Portland is the City of Roses, but sometimes roses struggle here
Our rainy spring weather and temperate early summers contribute to conditions that support many fungal issues, and aphids are always problematic. The good news is that most common rose problems in the Pacific Northwest don’t kill plants, they just make them look bad. On this page we review best practices to prevent pests and diseases, and offer solutions for when they occur.
Keep in mind that fungi evolve quickly, so treating them with the same chemicals every time will not be effective. We recommend rotating treatments between two different types of fungicides.
To prevent disease from occurring, start spraying when shoots and flower buds are emerging – fungal spores are active at this point, but haven’t yet bloomed, so aren’t visible.
• Be sure to follow labels carefully when diluting and applying chemicals.
• Do not apply when temperatures are of 80f or on windy days.
• Treat early in the morning to avoid harming beneficial insects.
Call us or come in to our nurseries to get recommendations on specific sprays.
The information on this page has been compiled from the Pacific Northwest Pest Management Handbooks.
Aphids – small soft bodied insects cover flower buds and hang out on new leaves. Aphids suck sap from plant tissues and excrete sticky honeydew that attracts ants. They don’t cause a lot of damage to roses, but heavy infestations can reduce the quality of the flowers (besides just being gross).
Ladybugs are a great insecticide as are little birds, and aphids can be knocked off of roses with a strong stream of water. If that’s not enough, there are plenty of effective treatments.
Both treatments kill adult aphids when they come into contact with insects. Neither works effectively to kill eggs, so they must be reapplied periodically through the growing season.
Find more info about rose pests and treatments in this handout.
Black Spot Diplocarpon rosae
Powdery Mildew Podosphaera pannosa