Canna 'Panache'
In this type of canna (derived from Canna glauca), infection can be seen as discolored stripes in the leave.
One should see it more or less in every leave, because sometimes a problem with the production of chlorophyll can happen.
Closely inspected, as can be seen in the photo, the discolored zones consist of small and sharply delimited lines;
Also the leaves more quickly develop brown edges. The plant grows to it's normal height.
We suspect it's the cucumber virus.
To inspect it is best is to hold the leave against the sun.
The healty leave has 2 raindrops on it, and shade from the sun and the way the leave curls.
It's quite easy to fool people photographing plants, so do you want perfection? Here it is.
Some canna's bred from seed
Sown and grown in the same conditions, these seeds produce a marked difference :
On the left from a Belgian supplier ; the plants have inhibited growth, disformed leaves.
On the right the tall canna's (here Canna 'Burgundy Blush') from seed, bought from Karchesky Canna, USA
So we're convinced a virus can spread through seedlings.
We have no evidence of a virus spreading through the air.
Canna 'Pretoria' (Bengal tiger)
This is what we call 'rust', because there is a brownish layer, likely dead material on top of the leave.
It does not harm the plant, not all the leaves show these signs, but we disgard them, suspecting it's a virus that can spread.
We're uncertain it isn't sunburn, but can exclude burn from cold, very low temperatures. We see all canna becoming ugly when temperatures dive under 7° Celsius (45° Fahrenheit).
Canna Pretoria is variegated, and as you can see, this isn't always very 'evenly'; the lines can be dotted, having a wide range of different amounts of chlorophyll.
The damage makes the variegation less pronounced.
This canna is at it's best in light shade, only few direct sunlight needed.
It was planted in a classic container.When taken out of this container we noiticed a loot of ants, and a quick research made us suspicious of aphids feeding on the roots.
Canna has 'juicy' roots, because it's a plant for wet conditions.
Here's a small photo of how the leaves look. Again, it's quite unlikely that it's a virus, it's an insect! Click to enlarge in a new page.
So now we know why in 2009 a lot of cannas had this problem, and why they do not suffer in our pots. Classic containers are open, drained, so everybody can live happily between the roots.
our pots are closed, not drained, so have worse conditions for insects between the roots.
Canna 'Durban' (Phasion or Tropicanna)
Is this difference in leaf a sign of infection?
Perhaps, but in the year 2007 this plant was in the same pot as the 'Panache', and only 'Panache' survided the winter.
In 2008 the 'Panache' shows no signs of infection. This contrary to the expection of being planted with an infected one,
the roots intermingled.
So we suspect that this 'Durban' is variable in its appearance. Also we see that it depends on the shoot ;
- one has the marvelous look, and the leaves turn to more greenish when they get older,
- the other shoot has this more 'spotted' look, and that stays.
We have this canna already 3 years, and it's every year the same.
We suspect that all illness, appearance is blamed by a virus, while this proves that a cultivar can be a bad one. We see this also in the seeds we bought.
We do not know if these 4 examples illustrate the same infection, because the effects differ greatly.
Damage can also be due to excessive sunlight, too cold, wind.
It is also reported that aphids may cause an infection, when they are flown in with the wind.
Although flowering is important, also the overall look of the plant is essential.
Too many websites only show flowers of a certain cultivar, and we discard them because they don't give any idea of how the plant looks, of perhaps a genetically inferior look, an illness.
To the page with a description of all our cannas