Some introduced plant pathogens have become established throughout Pennsylvania
such as Chestnut blight (American chestnut), and Dutch elm disease (American elm)
which have vastly changed the composition of our North American forests. Others
remain outside our borders, held at bay principally by regulatory restrictions on
movement of plant material and by certification programs in major crop systems and
in nursery stock. Since a plant pathogen may well be impossible to detect with visual
inspection, it is very difficult to stop all movement of plant pathogens without
stopping all movement of plants and plant parts, making regulatory programs vital.
A certification program of best practices and testing for disease-free seed keeps
pathogens such as ring rot or potato wart from destroying our potato industry. The
stone fruit industry relies on import restrictions that keep plum pox or European
stone fruit yellows from impacting the largest part of the U.S. fruit industry.
Eradication of plum pox virus has cost federal and state governments over 40 million
dollars in the first six years of the program – it has cost Pennsylvania fruit growers
far more, seriously affecting their livelihoods. Yet the program is succeeding in
keeping the disease from spreading to more orchards. [Revised 4/10/2008]
Note: The table below contains examples of Plant Pathogens with invasive characteristics
that are of concern in the
World, the Nation, or in the Commonwealth. Please check the
Pennsylvania Department of Agriculture
for current information on the regulatory status of any of these species in Pennsylvania.