Shallot aphid (Myzus ascalonicus)
Strawberry aphid (Chaetosiphon fragaefolii)
Pest description and crop damage Shallot aphids are small and pale greenish-brown. Aphid feeding causes the plants to be stunted, with crinkled and curled leaves. Damage may spread from small, circular patches to entire plantings. The shallot aphid transmits strawberry mottle virus. It is seldom a pest in Oregon strawberry fields. Strawberry aphid adults are generally yellow and wingless with small, clubbed hairs on the dorsal surface. Winged forms are pale green with black markings on head, thorax and abdomen. They are about 2 mm long. This aphid generally does not directly injure the plants but may transmit virus diseases.
Biology and life history Shallot aphids overwinter as adults and nymphs deep in the plant crown or amongst weeds. They resume feeding in early spring and continue through early summer. Winged forms leave strawberries in June and return in the fall. Strawberry aphids overwinter as adults or nymphs in the crown, or as black eggs on the undersides of older leaves. Winged adults appear in May and begin dispersing within the field or between fields. Peak aphid numbers occur in June, but in some years another peak may occur in September or October. There are several overlapping generations produced each summer.
Scouting and thresholds Inspect plants, especially the underside of leaves and in the crowns, for aphids in early spring. When aphid populations average half to one aphid per leaf, treatment may be necessary. Continue to monitor for aphids, especially after harvest and in early fall.
Many naturally occurring parasites and predators attack aphid. Monitor the proportion of aphid mummies to unparasitized adults and the number of predators such as lady beetles. If the biocontrol agents appear to be gaining control, avoid sprays which would disrupt this system. Most products available for aphid control are highly disruptive of natural enemy populations.
Aphid populations tend to be higher in plants that are fertilized liberally with nitrogen. Use a floating row cover where feasible-this will not be effective on currently infested plants! The use of virus-resistant plants is probably the most effective control. Among June-bearing varieties, 'Hood' is very susceptible to virus, 'Redcrest' is less so. Most other June-bearing varieties, including 'Totem,' are fairly resistant. Day-neutral varieties have not been tested for virus resistance.
Home gardeners: Wash aphid from plants with a strong stream of water.
Management-chemical control: HOME USE
Chemicals applied for aphid control have not prevented the spread of virus diseases in strawberries, and aphid damage has not warranted the use of control measures; therefore, chemical control is not suggested.
- insecticidal soap-Some formulations are OMRI-listed for organic use.
Management-chemical control: COMMERCIAL USE
Aphid control helps suppress viruses when supported by use of certified plants, field rogueing of abnormal plants, very thorough application of an insecticide, isolation from infested fields, and regional spray programs. To prevent aphid migration to new fields and spread of virus within a field, treat bearing fields when aphids appear.
- acetamiprid (Assail) at 0.035 to 0.075 lb ai/a. PHI 1 day. Do not exceed more than two applications per season.
- azadirachtin (Neemix and other brands)-Consult label for rate and use directions. Some formulations are OMRI-listed for organic use.
- Beauveria bassiana (Mycotrol and other brands)-Consult label for rate. Some formulations are OMRI-listed for organic use.
- flonicamid (Beleaf 50 SG) at 0.089 lb ai/a. PHI 0 days. Apply when aphids first appear. Limited to three applications per crop season.
- flupyridifurone (Altus, Sivanto) at 0.09 to 0.14 lb ai/a. PHI 0 days. Toxic to adult bees in laboratory studies via oral exposure, however, not toxic to bees through contact exposure, and field studies conducted with this product have shown no effects on honeybee colony development. Limited to two applications, 10 days apart, and no more than 0.365 lb ai/a allowed per season. Avoid rotation with neonicotinoid products, if possible.
- imidacloprid (Admire Pro and other brands) at 0.38 to 0.5 lb ai/a. PHI 14 days. Soil application. It must be incorporated with 0.25 inch irrigation or rainfall within 2 hours of application. Do not apply immediately prior to bud opening or during bloom or when bees are foraging. Note "Bee Advisory Box" and restrictions on the label.
- imidacloprid (Admire Pro and other brands) at 0.047 lb ai/a. PHI 7 days. Foliar application. Do not apply during bloom, within 10 days of bloom, or when bees are actively foraging. Note "Bee Advisory Box" and restrictions on the label.
- insecticidal soap (M-Pede and other brands)-Consult label for rate. PHI 0 days. Some formulations OMRI-listed for organic use.
- malathion at 1 to 2 lb ai/a. PHI 3 days.
- naled (Dibrom) at 0.9 lb ai/a. PHI 1 day.
- sulfoxaflor (Closer SC) at 0.043 lb ai/a. PHI 1 day. Do not apply when bees are actively foraging. Note: Strawberry registration was cancelled on 11/12/2015 but EPA ruled that all product still in the hands of growers is allowed to be used until exhausted.
- thiamethoxam (Actara) at 0.023 to 0.047 lb ai/a. PHI 3 days. Actara and Platinum have the same active ingredient; for resistance management, do not follow one with the other. Do not apply during bloom or when bees are foraging in the area.
- thiamethoxam (Platinum) at 0.078 to 0.188 lb ai/a. PHI 50 days. Apply to soil and incorporate with irrigation. Platinum and Actara have the same active ingredient; for resistance management, do not follow one with the other. Do not apply when bees are foraging. Wait at least 5 days before placing beehives in the treated field.