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EASTERN GALL RUST
Spherical gall of eastern gall rust on the branch of a sand pine. Orange droplets are the pycnial spore stage of the pathogen which is seen only on rare occasions.
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| Pathogens: |
Fungus Cronartium quercuum |
| Common Hosts: |
Sand Pine Pinus clausa
Shortleaf Pine Pinus echinata
Other Pines Pinus spp. |
| Alternate Host: |
Various Oaks Quercus spp. |
Significance: |
Eastern gall rust is a very close relative of fusiform rust. Although many similarities exist between these two pine rust diseases, eastern gall rust is far less damaging than its fusiform rust cousin. Although occurring less frequently than fusiform, eastern gall rust is found in abundance on sand pine in Florida. It also occurs on shortleaf, loblolly, and slash pines. For the most part, eastern gall rust is of little economic significance. Stem and branch deformations resulting from infections may be a problem in some cases, however, especially in certain urban or shade tree situations. Occasionally stem or branch breakage may occur at the points of infection, often as a result of associated wood decay organisms. |
Recognition: |
This disease is most readily recognized by the distinct globose (spherical) to subglobose swellings or galls it produces on infected hosts. Galls may occur on branches or stems. Witches' brooms - proliferation of small branches - often accompany the galls. The production of bright yellow spore sacs (aecia) and their masses of yellow to orange spores (aeciospores) on the gall surfaces during the spring renders this disease quite striking. The distinctive spore sacs, together with the shape of the galls, sometimes results in galls being cerebroid or brain-like in appearance. This disease is most readily recognized by the distinct globose (spherical) to subglobose swellings or galls it produces on infected hosts. Galls may occur on branches or stems. Witches' brooms - proliferation of small branches - often accompany the galls. The production of bright yellow spore sacs (aecia) and their masses of yellow to orange spores (aeciospores) on the gall surfaces during the spring renders this disease quite striking. The distinctive spore sacs, together with the shape of the galls, sometimes results in galls being cerebroid or brain-like in appearance. |
Infection Biology: |
As in fusiform rust, the eastern gall rust fungus produces alternate infections between susceptible pines and a variety of alternate host oaks. For all practical purposes, the life cycles of the two different pathogens are the same (Figure 15). Eastern gall rust infections, in contract to those of fusiform rust, tend to be more localized, remaining restricted to the locus of initial infection. The eastern gall rust fungus is less apt to grow from an infected branch into a larger branch or main stem than is its fusiform counterpart. |
Control: |
Practical controls for eastern gall rust in commercial forest stands are few. Infected trees, especially those with infected stems, should be removed from pine stands during thinning operations where practicable. Pruning of infected branches may be useful in ornamental plantings. If nursery infections are a problem, the use of a appropriately registered fungicides should provide good protection for disease-free seedlings.
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Bulletin No. 196-A | Printed October, 1983 |
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Forest Health Section
