Knowledgebase
All things aphids #870682
Asked May 29, 2024, 11:12 PM EDT
Linn County Oregon
Expert Response
Hello!
I'm so sorry to hear about your aphid issues. They can be annoying pests in any garden. Thank you for attaching pictures. It is difficult to see the pests, but I will attach some links that can help you make a positive identification.
Rose aphids can damage leaves and blooms when their numbers skyrocket. And their damage can lead to other issues like disease spread and fungus growth. Aphids do have natural predators (such as birds, spiders, lady bugs and green lacewings). Encouraging these natural predators in your garden can be quite helpful. Rose aphids can also be dislodged with a strong stream of water. This doesn't kill them, but they might move along.
You can trap aphids using sticky yellow traps (sold in garden stores) or by using trap plants. A trap plant (such as nasturtiums) attract the aphids away from plants you are trying to protect (roses and plum trees).
For the plum trees, if the infestation is localized, you can hand wipe them off or the strong blast of water can be effective (before leaves curl). You can also prune the affected area (if leaves have begun to curl) to prevent spread. High levels of nitrogen in the soil attract aphids to plum trees. For future management, if you do fertilize, switch to a slow release or low nitrogen fertilizer (depending on what your individual soil and trees might require).
In both cases, there are insecticides that can be effective, however they also impact beneficial insect species and should be used as a last resort.
For more information on aphids, see the articles below:
https://solvepestproblems.oregonstate.edu/plant-problems/rose/aphid
https://hortsense.cahnrs.wsu.edu/fact-sheet/plum-prune-fresh-aphids/
https://extension.oregonstate.edu/news/how-control-aphids-less-toxic-methods
Happy gardening!