Home  About us  Contact
 

Fungicide Concentration (fungicide + concentration)

Distribution by Scientific Domains
Life Sciences100%

Selected Abstracts

Leaf Disc Inoculation, a Fast and Precise Test for the Screening of Metalaxyl Tolerance in Sunflower Downy Mildew

JOURNAL OF PHYTOPATHOLOGY, Issue 6 2001
B. Rozynek
A new method, based on leaf disc inoculation, was developed for the screening of metalaxyl tolerance in field isolates of Plasmopara halstedii. High-pressure liquid chromatography (HPLC) was used to determine the fungicide concentration in the inoculation medium and in the incubated leaf tissue over the test period. These measurements revealed that the fungicide concentration inside the leaf tissue within 24 h had adjusted to the concentration in the outer medium and remained constant for the time of cultivation over a period of more than 11 days. In contrast to whole seedling tests with application of the fungicide via seed dressing, the leaf disc method allows precise quantification of the effective fungicide concentration at the site of infection and is less space and time consuming. Metalaxyl tolerance of P. halstedii isolates was gradually determined according to the sporulation of the pathogen on sunflower leaf discs in the presence of increasing fungicide concentrations. Isolates collected in South Germany showed no tolerance and sporulation was prohibited when tests were carried out at 0.02 ,g (a.i.)/ml of metalaxyl or more. In contrast, a tolerant French isolate developed sporangia on leaf discs incubated in a metalaxyl solution of 100 ,g (a.i.)/ml. [source]

Modulation of water activity on fungicide effect on Aspergillus niger growth in Sabouraud dextrose agar medium,

LETTERS IN APPLIED MICROBIOLOGY, Issue 5 2005
X. Ni
Abstract Aims:, To examine whether water activity (aw) in combination with low concentration of fungicides can be used to effectively control Aspergillus niger van Tieghem growth in cultural medium, the Sabouraud dextrose agar (SDA). The data would be used as baseline information for reducing A. niger contamination in insect artificial diets. Methods and Results:,Aspergillus niger was isolated from an insect artificial diet. Four concentration levels (i.e. 0, 1, 10 and 20 ,mol) of two fungicides (i.e. amphotericin B and itraconazole) were tested against A. niger under four aw levels (i.e. 0·994, 0·961, 0·921 and 0·859) adjusted by including 0, 12·5, 25 and 38% of glycerol in the medium mixture. Aspergillus niger growth was significantly reduced at low fungicide concentration (1 ,mol), and at reduced aw. The spore germination was prevented with either higher fungicide concentration (>10 ,mol), or low aw in the medium (aw < 0·921). The two ecological determinants (fungicides and aw) showed a significant impact on A. niger survival in the medium (P < 0·0001). Itraconazole is more effective than amphotericin B in controlling A. niger contamination in the agar medium. Conclusion:, Adjustment of aw (with 12·5% of glycerol) in combination with 1 ,mol of itraconazole can effectively prevent A. niger growth in the SDA cultural medium. Significance and Impact of the Study:,Aspergillus niger contaminations have frequently affected the quality of insects produced from mass rearing facilities. Low aw in combination with low fungicide concentration has the potential to become one of the most cost-effective management strategies to prevent A. niger contamination in insect artificial diets. The effect of fungicides and low aw in artificial diets on insect biology needs to be further examined. [source]

Leaf Disc Inoculation, a Fast and Precise Test for the Screening of Metalaxyl Tolerance in Sunflower Downy Mildew

JOURNAL OF PHYTOPATHOLOGY, Issue 6 2001
B. Rozynek
A new method, based on leaf disc inoculation, was developed for the screening of metalaxyl tolerance in field isolates of Plasmopara halstedii. High-pressure liquid chromatography (HPLC) was used to determine the fungicide concentration in the inoculation medium and in the incubated leaf tissue over the test period. These measurements revealed that the fungicide concentration inside the leaf tissue within 24 h had adjusted to the concentration in the outer medium and remained constant for the time of cultivation over a period of more than 11 days. In contrast to whole seedling tests with application of the fungicide via seed dressing, the leaf disc method allows precise quantification of the effective fungicide concentration at the site of infection and is less space and time consuming. Metalaxyl tolerance of P. halstedii isolates was gradually determined according to the sporulation of the pathogen on sunflower leaf discs in the presence of increasing fungicide concentrations. Isolates collected in South Germany showed no tolerance and sporulation was prohibited when tests were carried out at 0.02 ,g (a.i.)/ml of metalaxyl or more. In contrast, a tolerant French isolate developed sporangia on leaf discs incubated in a metalaxyl solution of 100 ,g (a.i.)/ml. [source]