Aftermath of the summer floods

Claines Canna Collection, September 2007

Now that mid-September has arrived, the travails of the early summer have now almost been forgotten. They will go down in folklore, and many lessons have been learnt. Perhaps the greatest lesson of all is related to the preceding article, the identification of Canna virus. I do not like to think how many cultivars I have despatched from this life, believing them to be contaminated with virus. The effect of very poor light conditions for a prolonged period have made me realise that very often that is the only problem. Also, surprisingly, when such foliage is again exposed to high light conditions the quality of the existing leaves also improves.


There were two plants that I suspected of having virus, and sure enough, they are the only two in the collection that have failed to produce new, good foliage now that sunlight has been restored again.

Claines Canna Collection, September 2007

The only long-term problem is this years seedlings. Four hundred seedlings and no more than 15% have so far flowered. If the Indian summer we are currently enjoying lasts for another few weeks then we may see 80-90% in flower before the frosts close the Canna year.

Canna yellow streak virus

Keith Hayward of Hart Canna, the UK National Canna Collection, has reported to the International Canna Group that the formal report on this new canna virus has now been published: "Archives of Virology" (2007) 152: 1527-1530. "Canna yellow streak virus: a new potyvirus associated with severe streaking symptoms in canna" WA Monger, V Harju, SE Seal, RA Mumford. You can read a summary on the website http://www.springerlink.com/content/0304-8608, though to download the full article you need to be a subscriber.

Keith provided the Central Science Laboratory with most of the diseased and healthy stock, and so the author has kindly sent him a reprint, which Keith is kindly sending a copy on to us as well.

They say that there are now 5 viruses which are known to infect cannas:

1. Canna yellow streak virus CaYSV (the new virus)
2. Canna yellow mottle virus CaYMV
3. Bean yellow mosaic virus BYMV
4. Cucumber mosaic virus CMV
5. Tomato aspermy virus TAV
   

Test results

They screened 14 samples for each of the 5 viruses.

• 7 samples were showing severe symptoms of virus disease and 7 looked healthy.
• CaYSV was detected in all the 7 diseased-looking samples.
• Of these 7 diseased-looking samples, 3 were also infected with CaYMV and 2 were also infected with BYMV.
• 2 of the 7 diseased-looking samples were infected only with CaYSV.
• 2 samples that looked healthy were infected with CaYMV.
• No sample that looked healthy was infected with CaYSV.
• None of the samples tested positive for CMV or TAV (by ELISA).

It therefore seems that, in these tests, the predominant cause of severe visible symptoms of disease was the new virus CaYSV.

They say that the closest relation in the virus world to CaYSV is the Johnsongrass mosaic virus JGMV which infects grass and cereal crops in Australia and the USA.

Keith said that he is hoping that the CSL will continue to do research on canna virus.

A revelation

An interesting new angle is that, this year, Keith was sent 5 rhizomes of C. tuerckheimii collected in the wild in a distant part of Belize, with no other cannas for miles. When he grew them, guess what? They all had rampant virus disease! So, virus is not just a disease of cultivated canna, it also exists in the wild.

Now we are starting to understand the problems...

Luther Burbanks first Canna

Garden and forest. / Volume 9, Issue 432. [June 3, 1896, 221-230]

Correspondence.
A New Hybrid Canna.

To the Editor of GARDEN AND FOREST: Sir, - During a recent visit to Santa Rosa, California, I called upon Luther Burbank, and among other things was shown a new hybrid Canna which, when introduced, will probably create as great a sensation as Madame Crozy did. This plant is not a seedling of the well-known strains so deservedly popular, but is a hybrid between Madame Crozy, which has so long been the standard of excellence, and Canna flaccida. Canna flaccida is a native of Florida, of a dwarf habit, and not a strong grower. Its exquisite light yellow flowers would, in spite of these defects, give it a high place in the garden were they not so very ephemeral. So frail and fleeting are they that an hour in the morning often measures their term of existence. I remember well that it was days before I got a sight of the flowers on a blooming plant of my own. The flower of C. flaccida is unique among Cannas in having something of the grace of an Iris and a peculiar silvery sheen that is very beautiful.

