Introduced plant pathogens threaten North American forests. Some arrived in the distant past: chestnut blight, white pine blister rust, beech bark disease, Dutch elm disease, butternut canker. Damaging introductions continue through the late 20th Century (sudden oak death, laurel wilt) and recent decades (ohia rust, Fusarium blight, rapid ohia death, beech leaf disease). Introduction of pathogens to naïve ecosystems is a global problem: North American and Asian pathogens are killing millions of trees in Europe.

Most of these pathogens probably entered on plant imports; others associated with ambrosia beetles could be introduced on plants, or on wood. The U.S. imported ~5 billion plants in 2021. One type of wood imports known to transport ambrosia beetles is, and wood packaging, e.g., crates and pallets. The U.S., Canada, and Mexico together import more than 31 million shipping containers per year. Between 11,000 and 25,000 of these containers are probably transporting a wood-boring pest. (While not all ambrosia beetles, this group is among the most commonly detected insects.)

When the World Trade Organization came into effect in the mid-1990s, countries adopted an international system intended to protect plants from pest introductions associated with trade. However, this system has demonstrably failed to curtail introductions. I will discuss the following reasons:

• the system does not allow countries to regulate an organism until scientists can name it & demonstrate damage. Achieving this knowledge is hampered by
• sometimes years of delay in establishing causal agents of disease
• confusion over which barrier a disease-causing organism has overcome: geographic, environmental, or evolutionary. Only the first meets the definition of an “invasive species”, which is necessary to be eligible for regulation
  pathogens are extremely difficult to detect during visual inspection

The USDA has amended its plant import regulations, but data analyses to date have been inadequate to say how effectively the current regulations prevent introductions. Open discussion is needed by regulators, scientists, trade, stakeholders to try to identify steps that would result in enhanced protection.