Three concentrations i.e 1, 2.5 and 5% of five essential oils were tested to study their effect on
growth of Sclerotinia sclerotiorum. Results showed that Clove and Marjoram oils were inhibited growth of
S. sclerotiorum. Under greenhouse conditions results revealed that amending vegetarian compost to soil
increased the activity of all plant oils than the individual treatment in reducing disease severity of Sclerotinia
rot. Clove oil alone or in combination with compost completely prevented the disease incidence. Seedling
soaking with nigella, marjoram and clove oils and their combinations with or without compost against
Sclerotinia rot disease. Clove oil combined with compost completely prevented the disease incidence in
2017 and disease severity recorded 2.36 % in 2018 growing season. Moreover, increase of fruit yield was
recorded with the combined treatments between compost + clove oil then compost + marjoram and clove
oils during growing seasons 2017 and 2018 respectively. All tested treatments positively increased the
activity of peroxidase (PO), Polyphenol Oxidase (PPO) and PAL enzymes in cucumber. Moreover, chitinase
and p 1,3- glucanase were greatly increased in treated cucumber with treatments compared with control. The
results of SDS (PAGE) showed that 15 protein bands with molecular weights ranging from 234.433 to
50.017 kDa are contained in cucumber plants. New protein bands expressed as a result of treating cucumber
with plant oils. One band with 90.783 KDa was appeared in plants treated with marjoram and Clove oils,
while absent in other treated plants