الفهرس 
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Abstract
Pathological studies on cumin blight disease and its control using green methods under Egyptian conditions. Cumin plant is one of medicinal and aromatic importance. According to the 2017 statistics, the cultivated area of it in Egypt was 3674 feddan, which produced 2195 tons. Given the importance of this plant, this study was conducted with the aim of increasing the productivity of the cumin plant and controlling fungal diseases that affect it, by using green chemicals and biocontrol agents as a safe alternative to using chemical pesticides that have negative effects on the environment and people. The most severe cumin pathogens are Alternaria burnsii, Fusarium oxysporum, and Rhizoctonia solani. This study focused on the pathogens associated with cumin in order to control them with safe and environmentally friendly means. The results of the study can be summarized as follows : 1. Isolation of the associated fungi to symptoms of diseases under study : 1. A survey for cumin diseases was carried out during 2016/2017 and 2017/2018 growing seasons to determine natural infection by Alternaria blight on cumin in El Qusia, Dairout, and Abnob (Assuit governorate), Basioun, Qutor and Tanta ( Gharbia governorate), and Maghagha, Beni Mazar, Smalout, and Matai ( Minia governorate). Mean percentages of infection in both seasons were 23.96 & 26.47%, while Gharbia governorate recorded the highest natural infection. 2. Fourteen fungal genera from blighted cumin plants (Alternaria burnsii, Asprgillus flavus, A. niger, Bipolaris sp., Cephalosporium sp., Chaetomium sp., Cladosporium sp., Curvularia sp., Drechslera sp., Nigrospora sp., Penicillium sp., Stemphylium sp., and Trichoderma spp.) were recorded. The most recovered fungus was A. burnsii (81.9%), while the rest of fungi recorded only 0.2 -2.2%. 2. In vitro experiment : Green chemicals and biological control agents were tested for their effect on growth inhibition of the causal agent of cumin blight A. burnsii. Nano silica (1.5mM, 2mM, 2.5mM, 3mM and 3.5mM), potassium silicate (0.05g/L, 0.1g/L, 0.2g/L, 0.3g/L and 0.4g/L), T. harzianum, T. hamatum, were tested in comparison with the fungicide Ridomil gold plus (1.5g/L water). All treatments caused growth inhibition to. A. burnsii colonies on PDA medium. 3. Studies on relationship between certain environmental factors and severity of cumin blight: Disease severity was increased when air temperature and relative humidity increased. The disease started to appear when minimum and maximum air temperature and relative humidity were 5.4, 22.6oC and 32,70% RH and 8.4, 23.4oC and 41.88% RH in 2017/2018 and 2018/2019 growing seasons, respectively. Maximum infection was at 6.8-23oC and 28-66% RH and 9.6–22.2oC and 49-86% RH in both seasons, respectively. 4. Effect of planting date, number of irrigations on disease severity of cumin blight : 1. Early planting (1st of November) caused the highest disease severity, while the latest planting date (1st of December) gave the lowest disease severity. 2. Severity of the disease was increased by increasing the number of irrigations. Plants irrigated 5 times recorded the highest level of disease severity followed by plants irrigated 3 or 4 times. 5. In vivo experiments : 5.1. In the greenhouse : Spraying cumin plants with the emulsion of T. harzianum dried spores (1×107 spores/ml) in corn oil gave the greatest disease control (80.46%) after the chemical fungicide (Ridomil gold plus) (92.01%). However, all other treatment tested i.e., nano silica (2.5mM, 3mM, and 3.5mM), potassium silicate (0.2g/L, 0.3g/L, and 0.4g/L), T. harzianum (1x106 spores/ml), T. hamatum (1x106 spores/ml) had significantly reduced the blight disease severity than in the untreated control. 5.2. In the field : Spraying cumin plants in the field with emulsion of dried spores of T. harzianum at a concentration (1 x 106 spores/ml) in corn oil gave the greatest control of the disease (51.35 and 43.90% in both seasons 2018/2019 and 2019/2020, respectively) and spraying of the chemical fungicide (Ridomil Gold Plus) gave control of 56.76 and 52.44% in the growing seasons 2018/2019 and 2019/2020, respectively), and there was no significant difference between it and the chemical fungicide with regard to its effect on the weight of 100 grains and the content of seeds of essential oil in the two growing seasons. Spraying plants with potassium silicate (0.3g/L) or nano silica (3 mM) reduced the disease severity and increased the proportion of oil components in addition to increasing the seed yield compared to the untreated control. On the other hand, the contents of the essential oil components (terpinene, α-pienene, ß-pienene, geranyl acetate, and linalool) in cumin seeds were affected by the tested treatments. The use of an emulsion of dry spores of T. harzianum increased the contents of these components in the oil compared to the untreated control, with the exception of geranyl acetate, which decreased. Conclusion and Recommendation : It can be concluded from this study that spraying plants with an emulsion of dry spores of T. harzianum at 1 x 106 spores/ml can effectively manage the cumin blight disease caused by the fungus A. burnsii and improving the oil quality of the resulting cumin seeds and improving the cumin seed yield. It is also recommended to continue searching for safe alternatives to control plant diseases that affect vegetables, fruits and field crops to protect the environment and human from the hazards and harmful effects induced by using chemical pesticides.