Beet western yellows virus

Symptoms

On Winter Oilseed Rape

In late autumn, the first symptoms are visible as anthocyanous and/or red discoloration at the margins and tips of leaves. Following a mild winter or early spring infection, plants show conspicuous anthocyanous discoloration of whole leaves. The symptoms are most obvious before stem extension. After stem extension, the newly developed leaves show no discoloration, but the TuYV-infected plants have reduced growth and fewer lateral shoots. Later in the spring and early summer, especially after a period with temperatures above 25°C, strong reddening is again visible on many plants.

On Other Crops

More conspicuous symptoms may develop on some other susceptible crop species. Infected turnips develop a yellowing or reddening of the outer leaves, gummosis of the phloem, starch accumulation in the shoots, and growth is reduced to about one-third of uninfected plants.

Infected radish and cress exhibit conspicuous yellowing and sometimes growth reductions.

Infected lettuce shows interveinal yellowing on the outer and sometimes middle head leaves; for this reason, the disease was known for many years in the UK as 'June yellows'. Growth is also reduced.

On spinach, the damage is characterized in overwintering fields by losses of plants, reduced growth and gradual yellowing of diseased plants, depending on the susceptibility of the cultivars
Strong reddening and growth reduction are visible on the winter and summer forms of false flax (Camelina sativa).

On Weed Hosts

Most weed hosts express symptoms of yellowing/reddening of older leaves and/or stunting in the autumn and spring when infected by TuYV in early autumn.