The Washington State Department of Agriculture finalized a rule change that adds soil and growing medium to the list of regulated materials under the apple maggot quarantine. The updated rule takes effect July 11, according to a news release from WSDA.

The apple maggot quarantine regulates the movement of fruit, green waste and, now, some soils from apple maggot quarantined areas to pest-free areas of Washington. The rule change applies to soil and growing medium, both in pots and on root balls, of apple maggot host plants and nonhost plants grown within the drip line of host plants that have fruited. Soil that is not associated with plants is not regulated as part of the rule.

Plants that contain soil originating from a quarantined area must have a phytosanitary certificate if they will be moved into the pest-free area in Eastern Washington.

The change will affect nurseries in any location quarantined for apple maggot, whether in Washington or another state.

According to the release, the tree fruit industry first proposed the change after recognizing that the movement of soil — specifically the soil in pots and attached to root balls of host plants and some nonhost plants — could transport apple maggots into pest-free areas. 

Apple maggot was first detected in Washington in 1980, and it spread rapidly along the I-5 corridor, throughout Western Washington and into parts of several Eastern Washington counties. Despite its spread, WSDA trapping and monitoring efforts and work done by local county pest boards have kept the pest at low levels in most of the state’s main apple production areas, according to the release.

The spread of apple maggot into pest-free areas of the state could have serious impacts on international and domestic trade for Washington’s apple industry, valued at more than $1 billion annually. 

Visit the WSDA website at for more information about apple maggot, the apple maggot quarantine and more details about the rule change.

by Jonelle Mejica