Novel phosphite and nutrient application to control Phytophthora cinnamomi disease

Systemic treatment of stems with injections of phosphite liquid and novel soluble capsule implants of phosphite, PHOSCAP® (phosphorous, potassium, iron, manganese, zinc, boron, copper, magnesium and molybdenum) and MEDICAP MD® (nitrogen, phosphorous, potassium, iron, manganese, and zinc), were applied to Banksia grandis and Eucalyptus marginata trees to control Phytophthora cinnamomi. Four weeks after treatment application, excised branches were under-bark inoculated with P. cinnamomi. In B. grandis, phosphite implants and liquid injections significantly reduced lesion length compared to the control, and MEDICAP MD® implants; however, there was no significant difference in lesion length between trees treated with phosphite implants and liquid injections and PHOSCAP implants. In E. marginata, phosphite implants and liquid injections significantly reduced lesion length compared to the control, PHOSCAP® and MEDICAP MD® implants. In B. grandis and E. marginata, PHOSCAP® and MEDICAP MD® implants reduced the average lesion length compared to the control; however, the interactions were not significant. Results show that both liquid phosphite injections and novel phosphite implants are effective at controlling lesion extension in B. grandis and E. marginata, caused by P. cinnamomi. Further work is required to determine if nutrient application reduces Phytophthora disease through improving plant health

Treatment of endobronchial metastases with intraluminal radiotherapy

AbstractMetastasis to the lung occurs quite commonly from certain types of extrapulmonary primary carcinoma. Spread to the bronchial lumen is relatively rare. When this does occur, symptoms resembling those of primary bronchial carcinoma are often present, in association with partial or complete obstruction of the bronchial lumen. Palliation of such symptoms is possible with the use of intraluminal radiotherapy (ILT). Between 1990 and 1998, 37 patients with endobronchial metastases were treated using this modality; a single fraction of radiation was delivered by the remote afterloading high dose rate microSelectron system. Data regarding these patients' characteristics and outcome are presented, following a retrospective review of case notes.The commonest symptoms were dyspnoea, cough and haemoptysis; the commonest primary tumour sites were breast, colorectum, oesophagus and kidney. Twenty-four (64·9%) patients had some improvement in symptoms following treatment. Mean overall survival was 280 days, range 9–1145 days. No serious adverse effects occurred. ILT is a relatively simple, safe and effective treatment in the palliation of symptoms due to endobronchial metastases

Calcium chelate is as effective as phosphite in controlling Phytophthora root rot in glasshouse trials

Species in the genus Phytophthora cause significant economic losses in crops and damage to forests and natural ecosystems worldwide. Currently, phosphite is the most effective chemical for disease management, but excessive phosphite concentrations can result in phytotoxicity in plants and the development of tolerance by the pathogen. Two newly developed metal chelates and phosphite (alone and in combination) were tested for their in vitro and in planta efficacy against Phytophthora cinnamomi. In glasshouse trials, 0.25% and 0.5% of each chemical treatment (phosphite, Ca chelate, Zn chelate) and Ca chelate + phosphite were used as a foliar application on 3-month-old seedlings of Banksia grandis (experiment not repeated) and Eucalyptus marginata, prior to inoculation with P. cinnamomi. All noninoculated control plants remained healthy, while significant root damage and reduction of dry root weights were observed for inoculated untreated plants. Individually, phosphite and Ca chelate significantly reduced root lesion development of P. cinnamomi compared to the control, with Ca chelate attaining superior results to phosphite at the same concentration. In combination, Ca chelate + phosphite had the largest reduction in root lesion development in both plant species; however, this result has not yet been replicated but did reflect previous in vitro results. The Zn chelate applications were not effective. Ca chelate has the potential to be developed as a fungicide to control Phytophthora species

Reassessing Vermisporium (Amphisphaeriaceae), a genus of foliar pathogens of eucalypts

