly.

Although a large literature exists on human impacts on lichens, almost nothing is known on this topic in the Sierra Nevada specifically. We are largely ignorant of the biodiversity, ecology, and ecological roles of lichens in the Sierra Nevada Park system (the “Sierra parks”: Sequoia and Kings Canyon National Park, Yosemite National Park, and Devils Postpile National Monument ). This paper synthesizes existing data, written reports and other information about lichens in and near the Sierra Nevada parks, as a first step toward developing better baseline data and assessing lichen populations or communities as potential indicators of ecosystem change.

Lichens are diverse in their ecosystem roles and functional significance. Organizing the hundreds of lichen species present in the Sierra parks into functional groups helps us to understand, interpret, inventory, and monitor the diversity of lichens. We therefore divided lichens of the Sierra parks into the following functional groups: forage lichens, nitrogen fixers, acidophiles, wolf lichens, crustose lichens on rock, crustose lichens on bark and wood, biotic soil crusts, aquatic, other green algal macrolichens, and pin lichens (calicioids).

Management issues that relate to lichens include biodiversity, air quality, water quality, fire, grazing, and the possibility of draining Hetch Hetchy Reservoir. Existing lichen data from the west slope of the Sierra Nevada, of relevance to the management of Sierra parks include: extensive lichen community data from the Forest Inventory and Analysis program (FIA), a few floristic studies focused on the parks, photo points on prescribed fire transects, lichen biomass estimates from four locations, elemental analysis of lichens from a small number of locations, lichen communities in relation to various nitrogen species in Kings River watershed, the Western Airborne Contaminants Assessment Project, Bryoria fremontii studies at Teakettle Experimental Forest, and herbarium databases.

We recommend the following short list for future inventory and monitoring work: population status and trend of Bryoria fremontii, macrolichen community monitoring, revise and update the inventory of lichen biodiversity, and preliminary surveys of lichens in neglected habitats.


New North American Records of Anamorphic Powdery Mildew Fungi (Erysiphales) Parasitizing Species of Leucothoë and Limnanthes PDF
Melodie L. Putnam, Dean A. Glawe 1-6
This paper documents the presence of two species of Erysiphales previously unreported in North America. The fungi were encountered on greenhouse-grown host plants in Oregon during the 2006 growing season. Oidium ericinum was found on potted plants of Leucothoë axillaris (Ericaceae) grown at a wholesale nursery where it resulted in a substantial financial loss to the grower.Oidium limnanthis was found on potted plants of Limnanthes alba (Limnanthaceae) where it was associated with premature senescence of plants and reduced seed production. This appears to be the first record of a powdery mildew fungus parasitizing a member of the Limnanthaceae in North America. Both species are described and illustrated.


First report of powdery mildew of Lactuca sativa (garden lettuce) caused by Golovinomyces cichoracearum in the Pacific Northwest PDF
Dean A. Glawe, Ellen C. S. Duffield 1-4
During continuing surveys for powdery mildew fungi in the Pacific Northwest, Golovinomyces cichoracearum was found on Lactuca sativa (garden lettuce) in Seattle, King County, Washington. This paper documents the occurrence of G. cichoracearum on L. sativain the Pacific Northwest with illustrations of the fungus from fresh material.


Mycoflora of seed of common teasel (Dipsacus fullonum) in Washington State PDF
F. M. Dugan, B. G. Rector 1-10
Seeds of standing common teasel (Dipsacus fullonum ) were harvested in January 2007 in Pullman, Washington, and divided into two categories, symptomatic versus asymptomatic, on the basis of signs of fungal colonization at 10-50X magnification. The most common signs were pseudothecia of Davidiella tassiana. Fungi were recovered from all seeds of both categories when seeds were surface-disinfested and incubated on agar media. Aureobasidium pullulans accounted for 57-72% of fungal isolates from asymptomatic seed, but only 16-26% of isolates from symptomatic seed. Cladosporium spp. and Alternaria spp. exhibited a combined frequency of 54-64% from symptomatic seed, versus 16-35% from asymptomatic seed. Asymptomatic seed germinated at incidences of 44-76% whereas symptomatic seed germinated at incidences of 2-6%. When seeds or germinated seedlings were inoculated with conidial suspensions of representative isolates of Au. pullulansC. herbarum (anamorph of D. tassiana ) orAlternaria sp., and incubated under conditions favorable for germination or growth of teasel, no differences were apparent between treated seed and non-inoculated control seed. The correlation between colonization by Alternaria and Cladosporium species and diminished germination ability probably reflects unidentified, predisposing factors for diminished germination. Immature pseudothecia of D. tassiana were repeatedly observed to germinate directly on the seed by production of fertile conidiophores from the apices of the papillae.


Septoria musiva isolated from cankered stems in hybrid poplar stool beds, Fraser Valley, British Columbia PDF
B. E. Callan, I. Leal, B. Foord, J. J. Dennis, C. van Oosten 1-9
Septoria musiva, a pathogen causing leaf spots and stem cankers, was isolated from cankered hybrid poplar stems (TXM 271–287 and TXM 271–286) in commercial stool beds in the Fraser Valley, southwest British Columbia (BC) in November, 2006 and January, 2007. The identity of this pathogen was confirmed both morphologically in culture and by using species-specific PCR primers, unlike earlier questionable reports of this pathogen in BC. A survey of stems larger than 1 cm diameter in one stool bed revealed that 199 out of 458 (43.4%) stems bore one or more cankers. Septoria musiva was isolated in culture from 44% of 50 cankered stems sampled in this stool bed. In the past, leaf spots on BC poplars have occasionally been attributed to Smusivabased on conidial morphology, but S. populicola is far more prevalent in natural and commercial cottonwood and hybrid poplar stands, and the latter pathogen is not associated with stem cankers. The conidial size range of these two species overlaps, which adds uncertainty to earlier diagnoses of S. musiva based on morphology alone, especially since it had not previously been isolated from cankers collected in BC. This isolation and PCR-confirmed identification of S. musiva documents the first record of its association with a high incidence of stem cankers in commercially grown hybrid poplars in BC.


New records for powdery mildews and Taphrina species in Idaho and Washington PDF
Frank M. Dugan, George Newcombe 1-5
Podosphaera (Sphaerothecaeuphorbiae on Euphorbia epithymoides (= E. polychroma, cushion spurge) is reported for the first time in North America. Neoerysiphe Erysiphe galeopsidis on Lamium amplexicaule (henbit), Blumeria (Erysiphegraminis onFestuca idahoenis (Idaho fescue), Taphrina johansonii on Populus tremuloides (trembling aspen), and Taphrina occidentalis on Alnus rubra (red alder) are reported for the first time from Idaho. Reports of Erysiphe cichoracearum on henbit may reflect misdetermined Neoerysiphe galeopsidis.