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UC Cooperative Extension Ventura County
669 County Square Dr. Suite 100
Ventura CA 93003
Phone: 805.645.1451
Fax: 805.645.1474

Office Hours
Monday - Friday from 9 a.m. to 4 p.m. 
Please phone ahead as staff schedules vary due to COVID-19.
We are also available via phone and email. 

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Aphids on Roses

Many gardeners use the systemic rose food. This product is a combination of fertilizer and an insecticide. The product needs to be applied on the soil around the base of the plant and lightly worked in. As the roses are watered, the fertilizer and insecticide are absorbed by the roots. When aphids or other sucking insect feed on the rose they are killed by the insecticide in the plant sap. This treatment will usually provide good protection from aphids for 4-6 weeks after application. You should apply the systemic rose food when the roses first start to grow as the systemic should be in the plant before the aphids arrive. So try to remember this treatment for next spring. Another option is high pressure water sprays. You can wash most aphids off the plants with a good stream of water. Many of the aphids that are knocked off the plant will die. Others will find their way back onto the plant, so washing has to be repeated on a 4- to 6-day schedule, if you wish to keep the aphid population at a low level. A third option is insecticidal soap. Spraying plants thoroughly with this compound will kill all the aphids that are coated with this chemical. Complete coverage of all plant parts, especially the new growth and buds, is important to good control. Finally, there are a number of insecticides that will kill aphids. Thorough coverage of all plant parts is essential to good control. One application is often enough to eliminate aphids for most of the season. However, a periodic scouting of all plants is needed, and spot treatments may need to occur to keep aphid populations in check. Always read and follow plant protection product labels for best results.