From: pharvey@quack.sac.ca.us (Paul Harvey)
Subject: Re: Hardy Citrus was List of cold climate gums
Organization: The Duck Pond public unix: +1 408 249 9630, log in as 'guest'.
	<fVyZc6b@quack.sac.ca.us> <1992Nov23.041926.11953@sserve.cc.adfa.oz.au>
Date: 23 Nov 1992 22:27:26 UTC

In article <1992Nov23.041926.11953@sserve.cc.adfa.oz.au> 
rim@csadfa.cs.adfa.oz.au (Bob McKay) writes:
>The more we discuss this, the more puzzling it gets. I'm starting to think
>the mercury in our thermometers here must be upside down! Assuming the
>temperatures Paul quotes are air temperatures, rather than ground temps
>(which can be significantly colder), the table mostly fits the Oz experience. 
>But there's one exception, lemons, which as I mentioned, are considered 
>relatively hardy here, despite minima down to around 21F most Winters, and 
>extremes down to around 16F. It may be partly varieties (Meyer, the one
>mentioned, originated in Canberra), but other varieties, while not so hardy,
>are still regarded as hardier than mandarins, grapefruit or oranges. Anybody
>have an explanation??

Well, who knows. They say that east is east and west is west and never
shall they meant. Maybe it should be north and south instead. Anyway,
Meyer is not a commercial variety but it is a common home variety
because it is the most cold tolerant of the true lemons (C.limon). If
Meyer originated in Canberra as you say, you might have a selection that
is most hardy in Canberra but differs elsewhere, who knows why. Here is
some more data from Sunset Guide to Western Gardens (ISBN:0-376-03889-6):

Hardiness: Citrus of one kind or another are grown in every Arizona and
California climate where winter temps do not fall much below 20oF. From
least hardy to hardiest they rank generally in this order: Mexican or
Key lime (28oF), limequat, grapefruit, regular lemon, tangelo and
tangor, Bearr's lime, sweet orange, most mandarin oranges (tangerines),
Rangpur lime and Meyer lemon, Owari Satsuma mandarin, sour orange,
kumquat, calamondin (20oF).

Improved Meyer: By law, this strain replaced the old-friend variety
Meyer in 1978. It supposedly has more resistance to infection and virus
diseases. Other than that, it should be like the original. Fruit is
quite different from commercial lemon - rounder, thin skinned, more
orange-colored. Tangy aroma, very juicy, but less acid than standard
lemon. Bears fruit all year round, at early age. Tree is not a dwarf on
its own roots. Will grow to 12ft with a 15ft spread. On dwarf rootstock
it's half that size.

----
Actually, Cali is a leader of citrus plants and buds in the world and
someone discovered that we have a common virus here that doesn't affect
the plants much in Cali, but may in other climates. Viruses are not at all
cool amongst commercial growers and propagators, so Cali Improved Meyer
is a virus-free selection of Cali Meyer and by law is the only one that
can be commercially propagated in Cali. If Cali did not take this step
to insure that all strains propagated are free of all viruses, they
would have been banned from most if not all of the other commercial
citrus areas. Viruses are as dangerous amongst plants as they are
amongst humans. Yet another reason to follow plant importation laws when
moving plant material from region to region.