Strawberry Aphids
ID/Life Cycle: There are several species of aphids that infest strawberries including
Chaetosiphon fragaefolii, C. jacobi, C. minor and C. gossypii. Adults are small, soft-bodied insects. Winged or wingless, they may be green yellow, pink, white, bronze, dark-brown or black. These insects tend to congregate on the underside of leaves, where their feeding causes the leaves to curl downward and be deformed. Root aphids have been found on rare occasions.There are multiple generations per year and populations can build up rapidly to damaging levels.
Damage: Aphids feed on leaves and succulent new growth.
Damage occurs primarily when aphids transmit viruses (see below) from infected to non-infected plants. When present in great numbers, feeding can result in stunted, malformed plants.
(photos from Ontario Crop IPM and NCSU: Left, aphids on new leaf; middle, aphid debris and honeydew on older leaf; right, root aphids)
Management
Monitoring: Monitor by checking plants for signs of aphids when sampling for other key pests starting when growth begins in the spring.
Control strategies
Cultural/Biological:
*= Restricted Use Material, ⊗= OMRI approved for Organic Production
Not all available formulations are listed. See the current New England Small Fruit Management Guide for application rates and additional information. Read labels thoroughly for application rates and restrictions (REI, PHI, etc.)
Strawberry Mottle Virus and Strawberry Mild Yellow Edge Virus
(Angela Madieras, PhD - UMass Extension Diagnostic Lab)
(photos by Dr. Frank Louws at North Carolina State Univ.)
Strawberry viruses can cause significant crop loss, particularly in areas where strawberries are grown as perennial crops. Recently, Strawberry mottle virus (SMoV) and Strawberry mild yellow edge virus (SMYEV) have become pathogens of special concern for growers in the northeastern US. In a recent survey of 11 viruses in field-grown strawberries from throughout the US and Canada, SMoV and SMYEV were the viruses most frequently detected in plants from the Northeast.
Symptoms
SMoV alone can cause up to 30% reduction in yield and runner production; however, strawberry plants infected with a single virus seldom display visible disease symptoms. Symptoms can be severe when plants are infected with both viruses, or in multiple infections with other viruses. These symptoms may include stunting, chlorosis and/or necrosis on newer leaves, reddening of older leaves, leaf distortion, and diminished yield.
Transmission
The strawberry aphid, Chaetosiphon fragaefolii, is the major vector for both SMoV and SMYEV. Chaetosiphon jacobi and C. minor may also transmit both viruses; in addition, C. gossypii can transmit SMoV. Strawberry aphids overwinter as black, oval eggs up to 0.5 mm in length on the undersides of leaves close to the ground. Once hatched, nymphs will move to younger leaves. Nymphs will mature and begin giving birth to live young within about two weeks. As the population increases, adult aphids will grow wings and become more mobile, enabling them to spread viruses further.
Although they are both transmitted by aphids, these viruses have different relationships with their vector. SMoV is transmitted in a semi-persistent manner. The virus enters the aphid’s foregut, but not the hindgut. It does not reproduce inside the vector. Aphids acquire the virus within minutes of beginning to feed on an infected plant and can transmit the virus for 2-3 hours. SMYEV is transmitted in a persistent manner. The virus enters the aphid’s hindgut and can reproduce there; the aphid therefore remains infective for the span of its life. Aphids pick up the virus from infected plants in about 2 hours and can transmit it to uninfected plants after 8 hours.
In addition to aphids, both viruses may also be spread through propagation and dissemination of infected plant material. All species of Fragaria are believed to be susceptible to both viruses.
Management
