Prevalence and pathogenicity of spinach root pathogens of the genera Aphanomyces, Phytophthora, Fusarium, Cylindrocarpon, and Rhizoctonia in Sweden

Abstract

In a 4‐year disease survey in commercial spinach fields, pathogens were isolated from spinach root pieces placed on selective agar media. Aphanomyces cladogamus was the most abundant pathogen, followed by Phytophthora. cryptogea and Fusarium oxysporum. Rhizoctonia solani was found only occasionally. Other pathogens isolated were F. redolens, F. sambucinum and Cylindrocarpon destructans. P. cryptogea was the most severe pathogen, causing death of most plants, but A. cladogamus also caused severe root damage. Isolates of F. oxysporum ranged from highly pathogenic, i.e. P. oxysporum f.sp. spinaciae race 1. to moderately pathogenic and non‐pathogenic, Rhizoctonia solani isolates also varied widely in their pathogenicity. Only a small number of the F. redotens and F. sambucinum isolates were pathogenic and most C. destructans isolates were weakly pathogenic. Isolation frequencies were relatively stable from year to year, but P. cryptogea was isolated more frequently in autumn than in spring. No clear relationships were found between pathogen prevalence and disease severity index of surveyed field plants, between pathogen prevalence and plant developmental stage, or between prevalence of the different pathogens isolated.

Prevalence and pathogenicity of spinach root pathogens of the genus Pythium in Sweden

“…In investigations in Swedish spinach fields, partly reported by Larsson & Olofsson 1994: accompanying paper), we also isolated several pathogenic Pythium spp., of which P. sylvaticum and P. heterothallicum have not previously been reported as spinach pathogens. This paper focuses on the prevalence of the Pythium pathogens found in the fields surveyed and their pathogenicity in greenhouse tests.…”

“…Damping off and root rot of spinach (Spinacia oleracea) seriously limit production in several countries (Sumner et al, 1976;Naiki et ai, 1986;Larsson & Gerhardson, 1992), In addition to several soil-borne pathogens of the genera Aphanomyces, Phytophthora, Pusarium, Cylindrocarpon, and Rhizoctonia (Larsson & Olofsson, 1994), many Pythium spp. have been reported to be involved in this damping off and root disease complex.…”

Molecular and Pathogenic Characterization ofFusarium redolens, a New Causal Agent of Fusarium Yellows in Chickpea

“…Finally, because several pathogenic forms of F oxysporum and F redolens may cause similar symptoms on a host plant, as has been shown on several crops (for example, asparagus [6,65], broad bean and pea [10], carnation [21], lentil [56], and spinach [41]) and chickpea (this study), our results emphasize the importance of assuring the accurate identification and distinction between these two species in a geographical area for which suitable molecular protocols are available. This approach would facilitate the development of resistant germplasm for the.se crops, if available, and better the understanding of the etiology and epidemiology of the diseases caused by the different formae spéciales of F oxysporum and F redolens.…”

Fusarium species associated with plants in Australia

“…redolens Fusarium redolens is a relatively common soil borne fungus found in temperate parts of the world. It has been recorded on a variety of hosts associated with root rot diseases, in particular with asparagus, beans, carnation, peas, roses and spinach (Booth 1971;Clarkson 1978;Gordon-Lennox and Gindrat 1987;Larsson and Olofsson 1994;Ypema et al 1987). It also has been recovered from native grasslands in North America (McMullen and Stack 1983).…”