Many insects and diseases rarely infest healthy trees; instead they are typically secondary invaders. Secondary invaders are pests that only infect trees after they are in a weakened state. This weakened state can be created by what are called stressors. Stressors are environmental or human inflicted situations that increase the tree’s susceptibility to attack; similar to how our immune system lowers when we don’t get much sleep, thus we end up catching a cold. For trees, stressors typically include drought, soil compaction, sun scald, or injuries. When a tree is exposed to stressors they become an easy target for insects and diseases.
Many theories have been proposed for why this phenomenon occurs. The two biggest being, the idea of insects and diseases responding to tree stress pheromones and the idea of insects and diseases responding to trees running a fever when stressed. At the end of the day researchers are not positive how insects and diseases spot weakened trees but they are positive it happens and that it’s imperative to protect our trees from becoming easy targets.
Think you have a secondary invader problem? With our Canopy Protection Program our Arborists will be able to identify your secondary invader and not only treat it but treat the underlying stressor to combat future infections and infestations.