Direct splash dispersal prevails over indirect and subsequent spread during rains in Colletotrichum gloeosporioides infecting yams

PLoS One. 2014 Dec 22;9(12):e115757. doi: 10.1371/journal.pone.0115757. eCollection 2014.

Abstract

Plant pathogens have evolved many dispersal mechanisms, using biotic or abiotic vectors or a combination of the two. Rain splash dispersal is known from a variety of fungi, and can be an efficient driver of crop epidemics, with infectious strains propagating rapidly among often genetically homogenous neighboring plants. Splashing is nevertheless a local dispersal process and spores taking the droplet ride seldom move farther than a few decimeters. In this study, we assessed rain splash dispersal of conidia of the yam anthracnose agent, Colletotrichum gloeosporioides, in an experimental setting using a rain simulator, with emphasis on the impact of soil contamination (i.e., effect of re-splashing events). Spores dispersed up to 50 cm from yam leaf inoculum sources, though with an exponential decrease with increasing distance. While few spores were dispersed via re-splash from spore-contaminated soil, the proportion deposited via this mechanism increased with increasing distance from the initial source. We found no soil contamination carryover from previous rains, suggesting that contamination via re-splashing from contaminated soils mainly occurred within single rains. We conclude that most dispersal occurs from direct splashing, with a weaker contribution of indirect dispersal via re-splash.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Colletotrichum / pathogenicity*
  • Dioscorea / microbiology*
  • Plant Diseases / microbiology*
  • Rain*
  • Spores, Fungal / physiology*
  • Weather*

Grants and funding

This work was funded as part of AGROECOTROP project, co-financed by the European Union (Fond Européen de Développement Régional) and the Guadeloupe Regional Council. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.