Wilting of Olive and Seedling Branches and its Relative Control by Soil Solarization in Zanjan, Gorgan and Mashhad

Wilt of one branch of olive trees and seedlings is one of main important disease in most parts of Iran and other countries. The disease was surveyed in various areas including Zanjan and Golestan provinces during recent years. Wilting branch، leaves، plant roots and soils around the roots have been collected from the studied areas. The samples were cultured on PDA and SDA media after surface sterilization with 0. 5% sodium hypochlorite. Soil samples were diluted in water agar for isolation of the pathogen. Morphological characteristics in particular phialide and sporse showed that the causal agent of the disease was Verticillum dahliae which is a soil borne fungi and isolated from all samples and soil. Investigation showed that some olive varieties were relatively resistant to the pathogen. After two to six weeks application of the soil solarization treatment on infected soil، the average population density of the pathogen was decreased from 30 -75% separately. Using solarized soil and resistant olive seedlings on pots in glasshouse showed the lessening of the disease visibly.