The phenology and spore dissemination patterns of Uredinopsismirabilis on Abiesbalsamea and Onocleasensibilis

1989 ◽  
Vol 19 (1) ◽  
pp. 88-95 ◽  
Author(s):  
M. Mazzola ◽  
D. R. Bergdahl
Keyword(s):  
Diurnal Periodicity ◽  
North Central ◽  
Teliospore Germination ◽  
Host Tissues ◽  
Spore Dissemination ◽  
Precipitation Events

Phenology and spore dissemination patterns of Uredinopsismirabilis (Peck) Magnus were monitored from 1982 to 1984 in the Champlain Valley and north central Vermont. Teliospore germination began as early as May 5 and basidiospore dissemination continued as late as the week of June 17. Maximum basidiospore dissemination occurred after measurable precipitation. Infection of Abiesbalsamea (L.) Mill, occurred between May 19 and 30. Pycnia were apparent on current-year needles of A. balsamea by the week of June 17. Aeciospore development was observed by the week of June 24 and dissemination of aeciospores was completed about July 29. Aeciospores were trapped at highest concentrations during precipitation events. During dry periods, aeciospore dissemination showed a diurnal periodicity, with most spores trapped in the late morning hours. Uredia were formed on Onocleasensibilis L. as early as July 28 and urediniospores were trapped as late as October 4. Teliospores were formed in host tissues as early as July 7.

scholarly journals Assessing the Influence of the MJO on Strong Precipitation Events in Subtropical, Semi-Arid North-Central Chile (30°S)

2012 ◽  
Vol 25 (20) ◽  
pp. 7003-7013 ◽  
Author(s):  
Cristóbal Juliá ◽  
David A. Rahn ◽  
José A. Rutllant
Keyword(s):  
Southern Oscillation ◽  
False Alarms ◽  
Madden Julian Oscillation ◽  
Antarctic Oscillation ◽  
North Central ◽  
Central Chile ◽  
Number Of False Alarms ◽  
Slow Moving ◽  
The Relationship ◽  
Precipitation Events

Abstract Annual precipitation in subtropical, semiarid north-central Chile (30°S) during rainy years comprises a few (3–5) strong events in the fall and winter, which are presumably modulated by the Madden–Julian oscillation (MJO). Precipitation from 1979–2009 was recorded daily at three stations along the Elqui Valley. The relationship between the MJO and precipitation is investigated from two perspectives: 1) examining a MJO index (MJOI) based on the actual precipitation events and 2) examining the likelihood of precipitation based on a favorable MJOI. About 80% of the strong precipitation events at the coast in La Serena are related to an active MJO near the central equatorial Pacific. These events are often typified by broad, slow moving synoptic systems in phase with the MJO propagation. Blocking in the far southeast Pacific is associated with precipitation 75% of the time, while deep troughs make up the rest. A relationship between a MJOI and strong rainfall suggests that, though it could be used as a potential diagnostic, the number of cases where there is a favorable MJOI but no precipitation (i.e., false alarms) limits its utility. Additional criteria such as the Southern Oscillation (SO) and Antarctic Oscillation (AAO) phases were used to reject false alarms. Rejecting cases with positive values of the SO index reduced the number of false alarms from 70% to 58%, leaving about two false alarms for every correctly diagnosed event. The AAO index could not discriminate between false alarms and real cases. While a favorable MJOI increases the likelihood of precipitation in the Elqui Valley, false alarms remain problematic.

