Ornamental & Tree Diseases
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.