Three systemic fungicides fenarimol, triflumizol, and triadimenol were used (mixed with mineral oil at 300 ml/100 L water or not) to evaluate the effects on powdery mildew of tomato in greenhouse. Results showed important role of mineral oil in inhan
cing the studied fungicides's effects by decreasing infection percentage and severity of the disease if the recommended doses are used or half of them. when these fungicides were used in low rates (50% of the recommended doses without mineral oil) infection percentage after a mounth of treating were 65.2 - 75.7% and severity 62.7 – 77.3% wherease when the fungicides were used with oil the infection percentage were decreased to 44.5 - 48.6% and severity to 16.9 – 45.8%
