Fusarium wilt of carnation caused by Fusarium oxysporum f.sp. dianthi (Fod) W.C.Snyder & H.N. Hensen, is the most important fungal disease in all main carnation growing regions of Iran. In 2020, sampling of infected plants was randomly carried out from carnation greenhouses in five provinces located in the North (Gilan, Golestan, and Mazandaran) and Middle (Tehran and Markazi) of Iran. Eighty-eight fungal isolates were identified as Fod by morphological characters (based on Nelson’s key identification), molecular method (PCR amplified of ITS region), and pathogenicity tests (according to the root dipping on sensitive cv. Rendezvous). In order to investigate on biodiversity of Iranian Fod isolates based on Vegetative Compatibility Groups (VCGs) and races, 70 isolates were randomly selected. These isolates were compared with eight Fod isolates from the collection of Dipartimento di Valorizzazione e Protezione delle Risorse Agroforestali (Di.Va.P.R.A) Patologia vegetale, Italy; which were used as references for races and VCGs. For DNA amplifying, primers R 1.8, R 2.1, and R 4.2 were employed. Amplified fragments of 295 bp and 564 bp were identified to race 1 (or 8; because these primers applied are not able to discriminate between the races), and race 2 (or 5 or 6), respectively. Furthermore, two VCG 0021 and VCG 0022 were identified amongst the Iranian Fod isolates. The relationship between the races and VCGs demonstrated that all race 1 (23 isolates) were categorized in VCG 0022, and race 2 (44 isolates) were grouped in VCG 0021. In addition, three isolates did not produce any amplification.

This study investigates the potential of epiphytic bacteria isolated from citrus fruits to control green mold post-harvest disease caused by Penicillium digitatum in Thompson Navel sweet oranges in the north of Iran. Twenty-three epiphytic bacteria were isolated and screened in vitro against P. digitatum, and 13 isolates with antagonistic activity were selected for further studies. Isolates B15 (Bacillus sp.), P17 (Pseudomonas sp.), and S13 (Streptomyces sp.) exhibited the most effective inhibitory effects on P. digitatum in vitro and in vivo. Among these, B15 showed the highest percentage of mycelium growth reduction and was further identified as B. cereus by 16S rRNA sequence analysis. Metabolic analysis of Bacillus sp. isolate B15 extract revealed the presence of the inhibiting antifungal substance Iturin A. The result showed that the application of epiphytic B. cereus decreased the percentage of green mold post-harvest diseases in orange fruit. This indicates their potential as an environmentally friendly alternative to chemical post-harvest control of orange diseases caused by P. digitatum.