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Phyllody

GARDEN BAD GUYS - PHYLLODY
by Nanette Londeree, Master Rosarian

You have a perfect rose – the long stem with the shapely bud looks like it could be a prize-winner, though by the time of the show, it may have to be exhibited as fully opened. So you plan accordingly and the flower opens, and ……what in the world is that????? Where you normally would have a boss of golden stamens, you have something that looks like a creature from outer space! What in the world is happening?

More than likely, your rose isn’t sick. The weird looking mass growing in the center of the rose is actually altered plant forms. The rose is exhibiting phyllody, pronounced fil-o-dee - a condition in which the floral part of a plant forms leaf-like structures. This condition can produce all kinds of different formations from the unusual growth of the stamens into stunted, thickened leaves, to a new stem and leaf growing right out of the middle of the plant! A single bloom might be affected with this malady while all other roses on the plant have a normal form. It may impact multiple roses, and in some cases, it may affect all the blooms on the plant. All other aspects of the plant look perfectly healthy. Some roses routinely exhibit phyllody, probably due to genetic susceptibility. The rose photographed above is ‘Eurostar’, and all the blooms have this characteristic appearance. If you’ve seen the “Green Rose” R. chinensis vividiflora, it has a stable mutation causing phyllody in all its flowers.

These strange and generally unsightly flowers are formed when plant hormones are out of balance. The imbalance may be a result of environmental conditions (often found in roses during hot weather), water stress, insect damage, and infection by viruses and phytoplasmas. Phytoplasmas are specialized wall-less bacteria that are parasites of plant tissue and some insects. They can have profound effects on the hormone balances in their hosts, affecting the appearance of leaves, petals, and other organs. Insects, most often leafhoppers, can spread these diseases so the appearance of phyllody in the garden may impact more than just roses. The viral disease Rose rosette, exhibits symptoms of reddening or witches’ broom of the foliage and phyllody. While there are many possible causes for phyllody, in most cases it is a result of environmental conditions and not disease.

To help determine the cause of phyllody in your roses, it’s beneficial to observe the plant throughout the year. See if the conditions appear only during hot weather then disappear, or if they are sustained. Also, assess whether the plant is otherwise vigorous and healthy, and if any adjacent roses also exhibit the abnormality. If it appears to be an isolated case, then an individual flower may be responding to specific environmental conditions, not a serious disease. If all the blooms on a plant exhibit phyllody, it may be genetically susceptible. If you observe multiple plants in close proximity being affected, then it’s time to look more closely at what type of stresses may be impacting the plants and correct them.

Photo by Nanette Londeree.


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Last Modified: 08/06/2013