European Plum and Yarrow

Yarrow planted near European plum functions as a banker plant for parasitic wasps, particularly braconid and chalcid species that target plum curculio larvae and eggs. The pairing works best when yarrow is established at the drip line or in groundcover strips rather than directly beneath the canopy, where competition for water and light can stress young plum trees.

Yarrow tolerates poor, dry soils better than European plum, so site selection matters. In heavier clay soils where plum roots need good drainage, yarrow's drought tolerance means it may go dormant before curculio pressure peaks in early summer. In loamy, well-drained sites the two coexist without conflict.

The practical benefit depends on ambient beneficial insect populations. Yarrow attracts predatory wasps; it does not generate them. Where those populations are already suppressed by nearby pesticide use, a few yarrow plants offer limited habitat value. For orchards managing curculio pressure with minimal spray inputs, yarrow is a low-cost addition with no documented drawbacks specific to European plum.