Incidence of Alternaria brassicicola (Schw.) Wiltsh. on Brassica oleracea seeds

Abstract

Samples of Brassica oleracea seed from Victoria, were tested for the presence of seed-borne Alternaria brassicicola and Alternaria brassicae. A. brassicicola was detected in 26 of 44 samples tested but A. brassicae was not detected in any. Between 24 and 37% of seed was infected, with 4-8% of infection found in the embryo tissues. Inoculation of seed with A. brassicicola resulted in loss of vigour in germinated seedlings, followed by death. The fungus retained its viability and pathogenicity on seed stored for up to 12 months. This investigation indicates that a high proportion of commercially available brassica seed are contaminated with A. brassicicola and may therefore be a primary source of disease for brassica crops in Australia.

Short‐term epidemic dynamics in the Cakile maritima–Alternaria brassicicola host–pathogen association

“…2001) that vertical transmission of A. brassicicola on C. maritima can occur, with the pathogen surviving through either direct infection of the developing ovule or more commonly through infection of the fruit coat. This reflects a range of studies showing that A. brassicicola is a major seed‐borne pathogen of many cruciferous crops (Knox‐Davies 1979; Tahvonen 1979; Sivapalan & Browning 1992), and in the Cakile‐Alternaria host–pathogen system provides a very effective means of pathogen dispersal among populations. Moreover, although initial infection may be derived from a small number of colonizing infected seeds, because Alternaria is a polycyclic pathogen, within‐season epidemics can still reach severe levels.…”

Frequency of Alternaria brassicicola in commercial cabbage seeds in Japan

“…In this study, we isolated the fungus from seeds stored at a lower temperature, approximately 7°C, and for longer periods. Pathogens, which can grow deeply into the coat or embryo of cabbage seed, surviving even after surface sterilization and water wash (Holtzhauzen and Knox-Davies 1974;Humpherson-Jones 1985;Maude and Humpherson-Jones 1980a, b;Petrie 1974;Pound et al 1951;Sivapalan and Browning 1992;Tahvonen 1979;Tohyama and Tsuda 1995;Vannacci and Harman 1987;Wu 1979) might keep their vigor longer than surface contaminants, because Maude and Humpherson-Jones (1980b) isolated A. brassicicola growing deeply within 12-year-old cabbage columnaris, and Aspergillus ostianus); Pen, Penicillium spp. a Not identified: the isolate was lost before the identification b Percentage of seeds infested with the isolates that produced spots on cabbage cotyledons c Percentage of the isolates in all isolated fungi seeds, but seldom after a superficial infection.…”

Expansion of Genetic Diversity in Randomly Mating Founder Populations ofAlternaria brassicicolaInfectingCakile maritimain Australia

“…Alternaria produces a suite of toxins (30) that, once introduced into Australia, has the ability to introgress into other Alternaria populations through gene flow and sexual recombination, thereby increasing the evolutionary potential and pathogenicity of the pathogen. While the majority of native brassicaceous species in Australia are found in the more arid inland zones (27), there are also a range of introduced weedy species, as well as economically significant agricultural and vegetable crops, that could potentially act as alternative hosts for A. brassicicola (e.g., Brassica napus [canola] and Brassica oleracea [cabbages]) in Australia (55).…”