Studies on Some Sooty Moulds on Guava In Malaysia

Sooty moulds proliferate in abundance on the foliage of guava, subsisting on the honeydew secreted by scale insects aphids, white flies, and mealy bugs. Nine species, five Ascomycetes species namely, Phragmocapnias betel, Scorias philippensis, Trichomerium grandisporum, Limacinula musicola and Aithaloderma clavatisporum; and four Deuteromycetes genera viz. Tripospermum sp., Polychaeton sp., Leptoxyphium sp. and Conidiocarpus sp., are described and reported as new records on guava for Peninsular Malaysia

Occurrence of a Mosaic Virus in Guava

Leaves from a shoot of guava cv. Burma Red were found to exhibit mosaic symptoms typical of a virus disease. Transmission electron microscopic studies of the sap from infected leaves revealed an isometric virus particle with a diameter of58-64 nm. The virus can be transmitted mechanically from cv. Burma Red to cv. Kampuchea seedlings. Based on the symptom, the virus can be tentatively designated as guava mosaic virus

A Rot of Detached Durian Fruits Caused by Sclerotium rolfsii

A new fruit rot of fallen durian fruits was observed in the Uiversiti Pertanian Malaysia fruit orchard in Serdang, Selangor during the fruit ripening month of October, 1988. The rot was characterized by a dense, white, fan-shaped mat of coarse my celial strands of the causal fungus growing on a water-soaked, brown necrotic patch on the fruit in contact with decaying weed vegetation on the ground. The causal organism was identified as Sclerotium rolfsii. Presence of a thick weed undergrowth and its decaying leaf debris, and warm, moist conditions were shown to be important predisposing factors conducive to the development of the rot

Crusty Leaf Spot Disease of Mango

A crusty spot disease on mango leaves was found to be ubiquitous on neglected mango trees throughout Peninsular Malaysia. Light and scanning electron microscope studies revealed the crusty structures to be the ascostromata of the fungus, Zimmennaniella trispora. This disease can cause severe leaf spotting of trees. This is the first report of z. trispora as a leaf parasite of mango in Malaysia

Control of Phytophthora palmivora on Orchids with Some New Systemic and Standard Fungicides

Three new systemic fungicides viz. Aliette (efosite-Al), Ridomil (metalaxyl) and Ridomil MZ (metalaxyl plus mancozeb) were screened against two standard fungicides viz. Terrazole (etridiazole) and Difolatan (captafol) for prophylactic and therapeutic efficacy against Phytophthora palmivora on orchids. Terminal shoots of Aranda Christine hybrids were effectively protected from Phytophthora infection when sprayed with metalaxyl at 0.05% a.i., metalaxyl-mancozeb mixture at 0.15% a.i. and captafol at 0.2% a.i. three days before artificial inoculation. Etridiazole and efosite-Al, both at 0.1%a.i. did not give adequate protection. Metalaxyl (0.05% a.i.) and its mixture with mancozeb (0.15% a.i.) retarded significantly disease development by Phytophthora when used as a curative spray. Etridiazole (0.1% a.i.) and efosite-Al (0.1% a.i.) gave moderate therapeutic control while captafol gave no therapeutic control. No phytoxicity was observed with Ridomil MZ, Terrazole and Aliette up to concentrations of 0.5% a.i., 0.4% a.i. and 0.8% a.i. respectively. The Ridomil products, Aliette and Terrazole exhibited similar rates of inhibition of linear extension of P. palmivora but differed in the degree of in vitro fungitoxicity. The Ridomil products and Terrazole had EDso values of less than 1 Ilg/ml while Difolatan was relatively less toxic (ED so 19.9 Ill/l)

Comparative Invitro Sensitivity of Selected Chemicals on Phytophthora palmivora from Cocoa and Durian

Five new systemic compounds vzi. metalaxyl, benalayxl, cyprofuran, propamocarb and fosetyl A I and two standard protectants, etridiazole and captafol were compared for invitro effects on representative isolates of Phytophthora palmivora from cocoa and durian. MetalaxyI, etridiazole and cyprofuram were highly inhibitory to mycelial growth, sporangium and chlamydospore product£on, direct sporangium germination and germ-tube development of both cocoa and durian isolates while benalaxyl was moderately inhibitory. Etridiazole and benalaxyl were more suppressive 9n zoospore germination but metalaxyl and cyprofuram were relatively ineffective. Captafol was also highly suppressive to mycelz'al growth, direct sporangium and zoospore germination but less so on sporangium and chlamydospore production. Propamocarb and fosetyl Al were comparatively the least effective against all the developmental stages of the zsolates except in the case of zoospore germination of the durian isolate where the latter was highly inhibitory

