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Weekly Gardening Guide: Aphids

August 27, 2015


In the spring, you will often notice aphid populations on many ornamental
plants. But this year, because of the humid, rainy, and relatively cool weather, you might find them on your plants now. 
Aphids are commonly found on spirea, willow, viburnum, and other fast-growing shrubs; they can be green, yellow, black and red. You might find them in clusters along the stems or nestled under leaves, or further down in the plant where multiple leaves come together.  They feed on the sap just below the surface of the tender new growth, and this can result in curled or wrinkly looking leaves and stems. Aphids are also capable of carrying disease, although this isn’t overly concerning in our area.
Aphids can be controlled by pruning out infested stems and disposing of them off property.  This will remove the majority of them, but a follow-up spray with insecticidal soap may be necessary.  Be sure to spray the affected plant along the stems and under the leaves and try to make direct contact with the aphids.
Keep in mind that aphids reproduce very quickly and bear live young.  A single female can produce up to 10 young every day, which are very small and easy to miss while pruning or spraying.  You will likely have to monitor the affected plants for several days to get good control. 
If you are still left with a major infestation of aphids after taking the above measures, you should check for nearby weeds that may be harbouring large populations and try to deal with those accordingly.  If there is no other source, you may need to use a stronger product, such as End-All or Bio-Mist, both of which are pyrethrin based.  In addition to these, Dormant Oil may be sprayed on the stems and leaves of all shrubs between November and March to kill off egg masses and reduce spring populations of aphids.
Good luck with your aphid hunting, and feel free to give us a call or drop by for further advice!


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