With spring green comes aphids

Aphids are just starting to collect on the top of this bud on

 a McCartney rose. A blast of water will knock them off.

(Photos: Kathy Morrison)

How to cope with these pests without chemicals

By Debbie Arrington

With the first warm days of spring (after so much rain), expect rapid growth in your garden – and aphids.

These pests flock to tender green shoots and buds. Roses in particular are vulnerable, but aphids also attack cabbage, tulips and a wide range of other plants.

Usually, aphids start being problematic earlier in March. But recent storms and colder than normal temperature have kept their populations down.

That will end very soon, probably this weekend.

Aphids feed by sucking the juices out of plants. They like new growth and flower buds best because the outer cell walls are thinner and therefore easier to eat. The faster the growth, the thinner the walls.

Applications of high-nitrogen liquid fertilizers speed that growth even more. As plants respond to these nutrients, they often attract more aphids.

How can aphids become such a problem so quickly? One mature female can produce 12 offspring a day – without mating.

Lady beetles can help keep the aphids under control, but they can't
do it alone once the population gets growing.

Beneficial insects such as lady beetles or praying mantis like to feast on aphids, but they can’t contain a rapidly growing onslaught. Encourage the good bugs, while also giving them a hand without harmful chemicals.

Knock down spring aphid infestations with water. A strong blast from the hose can knock them right off; soft-bodied aphids can’t survive the fall.

Other aphid-fighting solutions are more effective at the first sign of outbreaks. Puree 2 cloves of garlic and mix into 2 cups of water; put in a spray bottle and blast the bugs.

Or add 1 teaspoon of mild dish soap (such as liquid Ivory or Dr. Bronner’s pure-castile or peppermint liquid soap) to 2 cups of water in a spray bottle, then spray away.

Or just squish them. Wear gloves and lightly stroke them off buds. (This works well on roses.)

If aphids persist, look for ants. They may be introducing aphids to plants (particularly shrubs or trees), then “milking” them for honeydew. That honeydew often forms a black sooty mold.

To deter the ants, put sticky Tanglefoot or other barrier around the stem or trunk of the shrub or tree to dissuade ants from herding aphids onto that plant.

For more on aphids, check out this advice from the University of California pest management program:

http://ipm.ucanr.edu/PMG/PESTNOTES/pn7404.html