Ornamental
& Tree Diseases
Plant Disease Dispatch Sheets
September 25, 1997
M-302 - Diseases of Aucuba
Aucuba (Aucuba
japonica) is an evergreen shrub that grows well in deep shade.
The variegated-leaf ("gold dust") varieties are commonly used in
southeastern landscape settings. Although relatively problem free,
there are two common diseases associated with Aucuba in Mississippi.
- Leaf Spots
Several fungi (Alternaria, Phyllosticta, and Colletotrichum)
commonly attack Aucuba throughout the growing season, causing large
irregular spots along the margins of the leaf. These spots are often
large and may be up to two inches in diameter. In most instances, leaf
spot diseases of aucuba are associated with plants weakened by poor
fertility, drainage problems, or from root decay. Prune out as much
of the diseased plant parts as possible and spray with a broad spectrum
fungicide such as maneb, chlorothalonil, or captan. These fungicides
are available under a variety of trade names; check with your garden
supply store for product availability. Be sure to follow label directions.
- Root Rot
A number of soil fungi attack the root system of Aucuba causing severe
damage. The leaves begin to yellow from the base of the plant upward
and usually the tips of the leaves are severely burned. This burn
at times may involve the entire leaf. This disease is much more
severe in poorly drained and waterlogged soils. Control involves
improving the soil drainage wherever possible and drenching with
a soil fungicide such as Terraclor 75WP (PCNB) or captan. Make
sure the soil crust is broken beneath the plants so the fungicide
will penetrate down into the root zone of the plant. Water the
fungicide in with at least 1/4" of water.
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