Yellow dogwood tree infested with aphids

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Q: We transplanted a large 6 foot yellow twig dogwood bush last May to our garden. It didn’t take well to the transplanting and struggled the whole summer. It soon became infested with black aphids. We managed the aphids with insecticidal soap and by purchasing ladybugs through the summer. We hoped the shrub would regain its strength over the winter time. The shrub is looking much healthier this spring. However, the black aphids are back (or they may have overwintered on it?). We just can’t bear another summer of battling a black aphid infestation. It seems to be the only shrub in the garden that the aphids are attacking and we’re concerned about the aphids spreading to the other healthier shrubs. Any suggestions on how to deal with this? Should I cut the yellow twig dogwood down to a couple of feet and have it regrow? At this point, we’re considering getting rid of the shrub all together. Maybe it will never recover from the transplant shock?

Generally speaking yellow twig dogwood (Cornus stolonifera ‘Flaviramea’) does not exhibit excessive aphid problems. Yes, you can cut the bush right down to ground level (“coppicing”) to improve branch colour and to keep the bush growth in check.

I would suggest hosing down the branches at least twice a week with a moderate jet of water (try not to damage the plant in the process) to physically remove the aphids from the plant. Try planting other
flowering plants to possibly attract more beneficial insects into your garden, for example sweet alyssum (Lobularia), fennel (Foeniculum), yarrow (Achillea), and others.

Your bush dogwood will eventually recover. To speed up the process, try using some transplant solution as directed. Consider mulching the root zone area with compost to maintain even moisture during the growing season. If plants are grown in a stress-free environment, (bush dogwood likes moist soils) it’s less likely insects will feed on the plant. Your beneficial insects will eventually catch up and keep the aphids in check.

You will never get rid of all the aphids. All you can do is manage it, unless you remove the plant entirely.