Studies on a strain of Alternaria citri Pierce, the causal organism of brown spot of Emperor mandarin

Brown spot of the Emperor of Canton mandarin in Queensland was found to be caused by a distinct strain of Alternaria citri Pierce. In morphological and cultural characters the fungus is identical with A. citri, but differs in pathogenicity and the production of toxic filtrates when cultured on liquid medium. No evidence of cuticular or stomatal penetration by the germinating spores was found, and hyphae were not found in young lesions. When the fungus was cultured on Czapek's sucrose nitrate solution a toxic filtrate was produced which induced the same disease symptoms and showed the same host specificity as the pathogen itself. Non-pathogenic isolates of A. citri did not produce this host-specific toxic filtrate. Chloroform and Celite treatments increased the susceptibility of mature fruit to damage, presumably by removing a barrier of waxes which was impermeable to the toxin. The host range in Queensland was found to include Emperor of Canton mandarin, Sovereign mandarin and Calamondin

The Possibilist Transactional Interpretation and Relativity

A recent ontological variant of Cramer's Transactional Interpretation, called "Possibilist Transactional Interpretation" or PTI, is extended to the relativistic domain. The present interpretation clarifies the concept of 'absorption,' which plays a crucial role in TI (and in PTI). In particular, in the relativistic domain, coupling amplitudes between fields are interpreted as amplitudes for the generation of confirmation waves (CW) by a potential absorber in response to offer waves (OW), whereas in the nonrelativistic context CW are taken as generated with certainty. It is pointed out that solving the measurement problem requires venturing into the relativistic domain in which emissions and absorptions take place; nonrelativistic quantum mechanics only applies to quanta considered as 'already in existence' (i.e., 'free quanta'), and therefore cannot fully account for the phenomenon of measurement, in which quanta are tied to sources and sinks.Comment: Final version with some minor corrections as published in Foundations of Physics. This paper has significant overlap with Chapter 6 of my book on the Transactional Interpretation, forthcoming from Cambridge University Press: http://www.cambridge.org/us/knowledge/isbn/item6860644/?site_locale=en_US (Additional preview material is available at rekastner.wordpress.com) Comments welcom

Fusarium wilt of banana

Fact sheet on Fusarium wilt of banana: varietal susceptibility, symptoms, pathogenesis, control

Fungal Planet description sheets: 1383–1435

Novel species of fungi described in this study include those from various countries as follows: Australia, Agaricus albofoetidus, Agaricus aureoelephanti and Agaricus parviumbrus on soil, Fusarium ramsdenii from stem cankers of Araucaria cunninghamii, Keissleriella sporoboli from stem of Sporobolus natalensis, Leptosphaerulina queenslandica and Pestalotiopsis chiaroscuro from leaves of Sporobolus natalensis, Serendipita petricolae as endophyte from roots of Eriochilus petricola, Stagonospora tauntonensis from stem of Sporobolus natalensis, Teratosphaeria carnegiei from leaves of Eucalyptus grandis × E. camaldulensis and Wongia ficherai from roots of Eragrostis curvula. Canada, Lulworthia fundyensis from intertidal wood and Newbrunswickomyces abietophilus (incl. Newbrunswickomyces gen. nov.)on buds of Abies balsamea. Czech Republic, Geosmithia funiculosa from a bark beetle gallery on Ulmus minor and Neoherpotrichiella juglandicola (incl. Neoherpotrichiella gen. nov.)from wood of Juglans regia. France, Aspergillus rouenensis and Neoacrodontium gallica (incl. Neoacrodontium gen. nov.)from bore dust of Xestobium rufovillosum feeding on Quercus wood, Endoradiciella communis (incl. Endoradiciella gen. nov.)endophyticin roots of Microthlaspi perfoliatum and Entoloma simulans on soil. India, Amanita konajensis on soil and Keithomyces indicus from soil. Israel, Microascus rothbergiorum from Stylophora pistillata. Italy, Calonarius ligusticus on soil. Netherlands , Appendopyricularia juncicola (incl. Appendopyricularia gen. nov.), Eriospora juncicola and Tetraploa juncicola on dead culms of Juncus effusus, Gonatophragmium physciae on Physcia caesia and Paracosmospora physciae (incl. Paracosmospora gen. nov.)on Physcia tenella, Myrmecridium phragmitigenum on dead culm of Phragmites australis, Neochalara lolae on stems of Pteridium aquilinum, Niesslia nieuwwulvenica on dead culm of undetermined Poaceae, Nothodevriesia narthecii (incl. Nothodevriesia gen. nov.) on dead leaves of Narthecium ossifragum and Parastenospora pini (incl. Parastenospora gen. nov.)on dead twigs of Pinus sylvestris. Norway, Verticillium bjoernoeyanum from sand grains attached to a piece of driftwood on a sandy beach. Portugal, Collybiopsis cimrmanii on the base of living Quercus ilex and amongst dead leaves of Laurus and herbs. South Africa , Paraproliferophorum hyphaenes (incl. Paraproliferophorum gen. nov.) on living leaves of Hyphaene sp. and Saccothecium widdringtoniae on twigs of Widdringtonia wallichii. Spain, Cortinarius dryosalor on soil, Cyphellophora endoradicis endophytic in roots of Microthlaspi perfoliatum, Geoglossum laurisilvae on soil, Leptographium gemmatum from fluvial sediments, Physalacria auricularioides from a dead twig of Castanea sativa , Terfezia bertae and Tuber davidlopezii in soil. Sweden, Alpova larskersii, Inocybe alpestris and Inocybe boreogodeyi on soil. Thailand, Russula banwatchanensis, Russula purpureoviridis and Russula lilacina on soil. Ukraine, Nectriella adonidis on over wintered stems of Adonis vernalis. USA, Microcyclus jacquiniae from living leaves of Jacquinia keyensis and Penicillium neoherquei from a minute mushroom sporocarp. Morphological and culture characteristics are supported by DNA barcodes

