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How to Manage Pests
UC Pest Management Guidelines
Floriculture and Ornamental Nurseries
Calla (Zantedeschia spp.)
Disease Control Outlines
(Reviewed 1/02,
updated 1/02)
In this Guideline:
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Disease (causal agent)
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Symptoms
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Survival of pathogen and effect of environment
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Comments on control
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Crown rot
(Rhizoctonia solani) |
Base of stems of callas are infected at or below the
soil line, causing a general chlorosis of foliage. |
Favored by warm, moist conditions. Fungus is present
in most field soils. |
Avoid deep planting and overwatering. Treat soil with
PCNB before planting. |
Pythium rot
(Pythium ultimum) |
Roots may rot first. Pink and yellow corms develop irregular-shaped,
shallow, water-soaked lesions that may coalesce. Infection spreads
into interior tissues of root structures, producing irregular-shaped
gray lesions that are sharply delimited. |
Fungus enters root structures through wounds. It is
present in many field soils and has a wide host range. Disease is
favored by warm, moist conditions, heavy soils, and poor drainage. |
Avoid injuries. Clean and dry root structures soon after
digging. Store below 50°F. Some of the water mold fungicides
would probably be effective in controlling the disease. more
info |
Root rot
(Phytophthora cryptogea) |
Yellowing of leaf margins of outer leaves followed by
general yellowing and wilting. Feeder rootlets are rotted. |
Fungus is present in some field soils. Several other
types of plants may be infected. Favored by wet soil conditions. |
Grow on raised beds and provide good drainage. Do not
overirrigate. Treat with mefenoxam. more
info |
Soft rot
(Erwinia carotovora) |
A soft rot of the rhizomes. Plants may rot off at the
soil line. Bacterium is a common secondary invader of succulent plant
parts and generally requires some sort of injury to cause disease.
Has odor. |
Bacterium is present in some field soils. Favored by
warm, moist conditions and plant parts attacked by other organisms. |
Avoid injuries. Do not overwater. Yellow callas are
more susceptible than others, but there are new yellow cultivars that
are more resistant. |
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| Virus or viruslike diseases |
Symptoms |
Host range and natural spread |
Comments on control |
Dasheen mosaic
(Dasheen mosaic virus) |
Mosaic patterns in leaves, which may be severely distorted.
Infects plants low in vigor. |
Common because callas frequently propagated vegetatively,
which spreads the virus. Virus is also spread by aphids. Spread in
a planting can be rapid. Can be transmitted by sap but not by seed. |
Obtain or develop virus-free plants by heat treatment
and tissue culture. Control aphids. Eliminate infected plants. |
Spotted wilt
(Tomato spotted wilt virus) |
Foliage, petioles, and flower stalks are streaked or
spotted by whitish or yellowish areas, and sometimes by small, concentric
rings. Necrotic areas that develop in leaves may be colonized by secondary
fungi. Sometimes the necrotic areas are attributed to fungi, but usually
they are secondary invaders. |
Common because callas frequently propagated vegetatively,
which spreads the disease. Spotted wilt virus is also transmitted
by several kinds of thrips. Virus is acquired by nymphal stage and
transmitted by adult throughout its life. The virus has a very wide
host range including many weeds and ornamental plants. |
Control weeds and thrips. Destroy infected callas. |
Callas are also susceptible to leaf spots (Gloeosporium callae,
Coniothecium richardiae, and Cercospora richardiae), Armillaria
root rot (Armilliaria mellea), gray mold
(Botrytis cinerea), Phytophthora spp., seedling rot (Rhizoctonia
solani), southern blight (Sclerotium
rolfsii), and root knot nematode (Meloidogyne spp.).
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UC IPM Pest Management Guidelines: Floriculture and Ornamental Nurseries
UC ANR Publication 3392
Diseases
R. D. Raabe (emeritus), Environmental Science, Policy, and Management (ESPM),
UC Berkeley
M. E. Grebus, Plant Pathology, UC Riverside
C. A. Wilen, UC IPM Program, UC Cooperative Extension, San Diego Co.
A. H. McCain (emeritus), Environmental Science, Policy, and Management (ESPM),
UC Berkeley
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