ARS | Publication request: Spatial variation in soil-borne disease dynamics of a temperate tree, Prunus serotina

Submitted to: Ecology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: March 2, 2009
Publication Date: November 1, 2009
Citation: Reinhart, K.O., Clay, K. 2009. Spatial variation in soil-borne disease dynamics of a temperate tree, Prunus serotina. Ecology. 90(11):2984-2993.

Interpretive Summary: Soil-borne pathogens affect black cherry tree recruitment in Indiana * Soil-borne diseases caused by oomycetes (e.g. Pythium) are widespread in mesic deciduous forests in central Indiana. * Pathogenic effects are distance- and not seed/seedling density dependent. * Pathogenic activity and the density of a soil-borne pathogen genus (Pythium) varied around individual trees. * Soil-borne pathogens and their impacts are spatially variable in forests. * Theoretical implications- Attempts to characterize the effects of soil biota on plants must consider the spatial variation of the microbes and host. * Management implications- Black cherry trees are more likely to establish away from like species or in areas with low loads of soil-borne pathogens. Fungicides can be used to limit the deleterious effects of the pathogens.

Technical Abstract: Soil-borne pathogens (SBPs) are posited to maintain forest diversity; however, their in situ impact and spatial variation is largely unknown. We examined spatial patterns of pathogenic activity in deciduous forest using a common garden experiment, a natural experiment around replicated trees, and density of Pythium (a SBP) around Prunus serotina trees. In both experiments, P. serotina seedling survival was 52-57% greater in plots treated with an Oomycete-specific fungicide (i.e. Pythium) than untreated plots. Disease dynamics were not density-dependent but pathogenic activity and Pythium density were spatially variable. In the common garden experiment, pathogenic activity of soil inoculum varied among trees, while in the natural experiment pathogenic activity decreased away from P. serotina trees. Pythium density did not vary with distance away from P. serotina trees but did vary among trees. Understanding the spatial complexity of SBPs is critical to assessing their impact on populations and ultimately on forest diversity.