Brown spot disease of French bean caused by Pleiochaeta setosa

Brown spot disease of French bean (Phaseolus vulgaris L.) caused by Pleiochaeta setosa (Kirchn.) Hughes is described for the first time. The fungus is shown by pathogenicity tests to be a wound pathogen, and abrasion by sand particles during cyclonic weather apparently predisposes the plants to infection

Effect of organic amendments and solarisation on Fusarium wilt in susceptible banana plantlets, transplanted into naturally infested soil

Despite extensive research since pathogenicity was first established in 1919, no cultural or chemical control strategy has proven effective against Fusarium wilt of bananas. The efficacy of cultural control is attributed to the suppression of pathogen activity. Yet, amending naturally infested soil with aged chicken manure has been shown to enhance disease severity, without any change in the activity of the pathogen Fusarium oxysporum f. sp. cubense (Foc) in the soil. In this study, the effect of amending soil with composted sawdust, and of solarising soil, was compared with the effect of amending soil with chicken manure. Bioassays comparing the activity of Foc in the soil with the extent of invasion of banana pseudostem tissue by Foc were used to investigate why strategies targetting pathogen survival have not proven successful in controlling this disease. The enhancement of Foc invasion of the banana plantlets was reproduced with the addition of chicken manure to the naturally infested soil. However, changes in the activity of Foc in the soil were not associated with changes in the frequency of invasion of the plantlets. Invasion of banana pseudostems in the sawdust and solarisation treatments was not significantly different from invasion in the respective control treatments, despite a reduction in the activity of Foc in the sawdust-amended soil and an enhancement in the solarised soil. Moreover, the increase in Foc activity in the solarised soil recorded during the bioassays occurred despite the effectiveness of solarisation in reducing the survival of Foc in pre-colonised banana root tips buried in the soil. Changes in the frequency of invasion were associated with changes in the availability of mineral nitrogen, particularly ammonium N. These results suggest that the physiological response of banana cultivars to ammonium N may be associated with their susceptibility to Fusarium wilt. Accordingly, cultural strategies for controlling Panama disease will only be effective if they enhance the ability of the host to resist invasion

Bacterial wilt of ginger in Queensland

Bacterial wilt (Pseudomonas solanacearum) of ginger was recorded in Queensland for the first time, Two types of wilt caused by biotypes 3 and 4 could be distinguished. Seven weeds commonly found in ginger plantings were found infected with biotype 3. The pathogenicity of biotype 4 to a number of hosts was determined and its reaction on ginger was compared with that of biotype 3 and also biotype 2 isolated from potato

Vegetative compatibility and distribution of Fusarium oxysporum f.sp. cubense in Australia

Isolates of Fusarium oxysporum f. sp. cubense from wilted banana plants in Queensland and New South Wales were characterised for vegetative compatibility. Six vegetative compatibility groups VCGs) were identified. Race 1 (VCGs 0124, 01241.5, 0125) was widespread, being detected in northern and southern Queensland as well as northern New South Wales. Race 2 (VCG 0128) was found attacking Bluggoe in North Queensland. Race 4 (VCGs 0120, 0129, 01211) was detected in Cavendish plantations in southern Queensland and in Lady finger plantations in New (South Wales and southern Queensland. Isolates of the race 4 VCG 0129 from Lady finger plantations were pathogenic to Cavendish cultivars in glasshouse tests