Journal of Phytopathology 

About: Journal of Phytopathology is an academic journal published by Wiley-Blackwell. The journal publishes majorly in the area(s): Population & Plant virus. It has an ISSN identifier of 0931-1785. Over the lifetime, 7029 publications have been published receiving 105248 citations. The journal is also known as: Phytopathologische Zeitschrift (1986. Internet) & Phytopathologische Zeitschrift (1986. Print).

Deoxynivalenol and Fusarium Head Blight Resistance in Spring Cereals

Abstract: A single isolate of Fusarium graminearum (DAOM 178148) was used to infect experimentally 9 spring wheat, 5 rye and 6 triticale cultivars and the resulting amounts of fungal biomass (determined as ergosterol), deoxynivalenol and other mycotoxins at the same stage of development were compared. Resistant cultivars of wheat, rye and triticale contained low concentrations of deoxynivalenol (mean 0.6 ppm) in the kernels, whereas susceptible cultivars of wheat and triticale contained much higher concentrations (mean 10.2 ppm). The corresponding chaffs contained ca. 8 fold higher concentrations. Higher ergosterol concentrations in the susceptible cultivars showed that these cultivars had lower resistance to hyphal invasion. Ergosterol to deoxynivalenol ratios in the susceptible cultivars averaged ca. 2.4 and were much higher in the resistant, averaging ca. 12 and ca. 240 for the wheat and rye, respectively. The data suggest that resistant cultivars have factors that prevent synthesis and/or promote degradation of deoxynivalenol. Zearalenone was not detected in any sample and 15-acetyldeoxynivalenol was noted only in the chaff of the most susceptible wheat cultivar. Zusammenfassung Ein einzelnes Isolat von Fusarium graminearum (DAOM 178148) wurde eingesetzt, um experimentell 9 Sommerweizen-, 5 Roggen- und 6 Triticale Kultivare zu infizieren und die sich ergebenden Mengen pilzlicher Biomasse (bestimmt als Ergosterol), Deoxynivalenol und andere Mycotoxine zum gleichen Entwicklungsstand zu vergleichen. Resistente Kultivare von Weizen, Roggen und Triticale enthielten geringe Konzentrationen von Deoxynivalenol (Durchschnitt 0,6 ppm) in den Kornern, wahrend anfallige Kultivare von Weizen und Triticale wesentlich hohere Konzentrationen (Durchschnitt 10,2 ppm) enthielten. Das entsprechende Stroh enthielt ca. 8mal hohere Konzentrationen. Hohere Konzentration von Ergosterol in den anfalligen Kultivaren zeigten, daβ diese Kultivare eine geringere Resistenz gegenuber der Hypheninvasion hatten. Das Verhaltnis Ergosterol zu Deoxynivalenol in den anfalligen Kultivaren betrug im Durchschnitt ca. 2,4 und war in den Resistenten viel hoher, die im Mittel ca. 12 und 240 fur Weizen bzw. Roggen aufzeigten. Die Ergebnisse lieβen vermuten, daβ die resistenten Kultivare Faktoren enthalten, die die Synthese verhindern und/oder den Abbau von Deoxynivalenol unterstutzen. Zearalenon konnte in keiner Probe gefunden und 15-Acetyldeoxynivalenol konnte nur im Stroh der meisten anfalligen Weizenkultivare festgestellt werden.

Effects of Essential Oils on Phytopathogenic Fungi In Vitro

Abstract: The essential oils of Thymus vulgaris L., of Lavandula R.C. hybrid and Mentha piperita L. were tested in vitro against the pathogenic fungi Rhizoctonia solani Kuhn, Pythium ultimum Trow var. ultimum, Fusarium solani (Mart.) Sacc, Colletotrichum lindemuthianum (Sacc. & Magn.) Briosi & Cav. All the oils tested inhibited fungal growth. The most effective oil was that of thyme, with a fungicidal activity attributable to thymol, found in a concentration of 50.06% in the oil tested. SEM observations revealed that these oils cause degeneration of the fungal hyphae which appeared emptied of their cytoplasmic content.

Selection of Antagonistic Fluorescent Pseudomonas spp. and their Root Colonization and Persistence following Treatment of Seed Potatoes

Abstract: One hundred and twelve fluorescent Pseudomonas isolates from potato periderm were screened for antagonistic activity in vitro against 5 pathogenic and saprophytic fungi, 5 Gram-positive bacteria including Streptomyces scabies and 4 Gram-negative bacteria including Erwinia car. var. carotovora and Erwinia car. var. atroseptica. Fifty-seven percent of the isolates showed wide spectrum inhibitory activity, mostly due to the production of fluorescent siderophores. Only 4 % of the isolates were very strong antagonists. By adding iron (Fe3+) to the test medium, the antagonistic activity drastically diminished but revealed some strong antagonists of which the antagonism was not affected. Apparently growth-inhibiting substances other than siderophores were involved. Antibiotic-resistant mutants of the antagonists were used to establish that the bacteria on the seed tubers migrated to the roots under different conditions. Drying of the treated potatoes gradually diminished the number of viable cells, but subsequent planting in moist soil led to substantial increases in the first three days. Initially high numbers of the antibiotic-resistant antagonists on the roots tended to drop quickly in time, probably due to loss of resistance to the antibiotics in the selective medium.

Transmission of Cassava brown streak virus by Bemisia tabaci (Gennadius)

Abstract: Two whitefly species, Bemisia afer (Priesner & Hosny) and B. tabaci (Gennadius) were used in transmission experiments with Cassava brown streak virus (CBSV) (Ipomovirus; Potyviridae). Adults of whiteflies were given access to CBSV by containing them in clip cages on CBSV-infected cassava plants. Whiteflies were then transferred, together or separately, to CBSD-susceptible cassava plants of var. 'Albert' in a controlled environment. In glasshouse experiments, whiteflies were caged with CBSV-infected and virus-free cassava plants. Transmission of CBSV was sporadic and occurred in three of seven experiments when inoculated by B. afer and B. tabaci or B. tabaci alone, but not by B. afer alone. However, rate of transmission was low (maximum 22%) even when using high whitefly numbers of up to 120 per target plant. Successful transmission was confirmed by the detection of CBSV by reverse transcription-polymerase chain reaction. Spread of cassava brown streak disease (CBSD) in the field in Tanzania coincided with increases in whitefly numbers; further supporting the evidence that B. tabaci is a vector of CBSV. The results of this study establish for the first time that B. tabaci is the vector of CBSV, similar to other ipomoviruses.