The experiments were carried out during 2019/2020 and 2020/2021 seasons. Greenhouse experiments carried out at Department of Plant pathology, Faculty of Agriculture, Ain Shams University. While, the field experiments were carried out at El-Kanater Research Station, Qaluobia Governorate, to study the effect of some natural compounds (chitosan, methionine, and ascorbic acid) on the tolerance of strawberry plants to Rhizoctonia root rot disease, as well as the vegetative growth, chemical composition of the plant, fruit yield and its components, as well as the quality of the yield of strawberry Festival Cultivar compared to untreated infected strawberry plants. Obtained results showed that applications with chitosan at 500 ppm, methionine at 20 ppm and ascorbic acid at 20 mM via transplant root soaking, foliar spray, and combining the root soaking with foliar spray, or transplant root soaking with Rhizolex (1g/L) showed significant decrease in root rot incidence caused by Rhizoctonia solani. The combining of root soaking with foliar spray of chitosan or methionine resulted the highest significant decreases of disease incidence under greenhouse and field conditions. However, all applications except Rhizolex resulted in significant increases in phenolic compounds, oxidative enzymes activity i.e., PPO, SOD and CAT in roots during the two growing seasons.  Obtained results showed also that soaking plus foliar spraying with chitosan at 500ppm, methionine at 20 ppm and ascorbic acid at 20 mM significantly increased all vegetative growth characters, N, P, K and total carbohydrates in plant foliage, fruit yield and its components as well as physical and chemical fruit quality.