There are many symptoms of aphid damage, including decreased growth rates, mottled leaves, yellowing, stunted growth, curled leaves, browning, wilting, low yields and, eventually, death. Along with the loss of plant juices from direct feeding, aphids can spread diseases.
Check plants often for early outbreaks. Clip off and compost stems holding aphid clusters. Encourage beneficial insects including lady beetles, syrphid flies, and lacewings, which are important aphid predators.
In small outbreaks, a high pressure spray from the garden hose can help remove aphids from plants. Follow up with two applications of insecticidal soap, one week apart. Be sure to apply the soap spray to leaf undersides and crevices.
Lady beetles and their larvae are great beneficial insects to welcome into your garden. Ants tend to be attracted to the honeydew left by aphids, so ant activity can often lead you to aphid colonies.