Plant-Soil Pathogen Interactions

Plant-soil interactions affect plant population dynamics and community interactions. Both positive and negative feedbacks may occur where soil microbiota either favor the survival and growth of a particular species or actively inhibit it. Negative feedback has recently been documented between black cherry (Prunus serotina), and soil-borne fungal pathogens in the genus Pythium that inhibit seedling establishment in the vicinity of adult trees, in accordance with the Janzen-Connell hypothesis. The objectives of ongoing research are to determine how negative feedback changes with successional age of the community, to assess the host specificity of Pythium species causing damping-off in black cherry, and to evaluate whether other temperate tree species are affected in a similar way by soil-borne pathogens. A series of field, greenhouse and laborat ory experiments are being used to explore the role of soil-borne pathogens as regulators of seedling establishment, spatial dynamics and successional change within temperate forest communities. The results will provide valuable comparative data with results from tropical forests, and will have practical applications for forest and orchard management, and ecological restoration. (Collaborators on aspects of this research include Dr. Keith Clay and Dr. Kurt Reinhart at Indiana University; Dr. André Lévesque at Agriculture and Agrifood Canada).

Research students: Katie Richter and Ashley Shade
See .pdf of research poster

How spiders affect plant growth and reproduction
Dr. Matt Persons and Dr. Alissa Packer

Research students: Ryan Bell and Mike Cole

We are interested in how spiders affect plant growth and reproduction by influencing the natural enemies of plants. Spiders are common predators of insects in both natural and agricultural environments. Spiders interact with their prey directly, by eating them, or indirectly, by changing their behavior or feeding preferences. Because the insects consumed by spiders are often the same as those that eat plants (herbivores), the effects of spiders on their prey can potentially have dramatic effects on plants.

Despite the fact that spiders are widespread insect predators and common to all crop types, their potential positive impact on most plants remains largely unknown. Using soybean, a crop species of great economic importance, we are studying whether plants in enclosures wi th wolf spiders suffer less damage from insect herbivores. Additionally, we are exploring how the composition of the spiders in the enclosure influences the degree of herbivore damage on the soybean plant. Specifically, we are manipulating the presence or absence of all possible combinations of three different wolf spider species found in soybean fields. These species vary considerably in size, natural density, and activity time (nocturnal or diurnal). Because wolf spiders feed on other spiders as well as insects, the net effect of these multiple predators on herbivores and plants remains unclear. This study will allow us to better understand how natural predators can be effectively used to combat crop pests and will increase our understanding of the ecology of agricultural systems.

Mike Cole and Ryan Bell present their results
at the National Council for Undergraduate
Research (NCUR) conference in Virginia.
See .pdf of research poster



The enclosures are finally assembled. There is no longer any aluminum flashing or tulle fabric left in the Susquehanna Valley region.

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