Capability from Washington, Dc writes
Non container 3 year old crepe myrtle planting in back yard. Severe aphid infestation. 7 day cycle of Neem Oil with regular spot treatments of Insecticidal Soap doesn’t make a dent.
OHP Marathon 1% Granular can be used around trees for aphids, you just need to be sure to water in well so it gets down the roots and apply before they are an issue since it takes time to translocate throughout the tree. Treating as you have with Neem Oil and the soap when they are actively infesting is recommended if you can make contact. You may try a product like Bifen IT on the foliage which can leave a residual to continue to kill.
Answer last updated on: 09/04/2019