الفهرس 
IntroductionOnly 14 pages are availabe for public view
 |  | from | 131 |  |  |
| | | from | 131 | | |
Abstract
The obtained data of this study could be summerized as follows :
- Marjoram root rot /wilt diseases was surveyed in two districts belong to El-Minia Governorate. The highest infection was recorded in El-Edwa, followed by Maghagha district .
- Frequency of fungi associated with marjoram root rot /wilt, revealed seven fungi belonging to five genera, namely Rhizoctonia solani, Fusarium oxysporum, Sclerotinia sclerotiorum, Alternaria sp. and Helminthosporium sp. Rhizoctonia solani was the major one 42 % followed with Fusarium oxysporum 32% and Helminthosporium sp 30% The other isolated fungi Sclerotinia sclerotiorum and Alternaria sp. occurred lower frequencies 23% - 14% Respectively. The frequency of isolated fungi was differed depending on the localities. were isolated from naturally infected plants.
-Pathogenicity test of selected fungal isolates indicated that R. solani (R1) and F. oxysporum (F1) were the major wilt fungi against plants 95% -83.7 Respectively, and S.sclerotioum 65.1 % while Alternaria sp and Helminthosporium sp revealed non pathogen.
- Host range experiment declared that different ornamental and medicinal plants i.e. Basil, Rosemary, Anise, Caraway, Mint, Thyme, Fennel, Sage and Lavender revealed that F. oxysporum and S. sclerotiorum infected plants causing root rot and/or wilt disease with different degree of infection. Rhizoctonia solani was more aggressive one causing the highest percentages of disease incidence
Under Laboratory studies, tested fungi are significantly affected by different factors .
- Temperature: All the tested isolates were able to grow at a wide range of temperature (15 - 35oC). However, the optimum temperature for growth of Fusarium oxysporium was 20oC, whereas for Rhizoctonia solani and S. sclortiorum it was 25oC. all tested fungi failed to grow at 5oC .
- Growth media: the Czapek’s medium favoured the growth of any of the tested isolates followed by Potato dextrose (PDA) and nutrent agar media more than did the waksman’s media of the growth of all tested isolates .
- Carbon sources, all tested fungi grew on all media tested, however, dry weight determination showed that maltose followed by glucose were the best carbon sources for R. solani and S. sclortiorum respectively while starch was the best carbon source for Fusarium oxysporium .
- Nitrogen sources (sodium nitrate, ammonium sulphate, and peptone).it was previously reported that peptone gave the best liner growth of all tested fungi, while total growth of S. sclortiorum was the best when sodium nitrate used as nitrogen sources but both of R.solani and F. oxysporium had best total dry weight with peptone as a sources of nitrogen .
- Antioxidant compounds salicylic acid, ascorbic acid, citric acid, hydrogen peroxide, ferric chloride and potassium silicate are significantly inhibited the growth of tested fungi, reduced both liner growth and mycelial dry weight. Mineral compounds and H2O2 were more efficient in reducing the growth of the tested fungi than inducer chemicals.
Possible management :
-Pre-planting seedlings treatment of marjoram with H2O2, mineral and antioxidant compounds significantly reduced root rot/wilt artificially inoculated with tested pathogens when comparing with control. Disease incidence decreased with increasing the concentration of tested compounds. The antioxidant compounds decreased the disease incidence more than mineral compounds Citric acid (200 ppm), ascorbic acid, potassium silicate and ferric chloride, in descending order, caused the lowest percentages of root rot/wilt infection induced by R .solani, S. sclortiorum and F. oxysporium. Whereas, Effect of H2O2 to control marjoram root/wilt was nearly similar to antioxidants
- Amendements of Nile and AL obour tea compost to the soil before sowing significantly decrease of marjoram seedling rot/wilt incidence. The disease suppressions were recorded with R. solani, Fusarium oxysporum, and Sclerotinia sclerotiorum, respectively. Al obour compost tea drenching significantly reduced marjoram rot/wilt as compared to control, Al obour tea compost is benefits to suppresses marjoram rot/wilt as compared to Nile compost tea.
- Both Plant guard , and Rhizo-N were able to inhibit the mycelial growth of all isolates tested (R. solani, Fusarium oxysporum, and Sclerotinia sclerotiorum ) in vitro, but the bio agents varied in their ability to antagonistic effect. In general, Plant guard , exhibited the higher antagonistic effect toward the tested pathogens then Rhizo-N .The introducing bioagent and fungicide as well into the soil is facing undesirable conditions. Therefore, they must withstand these conditions in order to achieve the proposed approach.