Was Edible Bulbs - Allium, now crop rotation

Rodger Whitlock totototo@telus.net
Sun, 06 Nov 2011 12:32:02 PST
On 6 Nov 2011, at 8:07, Peter Taggart wrote:

> I have been advised by another nurseryman that control of "ink spot" on
> reticulata Iris is only really achieved by replanting in fresh ground every
> year, (though I do feel from observation of reticulata Iris, that Ink spot
> primarily is brought about by irregular temperatures and periods of drought
> during spring growth )

Important to distinguish between "control" and "eradication". A great deal of 
the commercial reticulata iris stock is infected in ink spot disease. The 
growers keep it under *control* by using fungicides, but that does not 
completely eradicate it from the stock.

If you are raising reticulata irises from seed (and hence have absolutely clean 
plants), it would be a advisable to completely refrain from bringing commercial 
forms into your garden.

If commercial reticulata irises are irresistible but you don't want to 
introduce ink spot into your garden, you may wish to try eliminating it from 
newly purchased stock. Peel the tunics off the bulbs. Carefully examine each 
bulb and using a new single-edged razor blade, cut out any lesions you find. 
Use a magnifying glass if your eyesight isn't perfect, and take your time. Dust 
the wounds with sulfur. Plant the bulbs in new soil in a clean pot and grow on 
in the normal way. When the bulbs go dormant the next summer, repeat the 
process, and do so annually until your bulbs have been lesion-free for two 

Be careful that the tunics you remove, and slivers of bulb you have cut out, 
the razor blade you use, and the soil you have grown them in (for just one 
year) all go into the garbage, not the compost. Clean the pots with liquid 
chlorine bleach before re-use.

And don't forget to wash your hands thoroughly after handling the bulbs, also 
sterilizing any surfaces or containers they have rested in or on. 

I've tried this and even after just one growing season, the number of lesions 
on the surfaces of the bulbs is greatly reduced. I can't say that I ever 
followed through to completion, being impatient and rather careless, but I am 
certain I was on the right track.
Rodger Whitlock
Victoria, British Columbia, Canada

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