Virus Decline

Are your strawberry plants looking pitiful? Do they fail to produce big, luscious fruits? It may be virus decline.


Causes of virus decline

Virus decline is a combination of viruses. It starts with either strawberry pallidosis-associated virus (SPaV) or Beet pseudo yellows virus (BPYV), spread by whiteflies. Then aphids come along with any of these other viruses:

• Strawberry crinkle
• Strawberry mild yellow edge
• Strawberry mottle
• Strawberry vein banding

Strawberry latent ringspot and Fragaria chiloensis latent viruses may also play a role. Research is currently underway.


Virus decline symptoms

Because virus decline is a combination of infections, plants may look fine one day and terrible the next. Initial infection of SPaV or BPYV may cause no symptoms. Add the second virus, and everything starts to fall apart.


Plants infected with virus decline will exhibit stunting, sometimes severely. Leaves turn purple or red, though new growth that forms near the center of the plant may remain green. There is little or no fruit production, and the roots are brittle and reduced. These plants will never be productive.


Control of virus decline

The only way to know if your strawberry plants have virus decline is to send a sample in for lab testing. County Agriculture Offices may offer this service free of charge. Either way, declining plants are best removed and replaced, preferably in a new location.


One way to reduce the likelihood of virus decline in your strawberry patch is to keep other plants that might host these viruses at a safe distance. The SPaV virus favors specific weeds, including nettle, creeping sibbaldia, mock strawberry, sharp leaf groundcherry, and cheeseweed. BPYV prefers melons, squashes, lettuces, cucumbers, endive, and spinach. Cheeseweed, dandelions, marigolds, and zinnia may also harbor BPYV.


Use these tips to reduce the possibility of virus decline in your strawberries:

• Buy certified pest- and disease-free plants.
• Quarantine all new plants.
• Control whiteflies and aphids.
• Remove nearby weeds.
• Plant strawberries away from potential host plants.

These steps are no guarantee, but they will significantly reduce the chance of your plants becoming infected.