What specific type of damage do subterranean Woolly Apple Aphid populations cause to roots?
Galls, swellings, and eventual decay
The root-feeding activity of the Woolly Apple Aphid creates significant pathological effects beneath the soil line that are highly detrimental to the host tree's long-term health. As the aphids tap into the roots to draw sap, the plant tissue reacts defensively and pathologically to the feeding. This reaction manifests as the formation of galls, which are abnormal swellings on the root structure, accompanied by general swelling in localized areas. Over time, if the infestation is persistent and deep-seated, this root damage progresses toward decay, severely compromising the root system's overall functionality. This compromised state directly impairs the tree's fundamental ability to efficiently take up essential water and vital nutrients from the surrounding soil, potentially leading to canopy decline even if the aerial parts appear superficially healthy.
