Over the past decade, there have been accumulating reports from farmers and field extension personnel on the increasing incidence and spread of onion (Allium cepa) bulb basal rot in northern Israel. The disease is caused mainly by Fusarium species. Rotting onion bulbs were sampled from fields in the Golan Heights in northeastern Israel during the summers of 2017 and 2018. Tissue from the sampled onion bulbs was used for the isolation and identification of the infecting fungal species using colony and microscopic morphology characterization. Final confirmation of the pathogens was performed with PCR amplification and sequencing using fungi-specific and Fusarium species-specific primers. Four Fusarium spp. isolates were identified in onion bulbs samples collected from the contaminated field: F. proliferatum, F. oxysporum f. sp. cepae, and two species less familiar as causative agents of this disease, F. acutatum and F. anthophilium. Phylogenetic analysis revealed that these species subdivided into two populations, a northern group isolated from white (Riverside cv.) onion bulbs, and a southern group isolated from red (565/505 cv.) bulbs. Pathogenicity tests conducted with seedlings and bulbs under moist conditions proved that all species could cause the disease symptoms, but with different degrees of virulence. Inoculating seeds with spore suspensions of the four species, in vitro, significantly reduced seedlings’ germination rate, hypocotyl elongation, and fresh biomass. Mature onion bulbs infected with the fungal isolates produced typical rot symptoms 14 days post-inoculation, and the fungus from each infected bulb was re-isolated and identified to satisfy Koch’s postulates. The onion bulb assay also reflected the degree of sensitivity of different onion cultivars to the disease. This work is the first confirmed report of the direct and primary cause of Fusarium onion basal rot disease in northeastern Israel. These findings are a necessary step towards uncovering the mycoflora of the diseased onion plants and developing a preventive program that would reduce the disease damage.

Since 2012, growers of coriander, Coriandrum sativum L., in Israel have been suffering from summer wilting that can result in entire fields collapsing. The current study aimed to determine the cause of the phenomenon and find a genetic solution to the problem. The disease was reproduced in a growth chamber using naturally-infested soil from a commercial field. Wilt became apparent within two weeks, and after ten weeks, all plants died compared to plants in sterilized soil from the same source. Fusarium oxysporum was isolated from infected plants, and Koch’s postulates were completed. Sequence analysis of the Elongation Factor (EF1α) encoding gene of the pathogen had a 99.54% match to F. oxysporum f. sp. coriandrii. Several coriander varieties were screened for resistance or tolerance to the disease. In four independent experiments, only the cultivar ‘Smadi’ showed high tolerance, while other genotypes were susceptible. In a trial in a naturally infested field, the cultivar ‘Smadi’ outperformed the commercial cultivar ‘Blair’. ‘Smadi’ provides a cropping solution to many Israeli farmers, yet this winter cultivar bolts early in the summer. There is a further need to characterize the tolerance mechanism and inheritance for informed breeding of late-bolting Fusarium-resistant coriander.