A field experiments has been conducted during 2003 and 2004 seasons under protected cultivation at Sakha Greenhouse Station, Karr El-Sheikh to study the impact of different compost levels (crop residuals) on growth, productivity and quality of cucumber as well as their effect on damping-off caused by pythium ultimum, fusarium solani and scierotinia clerotiorum. The applied compost levels were 0.68, 1.36, 2.05, 2.73 and 3.41 kgs/m⁷, while the control treatment was cattle manure fertilizer. The obtained results can be summarized as follows: Application of compost increased the values of most studied characters as compared to the manure organic fertilizer. Obtained results revealed that the compost levels of 1.36 and 2.05 kgs/m² recorded the best results of the plant growth, i. e. stem length, leaf area, number of branches and leaves, total chlorophyll as well as fresh and dry weight followed by the compost levels of 0.68, 2.73 and 3.41 kgs respectively. Data also showed that the highest increases in cucumber yield, number of fruits, diameter and length of fruits had been achieved when compost with 1.36 or 2.05 kgs/m² were applied. Application of 0.68 and 2.05 kgs/m² .compost gave maximum protection against post emergence damping-off and reduced the disease incidence to 7.5 and 11.25% respectively, compared with the fungicide Topsin M70 1.25%. While, the compost levels of 2.73 & 3.41 kgs gave less effect in this respect. The levels of compost (0.68 & 1.36 kgs) were most effective in controlling powdery and downy mildew diseases from 55.98 & 40.58% to 29.84 & 21.39% respectively, while higher levels (2.73 & 3.41 kgs) were least..The applied fungicides had the best effect on reducing powdery and downy mildew diseases severity being 10.38 & 9.23% respectively.