The investigation of the effect of the acidity and elements nutrition on greenhouse cucumber seedling damping-off disease caused by Phytophthora drechsleriTucker

The most important plant diseases of greenhouse plants is damping off by Phytophthora sp., the disease caused the most damage to these plants. The disease is distributed in the most parts of Iran, and it causes plant losses in about 25%. This disease is affected by environmental stresses. However, the management of these environmental factors, such as nutrition, salinity and acidity of soil could have an effective role on reducing disease. In this research, it was studied the effect of growth medium acidity on pathogen growth inhibition and the effect of some nutrients associated with the composition of changing of acidity, too. The results showed the effects of acidity on pathogen growth had significant difference between different treatments. KOH and HNO3had the highest (64.58%) and the lowest (26.25%) inhibitory effect on the pathogen growth, respectively. the results of the effect of nutrient solutions test showed that adding nutrient solution reduced the percent of damping off significantly compared to control in both Negin and Sina varieties. KNO3 had the highest reduction of damping off in both varieties of cucumber. K2SO4and KCl had most effective after potassium nitrate, and NH4NO3 showed the least effect. Based on the findings of the current study, it seems that improving plant nutrition could be a good way to reduce cucumber damping due to P. drechsleri.