Cause Beet western yellows virus is an increasingly significant pathogen in western Oregon. The principal vector is the green peach aphid, Myzus persicae, although other aphid vectors are likely. After acquiring the virus from infected plants, aphids may retain for life the ability to transmit virus. An enormous number of crop and weed species are susceptible to the virus; thus the natural inoculum reservoir is hardly avoidable. Crops commonly infected in western Oregon include beet (table and sugar), broccoli, most clovers, mustard, lettuce, pea, radish, spinach, Swiss chard, and turnip. Weed species commonly infected in western Oregon include burdock, Canada thistle, cutleaf geranium, dog fennel, groundsel, pigweed, redstem filaree, clover, and wild mustard.
Symptoms Leaves turn yellow prematurely, typically beginning at the margins and progressing in; veins and midribs tend to remain green. The oldest leaves tend to yellow first. Yellows symptoms progress up, resulting in reduced and abnormal growth.
- The variety 'Salinas' is tolerant. Attempts are underway to identify other lettuce varieties and breeding lines that are both suitable to the Pacific Northwest and resistant to this virus. No other control measures are considered practical.
Reference Hampton, R.O., Keller, K.E., and Baggett, J.R. 1998. Beet western yellows luteovirus in western Oregon. Plant Disease 82:140-148.