The Valley Forge West Trail at Heuser Park will close on Aug. 14 while officials treat for an invasive pest, Upper Merion Township officials announced Tuesday.

The emerald ash borer, an exotic beetle from Asia, has killed millions of ash trees nationwide since its discovery in southeastern Michigan in 2002. It was found in Pennsylvania in 2007 and in Delaware in 2016.

Upper Merion Township is taking a multistep approach to tackle this problem, beginning with an herbicide treatment to reduce or eliminate nonnative invasive plants along the trail. The mixture contains a water-soluble blue dye that will remain on the plants until a heavy rainfall.

The spray treatment will take about a week to 10 days to complete.

Visitors are barred from using the trail during the application and waiting periods. Township officials expect the trail to reopen Aug. 28.

In the future, the township plans to pretreat unaffected ash trees, remove any diseased trees, and eventually plant more trees in the area, officials said.