Pathogen Dispersal

*Note: the following information is for descriptive purposes only. Final, peer-reviewed results of research are not posted.

How an organism moves is an essential component in understanding its success or failure in different habitats.

Aerobiology data has been collected showing the comparative dispersal characteristics of P. punctiformis teliospores and urediniospores (the two aerial spore types responsible for different infection strategies on Canada thistle). Point-source releases of spores in windy field conditions show that teliospores have a steeper dispersal gradient than urediniospores. Fall velocities approximately three times faster were observed for teliospores in a particle settling chamber helping to explain the comparative spore flights.

Diagram of a 210 meter field release of spores in natural conditions

Pathogen dispersal data contributes to the understanding of P. punctiformis biological control limitations. The comparative spore movements help in planning inoculum use and predicting the secondary spread of the disease to avoid redundancy of initial infections. The limited availability of initial inoculum makes understanding secondary spread especially important.

Dispersal gradients for urediniospores and teliospores of P. punctiformis (L) Mean terminal velocities of urediniospores and teliospores (R)

Puccinia punctiformis disperses through the air via windblown spores but also moves locally through systemic infection of inter-connected ramets. The local dispersal was explored with experimentally inoculated thistle clones where the rate of mycelium and disease spread could be observed. The aboveground diseased ramets may exhibit a very different spread rate than the mycleial spread through the roots.

Dispersal kernel of healthy and diseased thistle shoots in a spreading patch (L) Radial spread of patch mapped after one season of growth