Cause Eleven reported viruses induce streak symptoms in peas. Alfalfa is the principal inoculum reservoir for streak-inducing viruses in eastern Oregon, eastern Washington, and Idaho. The two viruses that aphids transmit from alfalfa to peas are Pea streak virus and Alfalfa mosaic virus. Red clover is the inoculum reservoir for the principal streak-inducing virus of western Oregon and western Washington, Red clover vein mosaic virus. The pea aphid and probably several other aphid species can transmit all three viruses from reservoir hosts to peas.
Symptoms Gray, dark brown, or purple streaking of the stem. Leaves wither and die, and pods may be deformed. Plants may die back from the tip.
- Avoid planting peas near alfalfa, which is a reservoir for aphids and the virus.
- Removing volunteer red clover plants in pea fields in western Oregon and western Washington may be practical, but success depends on the incidence of red clover nearby.
Chemical control Controlling or reducing aphid populations does not control the viruses but may restrict their spread. See the PNW Insect Management Handbook for details.