Aphids on Strawberry Plants

Identification

• Several aphid species -- including strawberry, melon, potato and green peach aphids -- target strawberry plants. Of them, strawberry (Chaetosiphon fragaefolii) and melon aphids (Aphis gossypii) do most of the damage. Ranging from yellow, pink and pale green to greenish-black, these tiny, pear-shaped insects feed in dense colonies on tender new stems and lower leaf surfaces. Attaching with tissue-penetrating mouth parts, aphids seldom move when disturbed.

Damage

• Aphid damage ranges from curled, yellowing foliage and slowed growth to viral infection, although viruses seldom cause significant problems for homegrown strawberries. The most serious damage arises from the pests' honeydew production. This gooey, transparent sugar-laden waste glues the molting aphid larvae's white, shed skins to the plants. Honeydew also lures hungry ants and airborne sooty mold fungi. The ants protect their food source by killing the aphids' natural predators. Sooty molds cover the honeydew with velvety, black fungal mats that may block sunlight and interfere with the plants' photosynthesis.

Aphid Management

• Successful aphid management begins with checking your strawberries at least twice weekly during the growing season whenever temperatures are in the 65- to 80-degree Fahrenheit range. A forceful blast of water from a garden hose is usually enough to dislodge early infestations and their honeydew. An infestation of 10 or more aphids per strawberry leaf merits treatment with insecticidal soap spray. A solution of 1 or 2 tablespoons of liquid dish soap per 1 gallon of water applied with a hose-end sprayer suffocates the pests. Spray on a cloudy day, saturating both sides of the leaves. For thorough coverage, repeat in two or three days. The soap's residue isn't seriously harmful to lacewings, syrphid flies and other aphid predators.

Ant Management

• If ants are protecting the aphids, dab a few leaves on one strawberry plant with apple jelly and those on another with peanut butter. Mix 1/2 cup of whichever one attracts the most ants with 1 1/4 teaspoons of boric acid powder. After punching several holes in a jar's lid, place this bait in the jar, seal it and secure the lid with tape. Place the bait jar among your strawberries where children or pets won't find it. Ants entering the jar carry the slow-acting, low-toxicity bait back to their nests. You should notice decreasing ant numbers in about a week.