title: Direct splash dispersal prevails over indirect and subsequent spread during rains in Colletotrichum gloeosporioides infecting yams.
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.
authors.affiliation: INRA, UR1321, ASTRO Agrosystèmes tropicaux, F-97170, Petit-Bourg (Guadeloupe), France.
authors.forename: Laurent
authors.initials: L
authors.lastname: Penet
authors.affiliation: INRA, UR1321, ASTRO Agrosystèmes tropicaux, F-97170, Petit-Bourg (Guadeloupe), France.
authors.forename: Sébastien
authors.initials: S
authors.lastname: Guyader
authors.affiliation: INRA, UR1321, ASTRO Agrosystèmes tropicaux, F-97170, Petit-Bourg (Guadeloupe), France.
authors.forename: Dalila
authors.initials: D
authors.lastname: Pétro
authors.affiliation: INRA, UR1321, ASTRO Agrosystèmes tropicaux, F-97170, Petit-Bourg (Guadeloupe), France.
authors.forename: Michèle
authors.initials: M
authors.lastname: Salles
authors.affiliation: INRA, UR1321, ASTRO Agrosystèmes tropicaux, F-97170, Petit-Bourg (Guadeloupe), France.
authors.forename: François
authors.initials: F
authors.lastname: Bussière
mesh_terms: D020231:Colletotrichum / Q000472:pathogenicity*; D027742:Dioscorea / Q000382:microbiology*; D010935:Plant Diseases / Q000382:microbiology*; D011891:Rain; D013172:Spores, Fungal / Q000502:physiology*; D014887:Weather