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How to Manage Pests
UC Pest Management Guidelines
Floriculture and Ornamental Nurseries
Phytoplasmas
(Reviewed 3/09,
updated 3/09)
In this Guideline:
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Symptoms of phytoplasma (previously known as mycoplasmalike
organisms) diseases include yellowing and dwarfing, distorted foliage, and the abnormal production of
shoots. Flowers may not develop normally and are often replaced by green leafy
structures.
Phytoplasmas are microscopic organisms
that are 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 the 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.
| 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
S. T. Koike, UC Cooperative Extension Monterey County
C. A. Wilen, UC IPM Program, UC Cooperative Extension San Diego County
Acknowledgment for contributions to Diseases:
R. D. Raabe, (emeritus) Environmental Science, Policy, and Management (ESPM), UC Berkeley
A. H. McCain, (emeritus) Environmental Science, Policy, and Management (ESPM), UC Berkeley
M. E. Grebus, Plant Pathology, UC Riverside
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