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resent study was conducted in the seasons of 2017 and 2018 at the Central Laboratory for Agriculture Climate, Agriculture Research Center (ARC), Dokki, Giza., to investigate the influence of some phenolic chelate compounds (Humic acid, Potassium benzoate and Salicylic acid) in three levels (1.0gm., 1.5gm. and 2.0gm. /L) on the susceptibility of marjoram plants to the infection with Aphis gossypii Glover, Thrips tabaci Lind., and Tetranychus urticae Koch as well as yield, growth features and essential oil contents. The results proved that the using of 2.0gm./L of salicylic acid, potassium benzoate and humic acid as fertilizers to marjoram plants, caused highly significant infestation reduction of target pests' as well as the effects on the growth characteristics in the first and second cuts in both seasons. Resulted in an increasing number of branches per plant in addition increased plant height, also, it caused significantly increasing in fresh and dry weights. The highest oil yield / plant were obtained with applying salicylic acid at 2.0g/L. Leaf area (cm 2) of marjoram was increased by different foliar spraying by humic acid and salicylic acid in the 1 st and 2 nd cut of both seasons. Foliar application of potassium benzoate gave poor results in this concern.

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