Fars Agricultural Research Center, PO Box 73415-111, Fars Zarghan, Iran

Background and objectives
Sesame wilt caused by Fusarium oxysporum f.sp. sesami is considered to be a most serious disease and causes considerable losses to the crop [1]. The strategy for controlling Fusariumwilt is based on planting in non-infested soil, the use of clean seeds, and rotation with non-host species. The use of resistant varieties would be more effective and ecologically sustainable. Goyal et al. [2] evaluated 206 local and wild sesame cultivars against the pathogen, and found only 3 tolerant cultivars. In this work, 85 sesame germplasms were screened against wilt disease under natural field conditions.

Materials and methods
A disease infected plot with a history of Fusarium infection was prepared by planting a susceptible cultivar, Darab-2, consecutively for two years in Zarghan Station. In addition, wilted sesame plants were collected from infected fields, dried, chopped, and uniformly added to the soil in order to build up the inoculum in the infected plot. Eighty-five sesame germplasms collected from all over Iran were sown each in two replicated plot rows measuring about 5 m. Disease incidence and severity index were estimated on the basis of external symptoms and discoloration in the stem.

Results and conclusions
In the present investigation, 85 sesame germplasms were screened against F. oxysporum f.sp. sesami under natural field conditions. Based on the disease evaluation indices, the tested sesame could be classified into four groups. The results indicated that two of the 85 accessions were found moderately resistant, 6 were tolerant, 19 were moderately susceptible, and 31 were very susceptible. 23 accessions were wilted prior to flowering and classified as susceptible to Fusarium wilt of sesame. Resistant sesame lines 85, 54 possess good agronomical characters, and constitute a valuable germplasm in sesame breeding for Fusarium resistance.

1. Banihashemi Z, 1982. Trans. J. Plant pathology 17, 75-79.
2. Coyal SN, Patel PK, 1980. Gujarach Agric. Univ. Res. J. 5, 52-53.