engleski

A view on possible sources of pathogenic Fusarium spp. for winter wheat seedlings

Many weed species may be alternative hosts for fungal parasites of field crops (McKeen and Thorpe 1973, Anikster 1982, Helbig and Caroll 1984, Heiny and Wiedemann 1990, Jenkinson and Parry 1994). Because of weed spreading they may be important in maintaining the inoculum density in soil. Plant debris from previous season may be a very important source of parasites (Duthie and Hall 1987, Cotten and Munkvold 1988), especially in one-crop system or in narrow crop rotation in which crops could be attacked by the same parasites. In a three-year period (1996-1998) pathogenicity of Fusarium spp. were studied on plant material collected at locations in eastern Croatia. Isolations were made from wheat and maize debris and from the following weeds: Abutilon theophrasti Med., Amaranthus hybridus L., Artemisia vulgaris L., Capsella bursa-pastoris (L.) Med., Lamium purpureum L., Sorghum halepense (L.) Pers., Taraxacum officinale Web. i Urtica dioica L. by using ordinary laboratory technics. Seven Fusarium species known to be pathogenic to wheat spikes, ears, roots and subcrown internodes (Windels et al. 1989, 1992) were isolated from weed plants. Fusarium graminearum Schw. was isolated from four weed species (Amaranthus hybridus, Capsella bursa-pastoris, Sorghum halepense and Urtica dioica). The remaining Fusarium (F. culmorum (W.G. Smith) Sacc., F. moniliforme Sheld., F. poae (Peck) Wollenw., F. proliferatum (Mats.) Nirenberg, F. sporotrichioides Sherb. i F. avenaceum (Fr.) Sacc.) could not be found at not more than one weed species. The named Fusarium species including F. subglutinans (Wollenw. i Reink.) Nelson, Toussoun i Marasas) and Fusarium spp. were found on wheat and maize debris. In order to prove that isolated Fusarium species were pathogenic for wheat seedlings artificial infection according to Mesterházy (1978) was done, and seed mortality index (SMI) was determined. There were 46 isolates tested (21 F. graminearum, 7 F. monioliforme, 6 F. subglutinans and F. sporotrichioides, 3 F. avenaceum and 1 F. culmorum, F. poae and F. proliferatum). The highest pathogenicity was found in F. graminearum (SMI 3,25-4,25), F. sporotrichioides (SMI 2,75-3,75) and F. culmorum (SMI 3,00-3,25). Low germination percentage (43,33-73,33%) was recorded at those species and necrotic lesions were obtained on seedling roots if germination had been succesful. From this spots reisolation of Fusarium spp. was done. F. avenaceum (SMI 1,00-2,50), F. proliferatum (SMI 1,25-2,50), F. poae (SMI 1,25), F. moniliforme (SMI 0,25-3,00) and F. subglutinans (SMI 1,75-3,50) were notable less pathogenic. Germination percentage was higher (50,00-93,33%) and necrotic lesions were recorded on 0,00 -50,00 seedling roots.

wheat seedlings; Fusarium spp.; host

nije evidentirano