Knowledgebase
Aphid infestation of Aspen trees #760496
Asked July 07, 2021, 5:04 PM EDT
Arapahoe County Colorado
Expert Response
Hi Heather,
it appears that you have done your homework. The treatments you have applied are typically the first steps in treating aphids. To guide you on your next steps, check out this CSU Extension Fact Sheet: https://extension.colostate.edu/topic-areas/insects/aphids-on-shade-trees-and-ornamentals-5-511/
Also, dormant season treatment is important in aphid control: https://extension.colostate.edu/topic-areas/insects/insect-control-horticultural-oils-5-569/
You may consider consulting an arborist. They have the pesticides & spraying equipment to treat larger trees.
Good luck.