The main symptoms of WLD are spectacular, pure white
leaves. Heavily infested crops attract attention and it is
not difficult to spot these crops even when travelling past
at high speed. Initial symptoms consist of streaks along
one side of the younger leaves and some mottling – as
these develop, whole leaves may turn white. Generally the
younger leaves are affected first and diseased stools may
show white leaves in the spindle area, while older leaves
remain green.
When the disease is severe, stools become markedly
stunted and yield is greatly reduced. This leads to poor
rationing and failed crops. Advanced infestations are
characterized by very gappy crops and greatly reduced
yields. Yield losses can be 100%.
The differences between GGSD, GSD and WLD can be
summarized as: GGSD does not show any white leaves,
GSD has white leaves and grassy tillering, while WLD has
white leaves but does not lead to grassy tillers.