Studies of Colletotrichum dematium f. sp. truncatum on soybean

Growth and sporulation studies of Colletotrichum dematium var. truncatum were conducted using different media, temperatures and light regimes. Of the seven media employed oat meal agar supported the best mycelial growth, with sporulation best on Czapek Dox agar and potato dextrose agar. Greater mycelial growth was obtained under 12 hours alternating ultraviolet light and continuous light than in darkness. Sporulation was highest under 12 hours alternating light treatment. The optimum temperature for growth and sporulation was 25° C while germination was optimum at 20° C. Pathogenicity studies in the glasshouse showed that seedlings of cultivar 66D-16 were most susceptible while cultivar 66F-4A most resistant. Inoculation studies on detached green pods indicated that 66D-16 was most susceptible and Palmetto most resistant. An in vitro efficacy test of five fungicides against the fungus showed that Topsin M was the most toxic with an EDso of 2.2 pgjml

Measurement of the inclusive and dijet cross-sections of b-jets in pp collisions at sqrt(s) = 7 TeV with the ATLAS detector

The inclusive and dijet production cross-sections have been measured for jets containing b-hadrons (b-jets) in proton-proton collisions at a centre-of-mass energy of sqrt(s) = 7 TeV, using the ATLAS detector at the LHC. The measurements use data corresponding to an integrated luminosity of 34 pb^-1. The b-jets are identified using either a lifetime-based method, where secondary decay vertices of b-hadrons in jets are reconstructed using information from the tracking detectors, or a muon-based method where the presence of a muon is used to identify semileptonic decays of b-hadrons inside jets. The inclusive b-jet cross-section is measured as a function of transverse momentum in the range 20 < pT < 400 GeV and rapidity in the range |y| < 2.1. The bbbar-dijet cross-section is measured as a function of the dijet invariant mass in the range 110 < m_jj < 760 GeV, the azimuthal angle difference between the two jets and the angular variable chi in two dijet mass regions. The results are compared with next-to-leading-order QCD predictions. Good agreement is observed between the measured cross-sections and the predictions obtained using POWHEG + Pythia. MC@NLO + Herwig shows good agreement with the measured bbbar-dijet cross-section. However, it does not reproduce the measured inclusive cross-section well, particularly for central b-jets with large transverse momenta.Comment: 10 pages plus author list (21 pages total), 8 figures, 1 table, final version published in European Physical Journal

Search for displaced vertices arising from decays of new heavy particles in 7 TeV pp collisions at ATLAS

We present the results of a search for new, heavy particles that decay at a significant distance from their production point into a final state containing charged hadrons in association with a high-momentum muon. The search is conducted in a pp-collision data sample with a center-of-mass energy of 7 TeV and an integrated luminosity of 33 pb^-1 collected in 2010 by the ATLAS detector operating at the Large Hadron Collider. Production of such particles is expected in various scenarios of physics beyond the standard model. We observe no signal and place limits on the production cross-section of supersymmetric particles in an R-parity-violating scenario as a function of the neutralino lifetime. Limits are presented for different squark and neutralino masses, enabling extension of the limits to a variety of other models.Comment: 8 pages plus author list (20 pages total), 8 figures, 1 table, final version to appear in Physics Letters

Measurement of the polarisation of W bosons produced with large transverse momentum in pp collisions at sqrt(s) = 7 TeV with the ATLAS experiment

This paper describes an analysis of the angular distribution of W->enu and W->munu decays, using data from pp collisions at sqrt(s) = 7 TeV recorded with the ATLAS detector at the LHC in 2010, corresponding to an integrated luminosity of about 35 pb^-1. Using the decay lepton transverse momentum and the missing transverse energy, the W decay angular distribution projected onto the transverse plane is obtained and analysed in terms of helicity fractions f0, fL and fR over two ranges of W transverse momentum (ptw): 35 < ptw < 50 GeV and ptw > 50 GeV. Good agreement is found with theoretical predictions. For ptw > 50 GeV, the values of f0 and fL-fR, averaged over charge and lepton flavour, are measured to be : f0 = 0.127 +/- 0.030 +/- 0.108 and fL-fR = 0.252 +/- 0.017 +/- 0.030, where the first uncertainties are statistical, and the second include all systematic effects.Comment: 19 pages plus author list (34 pages total), 9 figures, 11 tables, revised author list, matches European Journal of Physics C versio