The infection process of Puccinia xanthii f. sp. ambrosiae-trifidae on Ambrosia trifida

Botany ◽  
2011 ◽  
Vol 89 (11) ◽  
pp. 771-777 ◽  
Author(s):  
Ping Zhang ◽  
Guo-zhong Lu ◽  
Xiao-dong Sun ◽  
Wei Zhang ◽  
Bo Qu ◽  
...  
Keyword(s):  
Leaf Surface ◽  
Rust Fungus ◽  
Infection Process ◽  
Host Tissue ◽  
Liaoning Province ◽  
Invasive Weed ◽  
Ambrosia Trifida ◽  
Teliospore Germination ◽  
Germ Tubes ◽  
Host Tissues

Puccinia xanthii Schwein. f. sp. ambrosiae-trifidae S.W.T. Batra is an obligate parasitic rust fungus of Ambrosia trifida Linn. Field investigations in Liaoning Province, China, showed that it is an effective biocontrol agent of this alien invasive weed. Its infection of the plant was observed by light microscopy combined with Coomassie Brilliant Blue R-250 staining. We report the infection process, including teliospore germination and basidiospore formation on the host leaf surface, penetration of host tissue, and development of fungal hyphae within the host tissue. Fresh teliospores began to germinate from the germ pore within 1 h under suitable conditions and soon produced basidiospores or secondary basidiospores. Basidiospores falling on host leaves germinated from the end of the basidiospore opposite to the apiculus. Appressoria of germ tubes tended to orient along leaf epidermis cell ridges or at junctions near stomata rather than fixing randomly on the leaf surface. These germ tubes grew for short or longer distances before forming appressoria. The rust fungus directly penetrated the host epidermis by infectious pegs rather than through stomata. Within host tissues, the rust fungus formed intraepidermal vesicles, primary hyphae, intracellular hyphae, and M-haustoria. The intricate infectious structures formed by P. xanthii f. sp. ambrosiae-trifidae on or in host tissues suggest that the rust fungus is a suitable organism for researching the interaction between the pathogen and host plant.

Stromatoporoids from the Famennian (Devonian) Wabamun Formation, Normandville oilfield, north–central Alberta, Canada

1988 ◽  
Vol 62 (03) ◽  
pp. 411-419 ◽  
Author(s):  
Colin W. Stearn
Keyword(s):  
Patch Reef ◽  
Abundant Species ◽  
The Other ◽  
North Central ◽  
Biotic Crisis

Stromatoporoids are the principal framebuilding organisms in the patch reef that is part of the reservoir of the Normandville field. The reef is 10 m thick and 1.5 km2in area and demonstrates that stromatoporoids retained their ability to build reefal edifices into Famennian time despite the biotic crisis at the close of Frasnian time. The fauna is dominated by labechiids but includes three non-labechiid species. The most abundant species isStylostroma sinense(Dong) butLabechia palliseriStearn is also common. Both these species are highly variable and are described in terms of multiple phases that occur in a single skeleton. The other species described areClathrostromacf.C. jukkenseYavorsky,Gerronostromasp. (a columnar species), andStromatoporasp. The fauna belongs in Famennian/Strunian assemblage 2 as defined by Stearn et al. (1988).

Effect of acid deposition on trichome morphology and dogwood anthracnose biology

1992 ◽  
Vol 50 (1) ◽  
pp. 840-841
Author(s):  
Kyle T. Thornham ◽  
R. Jay Stipes ◽  
Randolph L. Grayson
Keyword(s):  
Acid Deposition ◽  
Disease Incidence ◽  
Natural Populations ◽  
Tree Disease ◽  
Flowering Dogwood ◽  
Discula Destructiva ◽  
Disease Induction ◽  
Dogwood Anthracnose ◽  
Trichome Morphology ◽  
Precipitation Events

Dogwood anthracnose, caused by Discula destructiva (1), is another new catastrophic tree disease that has ravaged natural populations of the flowering dogwood (Cornus florida) in the Appalachians over the past 15 years, and the epidemic is prognosticated to continue (2). An estimated 9.5 million acres have been affected, primarily in the Appalachian Mountains, from VA southwards, alone, and an estimated 50% of all dogwoods in PA have been killed. Since acid deposition has been linked experimentally with disease induction, and since the disease incidence and severity are more pronounced at higher elevations where lower pH precipitation events occur, we investigated the effect of acidic foliar sprays on moiphologic changes in the foliar cuticle and trichomes (3), the initial sites of infection and foci of Discula sporulation.

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