<i>Alternaria cichorii</i>in Brazil on<i>Cichorium</i>spp. Seeds and Cultivated and Weedy Hosts

Summary 1.Pathogen spillover occurs when disease levels for a given population are driven by transmission from a reservoir species that carries a high pathogen load. Pathogen spillover is widely documented in crop systems, but has been little studied in natural plant communities. 2. The abundant seed production of weedy species may create a scenario where spillover of a generalist seed pathogen onto less abundant seeds of native hosts is possible. The invasive annual weed cheatgrass (Bromus tectorum) is a potential reservoir species for Pyrenophora semeniperda, a multiple-host fungal seed pathogen that naturally occurs in the semi-arid western United States. 3. To investigate potential community-level consequences of spillover by this pathogen in plant communities invaded by cheatgrass, we first used artificial inoculation studies to determine the relative susceptibility of seeds of cheatgrass and five co-occurring native grasses to P. semeniperda. Secondly, we quantified the pathogen reservoir (density of pathogen-killed seeds) in the spring seed bank for cheatgrass monoculture, cheatgrass-invaded native grass, and uninvaded native grass patches. Thirdly, potential pathogen spillover onto co-occurring native grasses was quantified by planting native grass seeds into field-collected seed-zone samples from each vegetation patch type and scoring subsequent seed mortality. 4. All species tested were susceptible to infection by P. semeniperda, but their vulnerability to seed death varied as a function of germination time and degree of susceptibility. 5. Seed bank samples from cheatgrass-dominated patches contained seed densities over four times higher than samples from uninvaded native grass patches, and P. semeniperda-killed seeds were also present at much higher densities, indicating that cheatgrass can function as a reservoir for P. semeniperda. Native seeds planted into seed-zone samples from cheatgrass-dominated patches were more likely to be killed by P. semeniperda than those planted into samples from uninvaded native patches. Seed mortality also varied across years, sites and host species. 6. Synthesis. Pathogen spillover onto native seeds is likely to operate within seed banks of semi-arid communities invaded by cheatgrass, and perhaps other weeds, and may have broad consequences for community structure. Our findings also demonstrate the ecological significance of multiple-host pathosystems that operate at the seed stage.

show abstract

“…2002; Pandey et al. 2005; Barreto, Vieira & Santin 2008) and few have focused on seed pathogens (but see Mengistu & Reddy 2005).…”

Section: Discussionmentioning

confidence: 99%

Cheatgrass facilitates spillover of a seed bank pathogen onto native grass species

et al. 2009

View full text Add to dashboard Cite

show abstract

“…The occurrence of different species of Alternaria on seeds and their role in the spread of diseases were reported also in the case of Ocimum basilicum (Gilardi et al 2013a), Brassica oleracea (Humpherson-Jones and Maude 1982;Kohl et al 2010), Cichorium spp. (Barreto et al 2008) and Helianthus annuus (Jackson et al 1987).…”

Section: Resultsmentioning

confidence: 99%

Occurrence of Alternaria japonica on Seeds of Wild and Cultivated Rocket

Gilardi

Demarchi

Ortu

et al. 2014

Journal of Phytopathology

View full text Add to dashboard Cite

In vitro evaluation was carried out on seed samples of wild and cultivated rocket cultivars, most frequently grown in Italy, and obtained from farms affected by the leaf spot caused by Alternaria japonica in Piedmont and Lombardy during the fall of 2010. Twelve seed samples were collected and assayed for the presence of A. japonica. The pathogen was isolated only from not disinfected seeds. Among the two seed samples of cultivated rocket (Eruca vesicaria), only one was infected by A. japonica at a level of one infected seed out of 800. Four out of ten samples of wild (Diplotaxis tenuifolia) rocket seeds were contaminated by A. japonica with the highest level of infection detected in a single sample of 3 out of 800. All tested isolates of A. japonica obtained from seeds were pathogenic on both wild and cultivated rocket.

show abstract

Seed and Propagative Material

Munkvold

Gullino

2020

Integrated Pest and Disease Management in Greenhouse Crops

View full text Add to dashboard Cite

Alternaria cichoriiin Brazil onCichoriumspp. Seeds and Cultivated and Weedy Hosts

Abstract: Alternaria cichorii was recorded for the first time in Brazil causing leaf spots on endive (Cichorium endivia)

Cited by 7 publications

References 7 publications

Cheatgrass facilitates spillover of a seed bank pathogen onto native grass species

Cheatgrass facilitates spillover of a seed bank pathogen onto native grass species

Occurrence of Alternaria japonica on Seeds of Wild and Cultivated Rocket

Seed and Propagative Material

Contact Info

Product

Resources

About