Tuesday, August 3, 2010 - 8:20 AM

COS 23-2: Edge effects, not connectivity, determine the incidence and development of a foliar fungal plant disease

Brenda L. Johnson, North Carolina State University and Nick M. Haddad, North Carolina State University.


Increased spread of infectious disease is often cited as a potential negative effect of habitat corridors, but the impacts of corridors on pathogen movement have never been tested empirically.  Using sweet corn and southern corn leaf blight as a model plant-pathogen system, I tested the impacts of connectivity and habitat fragmentation on pathogen movement and disease development. 

I found that corridors do not facilitate the movement of wind dispersed plant pathogens, that connectivity of patches does not enhance levels of foliar fungal plant disease, and that edge effects are the key drivers of plant disease dynamics.  Over time, less edgy patches had higher proportions of diseases plants, and distance of host plants to habitat edges was the greatest determinant of disease development.  Variation in average daytime temperatures and light intensities provided a possible mechanism for these disease patterns.  My results show that worries over the potential harmful effects of connectivity on disease dynamics are misplaced, and that, in a conservation context, diseases can be better managed by mitigating edge effects.