Friday, 18 September 2009

Can you see the mountain?

As a boy when I lived at home in Norway there was a joke that if you could see the mountain it was about to rain, otherwise it was raining! OK, not very original, but at least we did not have to suffer Arthur Askey! (US readers will probably not understand that reference to a busy bee). Well, this weather here in the mid-west of England is getting beyond a joke. I’m beginning to reconsider that it must be the global warming thing. The weather is so unpredictable.

If you think about it, extra heat causes extra evaporation from the sea causes extra rain. Now I’m sure some scientists are jumping up and down shouting ‘Idiot!’ but you can’t get away from the fact that we’ve had years of summers more like monsoons.
It seems that we do get some dry-ish weather and the moment I think I can head for the main Canna collection beds, down comes some more rain. Anyway, we managed to grab a few hours down there today, but we have already has 3 weeks of high winds that are violently draining all moisture from the ground and foliage, so much that my bean crops have stopped growing 3 weeks earlier than normal. Digging shows no water for 6" down into the soil, in spite of the rain showers.

Really, it was quite depressing in Cannadom. Nothing has grown to its full height, there is very little seed to collect and everywhere there is poor foliage. We have had a couple of weeks of half-decent sunshine and the later leaves that have unfurled are showing good healthy photosynethis and show no signs of stress markings, unlike those for the previous 6 weeks which sometimes did not have the energy to unfurl themselves and displayed signs of chlorosis. We had to manually unfurl the leaves to enable the growing point to continue upwards and not just rot inside the unfurled leaf. The resultant leaf is a mixture of green and yellow and often looks like it has virus. Maybe it has, and the lack of vitality that stops the unfurling of the leaves is due to that cause, or just as likely its the lack of light causing stress in the affected plant, which can't then unfold it's leaves. Sending to the labs will establish the cause, visual inspection is not enough.

With every other genus people accept that lack of light causes foliage damage, but in Canna there is a vocal minority who cannot acknowledge that poor light causes foliage stress, even though all learned treatises for 150 years state that Cannas must have their 8 hours of light every day. It beggars belief! If they don't get their 8 hours of light, what do they do? Start dealing cards and join a poker school? Of course not, they display stress through the only mechanism they have, i.e. their leaves. Now they have a limited vocabulary and such stress can easily be mistaken for one of the few virus types that affect Canna foliage. 

The defintion of chlorosis is "The loss of chlorophyll from the tissues of a plant, resulting from microbial infection, viral infection, the action of certain phytotoxins, the lack of light, to magnesium or iron deficiency, etc. Chlorotic tissues commonly appear yellowish. "

Lack of light, infection, and mineral deficiencies causes chlorosis. Can you see the mountain?

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