Butternut (Juglans cinerea) is a walnut native to eastern North America. Butternut's provide several important services economically and ecologically. Beginning in the late 1960's, foresters began to report a noteworthy disease infecting butternut trees. The pathogen Ophiognomonia clavigignenti-juglandacearum (Oc-j) spreads rapidly and now threatens Butternut trees everywhere. Trees of all ages can be infected and mortality rates are very high.
The population crash of a long-lived organism presents unique management challenges. For butternut, the genetic signatures of population decline are masked by slow growth and scant recruitment. I am interested in the genetic shift that occurs within a population following such a disturbance.
Introgression of Oc-j resistant conspecifics further confounds management plans. Butternut and Japanese walnut (J. ailantifolia) freely hybridize. The hybrid is known as a "buartnut". Historically the threat of genetic invasion was of little concern due to butternut's home-field advantage. More recently, concern of generic invasion has been raised in light of Butternut Canker. Butternut hybrids demonstrate greater resistance to Oc-j, swaying the balance from home-field to hybridization.