Search results for "Potato dextrose agar"
showing 10 items of 21 documents
Comparison of the Fungistatic Activity of Selected Essential Oils Relative to Fusarium graminearum Isolates
2019
The aim of the study was to determine the chemical composition of lemon, rosewood, geranium and rosemary oils, and compare their effect on the sensitivity of Fusarium graminearum ZALF 24 and Fusarium graminearum ZALF 339 isolated from infected cereals. The tested oils were added to Potato Dextrose Agar (PDA) medium at concentrations of 0.125%, 0.25%, 0.5%, 1.0% and 2.0%. The activity of the oils on inhibition of the linear growth of mycelium was evaluated by measuring the growth of fungal colonies (growth index), while the fungistatic activity was evaluated on the basis of the percentage growth inhibition of a fungal colony and calculated according to Abbott&rsquo
Validation of a predictive model for the growth of Botrytis cinerea and Penicillium expansum on grape berries.
2010
The objective of this study was to develop and to validate a model for predicting the combined effect of temperature and a(w) on the radial growth rate, mu, of Botrytis cinerea and Penicillium expansum on grape berries. The proposed strategy was based on the gamma-concept developed previously [Zwietering, M.H., Wijtzes, T., de Wit, J.C., van't Riet, K. 1992. A decision support system for prediction of the microbial spoilage in foods. Journal of Food Protection. 12, 973-979]: mu=mu(opt).gamma(T).gamma(a(w)), where the gamma functions were cardinal models with inflection (CMI), mu(opt) the radial growth rate on grape berries. Firstly, the cardinal temperatures and a(w)'s were estimated indepe…
First Report of Phytophthora spp. as Pathogens of Pandorea jasminoides in Italy
2019
In the summer of 2005, approximately 5% of a nursery stock of 12-month-old potted plants of bower vine (Pandorea jasminoides (Lindl.) K. Schum.) in Sicily (Italy) showed wilt, leaf chlorosis, defoliation, root rot, and collapse of the entire plant. Three Phytophthora spp. (20, 50, and 30% of the isolations of the first, second, and third species, respectively) were isolated from rotted roots on BNPRAH selective medium (2). Single-hypha isolates of the first species formed petaloid colonies on potato dextrose agar (PDA) and had an optimum growth temperature of 25°C (9.3 mm/day); on V8 juice agar, they produced uni- and bipapillate, ovoid to limoniform sporangia with mean dimensions of 45 × …
Blight Caused by Sclerotium rolfsii on Potted Ornamental Citrus in Sicily.
2019
Approximately 140,000 container-grown ornamental citrus plants are produced each year in the province of Catania (eastern Sicily). In the spring of 2006, a severe blight was observed in a commercial nursery in Catania on 2-month-old rooted cuttings of lemon (Citrus limon (L.) Burm.) and calamondin (× Citrofortunella mitis (Blanco) J. W. Ingram & H. E. Moore). Approximately 80% of the nursery stock of 2,000 cuttings was affected. Cuttings were grown in 7.5-cm2 pots made with compressed peat and wood pulp at 28 to 30°C with 95 to 100% relative humidity on benches in a greenhouse, The pot mix was composed of peat, perlite, and soil (2:1:2). Cuttings showed a dark brown necrotic lesion at …
A temperature-type model for describing the relationship between fungal growth and water activity
2001
Growth of Penicillium chrysogenum, Aspergillus flavus, Cladosporium cladosporioides and Alternaria alternata at their respective optimum temperatures was studied in Potato Dextrose Agar (PDA) medium at different water activities (a(w)) adjusted with glycerol. The growth rate (mu) was expressed as the increase in colony radius per unit of time. This paper extends the model that showed the relationship between temperature and bacterial growth rate developed by Rosso et al. [J. Theor. Biol. 162 (1993) 447] to describe the influence of a(w) on fungal development. An excellent correlation between the experimental data and the model predictions was obtained, the regression coefficients (r2) were …
First report of Phytophthora palmivora on Coronilla valentina subsp. glauca in Italy
2019
The genus Coronilla L. (family Fabaceae), which includes several species native to central and southern Europe, such as C. varia L. (axseed or crown-vetch), C. emerus (scorpion senna), and C. valentina L., is used in Italy as a landscape shrub or potted ornamental plant. During the summer of 2001, 80% of approximately 10,000 1-year-old plants of C. valentina subsp. glauca (L.) Batt. used to landscape an industrial area in the Caltanissetta Province (Sicily) showed symptoms of dieback associated with basal stem and root rot. Plants had been transplanted from pots in April and watered using a trickle irrigation system. A species of Phytophthora was isolated consistently from rotted roots and…
Root and Basal Stem Rot of Rose Caused by Phytophthora citrophthora in Italy
2011
Approximately 800 ha of cut flower roses are cultivated for commercial production in Italy. During autumn of 2004 in an experimental greenhouse in western Sicily (southern Italy), 60% of 2-year-old plants of rose cv. Red France on Rosa indica cv. Major rootstock grown in soil showed leaf chlorosis and wilt. A dark brown lesion lined by a water-soaked area was noticeable at the stem base near the soil surface. Root rot was found consistently associated with aboveground symptoms and plants collapsed within 4 months after the appearance of the first symptoms. The same symptoms were observed sporadically on rose plants of the same cultivar during the last 6 years in commercial nurseries in wes…
Resistance of Phytophthora capsici to metalaxyl in plastic-house capsicum crops in southern Italy
2000
In Calabria (southern Italy), control of crown and root rot of capsicum caused by Phytophthora capsici has relied primarily on soil drenches of metalaxyl. However, severe outbreaks occur every year in glasshouse crops, in which the practice of using plastic mulch and furrow irrigation favours the disease. Single-hypha isolates of P. capsici collected in Calabria in 1992/1998 were tested in vitro for their level of sensitivity to metalaxyl. Isolates of other species of Phytophthora were used as reference. Fungicide sensitivity was determined by plating mycelial plugs onto potato dextrose agar amended with metalaxyl, at final concentrations ranging from 0.1 to 1000μg mL−1 a.s. Inhibition of r…
Phytophthora palmivora a New Pathogen of Lavender in Italy
2019
Root rot caused by Phytophthora nicotianae is considered the most serious disease of lavender in commercial cultivations in Italy. In summer 2001, in the Gela area (Sicily), ≈60% of 34,000 2-year-old landscape shrubs of English lavender (L. angustifolia) grown in a clay loam soil showed symptoms of dieback associated with root rot. Plants had been transplanted from pots in May and watered using a trickle irrigation system. A species of Phytophthora was isolated consistently from roots of symptomatic plants using potato dextrose agar (PDA) containing benomyl, nystatin, pentachloronitrobenzene, rifampicin, ampicillin, and hymexazol. The species was identified as P. palmivora on the basis of …
Lag time for germination of Penicillium chrysogenum conidia is induced by temperature shifts.
2013
In the environment, fungal conidia are subject to transient conditions. In particular, temperature is varying according to day/night periods. All predictive models for germination assume that fungal spores can adapt instantaneously to changes of temperature. The only study that supports this assumption (Gougouli and Koutsoumanis, 2012, Modelling germination of fungal spores at constant and fluctuating temperature conditions. International Journal of Food Microbiology, 152: 153-161) was carried out on Penicillium expansum and Aspergillus niger conidia that, in most cases, already produced germ tubes. In contrast, the present study focuses on temperature shifts applied during the first stages…