Pathogenicity test of different fungi on date palm causing sudden decline disease of date palm (Phoenix dactylifera L.) in Khairpur, Pakistan

摘要

The date palm ( Phoenix dactylifera L.) is considered as one of the most important crop of the country and holds a very significant position on the agriculture horizon of Sindh. Khairpur is the biodiversity center of date palm. Dates plays major role in the socio economic stability of country to increase the national income of Pakistan and is grown in all four provinces. Since last few years the date palm orchards of district Khairpur are suffering from decline disease of unknown etiology. This disease has destroyed hundreds of orchards and puts the negative effects of farmers in those affected areas by creating social and economic problem. The disease has caused not only yield loss but also loss major source of income of the farmer of date palm. During the present investigation,. The date palm orchards of different areas of Khairpur, Sindh, Pakistan, were found to suffer from a decline disease that is severely damaging the trees and becoming epidemic in some areas. Typical disease symptoms include whitening and dying of the foliage followed by sequential death of the branches and whole tree. The pathogencity test on date palm seedlings were carried out on most commercial growing date palm varieties like Aseel, Fasli and Karbalian, by three different methods. The frequency of F. solani followed by P. ucladium and H. sativum was significantly highest on all the studied date varieties ranging from 30-57% on Aseel (57%). Var. Aseel appeared as the most susceptible as significantly higher fungi were isolated from it as compared to the vars. Fasli and Karblian. The inoculations of F. solani alone or with P. ucladium or H. sativum confirm the pathogenic nature of F. solani which not only greatly reduced the plant growth but also caused significant plant mortality and disease severity. Whereas, P. ucladium and H. sativum were found less pathogenic causing disease development and plant mortality. The Fusarium solani alone showed typical symptoms of disease in soil inoculation methods followed by stem inoculation method and spraying method. Whereas such symptoms were not observed on plants inoculated with combination in Fusarium solani + Phoma ucladium followed by Fusarium solani + Helminthosporium sativum and Phoma ucladium & Helminthosporium sativum alone.