The genus Vermisporium presently accommodates 13 species, 11 of which are associated with leaf spots of eucalypts in the Southern Hemisphere. Vermisporium is chiefly distinguished from Seimatosporium (Amphisphaeriaceae) on the basis of a short exogenous basal appendage, and the absence of a recognisable apical appendage. Due to the increasing importance of these species in native forests, and confusion pertaining to their taxonomy, a revision of the genus was undertaken based on fresh collections and dried herbarium specimens. Results from DNA sequence data analyses of the nrDNA-ITS and 28S nrRNA genes for species of Vermisporium indicated the genus to be a synonym of Seimatosporium. New combinations are introduced in Seimatosporium for several species: S. acutum, S. biseptatum, S. brevicentrum, S. obtusum, S. orbiculare, S. verrucisporum and S. walkeri. An updated key to all species occurring on eucalypts is also provided

Age-related susceptibility of Eucalyptus species to Phytophthora boodjera

Phytophthora boodjera is a newly described pathogen causing damping off and mortality of Eucalyptus seedlings in Western Australian nurseries. This study evaluated the age-related susceptibility of several taxa of mallee Eucalyptus to P. boodjera in sterilized washed river sand-infestation pot trials. Phytophthora cinnamomi and P. arenaria were included for comparison. Seedlings of Eucalyptus taxa were inoculated at 0, 2, 4, 12 and 88 weeks with individual Phytophthora isolates. Pre-emergent mortality in the presence of Phytophthora was almost 100%. Post-emergent mortality was 50-100%, depending on isolate, compared to 0% for the control. Mortality was also high for inoculated 1 month-old seedlings (46-68%) and root length of surviving seedlings was severely reduced. Death from root infection was not observed for seedlings inoculated at 12 and 88 weeks, but they developed root necrosis and reduced root dry weight compared to non-inoculated controls. Phytophthora boodjera is a pre- and post-emergent pathogen of mallee eucalypts. These eucalypts are susceptible to P. boodjera at all life stages tested, but the mortality rates declined with plant age. Similar results were obtained for P. cinnamomi and P. arenaria. The events leading to its recent appearance in the nurseries remain unknown and further investigations are underway to determine if this is an introduced or endemic pathogen. The approach used here to understand the impact of a Phytophthora species on multiple hosts at different seedling ages is novel and sets a benchmark for future work

Phytophthora multivora sp. nov., a new species recovered from declining Eucalyptus, Banksia, Agonis and other plant species in Western Australia

A new Phytophthora species, isolated from rhizosphere soil of declining or dead trees of Eucalyptus gomphocephala, E. marginata, Agonis flexuosa, and another 13 plant species, and from fine roots of E. marginata and collar lesions of Banksia attenuata in Western Australia, is described as Phytophthora multivora sp. nov. It is homothallic and produces semipapillate sporangia, smooth-walled oogonia containing thick-walled oospores, and paragynous antheridia. Although morphologically similar to P. citricola, phylogenetic analyses of the ITS and cox1 gene regions demonstrate that P. multivora is unique. Phytophthora multivora is pathogenic to bark and cambium of E. gomphocephala and E. marginata and is believed to be involved in the decline syndrome of both eucalypt species within the tuart woodland in south-west Western Australia

Nature of Sonoluminescence: Noble Gas Radiation Excited by Hot Electrons in "Cold" Water

We show that strong electric fields occurring in water near the surface of collapsing gas bubbles because of the flexoelectric effect can provoke dynamic electric breakdown in a micron-size region near the bubble and consider the scenario of the SBSL. The scenario is: (i) at the last stage of incomplete collapse of the bubble the gradient of pressure in water near the bubble surface has such a value and sign that the electric field arising from the flexoelectric effect exceeds the threshold field of the dynamic electrical breakdown of water and is directed to the bubble center; (ii) mobile electrons are generated because of thermal ionization of water molecules near the bubble surface; (iii) these electrons are accelerated in ''cold'' water by the strong electric fields; (iv) these hot electrons transfer noble gas atoms dissolved in water to high-energy excited states and optical transitions between these states produce SBSL UV flashes in the trasparency window of water; (v) the breakdown can be repeated several times and the power and duration of the UV flash are determined by the multiplicity of the breakdowns. The SBSL spectrum is found to resemble a black-body spectrum where temperature is given by the effective temperature of the hot electrons. The pulse energy and some other characteristics of the SBSL are found to be in agreement with the experimental data when realistic estimations are made.Comment: 11 pages (RevTex), 1 figure (.ps

Unravelling Mycosphaerella: do you believe in genera?

