Abstract Detail

Host/Plant Pathogen Interactions and Plant Health Management

Kerrigan, Julia [1], Meadows, Inga [1], Walker, Joan [2].

Fire timing influences smut distribution in wiregrasses of longleaf pine savannas.

Longleaf pine savannas are unique to the Southeastern U.S.A., they are characterized by an open canopy dominated by longleaf pine (Pinus palustris) and a dense ground layer dominated by herbaceous species. A high frequency, low intensity surface fire regime both maintains and is facilitated by the classic longleaf pine forest structure. Once the predominant forest type in the southeast, longleaf pine ecosystems have been reduced to a fraction of their size due to land use changes, urbanization, and fire suppression. Longleaf pine and wiregrass bunchgrasses, Aristida stricta and A. beyrichiana, are keystone species and efforts are being made to preserve and propagate them, as well as other species in these disappearing ecosystems. Smut teliospores have been reported from ovaries of developing flowers of Aristida stricta and A. beyrichiana, and the effect of this pathogen on seed viability is a concern. The smut has been tentatively identified as Langdonia confusa, based on morphology and host. DNA sequencing is being performed to confirm the identity and compare sequences by host species and location. The effects of fire timing and soil factors on incidence of smut infection were also examined. We predicted that later burn dates would reduce smut infections. In 2014 85 sites (nested within 15 properties) were sampled; samples were distributed across the middle and south Atlantic coastal plain, 4 soil orders, and burning in every month from December 2013 through July 2014. At each site the presence of smut was tallied at 20-m intervals along transects, and culms were collected from 8 clumps. We quantified the presence of smut at site, clump, and culm levels. Both the burn month and soil order had significant effects (ANOVA; p<.05) on stand smut abundance; the interaction was not significant. Clump and culm infection were correlated (Pearson; r =.53; p<.01) and showed patterns similar to the stand level. Results showed that sites burned in May-July had significantly higher rates than early burns, contrary to expectation. Additional studies are being conducted to examine reasons behind these findings.

1 - Clemson University, Agricultural and Environmental Sciences, E-143 Poole Agricultural Center, Clemson, SC, 29634-0310, USA
2 - USDA Forest Service, Southern Research Station, 233 Lehotsky Hall, Clemson, SC, 29634, USA

Keywords:
Langdonia
smut
Aristida
wiregrass
longleaf pine ecosystem
fire.

Presentation Type: Poster:Posters for Topics
Session: P
Location: Hall D/The Shaw Conference Centre
Date: Monday, July 27th, 2015
Time: 5:30 PM
Number: PPA030
Abstract ID:652
Candidate for Awards:None