Yellow Speckling on Canna Leaves - Ask Extension
We moved to Houston from the Northeast two years ago. Our ornamental garden is one year old. Even before we put it in last summer, someone gave us Can...
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Yellow Speckling on Canna Leaves #255459
Asked June 19, 2015, 12:53 PM EDT
We moved to Houston from the Northeast two years ago. Our ornamental garden is one year old. Even before we put it in last summer, someone gave us Canna plants to transplant, and they are spectacular - the best thing in the garden. We now have about five clumps of them along a 30-foot stretch. Suddenly, the leaves on plants in one clump have begun exhibiting yellow speckling. They seem to discolorations in the leaves themselves, although sometimes when I shake a leaf yellow powder or dust seems to fall. The stuff is also on the stems (at the bases, mostly). I am wondering if it is a fungus that then discolors the leaves, or what. Initially, it was pretty heavy but confined to one bunch of plants. This morning I noticed traces of the stuff on other bunches. In researching, I've found a virus that produces yellow streaking but not speckling. Can you tell me what it is, whether it is serious and what to do. Photo attached. Thank you.
Harris County Texas
Expert Response
Your plant has canna rust,
a fungus resulting in orange spots on the plant’s leaves. With all the rain that we've had this spring conditions are ideal for canna rust. Rust infestation is facilitated by high humidity and high
soil moisture. The fungus can affect both the foliage and
the flowers. An orange rust often appears on the leaves
and stems of the plants. These are the fruiting bodies of the fungus. When this rust
first appears, the foliage that is infected must be removed
and discarded. If left there, the fungi will be allowed to
propagate.
Provide good air circulation and avoid long periods of leaf wetness, remove and destroy infected leaves, and if necessary protect remaining foliage and plants with fungicides, rotating between contact and systemic materials. Contact materials for rust management include mancozeb, chlorothalonil or coppers. Systemic materials include myclobutanil, kresoxim-methyl, triadimefon, triflumizole, azoxystrobin, trifloxystrobin, or pyraclostrobin. Read and follow label directions before applying any pesticides.
Thanks for the question.
Provide good air circulation and avoid long periods of leaf wetness, remove and destroy infected leaves, and if necessary protect remaining foliage and plants with fungicides, rotating between contact and systemic materials. Contact materials for rust management include mancozeb, chlorothalonil or coppers. Systemic materials include myclobutanil, kresoxim-methyl, triadimefon, triflumizole, azoxystrobin, trifloxystrobin, or pyraclostrobin. Read and follow label directions before applying any pesticides.
Thanks for the question.
