Since the discovery of myrtle rust in Tasmania in February 2015, three species of plants have been confirmed as being susceptible to the fungal disease;
Lophomyrtus, Chilean guava and
Agonis flexuosa.
Lophomyrtus
Lophomyrtus, is a common hedge, screening and potted plant with common names including: Black Stallion, Red Dragon, Rainbow's End and Krinkly. The planting pictured below shows a Lophomyrtus cultivar, but each will differ with distinctive variegations in leaves and stems. Colours range from light to dark green, through to red, dark red, brown, crimson and black.
Cultivars of Lophomyrtus all have a similar look but will differ with each having distinctive variegations in leaves and stems, with colours ranging from light green, through to red, dark red, brown, crimson and black (Images by NRE Tas/S.DeSalis).
The images below show myrtle rust on
Lophomyrtus leaves (click to enlarge).
Myrtle rust lesion on the upper surface of a Lophomyrtus leaf
|
 Close up of myrtle rust lesion on the upper surface of a Lophomyrtus leaf |
Close up of myrtle rust lesion on the lower surface of a Lophomyrtus leaf |
All images by NRE Tas/Ziqing Yuan 2015
Chilean guava
Chilean guava (Ugni molinaea) is also know as TazziberryTM. Chilean guava shrubs have evergreen foliage, and reach a height of between 1-5 m. The leaves are oppostie, oval, 1-4 cm long and 0.2-2.5 cm broad, entire, glossy dark green, with a spicy scent if crushed. The flowers are drooping, 1-2 cm diameter with four or five white or pale pink petals and numerous short stemens; the fruit is a small red or purple berry 1 cm in diameter.
Chilean guava plant with fruit showing signs of myrtle rust
The images below show the bright yellow spores on the leaves and stems of Chilean guava. The bright yellow spores are quite visible during the warmer months and may turn to light grey colour during the cooler months (see examples of myrtle rust winter symptoms below in the section on Agonis flexuosa infections).
Chilean guava with close-up of myrtle rust on upper side of leaf
Chilean guava with myrtle rust on underside of leaf
Chilean guava with myrtle rust on stem
All images by NRE Tas/Ziqing Yuan 2015
Agonis flexuosa (After Dark)
Myrtle rust was detected on Agonis flexuosa (common name: Willow myrtle, with varietal names including "After Dark") at a nursery that was treated for the disease.
Similar to the myrtle rust infection detected in some Chilean guava plants (TazziberryTM), it is highly likely that the infection in Agonis flexuosa is due to cross-contamination from infected Lophomyrtus plants, which were detected and subsequently treated in March 2015.
Agonis flexuosa - After Dark (Willow Myrtle) Photo by L. Broos
The images below show myrtle rust as it may appear during the cooler months in Tasmania - in this example on the on leaves and stem of Agonis flexuosa (click to enlarge):
Grey necrotic lesions on Agonis leaves
Close up of the grey rust pustules on the surface of the lesion
Infected Agonis stems with grey rust pustules
All images by NRE Tas/Ziqing Yuan 2015