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acterial soft rots, commonly caused by Erwinia carotovora subsp. carotovora or Erwinia chrysanthemi, and slippery skin, caused by Burkholderia gladioli subsp. allicola as well as sour skin, caused by Burkholderia cepacia of onion bulbs are among the most serious storage diseases of onion (Allium cepa L.) that lead to great loss in bulbs. In this study some biostimulants; chitosan, seaweed extract and humic acid were in vivo tested on onion plants, to determine their controlling potential against bacterial rot diseases. Application of biostimulants proved to be effective in reducing the bacterial rot in stored onion bulbs. All tested biostimulants increased photosynthetic pigments content in onion leaves and total phenols content in onion bulbs, meanwhile they declined lipid peroxidation and the electrolyte leakage percentage in onion bulbs. As a summary, chitosan, seaweed extract and humic acid could be applied to improve plant growth and stimulate plant defense against diseases in concern. These materials are cheap, available, easy to apply, hazardless and environmentally safe.

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Angular leaf spot disease caused by Pseudomonas syringae pv. lachrymans is worldwide bacterial disease of cucumber. The present study was undertaken to control the disease by using some copper compounds such as copper hydroxide, copper oxychloride, copper sulphate and cuprous oxide, as well as some bactericides such as Beltanol-L (Qchinosol), Starnar 20% (Oxolinic acid) and Streptorol 21.3% (Streptomycin sulphate). Different concentrations of chemicals and bactericides were applied in vitro and in vivo to study their effect on the growth of P.lachrymans and reducing the disease in greenhouse. The inhibitory effect was determined as a minimum inhibitory concentration (MIC) and by using the disc diffusion method. The results revealed that chemicals and bactericides were differed in their effect on the bacterium. However, the bactericides effect were more effective than the copper compounds in reducing the bacterial growth. Starner 20% showed the largest inhibition zone (18mm) followed by streptorol 21.3% (14mm), while beltanol-L showed the lowest effect (13mm), with respect of copper compounds, cuprous oxide, showed largest inhibitory effect, followed by copper hydroxide and copper oxychloride respectively, while copper sulphate showed no effect on the bacterial growth. In greenhouse experiments, all chemicals used significantly reduced the disease incidence comparing with the control treatment. Starner 20% was the most effective followed by beltanol-L, copper hydroxide, streptorol 21.3% or copper oxychloride and cuprous oxide. While copper sulphate was the least effective compound in controlling the disease.