Many fungal genera have been defined based on single characters considered to be informative at the generic level. In addition, many unrelated taxa have been aggregated in genera because they shared apparently similar morphological characters arising from adaptation to similar niches and convergent evolution. This problem is aptly illustrated in Mycosphaerella. In its broadest definition, this genus of mainly leaf infecting fungi incorporates more than 30 form genera that share similar phenotypic characters mostly associated with structures produced on plant tissue or in culture. DNA sequence data derived from the LSU gene in the present study distinguish several clades and families in what has hitherto been considered to represent the Mycosphaerellaceae. In some cases, these clades represent recognisable monophyletic lineages linked to well circumscribed anamorphs. This association is complicated, however, by the fact that morphologically similar form genera are scattered throughout the order (Capnodiales), and for some species more than one morph is expressed depending on cultural conditions and media employed for cultivation. The present study shows that Mycosphaerella s.s. should best be limited to taxa with Ramularia anamorphs, with other well defined clades in the Mycosphaerellaceae representing Cercospora, Cercosporella, Dothistroma, Lecanosticta, Phaeophleospora, Polythrincium, Pseudocercospora, Ramulispora, Septoria and Sonderhenia. The genus Teratosphaeria accommodates taxa with Kirramyces anamorphs, while other clades supported in the Teratosphaeriaceae include Baudoinea, Capnobotryella, Devriesia, Penidiella, Phaeothecoidea, Readeriella, Staninwardia and Stenella. The genus Schizothyrium with Zygophiala anamorphs is supported as belonging to the Schizothyriaceae, while Dissoconium and Ramichloridium appear to represent a distinct family. Several clades remain unresolved due to limited sampling. Mycosphaerella, which has hitherto been used as a term of convenience to describe ascomycetes with solitary ascomata, bitunicate asci and 1-septate ascospores, represents numerous genera and several families yet to be defined in future studies

Dark energy and Josephson junctions

It has been recently claimed that dark energy can be (and has been) observed in laboratory experiments by measuring the power spectrum $S_I(\omega)$ of the noise current in a resistively shunted Josephson junction and that in new dedicated experiments, which will soon test a higher frequency range, $S_I(\omega)$ should show a deviation from the linear rising observed in the lower frequency region because higher frequencies should not contribute to dark energy. Based on previous work on theoretical aspects of the fluctuation-dissipation theorem, we carefully investigate these issues and show that these claims are based on a misunderstanding of the physical origin of the spectral function $S_I(\omega)$. According to our analysis, dark energy has never been (and will never be) observed in Josephson junctions experiments. We also predict that no deviation from the linear rising behavior of $S_I(\omega)$ will be observed in forthcoming experiments. Our findings provide new (we believe definite) arguments which strongly support previous criticisms.Comment: 9 pages, no figure

Allelochaeta (Sporocadaceae): Pigmentation lost and gained

The appendaged coelomycete genus Seimatosporium (Sporocadaceae, Sordariomycetes) and some of its purported synonyms Allelochaeta,Diploceras and Vermisporium are re-evaluated. Based on DNA data for five loci (ITS, LSU, rpb2, tub2 and tef1), Seimatosporium is shown to be paraphyletic. The ex-type species of Allelochaeta, Discostromopsis and Vermisporium represent a distinct sister clade to which the oldest name Allelochaeta is applied. These genera were traditionally separated based on a combination of conidial pigmentation, septation, and the nature of their conidial appendages. Allelochaeta is revealed to include taxa with both branched or solitary appendages, that could be cellular or continuous, with conidia being (2–)3(–5)-septate, hyaline, or pigmented, concolourous or versicolourous. This suggests that these characters should be applied at species, and not at the generic level. Conidial pigmentation appears to have been lost or gained several times during the evolution of species within Allelochaeta. In total, 25 new species, 15 new combinations, and 10 new epitypifications are proposed