First Report of Fusarium oxysporum Causing a Leaf Twisting Disease on Allium cepa var. ascalonicum in Sri Lanka

Abstract

A disease of shallot onions, Allium cepa var. ascalonicum, that caused yield losses of up to 20 to 30% in some fields was reported from Kalpitiya Peninsula in the North Western Province of Sri Lanka in the late 1980s. Disease symptoms consisting of chlorosis followed by curling and twisting of leaves and abnormal elongation of the neck region appeared after germination of the onion bulbs, subsequently causing plant collapse. Symptomatic plants occurred randomly in most fields and the disease was prevalent throughout the year. Tissue pieces from leaves and the neck region of symptomatic plants plated on potato dextrose agar containing 1% streptomycin (PDAS) produced purplish pink fungal colonies identified as Fusarium oxysporum. Pathogenicity tests were performed with single-spore fungal isolates grown at 25°C for 14 days on PDAS. Shallot onion cv. Vathalan was inoculated by soaking bulbs, pierced with a sterilized needle, in a spore suspension containing 2 × 106 spores per ml for 10 min. Control bulbs were wounded, and soaked for 10 min in sterilized water. Bulbs were then planted in sterile sand and maintained in a green house at 25 to 28°C. After 2 to 3 weeks, typical symptoms, as observed in the field, developed in plants produced from bulbs inoculated with the F. oxysporum isolate. Symptoms were not observed on plants from the control bulbs. Koch's postulates were confirmed by reisolating the same fungus from the neck region of diseased plants. Onion twister disease described by Ebenebe (1) also had been observed in this region in Sri Lanka during 1992-1993. There were differences between these two diseases in disease symptoms and disease development in the field. Acer-vuli of Colletotrichum spp. were always detected in lesions of the neck region, as well as on leaf blades, of plants severely affected by onion twister disease. This disease developed from foci in fields that spread over time. Moreover, onion twister disease occurred only from October until January, coinciding with the rainy season. Reference: (1) A. C. Ebenebe. Plant Dis. 64:1030, 1980.

First Report on Association of <I>Meloidogyne graminicola</I> in Twister Disease of Onion:An Emerging Problem in Coastal Tract of India

“…In the recent years, twister disease of onion is assuming an epidemic proportion in major onion growing areas especially the west coast of southern India causing heavy yield loss (Hegde et al, 2012;Nargund et al, 2013). The onion disease with similar kind of symptoms are first reported from Zaria, north Nigeria, in 1969 with 50-100 per cent estimated severity (Ebenebe, 1980) and later during 1970 in Sri Lanka (Kuruppu, 1999). In India, the disease was first reported by Sinha and Singh (1994).…”

“…The aetiology of onion twister disease was initially suspected as nematodes. However, Kuruppu (1999) isolated the fungus F. oxysporum from the diseased shallot plants and reported that thrips, mites, nematodes and other fungi could also cause similar symptoms.…”

“…2008;Rodriguez-Salamanca et al, 2012), Colletotrichum coccodes (Rodriguez-Salamanca et al, 2012) and Fusarium oxysporum f. sp. cepae (Kuruppu, 1999). Nargund et al, (2013) also reported that, onion twister menace was observed to be caused by various plant pathogens viz., Colletotrichum gloeosporoides, F. oxysporum, Sclerotium rolfsii and also speculated a possible role of Meloidogyne spp.…”

Pengembangan Teknik Deteksi Fusarium Patogen Pada Umbi Benih Bawang Merah (Allium ascalonicum) di Laboratorium

“…cepae (Armstrong & Armstrong 1968). Serangan F. oxysporum pada bawang merah di Sri Lanka menyebabkan kehilangan hasil antara 20-30% (Kuruppu 1999 …”

Occurrence of Fusarium basal rot of onion (Allium cepa) in selected horticultural farms in Poland and evaluation of disease harmfulness

“…cepae (Foc), oznaczonego przez Snydera i Hansena w 1940 roku (Crowe 2008). Lacy i Roberts (1982), Kuruppu (1999), Cramer (2000), Galvan i wsp. (2008) (2015) podają, że straty spowodowane porażeniem cebul przez Foc przekraczają nawet 50%.…”