carissa macrocarpa

Forgot to pass on the details about C.macrocarpa's fate in the Dec. '98
California frost.  As you will remember a list member asked about how this
plant had fared.  Sean & I both mentioned a circular patch of these shrubs
on the University of California campus in Berkeley.  I related that I'd
remembered those plants from at least a dozen years previous--which meant
to me that they'd survived the Dec. '90 frost.
        According to Bob Cowden's article in Pacific Horticulture of a few
years ago I found that the low temp for the '90 freeze was 20 degrees in
Berkeley.  I don't have any official figures for '98 but based on what
Katherine Pyle and others reported I'd guess the low this time was around
26-28.
        With these details in mind I was confident as I slogged up the hill
toward the Education Library at Cal that I'd find the Carissa's with
moderate damage.
        Wrong.
        I found a bunch of stumps; little stumps that the grounds crew had
obviously made out of what was left of the plants.  I counted 24 remnants.
Three showed regrowth beginning.  The other 21...who knows?
        I also checked out a hedge of Carissa at a movie theater in
Emeryville, south of Berkeley.  They are on a south facing up against a
stucco wall, i.e. I'd bet the radiated heat kept those plants warm and
toasty while the campus shrubs got blasted.  These I found in near perfect
shape.  Like most Carissa's hereabouts(soil pH approx. 6.8) they are
showing extreme 'Lime Induced Chlorosis', aka iron deficiency.
        Does our S.African correspondent have any idea what the soil pH is
in Carissa's native soil?  It sounded as if it was desert, but desert soils
are generally of a very high pH, often over 8.0, so I'm confused.  I would
expect the pH to be low, perhaps 5.5.  That would explain why they show
such iron/zinc/manganese deficiency in our alkaline California soil.  But a
pH of 5.5 would indicate high rainfall, probably 40in or 100 cm/year. Any
info from SA would be greatly appreciated.
        Other uninteresting things I learned:
        I researched the 1972 frost, the last great freeze prior to Dec.
'90.   Chris Pattillo, who was then a grad student at Cal and is now (or at
least was the last time I spoke with her) a landscape architect in Oakland,
did a report on that freeze.  She reported the low on campus that Dec as 25
degrees.  She also reported that Carissa's suffered 'severe' damage or
total death.  {At the UC Botanic Garden where the '72 low was 14 degrees
all Carissa's were killed.}

        One last note:  I said I'd find a Chorizia and report on its fate.
I now know where there is one--at the Ruth Bancroft Garden in Walnut Creek,
east and inland from the San Francisco Bay--but I haven't had time to get
over there to take a look.  I will report.
Jerry Heverly, Oakland, CA
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