For years Mr. Burbank has been trying to make a cross in which some of these fine qualities of Canna flaccida might be united with the vigor and lasting qualities of the Crozy strain, but while many seedlings were grown and bloomed, all, with a pertinacity which is so often the despair of the hybridizer, followed one of the parents, and that Madame Crozy. Last summer, in the third generation of hybridized seedlings, the new seedling appeared, and any one knowing Canna flaccida would have instantly recognized its parentage. Only a single seedling among thousands, yet Mr. Burbank feels that it well repay the trouble. In the new and as yet nameless Canna are united, happily, the Iris-like form, the satiny sheen and the large size of flower of Canna flaccida, while the Crozy blood, giving to the plant a vigor of growth even surpassing either parent, and a lasting quality to the flowers about the same as Crozy possesses, is only apparent in the coloring in a lemon more intense than in flaccida, and a few reddish spots in the throat.

A marked feature of the new race is the development of some of the minor petals which in the Crozy strain are all but rudimentary. In the new Canna they are broad and flat, giving a bold fullness of outline until now quite unknown in Cannas. Considering the predominance of Canna flaccida in this seedling, the most critical point is its keeping qualities. In this regard it is not quite the equal of Crozy. The flower opens up a clear lemon-yellow never before known in Cannas, and is unspotted, except for a few dots well in the throat. With age it becomes lighter in color, and in ordinary weather will last about as long as Madame Crozy, and I think for exhibition it is superior to any other Canna. The foliage is of a light green, the growth a little stronger than that of Madame Crozy, the flowers well carried above the leaves and somewhat larger than those of the Crozy type. The breadth of petal in the new strain is a marked feature which we can expect future hybridizers to still further develop.

Ukiah, Calif. Carl Purdy.

An interesting link to Mr Carl Purdy, a notable gardening authority.

What is of particular interest here is that Luther Burbank did not show Purdy his Canna 'Tarrytown', which in Burbanks writings he states was developed at the same time. But, as we also keep many new cultivars to ourselves until we are sure about their worth, I am not at all critical. Burbank welcomed Purdy and gave him access to C. 'Burbank', as the one he describes here was later named, when released officially in 1897.

Worst summer ever - official

This summer appears to have been the wettest since rainfall records began in 1914, according to provisional data from the UK's Met Office.

Britain had 358.5mm of rain, just beating the 1956 record of 358.4mm.

The main reason for the high rainfall has been the unusually southerly position of the jet stream, a band of strong winds high in the atmosphere.

Following earlier floods in central and southern England, five areas of the country are still on flood alert.

The record rainfall was driven by conditions in England, where the downpour surpassed all other recorded years by a substantial margin.

Summer of disappointment

"These figures confirm what most people have already been thinking - this summer has been very wet and very disappointing for most," said the Met Office's head of forecasting.

While it has been wet, the summer has been distinctly average in terms of temperature. June, July and August saw a mean temperature of 14.1C, almost exactly the average for summers since the 1970s.

The jet stream, a ribbon of very strong winds about 10km up in the atmosphere which brings weather systems to the UK, has been much further south and stronger than usual this summer. This has brought depressions across many parts of the country.

How are Cannas surviving?

So, way out of their natural area, how are Canna surviving in this turbulent, dysfunctional climate? Surprisingly well, as it happens.

Not only did our Cannas suffer too much water, and no oxygen at root level with the swamped soil, but they also had very little light. Cannas rely on light to power their leaves, the world's best starch producing engines, into producing starch that will be accumulated down at root level to produce the famous Canna rhizomes. Without light the engines merely ticked over occasionally when the conditions allowed.

Many other plants have just given up on 2006, however Cannas have stuck in there and now there has been a few weeks of sunshine and warm temperatures they are producing good quality foliage and bursting into flower, albeit a month late! Of course, it is heartbreaking to see Cannas only half the size that they should be, but the majority have now reached a decent size, albeit very few are their normal size. All the mature Cannas have flowered now, which is also pleasing.

However, the Cannas that have suffered most are this years seedlings. I would estimate that no more than 2-3% have flowered yet. Many are in the process of producing flower spikes, but will not open for several weeks. Others are still growing foliage and will not flower this first year. That means that very few can be disposed of this Autumn as not being special enough to grow-on, which in turn means major storage problems over the winter, as we have over 400 seedlings growing this year.

Anyway, we are just grateful for what we have and we will have to use our ingenuity to overcome the winter storage problems. So what has the photograph at the top got to do with the summer weather? Nothing really, other than this is an old cultivar that we collected this year from a collector in Italy, and we really like the photograph!