[NAFEX] Fw: Pear Rust

Kieran &/or Donna holycow at frontiernet.net
Fri Jun 5 13:17:12 EDT 2009


Jim,
    It seems no one else has any thoughts on this subject.  So here is what 
I do know about it.  You may be looking at any of several rusts and only 
think it is PCR.  CAR grows for a year on cedars which have to be 
re-infected annually to keep the disease going.  There are two others I 
haven't sorted out yet, one makes the same sort of balls on cedars but 
smaller.  The other, which I think is quince rust, makes lesions on cedar 
trunks and branches.  This one lasts for years on cedars and can cause 
serious damage to the cedar.  (oops, translate juniper)  I had never noticed 
it before but after last year's severe rust on a chestnut crab I discovered 
that simply selecting CAR resistant apples is not sufficient.  There are so 
many species of this sort of cedar- rose family rust that apples, pears, 
hawthorns, quince and juneberries all need to be taken into account as well 
as the juniper host plants.  Most of the infection is on the haw, quince and 
juneberry fruits, if you are inspecting them.  You'll have to look up 
specific symptoms for each to sort them out.  On the cedars, wait for rainy 
damp weather and inspect for infection.  Cut out the little balls and 
consider removing at least the worst infected trees.  The bad one is the 
quince (I think) rust on the cedar trunks.  I found one small tree with a 
little bitty new infection.  A section of trunk about the diameter and 
length of my finger was sprouting little orange dots.  then I found a tree 
with a 2" dbh trunk that had a lesion as long as my arm down the trunk 
oozing great wads of orange goo.  THEN I found a 6" dbh tree in the woods 
with orange goo oozing at the base of the trunk.  At least it was low to the 
ground and pretty far from any of my fruit trees.
    You see how serious this problem can be, which is why we are advised to 
eliminate all cedars from our property if we want go grow fruit.  For me, 
that is impossible.  Not only would my husband object VERY strenously, but 
there are large junipers right on the edge of the neighboring property that 
plainly can drop any spores they like right down on some of my trees.  Plus 
junipers are a major part of our winter landscape and pleasure that time of 
year.  So while I was researching the subject with mounting horror last 
winter, I discovered that tangled up in my search results were lists of 
resistant junipers.  Most of the ones tested are older vars that are no 
longer trendy in the nursery trade and hard to find.  I was lucky that I 
called an old TTU prof about the 3 clones of cedars on Tech property and he 
told me they were Keetleri (resistant) and Canerti (infested, as was plain 
to see).  The lovely new clone Gray Owl has proved resistant.  And it seems 
that junipers are really easy to graft, and different species graft just 
fine on our native trees.  So though I was late getting started, it appears 
I got over 50% takes and learned that the recommended veneer graft is indeed 
the best way to graft junipers.  I hope to "collect the whole set" by next 
Feb even if it requires a trip over the mtns to the Raulston Arboretum where 
many the fine juniper clones collected by Raulston are on display. (Oh, I 
can just imagine how much suffering such a trip will cause, a terrible rash 
of tree envy that will only be mildly assuaged by  much more planting and 
grafting.)
    My idea is to veneer graft near the base of reasonably small cedars on 
the property, say 2" or 3" at the base.  I'm thinking about spiraling grafts 
up the trunk on some of the larger trees.  After a year or so I can start 
removing the existing tops and with time the larger ungrafted trees. 
Instead of impoverishing our winter landscape, I can enhance it with colors 
and shapes that citified landscape freaks would die for.  And all very 
cheaply.
    Any of you who think I am silly, make yourself a note to look for newer 
plantings of a beautiful low cedar that is brilliant blue gray.  And start 
looking more closely at junipers in your area this winter.  There is so much 
variation in form, it's quite interesting.  When I went to cut some branches 
on the 40 year old Keetleri trees at Tech, the more I looked the more I felt 
terrible for cutting anything off at all.  Every branch, every branchlet 
looked like a whole series of bonsai trees.  They were indescribably 
beautiful.  Fractals, phi ratios, Fibonacci series.....  I was utterly 
smitten.  They look very nice from a distance too.   Donna 




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