I am the horticulturalist at a golf club. This year, our annuals are covered with aphids. I have sprayed with insecticidal soap. Is this right? or is there something else I should be doing?
Yes, you are using the right product. Just remember that you will have to repeat the sprayings regularly to kill new generations as they appear. You can also direct a strong spray of water from the garden hose to knock the aphids off. Finally, you might also want to make sure you have a diverse planting scheme, to attract beneficial insects. For example, ladybugs will eat aphids, as will lacewings; parasitic wasps will attack aphids, caterpillars, beetles, scale, and flies. Cosmos is an attractive annual that attracts ladybugs, for example.
You might want to consult this website:www.gardeninsects.com