الفهرس 
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Abstract
Tomato Yellow Leaf Curl (TYLC) is an economic disease that results in dramatic losses in
tomatoes. It is caused by monopartite and bipartite whitefly-transmitted begomovirus individually
or associated with betasatellite DNAs. Recently, TYLC disease became more severe in Egypt, and
it destroyed completely tomato crops in some crop seasons around the year. Additionally, pepper
also suffers from (TYLC) disease and resulted in a decrease in pepper production. Two
begomoviruses were examined in this study: Tomato Yellow Leaf Curl Virus (TYLCV)
(Monopartite begomovirus) and Tomato Leaf Curl Newdelhi Virus (ToLCNDV) (Bipartite
begomovirus) besides new recombinants from TYLCV and Tomato Yellow Leaf Curl Sardinia
Virus (TYLCSV) isolates and associated DNA betasatellites.
Symptomatic tomato and pepper leaves were collected during the summer crop seasons of
years 2019 and 2020 from El Nubaria and Wadi El Natron regions. Low dispersal of whiteflies
was observed in the examined regions. Disease severity of TYLCV was estimated.
In El Nubaria agroecosystem, a sampling of TYLCV- infected hosts was conducted on
tomato and pepper- growing regions around the summer crop seasons of years 2019 and 2020. The
sampling was conducted under the supervision of Directorate of Agriculture of El Nubaria sectorBeheira governorate; tomato leaf samples were collected from three different locations in El
Bangar region along the month August 2020. Also, irrigation system was differentiated between
flood irrigation (FIS) and drip irrigation (DIS) systems within each examined location.
The statistical results of TYLCV disease severity in tomato fields indicated that the
interaction effect between Location and irrigation system was not significant, and there is no
significant effect in disease severity between location 1 and location 2; while disease severity of
location 1 was significantly higher than this of location 3; and location 2 has a significant increase
in disease severity than location 3. Irrigation system also showed significant effect on disease
severity between each other; as TYLCV disease severity in tomato fields which use floodirrigation system (FIS) was increased significantly in location 1 than Drip- irrigation system (DIS)
and the same significant effect was happened in location 2. No significant effect was explored for
the irrigation system in location 3.
Pepper leaf samples were gathered from three separate regions in the intended
agroecosystem: North of El Nubaria, Abu El Matameer, and El Bangar regions during the early
summer crop season along June and July 2020. Irrigation systems were differentiated in these
regions; as flood- irrigation system was used in El Bangar region, while drip- irrigation system was
used in North of El Nubaria and Abu El Matameer regions.
Statistical outputs of TYLCV disease severity in pepper showed that North of El Nubaria
region has no significant effect either with Abu El Matameer region or El Bangar region. Disease
severity in El Bangar region was significantly higher than this of Abul Matameer region; while did
not show any significant effect with North of El Nubaria region. On the other hand, irrigation
system outputs did not show any significant effect between irrigation systems on TYLCV disease
severity in the examined regions