Anahtar kelimeler: Soğan, Fusarium dip çürüklüğü, kalsiyum tuzları, alternatif kontrol Effect of some calcium salts on the growth and development of Fusarium oxysporum f. sp. cepae, the causal agent of Fusarium basal rot of onion Abstract Fusarium basal rot caused by Fusarium oxysporum f. sp. cepae is one of the most important pre-and postharvest disease of economic significance worldwide. Resistant onion cultivars, crop rotation, solarization, sanitation, biological control and fungicide applications (seed and seedlings) are recommended in the controlling of Fusarium basal rot. However, a few fungicides such as benomyl, carbendazim and vinclozolin are effective in the control of the disease, but they have recently been banned due to their carcinogenic effect. Therefore, alternative methods are needed for the control of the disease. In vitro studies showed that calcium propionate at concentrations as low as 0.1 % (19.75 %) and 0.25 % (41.44 %) reduced the mycelial growth of F. oxysporum f. sp. cepae more than calcium acetate, hydroxyde, chloride, lactate, oxide and citrate, and also the difference between the first salt and the effects of the second group of salts was statistically significant (P<0.05). However, while 1 %