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Rhododendron bud Blast is a fungal disease of
Rhododendrons and Azaleas, affecting the tight dormant flower buds. The
disease if more noticeable in the spring, when buds will be dark brown
and normally covered in small black hair-like growths of the fungus
disease.
The affected Rhododendron or Azalea buds will be firm
to the touch, unlike those brown buds which are sometimes associated
with either severe frost damage, or lack of water in important
July-September growing months of the previous year. The brown buds on
Rhododendrons and Azaleas caused by the bud Blast fungus are beyond
cure. They should be picked off and destroyed as soon as found, for the
fungus spores can live on the dead bud for up to three years. Any insect
visiting the infected bud is then a potential carrier for the disease to
other healthy buds.
The fungus spores are thought to be carried by the
Rhododendron Leaf Hopper, which lays it's eggs in the Rhododendron and
Azalea buds in late summer. The entry point is then open for the spores
to enter, or possible be carried in during the egg laying process.
Rhododendron Leaf Hoppers are active during late summer and early
autumn. If they are present, then a contact spray of Bifenthrin, or a
systemic spray of Provado should be applied. Other pests may also cause
enough damage for the fungus spores to enter, so routing spraying is a
good idea where there are problems with Bud Blast.
Any brown or otherwise discoloured buds should be
removed as a matter of routine and burned.
Rhododendron Bud Blast was at one time confined to SE
England, but cases have been recorded outside this area in recent years.
Possibly as a result of the milder winters. |
