الفهرس 
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Abstract
Fungal pathogens associated with leaf spot diseases of faba bean have been isolated and identified. However, based on the frequency occurrence, the more frequent fungi were Botrytis fabae, Alternaria alternata, Stemphylium botryosum and Cladosporium cladosporoides. It was found that chocolate spot disease was more prevalent in the second season compared to the first one, with the highest existence and frequency percentage in Beheira followed by El-Sharkia governorates by (100% and 75%) of existence and (37.4 and 36.1%), respectively. However, the average existence and frequency percentage of Botrytis fabae in the two seasons at different locations were 59.4% and 27.2%, respectively, while the most existent and frequent fungi were Alternaria alternata, Stemphylium botryosum and Cladosporium cladosporoides recorded (46.9, 43.75 and 37.5%) of existence and (14.9, 10.9 and 8.6 %) of frequency, respectively, in the two seasons (2017/2018 and 2018/2019) at different locations of the governorates under study. Four representative isolates of Botrytis fabae fungal pathogens were identified and selected for Polymerase Chain Reaction (PCR) and rRNA gene sequencing. These isolates represented different morphological variants and different localities. The identified B. fabae isolates showed different virulence against faba bean cultivars, where isolate Bf4 isolated from Sakha at Kafr El Sheikh governorate was the most virulent one. On the other hand, Giza 716 cv. was most resistant than Mariut 2 cv. to B. fabae isolates infection. Botrytis fabae isolates showed differences in growth rate and sporulation under different conditions where, Bf4 isolate was the best isolate in growth and sporulation than the other of tested Botrytis fabae isolates under the tested temperatures degrees 22ºC and 26ºC. It is noted that the media types showed significant differences in growth rate and sporulation of Botrytis fabae isolates under different light systems and temperatures. In general, growth rate and sporulation under a temperature degree of 22ºC were better than 26ºC. Tricoderma harzianum and C. globosum, were the most effective isolates against B. fabae, which significantly reduced the mycelial growth by 48.11 and 40.78 reduction percent, respectively. The results showed that culture filtrate of C. globosum was the most effective filtrate recoding 41.11, 48.00 and 54.44 % reduction of B. fabae mycelial growth at different concentrations i.e, 25, 50 and 75% respectively, followed by T. harzianum 75% concentration which recorded 42.55% reduction of B. fabae mycelial growth. The effect of different essential oils i.e., Garlic, Basil, and clove on B. fabae mycelial growth, were tested, however, only clove oil was recorded to have a significant reduction percent by 61.11% compared with control and the other tested oils. Transmission Electron Microscope (TEM) characterization represents the morphological structure of ChNPs that was uniform and spherical with an average particle size 7.54 nm and AgNPs was more spherical with an average particle size 8.043 nm. The results of our laboratory study showed that ChNPs followed by AgNPs were effective over conventional chemical fungicide carbendazim (CZ). where the radial growth of Bf4 decreased by increasing concentrations of treatments especially ChNPs (20-40ppm) recording 73.33% and 100% growth inhibition, respectively, while (100 ppm) of AgNPs and recommended dose of CZ recorded an inhibition growth rate of 75.33% and 46.11%. In addition, a Scan Electron Microscope (SEM) showed that the mycelia of Bf4 treated with AgNPs did not have significant changes at the concentration of 20 ppm. Contrary to Bf4 mycelia treated with ChNPs 20 ppm caused seriously shrunk at 72 h from treatment compared with the control. The antifungal effect of ChNPs, showed marked distorted mycelia and ChNPs covered mycelia. Most Bf4 spore morphology treated by AgNPs 20 ppm appeared to be shrunk with abnormal shape at 72 h in comparison with the control. On the other hand, spore production of B. fabae treated with ChNPs 20 ppm was inhibited completely after 72 h from treatment. The obtained results offer a possibility of developing new manufacturing of fungicides by using bioagents, essential oils and nanoparticles as substances for better control of faba bean chocolate spot disease to minimize the impact of conventional fungicides in the agri-ecosystem.