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How to Manage Pests
UC Pest Management Guidelines
Floriculture and Ornamental Nurseries
Phytoplasmas and Spiroplasmas
(Reviewed 1/02,
updated 12/98)
In this Guideline:
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SYMPTOMS
Symptoms of phytoplasmas (previously known as mycoplasmalike organisms)
and spiroplasmas include yellowing and dwarfing and the abnormal production of shoots. Flowers may not develop normally and are
often replaced by green leafy structures.
COMMENTS ON THE DISEASE
Phytoplasmas are minute organisms, somewhat smaller than bacteria. They
do not have a cell wall as do bacteria. The cytoplasm is bounded by a
three-layered membrane.
For many years aster yellows phytoplasma was considered a virus. This
phytoplasma is vectored by leafhoppers, in which it can multiply, and has a very wide host range. In
general, phytoplasmas are vectored by leafhoppers, plant hoppers, and
psyllids and invade the phloem of infected plants.
Spiroplasma citri has been cultured in artificial media while
aster yellows phytoplasma and several other important plant phytoplasmalike
organisms have not been fully characterized.
PHYTOPLASMALIKE ORGANISMS
| Virus |
Transmission |
Ornamental hosts |
Crop plant hosts |
Weeds and native plant hosts |
Aster yellows
(aster yellows phytoplasma) |
leafhoppers |
alyssum, calceolaria, calendula, china aster, chrysanthemum, cineraria,
daisies, delphinium, gladiolus, gloxinia, gypsophila, larkspur, petunia,
statice, sweet william, tagetes, veronica, zinnia, and many others |
buckwheat, carrots,
celery, lettuce, onion, parsley, parsnip, potato, safflower, spinach,
tomato, and many others |
California poppy, dandelion, plantain, and many others |
![[UC Peer Reviewed]](/IMAGES/logo-ucpeerreviewed.jpg)
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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